Commercial Rockets

— introduction —   [Hide] 

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I feel like running down the list of rockets available for orbital launch services, to see where we stand. I started on this at an exciting time: 2017 was a year when a whole lot of cool changes were coming along but hadn’t quite arrived yet, and that’s still the situation now. These included the return of the USA to manned spaceflight, the overtaking of traditional government-contractor launch companies by private startups, the construction of manned craft capable of flight beyond the moon, boosters of a larger size than have been used for decades, a booming market for very small launchers, and most of all, we hope, a dramatic lowering of launch costs through reuse of vehicles. This page is updated from time to time as progress is made on these goals. As of 2021, only the first of these exciting innovations can be fully checked off as done.

In 2017, only three surviving rocket families on this list had ever carried humans to orbit: R-7/Soyuz (hundreds), Atlas (four in the old days, with more coming soon), and Long March 2 (fourteen at that time). 2020 added the Falcon 9 to that list, and the next year it even started taking tourists to orbit. But that list could double in the next few years, with the Vulcan, the New Glenn, the Starship, and even India’s GSLV III all preparing to carry passengers, plus the Russian and Chinese space agencies both working on new spacecraft, without yet having specified the rockets to go under them.

Let’s begin with the old-line aerospace contractors and then move on to the new startups. Originally, I listed here only orbital rockets which are in active use today, or should be soon, with flights available to commercial buyers on the open market. Later, I added some governmental rockets which are not yet commercialized (of which there are surprisingly few), but they are hidden by default. I put some emphasis on rockets capable of launching crewed missions. These are generally medium or large sized rockets: of necessity much bigger than a smallsat launcher, but usually much smaller than, say, a Saturn V. There are small rockets of interest too, such as the Electron and the Astra; these are hidden by default, so to see them you must check the “Light” chechbox in the filters below.

The Russians (working with the Ukrainians in some cases) have some rockets which have not flown for a decade, but are not officially retired: the Tsyklon and the Volna. I omit these. The START was on that list but recently has been called back into service. The Tsyklon may be brought back by a Canadian venture. The Dnipr [or Dnepr or Dnieper] is officially retired, but the Russians are talking about bringing back under a new name, Baikal. This makes sense politically if not technically, because Dnipr is Ukrainian and for obvious reasons they are no longer on good terms with Russia. The Rokot [or Rockot] retired in 2019 for the same reason, but plans are afoot to bring back an updated version. For the others I will wait until there is solid evidence that something is going to fly. For rockets which have had major announcements but still exist only on paper, like the Irtysh [or Soyuz-5], Yenisei, and Amur, I have incorporated descriptions of their stated plans into articles on the earlier rockets to which they would act as successors, the Zenit and the Angara.

I skim briefly over several rockets developed in minor spacefaring nations which are not yet to the point of commercialization. The rockets of North Korea and Iran share a common article, as they share common designs. Minor efforts from Argentina, Brazil, and Turkey are described only as asides in other articles. I skip some small aerospace startups whose ambitions for orbital flight are still many years off, of which there are many. Once an entry is written, I’ll leave it in place if it gets retired.

I had originally expected to be listing lots of “new space” ventures, and was disappointed to learn how few of them have yet shown any signs of being competitive. But the number of such entries continues to gradually increase, though you won’t see most of them if you leave light rockets unselected. This list might look a lot different five years from now. But a lot of these new companies are likely to go bust; the road to space is already dotted with the wrecks of several ventures which have discovered firsthand how difficult rocketry really is. For instance, the exciting startup XCOR went broke shortly before the time I started writing this, and John Carmack’s Armadillo Areospace ran out of gas a year earlier (but a remnant is still active under the name Exos). Firefly also went bust but then revived, and now has an entry; we’ll see if it lasts. Apparently they absorbed another marginal startup, General Astronautics. The once very promising Vector Launch became another casualty in 2019. We’ve even had a startup failure in China, it looks like, with LandSpace, who actually launched a flight that just missed orbit, before running out of credit or something — the issues have not been made public. But they are apparently now coming back, abandoning their nearly-successful solid rocket and starting on a liquid one.

Rocketry can be a sucker’s game: there are few feats so simple on paper yet so difficult in practice as spaceflight. Those who have taken these lessons to heart have a saying: “In rocketry, you have to spend a billion to make a million.” And it can be a sucker’s game for backers too: it’s easy for entrepreneurs to talk a big game without actually managing to get any hardware up into the sky. I won’t speculate on how many new-space ventures might be outright scams.

(I once met a guy who was a founding partner in a rocket company. They had patented a “revolutionary” new type of engine. They were convinced that they could build something tiny that could reach orbit. In hindsight it was obvious that they had zero chance of success, but these highly intelligent people had allowed themselves to become converted into true believers despite the very clear obstacles in front of them... which may have included a fallacy in their basic math — I’m not sure. It was that experience, and trying to understand their patent, which eventually led to creating this page.)

I have included two examples of dubious companies’ promised rockets: the Haas by ARCA and the Neptune by Interorbital Systems, not because they have earned a legitimate place on this list but just because they bring up interesting topics. The Bloostar by Zero 2 Infinity might be another such case. All of these are in the “Light” category not shown by default. And maybe the Reaction Engines Skylon concept is also in that dubious-but-interesting group.

Some companies and rocket proposals not yet included here are Aevum (Ravn-X), ASRI (Ausroc), Dawn (Aurora), Earth to Sky, Equatorial (Volanis), Exos/Armadillo, Generation Orbit, Gilmour (Eris), Green Launch, Independence-X (DNLV), Interstellar Technologies (MOMO), Isar, Leaf Space (Primo), Lin (Taimyr), Lingkong Tianxing a.k.a. Space Transportation, Maritime (Tsyklon revival), Microcosm (Sprite), OHB’s Rocket Factory Augsburg (RFA 1), Pipeline 2 Space, Pythom, Rocket Crafters (Intrepid), Skyrora (Skylark), SpaceDarts, Space Engine Systems, SpaceLS (Prometheus), SpinLaunch, Stofiel (Boreas), VSAT, Wagner, and X-Bow. Most of these would also be in the “Light” category, aiming for the smallsat market. There are plenty more which are so obscure I know nothing about them yet. A few of them are briefly described in passing within other articles.

The SpaceFund Reality Index is one way to track minor companies and see which are emerging into serious status, but unsurprisingly, their coverage of companies in Asia can be spotty. The manager of that index, Megan M. Crawford, expects most of these ventures to fail, and further argues that they are all overestimating the size of the small launch market.

Around 2020, a new trend began: small rocket companies starting to emerge without warning, announcing that they are just months away from their maiden orbital launch when we’d previously heard nothing from them. Astra, the most secretive American company, was only the first to follow this pattern. When the Ceres-1 and Nebula 1 from China, the Blue Whale from South Korea, and the Hapith from Taiwan announced upcoming launch dates, I had never heard of any of them beforehand. This combination of surprise and urgency made it difficult to separate the serious contenders from the long shots. I may have been suckered into adding articles for some which are just hype and hope.

Some companies which have successfully gained entries from the list above are the then-secretive Astra in California, Relativity Space (Terran) also in California, Britain’s Orbex (Prime), China’s LinkSpace (New Line) and Deep Blue (Nebula), Taiwan’s TiSPACE (Hapith), and South Korea’s Perigee (Blue Whale). Some of the later names on that list may not be all that well qualified; I may have fallen for hype. We shall see. All of these hope to compete with the Electron in the low budget microsat market, but none have yet managed to do so.

Since this page was first published in 2017, only three interesting rockets have gone from hyped promises to actual orbital service: the Electron, the Falcon Heavy, and the LauncherOne. (The Astra rocket is almost there; they reached orbit, but did not deploy a real satellite as it was just a test flight. Many Chinese solid fuel models derived from military boosters have also had maiden flight attempts, three of them successfully.) There are plenty who hope to join that list within the next year or so, most immediately the Astra and the Firefly Alpha. Yet despite the supposed glut of innovative small launch services that will supposedly soon be upon us, in 2021 the Electron still stands largely alone — the LauncherOne is in theory now ready to compete equally with it, but we are still waiting to see them develop a regular cadence.

We will order the list by age, with the oldest surviving rocket families first.

— stats and specs explained —   [Show] 

— the space race era, 1957–1976 —   [Hide] 

This section includes the most storied and legendary names still in service... or to put it another way, the dinosaurs: the Soyuz and Proton from Russia, the Atlas and Delta from America, and the Long March 2, 3, and 4 from China. Every rocket in this group has a replacement model coming in the next several years, though there might be no hurry about retiring the oldsters in some cases, particularly in China. In other cases, the cutoff date is quite near.

R-7 / SOYUZ (Союз) — Russia, 1957

Most of the older orbital rockets originally started out as designs for intercontinential ballistic missiles. The R-7 is no exception. In fact, it was the daddy, the original ICBM — the first rocket in the world able to throw a heavy payload to a target 8000 miles away. In that role it was known as the Semyorka (Семёрка). It wasn’t long before they made bombs able to be ICBMed on significantly smaller rockets, making the R-7 obsolete for that role, so they improved it and used it to launch Sputnik. Then they improved it some more and launched Yuri Gagarin on it. Its creator, the legendary Sergei P. Korolev (Королёв), had this in mind all along; he designed it so that the military goals would end up also supporting space exploration. For this reason, he is called the father of spaceflight.

The R-7 has been evolving and improving ever since, and has done more orbital launches than any other rocket family, both manned and unmanned (though the Shuttle has launched more people, thanks to its larger seating capacity). Today, as the Soyuz FG and Soyuz 2 (taking on the name of the crew capsule it is famous for carrying), it had a nine year run as the only rocket able to transport astronauts to the International Space Station, until the Dragon 2 and Starliner capsules were ready. The Soyuz 2 is distinguished from its predecessors mainly by the fact that they’ve finally thrown out the analog automation circuitry and put in some modern control logic. The FG, which used the old analog system, was used for all crewed flights until 2019, when the 2.1a finally took over. The old system is so crude that the rocket’s target orbital inclination could only be set by rotating the entire launch pad on a giant turntable. It has been known to do things like ignite the upper stage while the rocket is still on the ground, half an hour after an aborted launch. Don’t laugh too hard at the FG, though: until its highly publicized launch abort in 2018, it had never failed, and the abort system worked perfectly to save the passengers.

The bottom stage is wrapped with four liquid-fueled side boosters which drop away — a so-called “stage and a half” design. They actually referred to the core part as the second stage — it’s as if the upper stage just had a long thin tube extending downward between the boosters, which are considered the true first stage. The reason they approached it this way is because in those early days, they wanted to avoid the problem of making sure that the upper stage could ignite in midflight. They did not add a proper upper stage above the core until developing the “Vostok” version which launched Gagarin, though the “Luna”, which launched the first lunar probe and got the first look at the far side, had a tiny one. Since then, the R-7 family went through a number of evolutions before finally becoming the Soyuz, some being called the Molniya (Молния), the Polyot (Полёт), and the Vozhkod (Восход).

Each side booster has four nozzles, plus two mini-sized ones on the outer edge for steering, all being part of a single engine. It’s called the RD-107A and was originally made by Kuznetsov (Кузнецова), but they went bust and the factory is now run by NPO Energomash (НПО Энергомаш). Their main business is equipment for power plants, but their V.P. Glushko division makes the engines of a large share of the world’s active rockets, though that share is now decreasing. The RD-107A’s turbine pumps are powered by a separate tank of peroxide, as in the ancestral V-2 engine built by the Nazis. The fuel is refined kerosene (or in recent years, a synthetic substitute), combined with liquid oxygen. The central booster’s engine, called the RD-108A, is the same except it has four minis stuck in the corners instead of two. The mini nozzles each pivot on only one axis, so they have to work in pairs. That’s a total of 32 rocket nozzles ignited at launch... a task which is accomplished by simply sticking a giant wooden match up each one before starting the fuel pumps. Recently they have worked on using a more modern igniter, but when or if this new ignition system is coming into use is not clear. Why does each engine have four main nozzles? Because they hadn’t yet gotten the hang of controlling destructive oscillations in a single large one.

The side boosters taper toward the top, giving the lower part of the rocket a conical outline. The Russian engineers nickname them “markovkas” (carrots). When they peel away at high altitude, they make a pattern in the sky which is called the “Korolev Cross”. That tapered profile is rarely used by anyone other than the Russians, despite some advantages such as lower coefficient of drag. The main disadvantage to a conical shape is probably less tank capacity for its weight.

Traditionally, up through the Soyuz 2.1a, the second stage uses an RD-0110 engine, which is a quad nozzle design like the main stage’s RD-108, but smaller and with a preburner instead of peroxide to power the turbine. But in the 2.1b this was replaced with the RD-0124, which looks similar but uses a fully modern staged-combustion cycle for substantially higher specific impulse, and gimbals as a unit so it does not need separate vernier nozzles. This improved engine raised the total payload capacity by fifteen percent. (The new Angara rocket uses a version of this same upper stage engine, and the Irtysh might use another version.) A third stage is optional, and typically one of the “Fregat” (Frigate) line, which burns hypergolic fuel.

Historically, Soyuz launches have been quite inexpensive, but lately there have been some sharp increases. Some are muttering about price gouging, but it’s probably due mostly to a rise in the value of the ruble, plus a stiff increase in insurance costs as the Russian space program in general has become less reliable, and several troubling incidents occurred for the Soyuz in particular.

There have been some efforts to update the Soyuz line. So far, the one concrete result of this effort is the Soyuz 2.1v, a light-duty version which omits the four side boosters and uses a tiny “Volga” upper stage. It has a new version of the core stage which uses a modern engine — the RD-193, which is more efficient and has more thrust than the old RD-108A, and has only one bell. It’s a variant of the RD-191 used by the Angara. Except not yet, because early iterations of the 2.1v are instead using refurbished old Kuznetsov NK-33 engines, which are relics of the failed Soviet moon rocket program. This pseudo-Soyuz has launched only a few times, and at one time it looked like it would gradually grow into a new Soyuz 3 which would replace the whole line, but now that’s looking unlikely. Now it’s apparently just a backup for the Rokot, which was having production difficulty.

The makers of the R-7 family, RKTs Progress, are now proposing an all-new rocket that they call the Soyuz 5, which is entirely unrelated to the R-7 legacy design. It would be a very simple two-stage with no side boosters, with one nozzle on each stage, burning liquid methane instead of kerosene. Later they could expand its capacity by adding extra first stage cores on the sides, but for now they’re keeping it basic. By using a simple design and modern fuel, they’re hoping to come up with something that competes fairly well on cost with the Falcon 9, and will be cheaper as a replacement for the Soyuz 2 than any iterative evolution of the old design could be.

But now it sounds like this methane-fueled plan is scrapped, and the new Soyuz replacement will instead be based on the Zenit, the powerful kerosene-burner which started out as a side booster on the huge Energia, and may return to that role at some indefinite future time when Russia re-enters the heavy lift market. See the Zenit section. Apparently this Zenit replacement will end up using the Soyuz 5 name, which would be odd. This may be why RKTs Progress is floating a Soyuz 7 proposal, which looks like a revival of the methane-fueled Soyuz 5 idea under a different name. It appears that Putin has already personally chosen the Zenit-based approach as the way forward, so I doubt the methane Soyuz will ever fly. Not only is the Zenit proven technology, it also has fifty percent more capacity than the Soyuz. The Angara, which is supposed to replace the Proton, is better suited to lighter payloads than any Zenit would be.

But hold on — since Russia obviously needs to go reusable, and come up with an answer to the Falcon 9, Roscosmos announced in 2020 that they would be building something called the Amur for that job, and it would be a methane burner of about the right size to replace Soyuz. But there is no clear heritage from the Soyuz 5 proposal to that, as it’s a very different design concept. See the Angara section for more details on the Amur proposal.

Soyuz-2.1b: mass 312 t, diam 2.95 m (10.3 m at base), thrust 4150 kN, imp 3.14 km/s, type Mk, payload 8.2 t (2.6%), cost $12M/t?, record 190/1/6 (59 crewed) for “2” and “FG” only (overall success record for previous orbital versions is somewhere in the ballpark of 1586/0/100).
Stage name Block B,V,D,G (≤2.1b) Block A (≤2.1b) Block A (2.1v) Block I (≤2.1a) Block I (2.1b,v) Fregat-M Fregat-MT Volga
Role (pos) count booster (S) ×4 core (1) core (1) upper (2) upper (2) kick (3), opt kick (3), opt kick (3), opt
Diameter (m)   2.68   2.95   2.95   2.66   2.66   3.35   3.80   3.20
Liftoff mass (t) 44.4 99.5 129.0  27.8 27.8  6.6  8.2  1.7
Empty mass (t)  3.8  6.6 10.0  2.4  2.4  1.0  1.1  0.8
Fuel mass (t) 11.3 26.3 ~31     7.6  7.6 ~1.9 ~2.4 ~0.3
Oxidizer mass (t) 27.9 63.8 ~88    17.8 17.8 ~3.7 ~4.7 ~0.6
Fuel type kerosene kerosene kerosene kerosene kerosene UDMH UDMH UDMH
Engine Energomash
NK-33A *
or RD-193
S5.92 l-n
S5.92 l-n
Power cycle peroxide (M) * peroxide (M) * staged (ZO) gas gen staged (ZO) gas gen gas gen ?
Chamber pres. (bar) 61   60   148    68   157    96   96  
Ox./fuel ratio   2.47   2.47   2.80   2.20   2.60   2.00   2.00   2.0?
Thrust, vac max (kN) 1020     920    1680     298    294    19.9 19.9  2.9
Thrust, SL initial (kN) 840    790    1510    
Spec. imp, vac (km/s)   3.14   3.14   3.25   3.20   3.52   3.27   3.27   3.01
Total imp, vac (t·km/s) 123    283    385    80.5 ~89    21.7 23.2  2.7

ATLAS — USA, 1957

This rather large rocket was also first developed as a long range ICBM, and was also quickly obsoleted from that role as smaller rockets became capable enough. It went on to far more positive uses: it has not only launched plenty of satellites, but it’s sent up manned missions as well during the Mercury program, and launched early interplanetary probes such as Surveyor and Mariner. Today’s version has a somewhat distinctive look due to its bottom end, which has two combustion chambers and two nozzles on a single engine, plus plumbing that bulges out of the rocket’s side. (This double-nozzle design was something once associated with the Titan booster, which was used for the Gemini program and for many historic interplanetary probes. Titan dwarfed the early Atlases but has been left behind by the V. It was discontinued in 2005.)

The fuel is kerosene, or “RP-1” as it’s officially called when refined for rocketry, combined of course with liquid oxygen, which is called “lox” for short. But embarrassingly, the engines used in the current Atlas versions are the Energomash RD-180, and NPO Energomash is majority owned by the Russian government, and furthermore the import company appears to be skimming millions of dollars per engine, which may be going directly to Putin. Naturally, there has been a lot of pressure to find an alternative motor. But no American engine builder has anything handy that can work as a replacement, and at this point, the plan is to just replace the Atlas with a new rocket: the Vulcan.

The original Atlas versions had a single nozzle in the middle, but also had two additional nozzles attached on the side, as small protruding bulges. They were not separate boosters, but extra engines which drew fuel from the main tank, and then dropped off once their additional thrust was no longer needed. Without the extra thrust, it was incapable of liftoff. It also had small vernier thrusters for steering, and unusually, they were mounted up on the sides rather than at the base. The booster’s steel tanks were incapable of supporting their own weight unless pressurized, even when empty. (It’s more common for rockets to require some pressure when full.) This unusual construction made the rocket so lightweight that it could take some satellites to orbit with no upper stage. Mercury capsules were launched this way, in fact... and at the time John Glenn rode one into orbit, the rocket’s failure rate was around fifty percent. They stopped using this “balloon tank” construction in the Atlas V, after having already switched to the RD-180 engine in the Atlas III. One legacy of this design is that today’s Atlas boosters still go to unusual heights and speeds before the second stage has to do any work.

Nowadays, lift can be enhanced for larger payloads by strapping small solid-fuel boosters onto the sides. But because the original rocket wasn’t designed for this, these strap-ons end up placed in odd and asymmetrical ways. They’ve never bothered to re-engineer the first stage’s exterior to correct this, even though the Atlas V is 25% bigger in diameter than earlier models. For most of the rocket’s life these boosters were made by Aerojet Rocketdyne, but ULA recently replaced them with Northrup Grumman’s new “GEM 63” model (developed by Orbital ATK before their merger), which is more powerful and way cheaper. This will pretty much leave Northrop with a monopoly on large solid rockets in the USA.

There’s a choice of “Centaur III” second stages: a classic single-engine model, and a high thrust one with two engines, which is rarely used... it had actually gone unused for many years until they brought it back for launching the Starliner crew capsule in 2020. The Centaur burns liquid hydrogen rather than kerosene, and ignites it electrically so it can start and stop as many times as needed. (Regardless of whether the igniter is chemical or electrical, it is actually quite challenging to ignite a cryogenic-fuel rocket engine in a vacuum, and to this day a lot of rockets have second stages which cannot re-ignite after their initial burn.) Hydrogen has higher efficiency but lower thrust, so it’s not uncommon to see it used on upper stages while using kerosene on the lower one... but the Centaur was the O.G., the first liquid hydrogen orbital rocket stage. It still uses balloon tanks, with the steel being just half a millimeter thick under the insulation. The difference of fuels does largely prevent the lower and upper stages from being able to share any parts. Its RL10 engine uses an expander cycle. The single-engine Centaur’s thrust is quite low at just 99 kilonewtons, only enough for about a third of a G with full tanks and a large payload. This is one reason why the first stage has to go high and fast.

In many ways the Atlas seems archaic and clumsy, but United Launch Alliance (handed down from Lockheed Martin, who took over from General Dynamics, who got it from Convair) managed to continue selling it by keeping the costs reasonable. They’ve even managed to cut prices in response to the competition from SpaceX. As mentioned, they now see the writing on the wall, and are trying to get their replacement ready in the next few years. But don’t laugh at the old-timer: the Atlas V has flown dozens of launches without ever losing a single payload — a record that no other rocket can match. We shall see if the Vulcan does likewise. (Other rockets have had longer runs of consecutive successful launches, after initial failures. For instance, Ariane V is now on a longer run that the Atlas V, with each streak having a single blemish where a satellite reached a mildly incorrect orbit which forced it to expend onboard fuel. Delta II had an even better run with 100 consecutive successes, ending with retirement, and the Falcon 9 also has a long streak going. But only Atlas V includes its very first launch in such a streak.)

What they have lost instead is any excuse to continue buying Russian engines. Congress has been trying for fifteen years to pass laws and policies which would end our dependence on imported engines for national security access to space, and Lockheed and ULA and Aerojet Rocketdyne have repeatedly evaded or simply ignored this mandate. For instance, when told to develop a US-built copy of the RD-180, Aerojet Rocketdyne accepted fat checks for years to spend on the effort, then announced that they didn’t feel like finishing the job. Getting away with that takes some hard-core cronyism.

Now that there is finally a firm schedule in place to move on from the Atlas V and stop buying RD-180 engines, Russia is hoping that some rocket maker in China will buy them. Since no current Chinese engine is even half as powerful, they may find one. They are aware that this may just lead to Chinese copies of the engine being made, but figure that selling some beats selling none. And meanwhile, Aerojet Rocketdyne eventually did finish their replacement, and now they’ve got no customer for it, except one startup named Firefly which has yet to get anything off the ground, but says that when they do, they want to use this engine for the bigger followup rocket they’ll make if the first one is successful.

The Atlas V model has never carried a human being, but the plan is that it will do so in its final year or two if the Starliner capsule can qualify soon, and that’s good, because despite the problematic politics of its construction, the V might well be the safest rocket a person could ride on.

Atlas V 401 (no extra boosters): mass 334 t, diam 3.8 m, thrust 3827 kN, imp 3.3 km/s, type ZOk(+S), payload 9.8 t (2.9%) [18.5 t (3.2%) with 5 boosters], cost $11M/t, record 89/0/0!
Stage name AJ-60A Atlas CCB Centaur
Role (pos) count booster (S) ×0-5 core (1) upper (2)
Diameter (m)   1.58   3.81   3.05
Liftoff mass (t) 46.7 305.1  23.1
Empty mass (t)  2.2 21.1    2.2 *
Fuel mass (t) ~13    ~76.3  ~3.0
Oxidizer mass (t) ~30    ~208     ~17.7 
Fuel type HTPB kerosene hydrogen
Engine Aerojet-Rocketdyne
RL-10C ×1-2
Power cycle solid staged (ZO) expander (EC)
Chamber pres. (bar) 267    24  
Ox./fuel ratio   2.3?   2.72   5.88
Thrust, vac max (kN) 1690     4152      106.3 *
Thrust, SL initial (kN) ~1110      3827    
Spec. imp, vac (km/s)   2.74   3.31   4.41
Total imp, vac (t·km/s) 117    943    ~91   

DELTA — USA, 1960

The Delta started as a three-stage variation of the Thor midrange ICBM made by Douglas Aircraft, and launched some of America’s first satellites, such as Echo 1A on its maiden flight, and Telstar soon after. The original Thor variants could barely eke the tiniest of payloads into the lowest of orbits, as the upper stages were so skinny that the rocket looked like an electric toothbrush... but they quickly improved its capabilities. It launched many satellites until 1981, when it was retired in favor of the space shuttle. But the shuttle’s expense brought it back as the larger Delta II in 1989. The II was made by McDonnell-Douglas, who were then assimilated by Boeing. They have now phased it out, with the final launch occurring in 2018. It does have a respectable history, having sent quite a few probes to distant destinations such as Mars and the asteroid belt.

The II used a single Aerojet Rocketdyne RS-27A kerosene engine, which has no gimballing and has to rely on small vernier engines for steering, just as were used in the original Thor. It used a hypergolic second stage, as the Thor-Delta did — in fact, the name “Delta” originally referred to the second stage only. The optional third stage for high orbits or interplanetary missions was solid fueled for some reason — again, like the Thor-Delta. At least three strap-on solid boosters (made by Thiokol and then by Orbital ATK) were necessary for the rocket to get off the ground, and they can cram up to nine of them around the first stage. These boosters were upgraded a couple of times. But even using all nine boosters only got its payload capacity up to six tons, and on one occasion in 1997 when they wedged all nine on there, one of them exploded the whole rocket, raining fiery debris on employees’ cars. But since then, it flew for its remaining 21 years without a single failure.

The Delta IV is a far bigger rocket. It retains little of the old design. It has a single large gimballed nozzle for the first stage. The first stage fuel is now liquid hydrogen instead of kerosene — a fuel which gives the best possible specific impulse, but as a tradeoff needs an enormous oversized tank which has to be super carefully made, because hydrogen not only has very low density, it will leak through leaks which don’t count as a leak to any other substance. The RS-68A engine, built by Aerojet Rocketdyne, is expensive and not the least bit reusable, as it has an ablatively cooled nozzle. This motor is basically an enlarged and cheapened-down version of the Space Shuttle Main Engine. Despite the many corners that it cuts, it remains one of the least cost-competitive large motors in the business. The second stage also burns hydrogen.

They make a version of the Delta IV with a triple first stage for the heftiest payloads, which is known as “Delta IV Heavy”. This has been used for a test flight of the new Orion space capsule being developed for NASA. For loads larger than the basic payload but smaller than the triple booster’s capacity, they can strap two or four solid rockets onto the sides of the first stage. Depending on the payload and on how high an orbit you need, it can be put together with either two or three stages, and the second stage has narrow (4 meter) and wide (5 meter) variants, the former being older. ULA liked to boast that the Heavy was the most powerful rocket available, but if so, the margin over some competitors such as the Long March 5 was thin... now, of course, the Falcon Heavy has left it far behind, and other new rockets are coming along which are going to be even more powerful: the SLS, the New Glenn, the Starship, and eventually the Long March 9 and the Yenisei if those get built.

Delta and Atlas were each other’s main competitors for governmental launches since 1960. Finally, Lockheed and Boeing got tired of competing with each other, and in 2006 formed a consortium called United Launch Alliance which sells both Deltas and Atlases. Though blatantly anticompetitive, the government decided to permit this because it helped rein in the spiralling costs of both rockets. Some parts can now be shared between them. (Both already used very similar motors in the second stage: variants of the Aerojet Rocketdyne RL10, originally made by Pratt & Whitney. When used on the Delta, this engine has a telescoping nozzle to keep it compact before stage separation.) For a while, this sharing arrangement led to the US government giving ULA a monopoly on military launches, but this was opened up in 2015 by SpaceX. (They had tried suing in 2005, but until their own system was mature this did no good). ULA hopes to retire the entire Delta line in a few more years, in favor of the Vulcan.

You may wonder what happened to the Delta III. Well, while the II has a run of 100 successful launches over the last twenty years, and the IV has never failed except for a too-low orbit on the first test flight of the Heavy with a dummy payload, the III failed on its first three flights, with a different problem each time, and was retired without orbiting a single satellite (though Boeing claimed that one flight counted as a success). The one piece of it still in use is the hydrogen burning second stage with the telescoping bell, which was carried forward to the IV. This is why the diameter did not match the IV’s booster at first... when they wanted more from it, widening the diameter to match was an easy way to get there. That bigger version will in turn be handed down for use by early versions of the SLS, where it will again be undersized for its booster, and be replaced later with something full-sized.

The III was a goofy-looking rocket. The bottom end was like the Delta II, with the same engine and the same 2.44 meter LOX tank, this diameter having been inherited from the original Thor. But the kerosene tank above it was 4 meters wide, like the upper stage, overhanging the nine solid boosters (all nine were mandatory). They did this to avoid making the III taller than the II. Little good that did them... in the IV, the first stage alone was as tall as the entire II or III. By replacing the first stage, the IV eliminated the last remnant of the Thor heritage.

Delta II 7320 (three added boosters): mass 152 t diam 2.44 m, thrust 2225 kN, imp 3.0 km/s, type Gk+S, payload 2.8 t (1.6%), cost $20M/t, record 153/0/2 (final).
Stage name GEM-40 Thor/Delta XLT Delta K PAM-D
Role (pos) count booster (S) ×3|4|9 core (1) upper (2) kick (3), opt
Diameter (m)   1.02   2.44   2.44   1.25
Liftoff mass (t) 13.2 104.4   6.9  2.1
Empty mass (t)  1.4  8.8  1.0  0.1
Fuel mass (t) ~3.5 ~29.4  ~2.0 ~0.6
Oxidizer mass (t) ~8.3 ~66.2  ~3.9 ~1.4
Fuel type HTPB kerosene UDMH+hydrazine HTPB
Engine GEM-40 RS-27A AJ10 Star 48B
Power cycle solid gas gen pressure-fed solid
Chamber pres. (bar) 48   ~40   
Ox./fuel ratio   2.3?   2.25   1.90   2.3?
Thrust, vac max (kN) 640    1090     44   66  
Thrust, SL initial (kN) 420    890   
Spec. imp, vac (km/s)   2.69   2.96   3.13   2.80
Total imp, vac (t·km/s) 32.7 283    18.9  5.8
Delta IV Medium (narrow second stage, no extra boosters): mass 257 t, diam 5 m, thrust 3140 kN, imp 4.0 km/s, type Gh(+S), payload 9.4 t (3.7%) [14.1 t (3.5%) with 4 boosters], cost $17M/t, record 30/0/0 (final).
Delta IV Heavy: mass 732 t, diam 5 m (15 m wide), thrust 9420 kN, imp 4.0 km/s, type Gh, payload 28.8 t (3.9%), cost $12M/t, record 12/1/0.
[Show stages] (all Delta IV versions)
Stage name GEM-60 CBC DCSS 4m DCSS 5m
Role (pos) count booster (S) ×0|2|4 core (1|S) ×1|3 upper (2) upper (2)
Diameter (m)   1.52   5.09   3.99   5.09
Liftoff mass (t) 33.8 226.4  24.2 30.7
Empty mass (t)  8.2 26.8  3.7  3.5
Fuel mass (t) ~9   29.5 ~3.0 ~4.0
Oxidizer mass (t) ~21    172.5  ~17.5  ~23.2 
Fuel type HTPB hydrogen hydrogen hydrogen
Engine GEM-60 RS-68A RL-10B-2-1 RL-10B-2-1
Power cycle solid gas gen expander (EC) expander (EC)
Chamber pres. (bar) 90   103    44   44  
Ox./fuel ratio   2.3?   5.97   5.88   5.88
Thrust, vac max (kN) 1370?    3560     110.1  110.1 
Thrust, SL initial (kN) 1155     3137    
Spec. imp, vac (km/s)   2.70   4.04   4.56   4.56
Total imp, vac (t·km/s) 79.8 811    93.4 124.1 

PROTON (Протон) — Russia, 1965

Like other rockets of the era, this was originally built for use as an ICBM. This one in particular was designed to hurl hydrogen bombs of titanic size. It was never deployed in that role. This was a big-ass rocket for the time, comparable in grunt to today’s Delta IV Heavy. But the thing is surprisingly compact for the amount of muscle it has. It launched the Salyut and Mir space stations, and some modules of the International Space Station. When used for satellites, they often load a dozen or more into one flight, distributing them around to various orbits. They were quite secretive about the rocket in the early days, allowing no pictures of the bottom stage.

Unlike the Delta or Atlas or even the Soyuz, it uses hypergolic fuels (unsymmetrical dimethylhydrazine and dinitrogen tetroxide, this being the most common of several available hydrazine mixes). As explained in the Stats & Specs section about engine type and fuel codes, “Hypergolic” means they need no igniter, as they immediately combust on contact with each other, but it also means they are very toxic in unburned form and nasty polluters when burned. The principal advantage of hypergolics is that they can be stored for long periods at room temperature, which makes sense for an ICBM.

Like other Russian designs, this rocket widens at the bottom, with six gimballed nozzles mounted in a ring around the central tank. But these do not detach; there is no central nozzle. Each engine is surmounted by an outboard fuel tank, while the central cylinder holds the oxidizer. The reason for this construction was just that they didn’t have any good way of transporting rocket bodies of larger diameter; this allowed the side parts to be bolted on at the launch site. Because of this radial design, the engines (Energomash RD-275M) are notably lopsided when viewed in the open.

The second and third stages are of a conventional cylindrical shape, using the same hypergolic fuel, and enormous by upper stage standards: over 200 tons for the pair. A fourth stage for high orbits or reaching escape velocity is optional, and there are a few choices for which to use. (In the early days, the Proton specialized in interplanetary probes, and the fourth stage was always used. The top stage used kerosene and lox, which made no sense. Nowadays the fourth stage is usually a “Briz-M”, which uses the same fuel as the rest of the rocket.) Unlike the R-7, this rocket has not evolved very much; it’s still much as it was in its early days. And unlike the R-7, it does not manage to pull off the tapered look with elegance and grace; even some who are fans of the rocket will admit that it’s butt-ugly.

The Proton has never done a crewed flight, but it was almost used a couple of times, and at one point was going to send two people on a circumlunar mission. Repeated failures with unmanned vehicles forced them to reconsider. I will note that the great Korolev felt that hypergolic fuels were inherently too unsafe to use on crewed flights... but then, the Proton team was competing for support with his N-1 moon rocket.

In an effort to lower costs, they were designing lightened variants of the rocket, including a version with only four engines instead of six. The first stage would be stretched a bit, and the huge second stage would be eliminated. But they never persuaded anyone to fund this. The head of the Roscosmos agency announced in June of 2018 that Proton production will now be halted so the facilities can start building Angaras instead. Some of the Proton’s workload will probably go in time to the Irtysh, a remake of the Zenit which has been widened to have the same exterior diameter as the Proton (the maximum diameter that can be transported by rail) and be compatible with much of its infrastructure. It seems strange that the light Angara will officially replace the heavy Proton, while the heavy Irtysh will replace the light Soyuz... I guess that’s Russian politics. And it means that during the transition, there might be a period where Russia has no heavy rocket in operation, so the only way to launch a twenty-ton payload will be by combining five Angara boosters, which can’t be cheap.

At present, it appears that the Proton will be retired once its currently booked launch contracts are completed. But that list still has about twenty launches over the next two to three years.

Proton M, three stage: mass 683 t, diam 4.1 m (7.4 at base), thrust 10000 kN, imp 3.1 km/s, type ZOd, payload 21.6 t (3.2%), cost $5M/t, record 375/0/46.
Stage name 8S810KM 8S811KM 8S812KM Blok-DM * Briz-M
Role (pos) count core (1) upper (2) upper (3) kick (4), opt kick (4), opt
Diameter (m)     7.40 *   4.10   4.10   3.70   4.10
Liftoff mass (t) 448    167    50   17.6 19.6
Empty mass (t) 29   11    3.5  2.2  2.4
Fuel mass (t) ~114     ~43.3  ~13.1  ~4.4 ~5.8
Oxidizer mass (t) ~305     ~113     ~33.4  ~11.0  ~11.7 
Fuel type UDMH UDMH UDMH kerosene UDMH
Engine Energomash
RD-275M ×6
RD-0210 ×3,
RD-0211 ×1
Power cycle Staged (ZO) Staged (ZO) Staged (ZO) Staged (ZO) gas gen
Chamber pres. (bar) 165    147    147   78   98  
Ox./fuel ratio   2.67   2.60   2.54   2.48   2.00
Thrust, vac max (kN) 11000      2400     630    83   19.6
Thrust, SL initial (kN) 10100     
Spec. imp, vac (km/s)   3.10   3.21   3.19   3.42   3.20
Total imp, vac (t·km/s) 1325     523    148   53.5 64.2

LONG MARCH (Chángzhēng, 长征) — “classic” models — China, 1970

The Chinese have put many different rocket models under this one name — so many that I’m going to put the newer ones in a separate article. Here we will look at models 1 through 4.

These older Long March rockets burn hypergolic fuel, like the Proton. Model 1 was a rather small rocket — they added a third stage to a ballistic missile (Dōng Fēng 4) and got a capacity of about 0.3 tons to low orbit, with which they launched their first two satellites. They quickly moved on to a more serious rocket, and used the Dong Feng 5 as a starting point. It was originally called the Fēng Bào (风暴), which means Storm, but then got dubbed Long March 2, with the name change coinciding with a move to a new manufacturer. The success record was poor at first but improved with revisions. Model 2A could lift 1.8 tons, 2C could lift 2.4, and 2D (which was lengthened) did 3.1 tons. These use four gimballed engines on the first stage, and one with a large nongimballed bell on the second, with separate little vernier rockets for steering.

Then for the 2E, they added the feature which has been characteristic of China’s heavier rockets ever since: four liquid fueled side boosters with one engine apiece, doubling the thrust and bringing the LEO capacity up to about 9 tons. The smaller 2C and 2D models remain in use to this day, along with the 2F which replaced the 2E.

The Long March 3 is similar to the 2 but with a hydrogen-burning third stage added, while at the same time shortening the second stage relative to the heavy version used in the 2. Again, models 3A, 3B, and 3C all remain in active use. This is used mainly for geosynchronous orbits. The 3C uses two side boosters instead of four; the different models are basically just optimized for different payload weights. The 3B has its own variations: 3B/E and 3B/G, with lengthened first stages and side boosters which made their first appearance in the 2F. There is also a 3C/E using the lengthened stages. I think the short stages are now dropping out of use, except in the lightweight Model 4. This is an upgrade which omits the side boosters and uses small upper stages — the second is even shorter than the one used in the 3, and the third is a small hypergolic one rather than the hydrogen burner. Models 4B and 4C are in use.

All of these rockets essentially form a single modular system, mostly built around a single engine, the YF-20. One in each side booster, four in the core stage, and one with a large bell (plus a small vernier engine) in the second stage. Only the third stages use a different engine.

At times these rockets have had a much poorer reliability record than their American and Russian competition, and have sometimes killed bystanders in downrange areas, yet now they claim a streak of 75 consecutive successful launches, from 1996 to 2009. In 2003 a Long March 2F, now dubbed “Shénjiàn” (神箭, Heaven Arrow — a reference to ancient gunpowder rockets which were commonly attached to arrows), carried China’s first astronaut — er, taikonaut — into orbit. It was a punishing ride because the rocket’s vibration was exceptionally harsh. They’ve managed to reduce it since then. (The 2E was even worse; it was retired after it shook a couple of satellites apart.) Later, a 2F/Shenjian launched a small orbital habitat, and then another was able to rendezvous with it.

China has recently started developing a much more modern range of rockets which burn kerosene and hydrogen — some of them quite large. These continue to use the Long March name but are covered in a separate article in the “modern era” section. Of these, model 7 is the one which retains the classic design while modernizing the propulsion. Model 6 is smaller, and model 5 is larger. But despite the obsolescence of models 2, 3, and 4, all three remain in heavy use, with a combined launch cadence which sometimes exceeds that of SpaceX, let alone Roscosmos.

Long March 2F: mass 464 t, diam 3.3 m (7.8 at base w/o fins), thrust 6500 kN, imp 2.8 km/s, type Gd, payload 8.4 t (1.8%), cost $15M/t?, record 139/4/10 (8 crewed).
Long March 3B/E: mass 459 t, diam 3.3 m (7.8 at base), thrust 5900 kN, imp 2.8 km/s, type Gd, payload 12 t (2.8%), cost $6M/t?, record 128/0/6.
[Show stages] (LM 2 and 3)
Stage name L-45 L-186 L-86 (LM-2) * L-54 (LM-3) H-18 (LM-3) * Yuanzheng
Role (pos) count booster (S) ×2|4 core (1) upper (2) upper (2) kick (3) kick (3|4), opt
Diameter (m)   2.25   3.30   3.30   3.30   3.30
Liftoff mass (t) 48.5 199    91   52   19.2
Empty mass (t)  4.0 13.0  4.8  2.8  0.9
Fuel mass (t) ~14.3  ~60    ~27.1  ~15.5  ~3.0
Oxidizer mass (t) ~30.2  ~126     ~59.1  ~33.7  ~15.3 
Fuel type UDMH UDMH UDMH UDMH hydrogen UDMH
Engine YF-20C YF-21C
(20C ×4)
YF-24E (22E +
23F vernier)
YF-24E (22E +
23F vernier)
YF-75 ×2 YF-50D
Power cycle gas gen gas gen gas gen gas gen gas gen ?
Chamber pres. (bar) 71   71   71   71   38  
Ox./fuel ratio   2.12   2.12   2.18   2.18   5.10
Thrust, vac max (kN) 810    3300     830    800    160     6.5
Thrust, SL initial (kN) 740    2960    
Spec. imp, vac (km/s)   2.83   2.83   2.97   2.97   4.30   3.09
Total imp, vac (t·km/s) 491    513    255    147    78.4
Long March 4C: mass 250 t, diam 3.3 m, thrust 3000 kN, imp 2.6 km/s, type Gd, payload 4.2 t (1.7%), cost $12M/t?, record 79/0/2.
Stage name L-176 L-36 L-14.5
Role (pos) count core (1) upper (2) kick (3)
Diameter (m)   3.30   3.30   3.30
Liftoff mass (t) 188    37.4 15.5
Empty mass (t) 12.3  2.0  1.0
Fuel mass (t) ~56    ~11.1  ~4.6
Oxidizer mass (t) ~119    ~24.3  ~9.9
Engine YF-21C
(20C ×4)
YF-24E (22E +
23F vernier)
YF-40B rs
Power cycle gas gen gas gen gas gen
Chamber pres. (bar) 71   71   46  
Ox./fuel ratio   2.12   2.18   2.14
Thrust, vac max (kN) 3300     800    101   
Thrust, SL initial (kN) 2960    
Spec. imp, vac (km/s)   2.83   2.97   3.00
Total imp, vac (t·km/s) 485    105    43.4

— the shuttle era, 1977–2007 —   [Hide] 

This is the era when spaceflight became commercialized, and some of the more successful rocket families of the period remain in heavy use, particularly the Shuttle’s European rival, the Ariane. The Russians developed a modernized commercial rocket in the Zenit, and converted military missiles to commercial use with the START and the Rokot. Japan developed a commercial rocket with the H series, India did likewise with their PSLV and GSLV with remarkable success, and Israel got a toe into space with the little Shavit. In America, Orbital Sciences, later known as Orbital ATK and now part of Northrop Grumman, developed small rockets for the commercial market: the Pegasus, and then the Taurus / Minotaur series.

ARIANE — EU, 1979

This is the signature rocket of the European Space Agency. Though developed by an intergovernmental initiative, it was the first orbital rocket system to be operated for commercial profit (though with substantial governmental support), by Arianespace SA in France, which now also sells some Soyuz launches. The first Ariane flew in 1979. Versions 1 through 4 were based on France’s Diamant rocket, after Britain withdrew its Blue Streak booster. It was the first rocket whose design was primarily guided by the mission of launching commercial satellites, particularly geostationary ones, in direct competition with the Space Shuttle. The Arianes pioneered the technique of launching more than one satellite per flight — even Ariane 1 could do two geostationary satellites per flight. The Ariane 4 had a long run: 116 launches with just three failures.

The current Ariane 5 is an all-new design, dropping much of the legacy of models 1–4. It’s bigger than a Proton, though not as big as a Long March 5. Like the space shuttle, the “Vulcain 2” main engine is hydrogen fueled, and it is always launched with a pair of very large solid-fuel boosters on the sides. (The old Arianes used hypergolic fuel.) The Vulcain’s thrust is low: less than a tenth what the pair of solid boosters puts out. The boosters use aluminum bound in HTPB and have steerable nozzles. They’re built in three segments and use a steel casing.

The second stages originally used hypergolic fuel (monomethylhydrazine), but lately they’ve come up with a much bigger one that burns hydrogen, called ESC-A (Etage Supérieur Cryotechnique de type A), or just ECA for short. It was first used on Ariane 4. So far they only use this for single payloads to GTO, as its engine is not restartable, so they also modernized the hypergolic stage for low-orbit work. This version is called ES. The majority of launches now use ECA. The Ariane 5 is rated for human flight, but has never been used for this purpose. The cancelled Hermes spaceplane was supposed to be launched with it. The 5’s success rate started out rough, but they’ve been nearly spotless since 2002 — the worst “failure” being a guidance error made on the ground which resulted in a slightly wrong orbit.

Arianes do not launch from Europe. The spaceport they use is in French Guiana, near the equator, on land that used to be part of the notorious prison colony there. The big solid boosters are manufactured right there at the launch center.

Ariane 6 is in development, and aims to be very competitive in cost per payload ton. They announced plans for it to have a main engine section that can detach itself from its tanks and land on a runway with little wings, thus recovering the majority of the money spent on the first stage. It would have little propellers and wheels tucked away inside it. This idea is known as “Project ADELINE” (a tortured acronym not worth spelling out).

But now they’re saying that the Adeline recovery trick will have to wait for Ariane 7. Ariane 6 should still be substantially cheaper than Ariane 5, though. For starters, it’s smaller — particularly the solid boosters, which will have the option of being used as a pair or a quad, so as to match the 5’s capacity. These shorter side boosters are a variant of the first stage of the capacity. These shorter side boosters are a variant of the “P80” first stage of the Vega, and are HTPB and aluminum in a single piece, encased in carbon fiber 25 centimeters thick. The nozzle is an update of the one from the old booster, and and it’s assembled and filled at the same facility in Guiana.

The new reusable engine is going to be called “Prometheus”. It will be cheaply 3D-printed, and burn methane. And in parallel with the development of the ADELINE trick, another project will (if they get the funding) be building a test booster to try to fly back and land vertically like the Falcon 9 does. This experimental hopper will be called “Themis”, and will also use the Prometheus engine. This will persumably happen some time after they do some initial flyback experimenting with a much smaller “Callisto” hopper which they announced earlier. This baby hopper will let them make their first efforts at flyback landing more inexpensively.

The Ariane 6 will use an ESC-B upper stage, updated with a new “Vinci” engine which is restartable up to five times.

Ariane 5 ECA: mass 780 t, diam 5.4 m (width 11.5 m), thrust 13000 kN, imp 4.2 km/s (core), type Gh+S, payload 19.3 t (2.5%), cost $7M/t, record 243/0/11 (106/0/4 for 5+).
Stage name EAP-E EPC H173 EPS L10 * ESC-A
Role (pos) count booster (S) ×2 core (1) upper (2) upper (2)
Diameter (m)   3.06   5.40   5.40   5.40
Liftoff mass (t) 273    185    11.2 19.4
Empty mass (t) 33   14.7  1.2  4.5
Fuel mass (t) ~72    ~22    ~3.4 ~2.4
Oxidizer mass (t) ~169     ~151     ~6.6 ~12.2 
Fuel type HTPB+aluminum hydrogen MMH hydrogen
Engine EAP P241 Safran
Vulcain 2
Aestus Snecma
Power cycle solid gas gen (GN) pressure-fed gas gen
Chamber pres. (bar) 100    11   37  
Ox./fuel ratio   2.3?   6.70   1.90   5.00
Thrust, vac max (kN) 6470     1350     27   67  
Thrust, SL initial (kN) 5975     960   
Spec. imp, vac (km/s)   2.70   4.24   3.18   4.38
Total imp, vac (t·km/s) 1312     737    31.3 63.5

ZENIT (Зеніт), IRTYSH (Иртыш) / SOYUZ-5, and YENISEI (Енисе́й) — Ukraine/Russia, 1985

Designed to replace the Proton, though not as powerful, they had some hope it could largely replace the Soyuz as well... this is a much more modern design than either, but it suffered from the turmoil of the Soviet breakup. It then went on to find a market elsewhere. Some versions were launched at sea by a company called the Sea Launch Consortium, from a converted drilling rig based in Long Beach. Others launch from Baikonur. But the relationship with the Ukrainian factory is kaput after the Crimean annexation, which appears to have also killed off Ukraine’s Dnipr rocket. There has only been one Zenit launch since 2015, so it may be a dead duck... Sea Launch claimed they’d be back to a regular launch schedule starting in 2019, but this was very overoptimistic, as delivery of Russian engines to either Ukraine or the USA remains problematic, and many of the skilled workers at the Yuzhnoye Design Office and associated PA Yuzhny Machine-Building Plant (commonly known as Yuzhmash / Южмаш), where the rocket is built, have now departed. Back in the day, Yuzhmash also built the Dnipr and Tsyklon rockets.

The Russian government would definitely like to get Sea Launch going again, because it’s their only launch option that can take off from near the equator... but the Ukrainian government would prefer to keep Sea Launch unavailable to them. The S7 Group, which bought the company in 2016, finally admitted that there are no foreseeable launches, but blamed the delay on Covid-19, which was of course affecting the whole industry. They moved the platform and its support ship to Vladivostok, but now they basically need to find a new rocket for it.

The Zenit’s first stage has a kerosene engine with a quadruple nozzle — the RD-171M. Its four combustion chambers are fed by a single set of turbopumps. It’s a variant of the RD-170, and is the most powerful liquid-fueled engine ever made, outperforming the mighty F1 used in the Saturn V. The engine weighs ten tons, and the whole thing gimbals as a unit. (Improved gimballing is the main difference between the 170 and the 171.) This belongs to the same family as the RD-180 used by the Atlas, which is basically half of an RD-171, and like that engine it has exceptional performance for a kerosene burner because it uses a closed cycle and can maintain an extremely high pressure in the combustion chambers. It took eleven years to engineer this staged-combustion motor, but it has proved worth the effort. Not only does the engine (and its many descendants) have world-leading performance, it also has the durability to be put into a reusable rocket, able to do ten flights before replacement. Some engines have reportedly survived up to twenty flights worth of test firings.

This big engine was originally used in the monstrous Energia (Энергия) rocket which once flew the Buran (Бура́н) shuttle. The Zenit’s main stage started out as a side booster on the Energia, which had four of these strap-ons attached asymmetrically to a hydrogen-burning core stage, and could lift 100 tons. There is still talk about bringing back the Energia, despite its high cost. The question of whether Russia can get away with just the cheap little Angara or whether it needs a much bigger rocket is apparently still being argued, but it looks like the case for the Angara-only approach has been lost. There were unfinished plans to build an Energia 2 which would allow them to recover and reuse both the Zenits and the core stage; if pursued, this might make the cost much more reasonable, even though with that version they planned to increase its capacity to a whopping 170 tons. But I don’t know, the plans looked a bit nutty... they involved giving each Zenit a big pair of folding airplane wings! Even in the original Energia,the side boosters used parachutes for a semi-soft landing, so they could be recovered and examined after use. These plans for a reusable superheavy rocket were interrupted by the fall of the Soviet Union, which is why the Buran (which means “blizzard”) never made a second flight.

The present-day Zenit’s RD-171M is a less expensive, mildly simplified version of the engine. Its second stage has two kerosene engines, the main one being a non-gimballing RD-120, with a four-nozzled RD-8 encircling it to provide steering. It’s the only vernier engine to use staged combustion. A third stage — usually a stubby Russian model also used atop the Proton, known as Blok-DM — is generally used for sea launches but not from land; this is for reaching geostationary and other high orbits. A Fregat kick stage can also be used. These fit inside the fairing. The Zenit has high performance for its cost, but the tradeoff has been a pretty bad failure rate.

With Yuzhmash out of the picture, the plan they settled on was to build a new Zenit-based rocket and call it the Sunkar (Сұңқар), an improved all-Russian version. Sunkar means “falcon” in Kazakh... in Russian it was going by the name Feniks (Феникс), then they said it was officially going to be Soyuz-5 (a complete misnomer as it shares no heritage with the Soyuz and doesn’t even come from the same manufacturers), but then they said the Russian name is going to be Irtysh (Иртыш), which like Angara and Dnipr is the name of a river. The Sunkar name is apparently being discarded along with Feniks. But they might be sticking with Soyuz-5 after all — it’s not clear. The engine would be a new version called RD-171MV, with improved controls and no imported components.

Apparently one minor part of the rocket’s purpose is to rebuild business ties with the Baikonur launch facility in Kazakhstan, which the Russians had been pulling away from in favor of new launch pads on Russian soil. They may be regretting that because none of those new pads have as low a latitude as that of Baikonur. If this gets built, it might kill off the rival proposals for a lightened Proton and for a methane-burning Soyuz replacement, and also make a significant dent in the ambitions of the struggling Angara system. Each design comes from a different rival aerospace outfit: the Soyuz coming from RKTs Progress in Samara, the Angara from the Khrunichev Center (which also makes the Proton), and the Irtysh from RKK Energia. If the Irtysh wins — and for the short term, it seems to be doing so — the two losing companies will probably each get some subcontracting work. But the latest plot twist is that a methane rocket, now dubbed the Amur, is the one with which they will go for reusability. They have not yet said who will build it. Those plans are described in the article for the Angara.

One condition the Kazakhs had was that any new rocket should use clean fuel. They were tired of the environmental hazards of the Proton, and knew what it was like to see one smack into the ground and not only shatter windows in the next town, but also leave behind a huge patch of poisoned soil.

The Irtysh would be widened from 3.9 to 4.1 meters, so its middle part would be externally compatible with the Proton. This would increase its payload capacity to 17 metric tons, maybe even 18. The base would be narrower, to be compatible with that of the Zenit. It would keep its overall height compatible with the Zenit 3. Keeping to these pre-existing constraints minimizes the changes needed for launch pads and transporters. (As with the Zenit and Proton, the stages would be shipped by rail.) To fit this height goal, they’re designing the new second stage to have eight small nozzles (divided between two RD-0124MS engines) to keep its base as short as possible. They hope to fly this in 2023, and to then restart Sea Launch with it.

There are plans to also restore the Irtysh to its role as a side booster in a superheavy rocket like the Energia. Some plans are to just update the classic Energia design, but there’s another approach which argues that by just hooking up five or six Irtysh cores horizontally, and then piling three more stages on top of the central one, they could lift payloads exceeding 100 tons without needing any oversized central stage.

And in 2018, it was a version of this plan which got the go-ahead for further development: a new superheavy launcher to be called Yenisei (Енисе́й — Russia’s largest river) would have four or six side boosters based on the Irtysh first stage, surrounding a core booster which would be similar but use the smaller RD-180 engine instead of the RD-171MV. Four of the side boosters would be used right away, while the other two (if used) would be delayed and stay attached longer. So the nomenclature they’re using is that the four early boosters would be designated as stage 1, the two late ones as stage 2, the core as stage 3, the upper (which would use dual RD-0146 motors that burn hydrogen in an expander cycle) would be stage 4, and at the top they could add a little stage 5 with an RD-58MF engine... which is odd as this is a kerosene engine, and I’ve never heard of a kerosene stage being carried by a hydrogen stage before. They plan to lift 100 tons with this design. In silhouette this stack would look scarcely bigger than a Falcon Heavy, but then you’d notice the four additional boosters.

The sneaky bit is that the the core booster may look like another Irtysh, as it’s 4.1 meters across and uses a similar engine, but it isn’t: it’s actually a super-fattened Angara rather than a slightly fattened Zenit. It would be built in the Angara factory. I assume there were good political reasons for distributing the construction contracts between the rival companies. But there may also be good engineering reasons, as the Angara was designed from the start to have an airframe capable of supporting large external boosters. They never planned on hanging this much mass and power off of it, but at least it’s only a matter of scaling up the thing’s structural strength by some percentage, rather than building up such a framework from scratch. It’s not clear that this saves much design effort when the diameter is drastically different, though.

But that’s just one version of the Yenisei proposal: in earlier ones the core would be Energia-like and burn hydrogen. It could change again if the Angara program continues to struggle.

Zenit 2M (no third stage): mass 462 t, diam 3.9 m, thrust 7550 kN, imp 3.3 km/s, type ZOk, payload 13.7 t (3.0%), cost $6M/t,record 65/7/12 (final?).
Stage name Zenit Blok-DM-SL * Fregat-SB
Role (pos) count core (1) upper (2) kick (3), opt kick (3), opt
Diameter (m)   3.90   3.90   3.70   3.35
Liftoff mass (t) 354    91  17.4 11.6
Empty mass (t) 27.6 ~8.4  2.1  1.4
Fuel mass (t) 90.2 22.8 ~3.4
Oxidizer mass (t) 236.6  58.9 ~6.8
Fuel type kerosene kerosene kerosene UDMH
Engine RD-171M RD-120 +
RD-8 vernier
RD-58M Lavochkin
Power cycle staged (ZO) staged (ZO) staged (ZO) gas gen
Chamber pres. (bar) 245    163    78   98? 
Ox./fuel ratio   2.60   2.72   2.00
Thrust, vac max (kN) 7890     990    85   19.9
Thrust, SL initial (kN) 7550    
Spec. imp, vac (km/s)   3.30   3.42   3.45   3.27
Total imp, vac (t·km/s) 1065     280    56   32.7

H — Japan, 1986

The original H-I was built by Mitsubishi based on a Thor first stage. The successor H-II was all-Japanese. It was replaced with the cheaper and more reliable H-IIA in 2001, and in 2007 it was privatized, so Mitsubishi has full ownership. The H-IIB arrived in 2009, featuring a fatter first stage with two engines. The prior model remains in use for lighter loads.

Japan had a lot of smaller rockets as they gradually built up their expertise, mostly named after letters of the Greek alphabet. Now those are all gone, except that they’ve gone back to that in naming the new Epsilon.

The core stage burns hydrogen, and is augmented with either two or four stubby solid boosters, sometimes with even smaller booster-ettes tucked in between. The H-IIB always uses four, as its whole point is for heavier lifting than the A. The second stage also burns hydrogen.

There were a couple of different plans to launch human beings on an H-IIA, with both capsule and spaceplane designs existing on paper, but none were built.

They are now working on an H-III. (They’re also working on saying “H3” instead of using roman numerals.) For this they’re replacing the dual LE-7A hydrogen engine with either two or three new engines called LE-9. The old engine used staged combustion, but for the new one they are building the world’s biggest expander-cycle engine, apparently on the belief that higher reliability matters more than higher specific impulse. Even with just two engines, this will increase the stage’s thrust considerably. The LE-5B expander on the second stage is getting a small upgrade. The III will have smaller solid boosters than the IIB used. Otherwise, not much has changed, so the cost is not likely to be reduced all that much. As this neared readiness, the IIB was retired, while the IIA remains active.

H-IIB: mass 531 t, diam 5.2 m (10.3 at base), thrust 8146 kN, imp 2.8 km/s, type ZFh+S, payload 19 t (3.6%), cost $6M/t, record 55/0/3.
Stage name Nissan L-178 L-17
Role (pos) count booster (S) ×4 core (1) upper (2)
Diameter (m)   2.50   5.20   4.00
Liftoff mass (t) 77   203    20  
Empty mass (t) 10.9 24.9  3.9
Fuel mass (t) ~20    ~26    ~2.7
Oxidizer mass (t) ~46    ~152     ~13.4 
Fuel type HTPB hydrogen hydrogen
Engine SRB-A3 LE-7A ×2 LE-5B-2
Power cycle solid staged (ZF) expander
Chamber pres. (bar) 127    38  
Ox./fuel ratio   2.3?   5.90   5.00
Thrust, vac max (kN) 2305     2196     137   
Thrust, SL initial (kN) 1615     1685    
Spec. imp, vac (km/s)   2.78   4.30   4.39
Total imp, vac (t·km/s) 734    770    74.2

SHAVIT (שביט) — Israel, 1988

Israel has a small rocket that they use once every few years to put up spy satellites. The name means “Comet”. It is based on a ballistic missile named Jericho. They tried to make a commercial version, which would have some parts built in the USA to satisfy import restrictions. That one had two sizes, with the larger one using a Castor 120 booster stage instead of the Jericho one, to expand its low orbit capacity of 0.8 tons. But the commercial program never got far enough to sell to customers. There is talk that they’re thinking of trying again with commercialization.

South Africa at one point licensed the Shavit tech and tried to fly their own variation of it, called the RSA-3, but gave up on it after three suborbital test launches. The whole program arose out of cooperation between Israel and South Africa to build nuclear missiles, in which Israel would bring knowhow and South Africa would supply the uranium. South Africa later renounced nuclear weapons; Israel did not.

The rocket consists of three solid-fuel stages and an optional hypergolic fourth. The original Shavit had nearly identical first and second stages, then the “Shavit 1” embiggened the first, then “Shavit 2” embiggened the second to match. Unusually, they launch it westward, against the rotation of the Earth. They do this just to avoid dropping anything onto any neighbor nations who may have sensitive feelings about Israeli hardware raining down on them. This increases the difficulty of reaching orbit by around ten percent.

The rival Iranian space program deals with the falling hardware problem by putting a parachute on the first stage. See the Korean/Iranian Unha section below.

Shavit 2: mass 38 t, diam 1.3 m, thrust 560 kN, imp 2.5 km/s, type S, payload 0.3 t (0.8%), cost unknown, record 9/0/2.


We now come to the first orbital launch rocket developed from scratch as a purely private commercial venture. Orbital Sciences Corporation was founded in 1982 and merged with Alliant Techsystems in 2006 to form Orbital ATK. Orbital is just one of many military and aerospace outfits borged by Alliant; they make lots of military gear, and were America’s leading manufacturer of bullets under numerous brand names, until they spun off their consumer-products branch as Vista Outdoor in 2015. Their run of acquisitions is at an end, though: they’ve now been absorbed by Northrop Grumman.

The important part is that one of these Alliant companies was Thiokol, which had long been America’s premier maker of big solid rocket boosters, and another was Hercules Aerospace. It was the latter which originally developed the small Orion rocket motors used to make the Pegasus. Orbital Sciences wanted to put up some satellites, and a partnership was born. And they soon got a lot of interest in a rocket that could replace the Scout — America’s best option for small cheap launches since 1961, which retired in 1994.

Orbital Sciences’ first satellite carrier was the Pegasus, a small torpedo-like device launched from under an airplane. It has three solid-fuel stages, and a fourth stage can be added for precise orbital insertion. This kick stage uses monopropellant: plain hydrazine, N2H4, which is broken down into gases by an iridium catalyst. This isn’t powerful, but it is simple and compact, making it popular for small thrusters, especially in situations where a satellite or probe has to retain a reserve capacity for several years.

The first stage steers using wings and a tail, while the second has vectorable thrust despite using solid fuel. They inject stuff on one side or another of the combustion chamber — extra oxidizer, I think — which steers the rocket by making its flame asymmetrical. It then coasts up to space before firing the third stage. In 1994 they lengthened it to raise performance, as the original Peg could lift only a quarter ton. The newer one is called the Pegasus XL. Launch prices have been offered as low as $6 million, but that’s for very barebones service — it’s the extra charges that get ya. And prices have gone up. Apparently it’s gotten rare to get away from the Pegasus dealership without spending $40 million or more.

A company called Stratolaunch Systems, which was owned by the late Paul Allen, has built a plane with the world’s widest wingspan, for the sole purpose of launching Pegasi from under it. The intent was to make a larger Pegasus model which would be able to launch a ton or more, but Orbital apparently backed out of that, so Stratolaunch was hoping to interest somebody else in making a heavier air-launched rocket. With small Pegasi, the plane can take up three of them at a time... but that’s a limitation of size, not weight: if a new rocket were designed for Stratolaunch, they say it could weigh up to 200 tons. Maybe then it’ll pay off; unfortunately, it turns out that running a big unique plane like that has costs that are comparable to those of using an expendable booster stages to get small rockets through the lower atmosphere. Below a certain size of rocket, it may not even break even. SpaceX was at one point going to build a suitable air-launched rocket with four Merlin engines, but they concluded that the airborne approach wasn’t worth the trouble, and pulled out. The Stratolaunch people have recently publicized some vague plans for a new midsized air-launched rocket that their plane will carry, but in early 2019 they gave up the idea, halting all in-house efforts to design a new rocket.

The Pegasus XL semi-retired in 2008. It came back in 2012, but only for very occasional use. Orbital insists that they are not retiring it, even if demand remains low because of the price increases... but given how many new small launchers are coming onto the market and promising far lower prices, it’s hard to imagine the Peg making any sort of comeback. Especially not now that the current owners of Stratolaunch just put the whole outfit up for sale, and Richard Branson offered $1 for the plane. Somebody bought it anonymously; it turned out to be a group led by billionaire Steve Feinberg. The plane has been called the spruce goose of our time.

Stratolaunch seemed dead, but new owners are now hiring. Their new long term plan is to build a small hypersonic rocket-plane to be carried by the big plane, and piggyback rockets on that — an idea that had been shelved by the old owners. (But they’ll start with a tiny payloadless hypersonic plane, to be called Talon-A, before building something bigger.) Boeing just gave up on the Phantom Xpress project as apparently not workable within a reasonable budget, but I think the basic idea of using a rocket-plane as a booster stage is still sound, so if they can get through the short term I think this might work well.

The one thing the Pegasus offered that other competitors did not was the ability to launch small satellites from the equator into orbits with zero inclination. But then SpaceX announced that they could do such orbits from Florida at a price no higher than the Pegasus; by putting a small sat onto a large second stage, they had enough delta-V to correct the orbital plane. This may indicate that SpaceX’s profit margins now have room for further cutting, should any of their competitors catch up on price. Then Virgin Orbit demonstrated that their cheaper air-launched rocket. This, according to industry observers, probably means the Pegasus is now dead, Stratolaunch or no Stratolaunch. But after they said that, the Peg did get one more military launch job in 2021. This was apparently done with a surplus rocket which had been built for Stratolaunch, and was discounted accordingly. One more surplus Peg is said to be available.

Respect where it’s due: the Pegasus may now be obsolete, but it was the first of a new breed. In fact, you could say it’s the first of two new breeds at once — one being air-launched orbital rockets, and the second being purely commercial rockets developed without any government funding. Like the Space Shuttle, it’s too expensive because it was ahead of its time.

Pegasus XL: mass 23.1 t, diam 1.3 m, thrust 560 kN, imp 2.8 km/s, type S, payload 0.44 t (1.9%), cost $25-$125M/t, record 41/0/4 (may be final).

PSLV and GSLV — India, 1993

PSLV (Polar Satellite Launch Vehicle) is an odd one. It evolved from predecessors named SLV and ASLV, which were small solid-fuel rockets. It has a solid fuel first stage with a multisegment steel body, commonly augmented by six small strap-ons, then a hypergolic second stage, a solid fuel third stage which is narrower but has an enclosing ring to support the fairing, and finally, inside the fairing, a tiny twin-engined fourth burning hypergolics... but not the same hypergolic chemicals as the second stage: it uses monomethylhydrazine and mixed oxides of nitrogen, whereas the lower one works with the more usual combination of unsymmetrical dimethylhydrazine (UDMH) and dinitrogen tetroxide. (Lately they’ve started mixing some hydrazine hydrate into the UDMH to make it more stable.) It’s as if they tried to develop and master as many different technologies as they could, all with one rocket. Even the solid stages differ: the upper one steers with a flexing nozzle, but the core booster steers by injecting liquid oxidizer into the sides. The stages also separate by different means, using explosives in some cases and mechanical latches in others.

The six strap-ons come in two sizes: the PSLV-G has short ones and the later PSLV-XL uses stretched ones with more thrust. The PSLV-CA (for “core alone”) has neither. When they are used, four of them ignite at launch time, and the other two not until 25 seconds later. In 2019 they added variants DL and QL, which use two and four side boosters respectively. This may mean the G-size boosters are now retired.

Despite this very idiosyncratic and irregular design, which seems to have been chosen to produce the greatest possible number of different ways to fail, the PSLV has a pretty good reliability record. It also set a record for the most separate satellites launched in a single flight, with 104 in early 2017. And it’s affordably priced.

The GSLV (for Geosynchronous) variant swaps out the solid third stage for a restartable hydrogen burner, adding another technology to the list. The little fourth stage is now optional, and I don’t think the option has yet been used. The GSLV uses much bigger strap-ons than the PSLV, and they burn liquid fuel — an inversion of the natural order for cores and strap-ons. These are loosely based on the hypergolic second stage, but longer and thinner. That stage uses an engine called the Vikas-4B, which started as a variant of the Viking engine used in older Ariane models. In the strap-ons, the engine is angled slightly away from vertical, and it has a sea-level sized bell; this variant is called the Vikas-2B. The four boosters don’t detach, but remain integrated with the first stage as it separates from the second... in fact, they carry the solid first stage for 40 seconds after it is exhausted.

The reliability record is not so good compared to the PSLV, despite the slightly less baroque design. It had to go through a major overhaul after a series of early failures. It has now been disused for a few years.

But the GSLV that’s based on the PSLV is old news. That’s the Mark II. Now here comes the GSLV Mark III, which is sometimes called the LVM3, but usually goes by the former name. Despite the familiar name, this is an all-new rocket. It’s quite a bit bigger than the old ones. Its core stage burns hypergolics in a pair of independently gimballed Vikas-2 engines, and it has two big fat solid boosters on the sides, giving it a silhouette similar to an Ariane 5. These boosters have steerable nozzle extensions. Unusually, the core stage does not ignite at liftoff, but near the time of booster separation. This lets its engines use larger bells, improving efficiency. The upper stage burns hydrogen, so once again we have a mix-and-match assortment of fuels, though this time it adds up to a much more conventional overall picture. As hydrogen burning upper stages go, this is a powerful one, and no further stage is needed. It seems less advanced than the Mark II upper stage, which had a staged-combustion cycle, while the new one is a gas generator... but that’s because the Mark II engine is a copy of a little Russian motor which they imported and used in the Mark I, while the big Mark III engine is all-Indian.

The rocket’s maiden suborbital test flight was used to test a heat shield for a future “Gaganyaan” crew capsule. They’re experimenting with a reusable rocket (to be called RLV), and also with a scramjet. The RLV would not only have a vertically-landing first stage, but a spaceplane second stage, and they are already doing drop tests to work on the automated landing. India is taking spaceflight very seriously. They want to show they can match anything offered by China. They hope to send a crew of three “gagannauts” into orbit by 2022.

Unfortunately the last couple of years have been tough. A failed lunar mission, followed by a major hit from the covid pandemic, have put the space agency ISRO far behind where it hoped to be. Maybe the next year can be a comeback.

PSLV-CA (no added boosters): mass 230 t, diam 2.8 m, thrust 2700 kN?, imp 2.3 km/s, type S, payload 2.5 t? (1.1%) [PSLV-XL 4.2t? (1.3%)], cost $6M/t?, record 50/0/3.
GSLV Mark II: mass 415 t, diam 2.8 m, thrust 4360 kN?, imp 2.6 km/s, type S+Gd, payload 5 t (1.2%), cost $9M/t, record 8/0/6.
[Show stages] (PSLV and GSLV)
Stage name PSOM (PSLV-G+) PSOM-XL (PSLV-XL) GS0/L40H (GSLV) PS1/GS1 PS2/GS2/L40 PS3 (PSLV) GS3/CUS15 (GSLV) * PS4/L2.6 *
Role (pos) count booster (S) ×0|6 booster (S) ×0|6 booster (S) ×4 core (1) upper (2) upper (3) upper (3) upper/kick (4) *
Diameter (m)   1.00   1.00   2.10   2.80   2.80   2.02   2.80   2.02
Liftoff mass (t) 11.1 14.7 48.2 161    42.8  8.4 17.6  3.6
Empty mass (t)  2.0  2.2  5.6 23    4.3  0.8  2.6  1.0
Fuel mass (t) ~2.7 ~3.8 ~15.7  ~41    ~14.2  ~2.3 ~2.5
Oxidizer mass (t) ~6.4 ~8.7 ~26.9  ~97    ~24.3  ~5.3 ~12.5 
Engine S9 S12 Vikas-2B S138 Vikas-4B S7 CE-7.5 L-2-5 ×2
Power cycle solid solid gas gen solid gas gen solid staged (ZF) pressure-fed?
Chamber pres. (bar) 59   59   75    8.4
Ox./fuel ratio   2.3?   2.3?   1.71   2.3?   1.71   2.3?   5.05
Thrust, vac max (kN) 719    765    4860     805    240    93   14.6
Thrust, SL initial (kN) 450?   678    2700?   
Spec. imp, vac (km/s)   2.60   2.60   2.80   2.60   2.96   2.89   4.45   3.02
Total imp, vac (t·km/s) 133    183    121    365    124    22   117     7.7
GSLV Mark III: mass 640 t, diam 4.0 m (width ~10.5), thrust 10300 kN?, imp 2.9 km/s, type Gd+S, payload 10 t (1.6%), cost $6M/t, record 3/1/0.
Stage name S200 L110 C25
Role (pos) count booster (S/1) ×2 core (2) * upper (3)
Diameter (m)   3.20   4.00   4.00
Liftoff mass (t) 237    125    33  
Empty mass (t) 31.2  8.9  5.1
Fuel mass (t) ~62    ~43    ~4.6
Oxidizer mass (t) ~144     ~73    ~23.3 
Fuel type HTPB UDMH+HH * hydrogen
Engine S200 Vikas-2 “X”? ×2 C25
Power cycle solid gas gen gas gen
Chamber pres. (bar) 57   59   60  
Ox./fuel ratio   2.3?   1.71   5.05
Thrust, vac max (kN) 5150     1678     200   
Thrust, SL initial (kN) 4330?    1513    
Spec. imp, vac (km/s)   2.60   2.90   4.40
Total imp, vac (t·km/s) 555    345    121   

START (Старт) — Russia, 1993

The START treaty between the USA and the USSR made both countries decommission a number of nuclear missiles. The Russians recycled one type, the RT-2PM Topol, into an orbital rocket, and named it after the treaty. The missile had three solid stages, so they slapped on a fourth and voila. For one launch they added a fifth stage, but that failed.

This rocket essentially retired in 2006, but in 2019 they decided to bring it back for some reason. Is this something that will continue, or an isolated fluke? No idea. The soonest it will fly again is 2022.

The one cool thing about the rocket is that it launches from a big truck: a transporter-erector-launcher unmodified from the Topol version.

Start-1: mass 47 t, diam 1.6 m, thrust 980 kN, imp 2.6 km/s, type S, payload 0.53 t (1.1%), cost unknown, record 6/0/1.


The Taurus is the second commercial rocket from Orbital Sciences. This one launches from the ground, with a solid fuel booster much bigger than that of the Pegasus (though still small compared to most of its competition). The Taurus is a variation of the Minotaur series, which has various models derived from the Minuteman and Peacekeeper ICBMs. They didn’t just copy the ICBM designs — as the Russians did with START, they actually recycled old booster cores as the missiles were decommissioned by the Pentagon. There is a large supply of these now being stored in military warehouses. Unfortunately for this brilliant plan, however, Congress decided it would be anticompetitive to allow the contractor recycling these old solid rockets to be able to underprice the other launch providers, so they made a rule that these recycled boosters could only be used for governmental launches, not commercial ones. So the Minotaur series are the government’s main small launch system, replacing the long-discontinued Scout. You’d think that would be a good useful role, since they’re abundant and cheap, but it gets surprisingly little use.

There are many models in the Minotaur series. The I and II are based on old Minuteman missiles, using their first and second stages with new upper stages. The I adds an Orion 50XL and an Orion 38, both as used in the Pegasus, with the option of a liquid kick stage. It can orbit 0.58 tons. The II has a choice of third stages and no fourth stage, and is for suborbital use only. The Pentagon liked to use it as a practice target for ICBM defense techniques. The III is based on a Peacekeeper’s first three stages, which are substantially bigger than those of the Minuteman. It’s also a suborbial rocket. The Minotaur IV is where they get serious: it uses three Peacekeeper stages and an Orion 38 (plus optional kicker) to huck 1.7 tons into orbit. The V uses a heftier Star 48V fourth stage and the Orion 38 as a fifth, and can do geosynchronous transfer orbits with up to 0.56 tons of payload. These missiles have huge thrust-to-weight ratios and take off with terrific speed; I’m told they reach the speed of sound in about fifteen seconds. You can see why that would be desirable in an ICBM; for other payloads, you’d sure better be ready for some G forces.

The Taurus is the commercialized version of this kind of launcher. It replaces the Peacekeeper booster stage with a civilian equivalent which can legally be used for private sector customers. This stage is known as the Castor 120 — Castor (like Star) being a product line of Thiokol, which was the original builder of the ICBM stages, and later got merged with ATK and then with Orbital.  This stage then essentially has a Pegasus stuck on top of it (without the wings and tail), acting as the second through fourth stages, which are much skinnier than the bottom stage. So basically they’ve substituted a “stage zero” booster for the carrier airplane, and by doing so have roughly doubled the payload capacity relative to the Pegasus. The resulting vehicle has occasionally been mocked as a “Frankenstein rocket”, but there’s a great tradition of rockets pieced together from mismatched preexisting stages, especially in the early days. The Taurus’s commercial mission success rate has not been good. It recently had a hiatus of six years after a particularly embarrassing failure, and the new version they came up with in 2017 has been significantly revised. It was then that they dropped the Taurus name, and called it “Minotaur-C”, for Commercial. It has found very few customers under that name.

Two of the Taurus’s failures were not Orbital’s fault: it was eventually found that a supplier involved in making the fairings, Hydro Extrusion USA, had been falsifying their test results and delivering substandard junk. This resulted in criminal charges. One testing supervisor got jail time, and the company had to pay around $45 million in penalties.

Unlike the commercial version, the governmental Minotaurs have never failed — hence the use of the Minotaur brand for the revised Taurus.

Minotaur-C: mass 73 t, diam 2.4 m, thrust 1600 kN, imp 2.3 km/s, type S, payload 1.3 t (1.8%), cost $30M/t, record 12/0/3 (including IV and V — record of I is 12/0/0).

ROKOT (Рокот) — Russia, 1994

Though derived from an ICBM, this is Russia’s first for-profit commercial rocket. Launches are sold by a consortium named Eurockot. It has three stages, all using UDMH hypergolic fuel. The first stage has four small Energomash engines, one of which is tweaked to feed hot gas into the reservoir used to pressurize the fuel tanks — an approach previously used on the second stage of the Proton. The Rokot’s second stage has a nongimballed motor with vernier thrusters. The third stage which enables it to reach orbit is a Briz (Бриз, “breeze”) — a model which also sometimes used as a kick stage atop a Proton or Angara (see below) in a version with larger tanks than are used here. On the Rokot I believe it is non-optional, and the first two stages cannot reach orbit. (ICBMs reach speeds around 75% or more of orbital, depending on how intercontinental they really are, and the UR-100N / SS-19 needed both stages for that.) The word “rokot” means “rumble” — it’s named after the noise it makes.

A variant called Strela (Стрела, “arrow”) is not commercialized — closer to its ICBM roots, they say. It uses a different third stage and has a somewhat lower capacity.

The original plan was for the Rokot to be retired in favor of the single-stick Angara. But now the original Rokot is retired early for an unrelated reason, as it depended on guidance hardware from Ukraine which is no longer available to Russian buyers. Efforts are underway to get funding for an all-Russian Rokot 2, as the wait for the Angara drags on.

Rokot: mass 107 t, diam 2.5 m, thrust 3100 kN, imp 2.8 km/s, type ZOd, payload 1.9 t (1.8%), cost $10M/t?, record 29/2/3 (final?).

— the modern era, 2008–present —   [Hide] 

This is the period where big-budget governmental rockets fade into the background, and for-profit corporations become the leaders in advancing spaceflight. SpaceX brought the revolutionary Falcon, and Orbital upped their game with the Antares. Small startups developed small rockets: the Electron is succeeding, and the LauncherOne, Astra, and possibly the Alpha look ready to do likewise, while some other ventures drop away. With price competition now a major factor in the launch business for the first time, Russia struggles to develop a modernized replacement rocket called the Angara to cover a wide range of lift capacities, while eyeing reusability for a followup effort, and China is revamping their Long March line with all-new designs. Japan modernized their small-launch capability with the cost-conscious Epsilon, the ESA did likewise with the Vega, and various Chinese companies did so with multiple small rockets based on military missiles: the Kuaizhou, Kaituozhe, Long March 11, and others, while small startups like i-Space and Galactic Energy seemed to have access to the same solid fuel tech as the governmental aerospace outfits. Meanwhile the North Koreans and Iranians teamed up to create orbital rockets with the Safir, Unha, and Simorgh, and the South Koreans answered with the Naro and the Nuri, proving that national space programs are now within reach of countries outside the first world.

FALCON — USA, 2010

Finally we get to the good stuff — the brand new wunderkind rocket which is obsoleting all the rusty crap which the space industry has been putting up with for too long. Elon Musk — easily the most important tech visionary of our time — tried to buy some services from existing rocket companies, and found them so unhelpful and uncompetitive that he decided to take the money he was going to offer them and start a rival company with it instead. In short, he found a market ripe for disruption. He soon found ways to undercut their prices, and in the process, almost by accident, produced some of the most rapid advances in rocketry that had been seen in decades. Many other space startups emerged around the same time, but so far only Space Exploration Technologies Corporation, better known as SpaceX, has made the new venture a sound commercial success on a large scale. They now boast a long track record of successful and profitable launches. SpaceX is far from his only company, of course. In all of his ventures, what separates him from other tech moguls is that he approaches things first as problems of basic physics, then of engineering, and finally of manufacturing processes, rather than in terms of finance or marketing.

Falcon 9 rockets, unlike any from previous eras of spaceflight, are designed to be highly reusable. The first stages soft-land themselves and are ready to go again after some refurbishment. They’ve pretty much perfected the “suicide burn” landing, in which the rocket stops exactly at ground level as smoothly as if you were watching a takeoff in reverse. But the reuse process is still in early stages, with time between landing and takeoff only gradually decreasing from months to weeks, with a turnaround in days still far away. If they succeed in getting a whole fleet of Falcons to do ten launches each, we could see prices falling through the floor, like under one million dollars per ton to orbit. It’s still an open question whether it’s feasible to do this rapidly and cheaply enough to accomplish that. In 2020 they reused some boosters over five times, and one of them reached ten in the spring of 2021, but the turnaround time is still weeks rather than days.

But even when reuse was still marginal, SpaceX became the number one launch provider in the world, except for the Chinese government at times — twice as busy as any of their commercial competitors. In 2017 they averaged one and a half launches a month, and said they were facing the challenge of speeding up toward a weekly pace, because customers were still backed up in a waiting list. The plan was to do thirty launches in 2018, but this slipped, as things often do with SpaceX due to their “agile” approach to engineering and their “aspirational” scheduling of innovative achievements. For a while, the limiting factor was the rate of manufacturing enough of the latest “Block 5” booster stages. As a result, SpaceX fell behind the pace set by China with the Long March 2, 3, and 4. With a bigger booster fleet, we might see that increased pace.

But not right away — the number of customers has been flattening out. In fact, in 2019 their overall launch rate decreased, and they actually had a three month dry spell with no launches at all. It appears that the queue of customers awaiting the launch of heavy satellites has emptied out. (ULA’s launch cadence has also decreased.) I think they were hoping that lower prices would stimulate demand, but so far, that isn’t happening. Maybe if they were a lot lower. As things are, most launch customers have needs which are fairly inelastic as to price, or they wouldn’t be in the market in the first place. It may be that no amount of price lowering significantly increases the demand for heavy satellite launches, as usually the craft themselves already cost plenty more than the launch does. Perhaps there will eventually be new opportunities for budget-priced large satellites, but if there are, nobody has figured them out yet. It may be years before the demand catches up to the supply.

Well, if no one else has a use for cheap mass-produced launches yet, Musk will have to come up with one himself. And he has: Starlink. It’s a plan to provide fast internet wirelessly using thousands of satellites — tens of thousands, if they grow to the scale they claim they could. At sixty quarter-ton sats per launch, they’ll be doing dozens of flights for this project for the next decade... and once they have the full set aloft they’ll be continuing afterwards with replacement launches, as the early versions of the sat are designed to stay in service for only five years and then ditch into the atmosphere, so that the technology can be continually refreshed. They plan to do about 25 launches a year for this project, starting in 2020. That will bring their cadence numbers up... they did 26 launches in 2020 despite covid, and in mid-2021 they were on pace for 40! But they slowed down in the second half. By this time they had plenty of boosters available, making five or six new ones per year and only losing one or two.

But astronomers are not happy about this large increase in the amount of “space junk”, and they’ll be even less happy when competitors start putting up their own satellite swarms. (We ought to build and launch several Hubble-sized telescopes — that might relieve the feelings of the astronomical community significantly.) Several outfits have announced plans for such networks, including Amazon and the Department of Defense. But competing won’t be easy... an outfit called OneWeb just launched about three loads of sats and then went bust. They then got bailed out and resumed launching, though it’s hard to imagine any success coming out of this effort. The Pentagon’s swarm, of course, doesn’t need to compete. The first launches of this swarm will be on Falcons.

With all this makework, SpaceX hopes to do almost fifty Falcon launches in 2021, but it’s looking like the logistics of the Florida space coast may not be up to that pace. Many companies and agencies have to share common infrastructure there, and increasingly often, a delay experienced by anyone affects everyone. Musk wants to review all the sticking points and push for changes to support busier schedules.

SpaceX is also now organizing ride-share launches which would carry sats from many small customers instead of from a few large ones. If you’re willing to share your orbit, this will underprice being launched on something like an Electron.

The Falcon 9 has nine kerosene-burning “Merlin” engines, all fully gimballed. Its second stage uses a single Merlin, with an oversized bell for efficiency in vacuum — not much smaller than the fuel tanks it’s attached to. That bell is made of exotic niobium alloy, and glows orange in use. They have said that their goal was to put a heat shield onto the second stage and soft-land it too, but they’re backing off from that nowadays. That sounds dubious anyway unless they cut the payload capacity way back, but I can see why they wanted to, as they now say that with reusability of the booster, the loss of the second stage accounts for something like one third of the cost of each flight. They might cost around $20 million or so apiece, by one guess I’ve heard. Musk admitted that this would only be feasible for “some payloads”, but he still wanted to see if they could do it. They are also working on landing and reusing the fairings which cover the payload, bringing them down on parachutes. They tried guiding them to a ship with four arms holding up a big circus-net made of cloth straps, but despite occasional successes, this turned out too unreliable and hazardous, so they settled for letting the fairings splash down. Trying to land them in that net was very difficult, like trying to throw a layup with a potato chip — it’s just too aerodynamically unstable. Though those fairings are very simple things compared to the second stage, they still cost like $5 million, and they have to buy them from a vendor, who apparently has taken advantage of SpaceX’s inability to get them anywhere else to not only keep prices high, but obstruct progress on making a larger size. This may be due to pressure from their other customers who compete with SpaceX.

Anyway, all of these hopes and plans for the Falcon are now fading, as Musk becomes increasingly committed to building an all-new rocket to obsolete it, instead of working on incremental improvements to it. See the Starship article in the “Not Flown Yet” section.

They’ve put together a triple booster “Falcon Heavy” version... about five years after they thought they would. With the recent Block 5 upgrades, even the basic Falcon now nearly matches the payload capacity of the Delta IV Heavy, so the Falcon Heavy is a huge leap in lift capacity. (The Delta looks bigger, but that’s because it’s full of hydrogen.) The Falcon Heavy’s claimed capacity is over sixty tons, without even using a bigger second stage. But that’s if you’re willing to pay them to discard stages instead of recovering them, as the payload limit is quite a bit less if the boosters need to land afterwards. In expendable mode, they can not only burn all the fuel for ascent instead of saving some, they can leave off unnecessary parts such as the landing legs and grid-fins. A regular Falcon can be reused up to about two thirds of its max expendable payload, but the Heavy can only manage about half. But the real point of the Heavy is not to lift giant stuff, but to make it so that they don’t have to expend boosters anymore, or at least only have to expend the center one for the worst cases. By losing the center core they can reach around 90% of the capacity they’d have by expending all three.

The rocket may not actually be able to support a sixty ton payload. (Their standard payload adapter is only designed to support eleven tons — just half of the amount a non-heavied Falcon can supposedly lift to orbit. What the limits of the stack might be with a better adapter, I have no idea. The heaviest loads actually launched are somewhere around twenty tons.) The main benefit of the Heavy is probably for reaching higher orbits. If the destination is geostationary transfer orbit (GTO), for instance, the Heavy would increase the nominal capacity from 8.3 tons to 26.7 tons, without reuse. They claim it could send 16.8 tons to Mars, or 3.5 to Pluto without using a gravitational slingshot. One could do even better by adding a third stage, but they don’t sell one — you’d have to bring your own, and fit it into fairing, which is smaller than that of competing rockets. (A bigger one is on their shopping list.) I will note that these GTO numbers are not that impressive, compared to the huge loads that it can lift to low orbit... the use of kerosene as fuel in the upper stage, instead of hydrogen, reduces its efficiency for reaching distant trajectories. With full booster reuse, the capacity to GTO is actually less than that of the Delta IV Heavy.

Some customers still fork over willingly for a nonrecoverable overweight launch. They hope the availability of the Heavy will make such launches largely unnecessary. Making the Heavy proved far more difficult than they anticipated, with practically the whole first stage needing a redesign to be able to support the additional thrust and vibration of adding side boosters. This highlights SpaceX’s general philosophy of shaving things as close to the limits as they can reasonably get away with, and leaving only a minimum of safety margin... when they decided to ask more of their booster, the margin they needed wasn’t there. The rebuild job was so challenging, and so hard to test on the ground, that they almost cancelled the project three times, and Musk said that if the rocket just managed to get a safe distance away before it exploded, and not destroy launch pad 39A in the process, he would “consider even that a win, to be honest.” But even the first test flight of the Falcon Heavy put reused boosters on the sides. They used a “silly” payload on the first test — they threw a Tesla roadster into what they hoped would be a Mars transfer orbit, and which ended up going out all the way to the asteroid belt, with the stereo playing David Bowie, and a dummy named Starman in the driver’s seat with its arm on the window sill, wearing one of their new space suits. (In 2010, they tested the first Dragon capsule by launching a wheel of Le Brouère cheese in it, so a degree of silliness is not unprecedented.)

With the Falcon Heavy they considered pulling off a trick known as “asparagus staging”, or as it’s more properly termed, propellant crossfeed. How this works is that with all three boosters burning at full power, the two side ones are also pumping fuel to the middle one’s engines. They run low and drop off in less than two minutes, and hey, the single remaining booster still has nearly full tanks. The traditional approach, as used in the Delta IV Heavy and its ilk, is to just run the center booster at minimum throttle for the later part of the initial burn, until the side ones are gone. But they’re not doing the asparagus trick yet. The reasons for caution are obvious, with all that might go wrong with such a scheme. This idea is dead for now, because it simply isn’t needed — to be honest, more lifting power is the last thing the Falcon Heavy needs. They originally thought the Heavy would be used for about half of their business, but they overestimated the demand for such heavy lift, and every time they improve the regular Falcon 9, it covers more of the weight range which they previously thought would require a Heavy. Nowadays, it looks like this hulking rocket might struggle a bit to find enough work to justify its presence.

Meanwhile, the familiar Falcon version that made it famous, which was apparently known in full as v1.2 “Full Thrust” Block 3, got upgraded to Block 5 (or “Fuller Thrust” as it has sometimes been unofficially termed), increasing its claimed payload capacity by 30% while also meeting NASA’s toughest safety standards for crewed flights. (Block 4, a transitional version with a minor increment to the engine thrust, was used for a few flights in late 2017 and early 2018.) This upgrade includes lots of fixes to the various weak points that have been revealed by inspecting landed boosters, such as replacing the aluminum grid fins with titanium, which is a lot more expensive but should last forever. They hope that the Block 5 will be able to refly up to ten times with no refurbishment at all, just an inspection and cleaning. (But I note that the rocket business in general is prone to the dashing of such hopes.) They pinned all their dreams of rapid and inexpensive reusability onto the Block 5, and started throwing away used Block 3 boosters, rather than saving them — they pretty much considered the successful Block 3 landings to just have been part of the program for learning how to make the Block 5, and didn’t feel like collecting old models that need heavy refurbishment to fly again. After this, they plan to do no further development on the Falcon booster, and eventually replace it with an all-new system. One of NASA’s hurdles was that they should make seven consecutive flights with no changes to the design, so their hope is that this version is truly final. By the end of 2018 they completed ten Block 5 launches with six boosters, one of which was the first to make three flights. But it wasn’t until 2020 that the Dragon 2 crew capsule was ready enough for NASA to put their astronauts into it.

Falcon 9 v1.2 Block 5: mass 564 t, diam 3.7 m, thrust 7600 kN, imp 3.1 km/s, type Gk, payload 22.8 t (4.0%) in expendable mode and 15.6 t (2.8%) with reuse, cost $4M/t, record 121/3/3 (4 crewed).
Falcon Heavy: mass 1420 t, diam 3.7 m (width 12.2), thrust 22800 kN, imp 3.1 km/s, type Gk, payload 63 t (3.7%) in expendable mode and 27.5 t (1.9%) with reuse, cost $3M/t, record 2/1/0.
Stage name Block 5
Role (pos) count core (1|S) ×1|3 upper (2)
Diameter (m)   3.70   3.70
Liftoff mass (t) 445    116   
Empty mass (t) ~22.2  ~4.5
Fuel mass (t) ~123     ~32   
Oxidizer mass (t) ~287     ~75   
Fuel type kerosene kerosene
Engine Merlin 1D+ ×9 Merlin 1D Vacuum
Power cycle gas gen gas gen
Chamber pres. (bar) 97   97  
Ox./fuel ratio  ~2.33  ~2.33
Thrust, vac max (kN) 8227     930   
Thrust, SL initial (kN) 7607    
Spec. imp, vac (km/s)   3.10   3.40
Total imp, vac (t·km/s) ~1330      ~371    

VEGA — EU, 2012

Developed mainly in Italy, which is now becoming the dominant EU country for space projects in place of France, this is Arianespace’s new small-payload launcher. It has three solid-fueled stages topped by a hypergolic stage. The bottom stage has a steerable nozzle extension tube for thrust vectoring. It’s basically the same “P80” motor that’s going to be used as a side booster on the Ariane 6. They’re going to lengthen the bottom stage by about 50% in a future version, calling it P120 and dubbing the taller rocket Vega C. With that, they’ll be able to launch a tiny unmanned spaceplane on this thing, which is apparently going to be called Space RIDER. It would launch from Guyana (where the Arianes go up) and land on a runway in the Azores.

The upper stages are skinnier than the three meter booster — the “Zefiro 23” and “Zefiro 9” solid stages are just 1.9 meters wide. The UDMH-fueled topper is called AVUM and weighs under one ton. A further evolution calls for the third and fourth stages to be replaced by a new methane-burning cryogenic stage. This will be called Vega E and isn’t expected to fly until 2024.

The Vega did go on hiatus for some months after the fifteenth launch, when the second stage blew out its top end. They say it’s fixed now. Overall it’s doing good business, but the European Space Agency is already starting to think that for the exploding small-sat demand, they might need something quite a bit lighter and cheaper.

As mentioned in the Ariane article, the ESA is also working on a very small hydrogen-fueled rocket called Callisto, which will explore the capability of doing vertical landings. It is not intended to fly real payloads; it is strictly a “hopper” testbed for gaining experience at landings and reuse in general. They figure that if it leads to something commercial, that rocket will be larger.

In 2019 they announced a plan to also develop a larger experimental hopper named Themis. In the concept art, this looks very much like a Falcon 9. It would use an inexpensive methane-burning engine named Prometheus, which would also be used in a future Ariane. I guess the idea is to practice the basics of hopping on a small rocket before building a realistically sized one.

Vega: mass 137 t, diam 3 m, thrust 2300 kN, imp 2.7 km/s, type S, payload 1.9 t (1.4%), cost $18M/t (dropping as usage ramps up), record 18/0/1.

UNHA (은하) ...and SAFIR/QASED (سفیر/قاصد‎), SIMORGH (سیمرغ) — North Korea, 2012

The world’s best-known shorter range ballistic missile is the Russian R-17, known in NATO countries as the Scud. Many countries bought these, but nobody tried to make anything orbital out of it, because it didn’t have anywhere near a useful range. But the North Koreans, having made their own Scud copies which they named Hwasong, decided to see how far they could push the technology, and embiggened the design to a substantially larger scale. The result was a missile called the Hwasong-7, which could reach targets 1000 kilometers away.

As soon as the missile was ready, they promptly exported it to Iran, just as they had done with the classic Scud copies. It appears that the development of the larger version was largely funded by Iranian money, so they got to use the missile almost before its makers did. In Iran it became the Shabab-3 missile, and by 2001 they were building them locally.

This is what the Iranians turned to when they decided they wanted an orbital rocket. Scuds and their derivatives are single stage rockets which burn dimethylhydrazine hypergolically with nitric acid as the oxidizer. By adding one additional stage, the Iranians gave it just enough capacity to get a basic satellite into orbit. They called it the Safir (ambassador). This may not sound like an impressive space program, but the Iranians reached orbit three years before their North Korean friends did, and now have twice as many sats up.

When North Korea wanted a longer range ballistic missile, they continued the basic Scud engine design, but switched the fuel to kerosene, while still using nitric acid as the oxidizer. They then embiggened the booster by simply using four engines. This resulted in the Taepodong 2 ICBM, which got people scared because North Korea now also had a nuclear bomb to put on top of it. It more or less uses a Scud as its second stage. Then they decided that they wanted to boast of having orbital capability, so they added a third stage and came up with the Unha (Galaxy) 3. They got a satellite up on their third try in 2012, but of course claimed to have succeded in earlier attempts, since of all governments on Earth, theirs is the one most utterly dependent on bullshit.

Iran got a piece of this rocket as well, and is now working on a Simorgh (phoenix) launcher based on it, apparently using the Safir booster as a second stage. It’s sometimes just been called the Safir 2. The Simorgh has yet to successfully reach orbit, with four consecutive failures. But in 2020 a new Safir variant named Qased (messenger) did reach orbit. Apparently this version has a solid second stage, and is operated by the military instead of by the space agency.

As of 2021 Iran is shifting further toward solid fuel, announcing a new rocket in the works named the Zoljanah (after a legendary horse), which is also the name used for the giant truck that it will launch from. It has two solid stages and a liquid topper. Not much is known yet, but the target capacity is a few hundred kilograms.

For South Korea’s response to the Unha, see KSLV.

Safir-1: mass 26 t, diam 1.25 m, thrust unknown, imp ~2.5 km/s, type Gd, payload 0.05 t (0.2%), cost unknown, record 6/2/2?

Unha-3: mass 90 t, diam 2.4 m, thrust 1200 kN, imp 2.5 km/s, type Gk*, payload ~0.35 t (0.4%), cost unknown, record 2/0/2.

Simorgh: mass 87 t, diam 2.5 m, thrust 1300 kN, imp 2.5 km/s, type Gk*, payload 0.15 t (0.2%), cost unknown, record 0/1/4.

KSLV / NARO (나로) / NURI (누리) — South Korea, 2013

When North Korea started working on their Unha satellite launcher, the South Koreans knew that it would not do to be shown up by the north, so they started working on one of their own. They tried to make an entirely domestic rocket but then cheaped out in order to finish quickly, and just imported a kerosene/lox booster — an Angara core purchased from Russia. An early Angara prototype, rather — it had a lower trust engine than the final version. Because this booster was larger than originally planned, their solid second stage now seemed undersized on top of it. This rocket was first called KSLV-1 for Korean Satellite Launch Vehicle, but then they changed the name to Naro-1, taking the name of the island where their launch pad was built.

There were only three launches of the Naro. The first was sent up in 2009, and fell back from space when the fairing failed to open. The second, in 2010, fell apart halfway through the first stage burn. Finally in 2013 the rocket got a satellite into orbit, about a month late to beat the North Korean program, which had also failed its first two attempts (but claimed that they were all successful). They had hoped to get some engineering secrets of the Russian staged-combustion engines out of this deal, but the Russians kept a tight lid on that.

The Naro-1 was then retired — after having checked off the necessary national achievement, they decided using Russian castoffs was not the long term strategy they wanted to follow. They resumed work on putting together an entirely domestic rocket. The result was the Nuri ("World"), or KSLV-2. Its first test launch was in 2021, with only a mass simulator for payload. This test fell a bit short when the third stage shut down prematurely.

The Nuri is bigger than the Naro, and has three stages where Naro had two. The booster burns kerosene — or rather, cheap jet fuel — and lox, in four “KRE-075” gas generator engines. The second stage uses a single KRE-075 with a vacuum bell. It has a steerable gas generator exhaust pipe which gives it roll control. The third stage uses a much smaller “KRE-007” engine, burning the same fuel. This makes it capable enough to do more than just smallsats, unlike any of the North Korean or related Iranian designs, with a low orbit capacity well over two tons — a size range that’s rather underserved now, as most people seem to have goals that are either under one ton or over six. Their most direct competitor is probably India’s PSLV.

A small suborbital rocket using a single KRE-075 engine was launched as a test in 2018.&ensp It was called the "KSLV-II TLV". They say they plan to use this in the future to launch little satellites, once they give it a second stage.

Further plans include upgrading the Nuri to be able to reach geosynchronous orbit, and eventually the moon. To do this they will develop an improved engine called KRE-090, and use four of them on the core, then add four side boosters with one KRE-090 apiece. The second stage will get a KRE-090V (the large bell version), and they plan to give the third stage a staged-combustion engine, to be called KRE-010V.

Meanwhile, a small South Korean company called Perigee Aerospace is trying to beat the government to orbit by building a rocket so tiny that the Nuri could lift it as a payload. See the Blue Whale article.

Naro-1: mass 140 t, diam 3.0 m, thrust 1670 kN, imp 3.3 km/s, type ZOk, payload unknown, cost unknown, record 1/0/2 (final).

Nuri: mass 200 t, diam 3.5 m, thrust 2940 kN, imp 3.1 km/s, type Gk, payload 2.6 t (1.3%), cost unknown, record 0/1/0.


Orbital ATK finally got out of the solid-fuel ghetto by building a kerosene burning twin-engine first stage... except not really, because they subcontracted that part to the Ukrainian company Yuzhnoye/Yuzhmash, who are basically building them a shortened Zenit variant. It uses two RD-181 engines, which are loosely of the same high-performance kerosene burning family as the Zenit’s 171 and the Atlas’s 180, but with single nozzles. The pair is about as powerful as a single 180. The earliest Antareses used old Kuznetsov NK-33 engines which were bought by Aerojet Rocketdyne, refurbished, and sold as the AJ26, but these were not reliable. They were originally built for the N-1, the rocket which was supposed to land cosmonauts on the Moon, but which kept breaking up after launch. In their day they were the best engines in the world, but that was long ago. Orbital ditched them after a turbine failure made an Antares fall back onto its pad and explode. The rockets with the new engines are designated as the “200 series”, with the originals being the “100 series”. The RD-181s are actually overpowered for the size of the rocket, and have to be throttled down to not overstrain the airframe. They hope in the future to strengthen it so they can use the extra 340 kilonewtons of available thrust. (But first they’d better hope for this rocket to have any future at all.)

There’s been some talk of maybe replacing the RD-181 engines with a single Blue Origin BE-4, because it doesn’t look much better for Orbital to be buying Russian engines than for ULA to be doing so. The BE-4 should have about 30% more thrust than the RD-181 pair, but it’s not clear how they would compare in cost. A Raptor would probably be a better fit for size, but SpaceX hasn’t yet shown any willingness to sell engines to third parties. They managed to continue Antares flights into 2021 despite the Yuzhmash plant being more or less shut down since the Crimea invasion... whether they can put any more together is an open question.

They still use solid fuel for the second stage — it’s based on the Minotaur’s first stage, but shortened. It’s called the Castor 30, or in the latest re-embiggened version, 30XL. This is skinnier than the booster, so the interstage goes around it rather than under it. They don’t light it up until both the interstage and the fairing are well clear.

The fairing has recently been upgraded with a feature called a “pop top”, which allows the tip of the nose cone to be removed and replaced very easily. This allows perishables to be put into the Cygnus after the rocket is already at the pad, just 24 hours before launch. Using this involves lowering the rocket back to horizontal after it’s been raised for checkout, which means the fuel tanks probably have to be empty.

They have a choice of optional third stages: two sizes of solid motor for high but imprecise orbits, and a little monopropellant one for tuning lower orbits accurately. (They used to have a hypergolic one in this role.) But no customer has yet taken any of these options. The rocket’s only use has been to deliver cargo flights to the space station in their Cygnus freight capsule (though these missions do allow other satellites to piggyback as ride shares). This doesn’t need a third stage because the Cygnus has a service module with its own propulsion. They recently signed up with NASA for a second batch of Cygnus flights to the space station, and this time they say the price they asked is lower than SpaceX’s... though I don’t see anybody showing any numbers to back this up. As yet, nobody else has paid for an Antares flight, which would be very strange if the price were really that affordable.

During times of hiatus, three Cygnus canisters ended up being launched on Atlases, which probably made them more expensive. These did have a higher weight capacity, but they are now doing heavier loads on the Antares itself.

The rocket was originally called the Taurus II, but that name got some bad branding juju thanks to launch failures, so the II became the Antares and the original Taurus became the Minotaur-C.

Antares-230: mass 298 t, diam 3.9 m, thrust 3850 kN, imp 3.3 km/s, type ZOk, payload 6.1 t (2.0%), cost $13M/t?, record 13/1/1.
Stage name Antares (200+) Castor 30XL OAM * Star 48BV Orion 38
Role (pos) count core (1) upper (2) kick (3), opt kick (3), opt kick (3), opt
Diameter (m)   3.90   3.90   1.24   0.97
Liftoff mass (t) 261    26.4  2.2  0.9
Empty mass (t) 20.3  1.5  0.2  0.1
Fuel mass (t) ~67    ~7.5  1.2 ~0.6 ~0.2
Oxidizer mass (t) ~174     ~17.4  ~1.4 ~0.6
Fuel type kerosene HTPB+aluminum hydrazine * HTPB+aluminum HTPB+aluminum
Engine Energomash
RD-181 ×2
Castor 30XL REA ×8 * Star 48BV Orion 38
Power cycle staged (ZO) solid pressure-fed solid solid
Chamber pres. (bar) 258   
Ox./fuel ratio   2.60
Thrust, vac max (kN) 2085     533     1.6 78   36.9
Thrust, SL initial (kN) 1922    
Spec. imp, vac (km/s)   3.30   2.90  2.1?   2.82   2.82
Total imp, vac (t·km/s) 8801    72   ~2.5  5.8  2.1

EPSILON (イプシロンロケット) — Japan, 2013

This is another of the small solid-fuel type which has been catching on lately. It has three stages, and no interesting features. A fourth stage option is available. Its purpose is to cut costs, that’s all. The first stage is recycled from one of the side boosters of the H-IIA. It’s taken very few flights.

I was doubtful that these baby launchers were a good market strategy. Elon Musk apparently agreed with me: SpaceX’s first rocket to launch a satellite was the Falcon 1, which was about this size, and as soon as they got it working he didn’t bother making any more, despite having some waiting customers at the time. But conditions have changed since then, and the number of customers with small satellites to launch has boomed. Currently there is an unmet demand for small launch services, but now so many companies are entering the market that within a couple of years, the deficit could turn into a glut. Some in the industry are now expecting a shakeout, where the less competitive small launch ventures fail to find customers. Solid rockets in particular may be vulnerable, as there may be hard limits on how low they can cut prices. (At the same time, SpaceX’s low prices may also be shaking out some large launchers, though there’s a lot more inertia in that market, particularly since so many of the customers are governments.)

Speaking of smallness, I should mention the SS-520, a little suborbital sounding rocket with two solid-fuel stages. The Japanese stuck a third stage onto one and orbited a single cubesat with it in 2018, setting a record for the smallest vehicle to ever lift anything to orbit. This was a one-time stunt; they are not going to offer launch services on it. For the record, the rocket had a mass of 2.6 metric tons and a diameter of 0.52 meters (20.4 inches). The payload weighed four kilograms.

Epsilon: mass 91 t, diam 2.5 m, thrust 2.3N, imp 2.8 km/s, type S, payload 1.2 t (1.3%), cost $32M/t, record 4/0/0.

KUÀIZHŌU (快舟), KĀITUÒZHĒ (开拓者), LONG MARCH 11, SMART DRAGON (Jiélóng, 捷龙), LANDSPACE (Zhūquè, 朱雀), OS-M, HYPERBOLA (Shuāng Qūxiàn, 双曲线), CERES (Gūshénxīng, 谷神星) — China, 2013

China has lots of nuclear-capable ballistic missiles, most of them named Dōngfēng (东风, “East Wind”), which gets abbreviated as DF- in western military discussions. But only a few of them live in silos, or in submarines. China has found an easier way to keep them mobile, concealable, and survivable: mount their launchers on wheels. Each missile sits on a Transporter-Erector-Launcher, which is either a railroad car or, more commonly, a large heavy truck. The trucks are said to be capable of crossing fairly rough terrain. These mobile missiles use solid fuel for all stages, and can be prepped for launch in minutes.

So naturally, some folks tried to adapt these truck-based missiles for orbital use, and now that China’s government is encouraging space enterpreneurship, quite a few companies are trying this adaptation as a way of getting a toe into the door. The Kaituozhe (“Pioneer”) was the first rocket to make the attempt, though not the first to succeed. Very little is publicly known about it. Apparently, the Kaituozhe 1 made its first try for orbit in 2002, but never got there. At least two attempts were made, and possibly four. A Kaituozhe 2 finally got a satellite to orbit in 2017. They probably launched it from a fixed pad. One rumor says there’s a 2A variant that uses side boosters. The missile it was based on is probably the DF-31, the longest-range wheeled ballistic missile in their currently deployed arsenal, which makes it significantly larger than some of the rival rockets described below. The missile has three solid stages; the Kaituozhe may have more, we don’t know. Kaituozhe is made by the China Aerospace Science and Technology Corporation, known as CASC, a major government contractor.

The rival China Aerospace Science and Industry Corporation (CASIC) came up with the Kuaizhou (“Swift Vessel”). It’s made by a subsidiary of theirs called ExPace. This rocket is quite a bit smaller than the Kaituozhe, and it can still be launched from a truck. This means that satellites can be sent up on very short notice, for instance if there’s a sudden need to replace a bad one. Backup sats can be stored already attached to the rocket. Though not as secretive as the Kaituozhe, we still know rather little about it. It may have three stages, and an optional fourth, but this is uncertain. Its first stage is apparently based on the DF-21, which in its military form has two stages and a range of well under 2000 kilometers, and is apparently designed mainly for use against aircraft carriers. Some upper stages come from an antisatellite missile called the SC-19, which rode that same booster.

So far, this particular model has shown no signs of public commercialization, but usage is ramping up fast. The first Kuaizhou 1 orbited in 2013, with the 1A following in 2017, and in 2018 they planned to raise the 1A’s cadence to about one launch every ten weeks. They went silent for much of 2019 but near the end of 2019 they picked up the pace sharply, launching two in November and two in December — the latter two both on the same day. The launchers are under 100% military control even if the payloads are civilian.

After long delays, 2020 saw the (failed) debut flight of the larger Kuaizhou 11. They say this bigger one will bring prices well under $10 million per ton. They’re talking up the possibility of building quite large solid rockets in the future: a Kuaizhou 21 to carry twenty tons, and a Kuaizhou 31 to carry seventy. These obviously would not launch from a truck, but the 11 does, despite its 78 ton bulk. After all, the military is apparently developing a DF-41 as a truck launched missile, and that is thought to weigh about eighty tons. The Kuaizhou 11 may be based on the DF-41 — we don’t know.

(CASIC has also announced plans to develop a reusable spaceplane — in fact, a double spaceplane where both stages land on a runway. It’s called Tengyun, and should get its own section if they get it to a point where it’s more than paper and hype.)

Now comes the Long March 11, the first solid-fuel small launcher to carry the name used by the major rockets of China’s space program. It was built by CASC, makers of the Kaituozhe, and might end up being its replacement. (I’m sure CASC would like to sell both, and though the Kaituozhe seems completely inferior on paper, maybe the government will decide to keep it active anyway.) The Long March 11 first flew in 2015, and so far, it’s been reliable. It has four stages, as is not uncommon when solid fuel is used. Its size is smaller than the Kaituozhe but larger than the Kuaizhou 1A. It appears that they have no problem with making solid motors in lots of different diameters — something that most builders would try to avoid. I don’t think they’re interested in launching this from a truck... no point to it. But that doesn’t mean it can’t be portable: in 2019 they started launching it from the deck of a ship, which gives them the opportunity to take off from near the equator. This version is dubbed the 11H.

Or maybe CASC won’t care about the Kaituozhe, because now they’ve got a subsidiary called Chinarocket which has a new product series called Smart Dragon or Jielong. The Jielong-1 (or SD-1) is much smaller than a Kaituozhe or a Long March 11, or even a Kuaizhou 1, aiming for a capacity of only 200 kilograms to sun-sync orbit. We heard nothing about it until it was nearly ready to fly, and its first test was a success. It has four solid stages and takes off from a transporter-erector-launcher, requiring only 24 hours of prep and checkout before a launch. The one distinctive and unusual feature of this rocket is that the payload and topmost stage are mounted upside down, so that the nose cone is a cover for the upper stage nozzle rather than for the payload itself. This does mean that most payloads should not be wider than the 1.2 meters of the rocket body itself, though they do have the option of a 1.4 meter fairing if you really need it. They say that they will next turn their design ambitions to a medium-large liquid-fueled rocket with some as-yes-undetermined form of reusability, to be called Ténglóng (腾龙, “Flying Dragon”, I think). They are also making Jielong variants 2 and 3 more or less simultaneously, but I fon’t know how they will differ.

And finally, we come to the new fully commercial startups. LandSpace is a Chinese company that sells launches, and their first rocket is the LandSpace-1, or Zhuque-1. (Zhūquè / 朱雀 means “Vermilion Bird”, which is a constellation or zodiacal region. The company name in Chinese is 蓝箭 or Lán Jiàn, which means Blue Arrow.) Early info said this was apparently a variant of the Long March 11, but this turns out to be wrong: the specs are similar to those of a Kuaizhou 1, and it may also be based on a DF-21 booster, or perhaps on the newer DF-26 anti-carrier missile, which has a longer range. Apparently they do launch this from a truck. They attempted a maiden flight in late 2018, which failed to reach orbit but didn’t miss by much. They want to follow it up later with a liquid fueled rocket, and say they’re building a methane-burning engine called Tianque-12 (or SkyLark-12) for it, plus a smaller Tianque-11. Unfortunately, it seems that they’ve been cut off by their solid booster supplier, and may now be out of the race? No wait, they’re back in, with new funding, and are apparently planning to skip Zhuque-1 and try a Zhuque-2 in 2021. They say they have now done many minutes of test stand firing on their methane engines, while apparently making no further attempt to redeem their failed solid-fuel launch. Maybe they looked at all the other solids and decided they needed to stand out.

Here come some more startups. OneSpace (零壹空间 / Líng Yī Kōngjiān, “Zero One Space”) offers the OS-M with a 0.2 ton capacity, to be followed by an OS-M2 and OS-M4 with side boosters to handle up to 0.75 tons. On this rocket, the upper stages are skinnier than the booster (which might be another DF-21 or DF-26 copy); this may also be true of some of the other similar models. So far, they have made one orbital launch attempt with the OS-M, which failed. Reportedly, their solid rocket motors are recycled from decommissioned missiles.

And i-Space (or 星际荣耀 / Xīngjì Róngyào, “Interstellar Glory”, also sometimes called “Space Honor”, and not to be confused with ispace of Japan) has a similar rocket called the Hyperbola-1 which aims to lift 0.3 tons. (I’m certainly noticing the trend for using fake Silicon Valley-sounding company names in English. “ExPace” may be the worst, as a blatant knockoff of SpaceX’s name.) The Hyperbola — also sometimes called the SQX-1 — was reported to have a liquid fueled kick stage atop three solid stages, but their manual lists four solid stages. The first stage has grid fins at the bottom, as do the Kuaizhou rockets. They plan to follow it with a Hyperbola-2 which will have a 1.9 ton goal, with a reusable methane-burning booster. (Nice work if you can get it.) They’ve even started hyping a hyperbola-3, which will have multi-booster configurations and a capacity near 14 tons with one core. As far as I can ascertain, the Hyperbola-1 has yet another DF-21 or DF-26 being used as the first stage. (The military rockets do not use fins.) Both OneSpace and i-Space have previously launched suborbital rockets.

Another company, appearing by surprise, is Galactic Energy (Xīnghé Dònglì / 星河动力). They not only launched their Ceres-1 (or Gūshénxīng-1) successfully on the first attempt, they did so with relatively little schedule slippage. This company seems to have more on the ball than most small nu-space outfits. The Ceres has three solid stages, and a little liquid fueled topper inside the fairing, integrated with the cubesat deployer. I could not find much more info than that, except that they plan to hoist up to 350 kilograms for a $4 million flat price. They hope to next work on a kerosene burning rocket to be called the Pallas-1. So far, they have tested a preburner. They openly describe this “Welkin” engine they’re working on as an imitation Merlin.

The Hyperbola was the first of these independent rockets to successfully reach orbit, the Smart Dragon was second (if you count it as independent), and the Ceres was third. The OS-M hopes to do so soon on their second attempt, and LandSpace hopes to try again with their new design. All of these companies had long quiet periods after their first launch attempts — nobody was ready for ongoing production. In the case of the Hyperbola, the second rocket was significantly taller and heavier than the first one was... and this time it failed. Even without changes like that, despite all five companies having built and launched completed rockets, definite specs on them are still not easy to come by.

One startup which does not belong in this bucket is LinkSpace (翎客航天, “Líng-kè Aerospace”), who are working on a liquid-fueled reusable launcher called New Line. They have their own article in the “Not Flown Yet“ section. Anyone above can also get one if they manage to graduate from solid fuel vocational school.

Another one which doesn’t fit here is Beijing Deep Blue Aerospace Technology Co. Ltd., which is building a small kerosene-lox rocket called Nebula-1, to be followed eventually by a larger Nebula-2. They are only a couple of years old. They also have their own article, though info remains scant.

Kaituozhe 2: mass 40 t?, diam 2.25 m?, thrust unknown, imp unknown, type S, payload >0.3 t? (>0.75%?), cost unknown, record 1/0/2?

Kuaizhou 1A: mass 30 t, diam 1.4 m, thrust unknown, imp unknown, type S, payload 0.3 t (1.2%), cost $20M/t, record 12/0/1.

Kuaizhou 11: mass 78 t, diam 2.25 m, thrust unknown, imp unknown, type S, payload 1.0 t (1.3%), cost $10M/t, record 0/0/1.

Long March 11: mass 58 t, diam 2.0 m, thrust 1200 kN, imp unknown, type S, payload 0.7 t (1.2%), cost unknown, record 10/0/0.

Smart Dragon 1: mass 23 t, diam 1.2 m, thrust unknown, imp unknown, type S, payload >0.2 t (0.9%), cost unknown, record 1/0/0.

LandSpace-1: mass 27 t, diam 1.35m, thrust 440 kN, imp unknown, type S, payload 0.3 t (1.1%), cost unknown, record 0/0/1.

OS-M: mass unknown, diam 1.4 m?, thrust unknown, imp unknown, type S, payload 0.2 t, cost unknown, record 0/0/1.

Hyperbola-1: mass 42 t, diam 1.4 m, thrust 770 kn, imp ~2.7 km/s, type S, payload 0.3 t (0.7%), cost unknown, record 1/0/2.

Ceres-1: mass unknown, diam 1.4 m, thrust 590 kN, imp unknown, type S, payload 0.35 t, cost $12M/t, record 1/0/0.

ANGARA (Ангара) and AMUR (Аму́р) — Russia, 2014

We are now getting into launch systems sufficiently new that their commercialization is becoming speculative. This one is not yet available for hired flights, but the company to sell flights on it is in place.

Some years back, the Russians decided that they had too many product lines going on in rocketry, and decided to make a single new model to replace several old ones in the middle size categories. Furthermore, they wanted every part to be Russian, including the ground infrastructure, so there would be no dependency on other countries such as Ukraine or Kazakhstan. This is that new model, and its goal is to cover a wide range of uses through modularity. (It’s named after a river — an unusual choice but not a unique one, as witness the Ukrainians’ recently retired “Dnipr”, and apparently now becoming a trend with “Yenisei”. The Angara name is also used by a commercial airline.)

Its “URM-1” (for Universal Rocket Module) first stage can be stacked together horizontally, giving it up to four full-sized side boosters (or even six in some early plans) to accomodate a range of payload weights. These boosters burn kerosene, as does the second stage, all with single gimballing nozzles. The RD-191 engine is the ancestor of the RD-181 used in the Antares, which has a shallower throttling range than the original. The “URM-2” second stage will apparently be made in different sizes. They started by copying the “Block I” upper stage of the Soyuz 2.1b, and for multi-booster variants they fattened the tanks while keeping the same four-nozzled RD-0124A engine. For single-core Angaras they will use skinnier tanks, but the exact design is not finalized yet as far as ispublicly known, and we don’t know if it will be as narrow as the Soyuz stage, or an in-between size that would better fit the booster core. The optional third stage is a hypergolic “Briz” for now, but they are moving away from hypergolics because of the environmental hazards, and a fancier hydrogen burner known as “KVTK” is in the development pipeline. All these variations cover a huge range of payload sizes, from less than four tons on the most basic Angara to the mid twenties on the five core versions. A three core version would be possible too, but is not included in current plans.

Many variations are proposed but not yet built: for instance, an “A-5V” with a big hydrogen-burning “KVRB” (or “URM-2V”) second stage, and the KVTK on top. (The V stands for vodorod (водород), Russian for hydrogen.) With four side boosters, this layout would stretch the payload capacity to 35 tons... which is awkward because some of the missions they’re planning need about 38. They later thought they could get that setup to 40 tons, but then that idea got shelved in favor of the much bigger Yenisei rocket, which would surround a fattened Angara core with six Irtysh boosters. (See the Zenit / Irtysh / Yenisei article in the “Shuttle Era” section.) They also considered using propellant crossfeed, and giving the A-5V a fourth stage. There was even talk of making a reusable soft-landing version, and the RD-191 is indeed designed to survive several uses... but as far as I know it remains just talk. The official Russian plan for reusability is to work on it in the 2020s for use in the 2030s. And I figured, maybe once the Angara’s issues are worked out, it’ll be a good platform for that... though the Irtysh would be at least as good a starting platform, as the original Zenit it’s based on was designed to move toward this goal frim the beginning, even before SpaceX was founded.

In late 2020 they announced a plan for this future reusable rocket, and it’s not going to have any relation to either Angara or Irtysh, except that it shares the latter’s 4.1 meter tank diameter. The plan is to have five methane-burning engines, and Falcon-like landing legs and grid fins. They’re naming it Amur (Аму́р). They hope to lift 10.5 tons for just $22 million. Much more than either the Angara or the Irtysh, this would directly replace the Soyuz. If it does, that might not leave much for the Angara to do, except in the five core version, and not much more for the Irtysh either, except as a side booster on the superheavy Yenisei. But for this to happen, they first need to build the RD-0169A methane engine. (This would presumably be a variant of the RD-0162/0164 which they have been working toward since 2002 — a medium pressure staged combustion design in two sizes.) This engine is being built not by Energomash but by KB Khimavtomatika (КБ Химавтоматики), or Chemical Automatics Design Bureau.

A decade to get there sounds about right, though ideally they hope to fly it by 2026. After their years-long campaign of disparaging reusability in general and SpaceX in particular, this blatantly SpaceX-inspired design ended up getting enough negative public reaction that they would prefer to just not discuss it for a while. The Amur will get its own section if and when they make some progress on it, as will the Yenisei.

Is Amur the name of a river? Yes, it is — the one along the border with China, known as Hēilóng Jiāng (黑龙江, “Black Dragon River”) on the other side. The Amur would take off from Vostochny near the headwaters, and land near the mouth of the river, so the name is highly appropriate in this case. The Angara would launch either from there, or from Plesetsk (northeast of Petrograd) for polar orbits.

The Angara is still in the test-flight stage, with no commercial payloads yet. And they sure do seem to be taking a very relaxed schedule, with test flights spaced years apart. Apparently they’ve been having considerable logistical trouble with getting these rockets built, as well as difficulty fighting destructive vibrations when they finally manage to fire one up. Even the launch pad refit is behind schedule. The whole program is seeing its costs spiral ever upwards.

Another part of the same general modernization is the ongoing construction of the new cosmodrome at Vostochny in Amur Oblast, which is supposed to take over a fair fraction of the work now being done at Baikonur, in order to keep it on Russian soil when orbital inclinations permit. It already supports Soyuz launches, it’s almost ready for Angara launches, they’re adding a Yenisei pad (despite the fact that the current Roscosmos budget is far too small to build the Yenisei), and eventually the Amur will get one. They are considering naming the place after Putin. According to some activists, the construction is riddled with theft and corruption, which would make putting Putin’s name on it entirely appropriate.

Dmitri Rogozin, the head of Roscosmos since 2018 and Putin’s former Deputy Prime Minister, is one named by activists as appearing to line his own pockets with agency money. He was already under financial sanctions and persona-non-grata status by the USA and EU for his prominence in the Crimean annexation. He’s also loudly belligerent toward the west, racist toward the east and Russia’s minorities, highly militaristic, and all in all a pure fascist. He may yet manage to ruin future collaboration with NASA in areas like the ISS.

They do intend to carry human beings on the Angara at some point... or did once. And the Russian government once planned to use the Angara to help construct the Lunar Orbital Platform-Gateway out by the moon, which like the International Space Station was (at least in some plans) intended to be a joint international effort. They have now rejected collaboration on that, and instead signed an agreement to team up with China on lunar stations and bases. But whatever their ambitions, the program to build the Angara is apparently mired in budget cutting, despite that the whole purpose of having such a flexible rocket system is to be an affordable fallback for the larger and heavier rockets whose budgets got cut entirely, such as the Energia and the Proton. Apparently morale is not good, and the political decision to try to make the Angara do the job of larger rockets led to a lot of conflict and bitterness. If they build the Yenisei, that will make it a lot easier to do lunar missions to compete with the USA’s Artemis program... maybe just in time to see Artemis finally be cancelled because SpaceX’s Starship is doing everything it does at a tenth of the price.

After the cold war, it was US policy that the Russian space program should not be allowed to wither away, because then skilled rocket engineers might start finding employment with minor countries who want to have ICBMs. Apparently that worry was a big part of the reason why the International Space Station got built. Now that something like a cold war is back on again, I don’t know if such a policy still applies. If it does, it’s now failing, because the price competition from SpaceX is now causing Russian aerospace companies to see building orbital rockets as unprofitable, and they’re turning their focus more toward satellite construction, which is where the money is now. So if you’re the dictator of a developing country and want to develop an ICBM, the next few years may be an excellent time for hiring experienced rocketeers... if it isn’t already because of the collapse of Yuzhmash in Ukraine after the Crimean invasion.

The news lately is that the Angara program is in trouble, and may be losing out to the rival proposals for some missions, notably those carrying live passengers. The Russian government is apparently feeling nervous about putting too many eggs into the Angara basket, as said basket is now looking a bit fragile. The Irtysh looks like it could do about anything the Angara can do, with more capacity for less money. If the Angara program had gone well, they would have replaced the Zenit with a three-booster version, but now the opposite may happen. And the Amur might well be the last one standing. Will the Angara manage to even do ten missions before it’s obsolete? It sure isn’t making a strong start.

And yet, despite its dreadfully slow and late progress... it’s still shown more real-world advancement than any other new Russian launch system. The Irtysh sounds good, and the Amur sounds better, but when are we going to see any actual hardware for either one?

Angara 1.2 (no side boosters): mass 172 t, diam 2.9 m, thrust 1920 kN, imp 3.3 km/s, type ZOk, payload 3.8 t (2.2%), cost unknown, record 0/1/0.
Angara A5 (four side boosters): mass 760 t, diam 2.9 m (8.9 at base), thrust 9600 kN, imp 3.3 km/s, type ZOk, payload 24.5 t (3.2%), cost unknown, record 0/2/0.
[Show stages] (all variants)
Stage name URM-1 URM-2 * Briz-M KVTK (future)
Role (pos) count core (1|S) ×1|3?|5 upper (2) kick (3), opt kick (3), opt
Diameter (m)   2.90     3.60 *   4.10
Liftoff mass (t) 142    39.7 22.2
Empty mass (t)  9.7  4.8  2.4
Fuel mass (t) ~36    ~9.6 ~6.6
Oxidizer mass (t) ~96    ~25.3  ~13.2 
Fuel type kerosene kerosene UDMH hydrogen
Engine RD-191 RD-0124A Lavochkin
Power cycle staged (ZO) staged (ZO) gas gen closed expander
Chamber pres. (bar) 258    157    98   59  
Ox./fuel ratio   2.63   2.63   2.00
Thrust, vac max (kN) 2090     294    19.6 69  
Thrust, SL initial (kN) 1920    
Spec. imp, vac (km/s)   3.30   3.52   3.20   4.54
Total imp, vac (t·km/s) 438    90.3 64.2

LONG MARCH (Chángzhēng, 长征) — new models — China, 2015

The Chinese finally got tired of hypergolic fuel, what with its toxicity and pollution and mediocre performance, so they started working on some more modern rockets with cryogenic fuels. (They’re also tired of dropping spent rockets onto rural villages, so they’re finally building some launch facilities on an island.) And to start off this new era, they decided to build something big. They called it the Long March 5. And as before, they are making a modular system out of it.

Like the Long March 2 and 3, the 5 has four liquid fueled strap-on boosters. Each side booster has two kerosene burning staged combustion YF-100 engines, and is the size of a core stage from a classic Long March 2, 3, or 4. And later, there are supposed to be two versions of the side booster, with the other being a skinny version with only one engine, but that has yet to fly. They even talk about an in-between version of the rocket, using two fat boosters and two skinny ones. The new king-sized core stage also has two engines, and as in the Ariane 5, they burn hydrogen. This new engine is called the YF-77. The upper stage also has two hydrogen engines, in a much smaller size, and there’s an optional hypergolic third stage. This rocket has plenty of muscle. But its second flight was a failure due to a bad YF-77 turbopump, so it has been a struggle to get the thing into regular use. After three launches they added a 5B version, which has no upper stage. It’s intended for heavy loads in low orbit, which go directly atop the hydrogen core. They use this for space station modules.

They also wanted a small modern rocket, so they made the Long March 6 by taking one of the new fat side boosters, shortening it, removing one engine, and using that as a first stage. This was the first rocket in the new family to fly. It uses no strap-ons of its own, and has dinky upper stages. The second stage burns kerosene conventionally, but the third is... I have little information, but one source says it burns kerosene hypergolically with peroxide. The 6 is designed for rapid preparation. Apparently there is also a 6A version in the works, which will use the full length two-engine version of the booster, and apparently have solid strap-ons — a first in their space program.

And finally, they wanted a midsize rocket to carry forward the classic design of the old school Long March models, reusing many of the old parts — specifically, those of the 2F — with the new motors. This became the Long March 7. This also uses YF-100 engines (or a very similar related model), and essentially they just put four of the new skinny boosters around one of the fat ones. This means the 6A would pretty much be just a 7 without the strap-ons... at least superficially. Behind the scenes, though the 6 and the 7 use compatible dimensions and engines, the two were actually developed by different teams, and have many differences — the 7 being a direct offshoot of the Long March 5 project and the 6 being done by the Shanghai Academy of Spaceflight and Technology. In 2020 they added a 7A which has a hydrogen-burning upper stage, updated from the one used on the Long March 3. You could say that the original 7 replaces the Long March 2 and the 7A replaces the Long March 3. I guess the 6 could be considered as the new Long March 4, though it’s a step down in capacity. So the new system covers a wider range than the old, at both ends. Between the 6 and 7, they ended up cancelling the lighter versions of the 5 — they had originally planned to not only include a version with no side boosters, but also to make the core stage in two different diameters.

With the Long March 5/6/7 project they also debuted a new kick stage, the Yuanzheng-1, which can deposit satellites in high or multiple orbits. It uses hypergolics, and can fly on the old rockets as well as the new ones.

They are now working on proposed models 8 and 9. At first glance the 8 was just going to be a cheaper variant of the 7 using solid fuel for the side boosters, but then they decided that this was the one where they would try for reusability, with both the core and the side stages able to land themselves in some way, probably vertically like the Falcon. It looks, as far as I can tell from graphics they’ve shown, like it’ll use a lighter second stage than the 7 — perhaps an expander-cycle hydrogen burner, like a small version of the 5’s second stage — but that may be outdated information from the older expendable design. Another report says the new second stage will be based on the third stage of the 3A. They apparently plan to put grid fins on the core stage, like a Falcon; such fins have been added to a Long March 4 booster to try them out. They want to achieve reuse by 2025.

They also want to increase the smarts of their automation, using AI techniques. They say at least a third of historical rocket failures could have been prevented if the guidance control had been more intelligent and adaptable. These improvements will be tested in the old Long March series, which will be upgraded for as long as they stay in service.

The 9 is much more ambitious. If built, it will be enormous, with a capacity larger than the Saturn V and a mass of over 4100 tons. In their preliminary designs, it would apparently have four kerosene engines on each of the four side boosters, and four really big dual-nozzle kerosene engines on the core. The core would be 9.5 or 10 meters across — as thick as a Saturn V first stage, and a lot taller — and each booster five meters wide, like the core stage of the 5. The Russian Yenisei would look puny next to it, though the 9’s gain in capacity over the Yenisei would be only about 40 percent. Even the upper stage would be not much smaller than Apollo’s second stage. They’re building a new staged-combustion hydrogen engine for that derived from the YF-77 gas generator used in the 5’s core stage, but with triple the thrust. They will try for some reuse in the 9, but not at first.

No wait, maybe that design is out now. Apparently the new plan is to increase the power of the core and ditch the side boosters. Details are not clear yet... this may or may not be connected to a plan to imitate SpaceX’s Starship. We shall see how this plan evolves.

And they might still cancel the Long March 9. The alternate plan is apparently to build a 5 Heavy with a triple core. But for now, the 9 is still going ahead. They want to use it to send a sample return mission to Mars, and eventually people. But they don’t expect the 9 to fly until 2030. With that big boy, they’re talking up plans to send people to Mars, and put huge solar arrays into geosynchronous orbit.

Speaking of ambition, their last two missions for the 5 were a Mars lander, and a lunar lander that successfully brought moon rocks back to Earth. Then they commenced building a space station with the 5B. They’re planning a second moon-rock flight, and two orbital telescopes. And note that the maiden 5B flight was a test of a new crew capsule. They’re counting on this beast for the kinds of high-prestige missions which will put China solidly in the front rank of space powers. And China is already so active and ambitious in space that I think Russia is now clearly the number three spacefaring nation.

One controversial aspect of these missions is that they don’t control where the top stage reenters the atmosphere. American rockets save a drop of fuel for the upper stage to put itself back into the atmosphere when and where it’s safest to come down. But the Chinese don’t, and with the 5B especially, this means that a really big core stage with heavy engines might come down in an inhabited area.

(There’s also a Long March 11, which is a quick and dirty solid fuel job with four stages, which they keep around if they need to do an emergency launch in a hurry and nothing else is available. This was covered in the earlier article on China’s missile-derived solid fuel launchers.)

Long March 5: mass 879 t, diam 5 m (11.7 at base w/o fins), thrust 10600 kN, imp 4.2 km/s, type Gh+ZOk, payload 25 t (2.8%), cost unknown, record 6/0/1.
Stage name L-137 L-67 L-157 L-27 Yuanzheng-2
Role (pos) count booster (S) ×2?|4 booster (S) ×2?|4 core (1) upper (2), opt kick (3), opt
Diameter (m)   3.35   2.25   5.00   5.00
Liftoff mass (t) 150    73   171    33.6
Empty mass (t) 13   15    6.7
Fuel mass (t) ~37    ~18.1  ~24    ~4.5
Oxidizer mass (t) ~100     ~48.9  ~132     ~22.4 
Fuel type kerosene kerosene hydrogen hydrogen UDMH
Engine YF-100 ×2 YF-100 YF-77 ×2 YF-75D ×2 YF-50D
Power cycle staged (ZO) staged (ZO) gas gen closed expander ?
Chamber pres. (bar) 180    180    102    41  
Ox./fuel ratio   2.70   2.70   5.45   5.00
Thrust, vac max (kN) 2680     1340     1400     166nbsp;    6.5
Thrust, SL initial (kN) 2380     1190     1020    
Spec. imp, vac (km/s)   3.30   3.30   4.20   4.30   3.09
Total imp, vac (t·km/s) 445    215    658    117   
Long March 6: mass 103 t, diam 3.3 m, thrust 1200 kN, imp 2.9 km/s, type ZOk, payload 1+t?, cost unknown, record 7/0/0.
Stage name L-77 L-14 PBV? *
Role (pos) count core (1) upper (2) kick (3), opt
Diameter (m)   3.35   2.25   2.25
Liftoff mass (t) 84   15   1.0?
Empty mass (t)  1.6
Fuel mass (t) ~20.8  ~3.80
Oxidizer mass (t) ~56.2  ~9.6
Fuel type kerosene kerosene kerosene? *
Engine YF-100 YF-115 ?
Power cycle staged (ZO) staged (ZO) pressure-fed?
Chamber pres. (bar) 180    120   
Ox./fuel ratio   2.70   2.50
Thrust, vac max (kN) 1340     180    16  
Thrust, SL initial (kN) 1190    
Spec. imp, vac (km/s)   3.30   3.28   2.80
Total imp, vac (t·km/s) 248    44  
Long March 7 (four added boosters): mass 594 t, diam 3.3 m (7.8 at base w/o fins), thrust 7200 kN, imp 2.9 km/s, type ZOk, payload 13.5 t (2.3%), cost unknown, record 5/0/1.
Stage name L-67 or K2 L-137 or K3 L-72 ? (7A only) Yuanzheng-1A
Role (pos) count booster (S) ×0|2|4 core (1) upper (2) upper (3) kick (3|4), opt
Diameter (m)   2.25   3.35   3.35   3.00
Liftoff mass (t) 73   150    90   ~20   
Empty mass (t) 13   19  
Fuel mass (t) ~18.1  ~37    ~20.3   ~2.98
Oxidizer mass (t) ~48.9  ~100     ~50.7  ~15.2 
Fuel type kerosene kerosene kerosene hydrogen UDMH
Engine YF-100 YF-100 ×2 YF-115 ×4 YF-75(D) ×2 YF-50D
Power cycle staged (ZO) staged (ZO) staged (ZO)? gas gen ?
Chamber pres. (bar) 180    180    120    37.6 
Ox./fuel ratio   2.70   2.70   2.50 ~5.1 
Thrust, vac max (kN) 1340     2680     590    167.7   6.5
Thrust, SL initial (kN) 1200     2400    
Spec. imp, vac (km/s)   3.30   3.30   3.30   4.30   3.09
Total imp, vac (t·km/s) 215    445    235    ~78.2; 

ELECTRON — New Zealand, 2018

These guys are making a success of the tiny rocket business, as they cut the cost per launch to $6 million despite having no reusability yet. One market is “cubesats” — tiny orbital devices consisting of one or more cubical sections with a standardized size (10 cm) and strictly limited mass per cube (1.3 kg). This rocket could launch a hundred or more of them at a time. They aim to schedule such launches very frequently, like once or even twice a week, so that small budget satellite customers won’t have to wait for a berth on a big rocket, which can take months or even years, and might make you settle for a less than ideal orbit. The company is called Rocket Lab, and one of the seed investors is actually named Mark Rocket, though he is not a founder. They moved the company to Los Angeles, but the launchpad is still in New Zealand, on a cliff at the end of a peninsula, making it the prettiest launchpad in the business, as well as (they hope) being capable of really fast turnaround for frequent launches.

For 2020 they built a new launchpad at Mid-Atlantic Regional Spaceport on Wallops Island, Virginia. This will be more suitable for equatorial orbits.

This little carbon fiber missile is a two stage kerosene burner based on a very compact and inexpensive engine they call the Rutherford, after the famous New Zealand-born physicist. It’s small enough for one person to easily pick up, and can be made very quickly with 3D printing. It was the first rocket engine to use electric motors to pump the fuel — hence the rocket’s name. (I do not know if the name was also chosen to complement Russia’s big Proton.) This electric motor makes the engine much more efficient, with the tradeoff that the rocket has to lift a big pack of lithium batteries. Each engine has two soda-can-sized brushless DC motors of 37 kilowatts each, or 50 horsepower.

Like a quarter-scale Falcon, the Electron’s booster uses nine Rutherfords, and the second stage uses a single Rutherford with a vacuum bell. Their first flight attempt came up just short of reaching orbit, and their second delivered a payload. They’ve also got a tiny third stage, or “kick stage” as they call it, available for tasks such as raising or circularizing orbits. It doesn’t extend the rocket stack, it just fits inside the fairing. It has a little engine called the Curie which consumes monopropellant. It doesn’t use hydrazine — they’ve got some “green” alternative. I don’t know what it’s made of, but it might be based on hydroxylammonium nitrate (NH3OHNO3) liquified in a solvent. The miniscule thrust allows orbital insertions to be extremely precise.

They went on to evolve this kick stage into a general-purpose satellite bus onto which customer devices could be mounted, so you can just build the instruments you want and not the complete satellite. They call this the Photon. It can be had in various sizes, with monopropellant or bipropellant. A basic Photon takes up around 100 kg of your payload allowance. They have a stretch version of it which is intended to send a tiny payload to the moon, and a customer who wants to use two electrons for a “Moon Express” mission. That launch was supposed to happen in 2019, but now it’s not scheduled until 2021. This version is getting an upgraded “Curie 2” engine which has electric pumps where the original was pressure-fed, and is still not much bigger than your hand. The Photon has solar cells on the back, around the Curie nozzle, like a Starliner service module, and on the sides.

They are currently a long way from getting their launch cadence to a weekly pace, but they are still looking like the most successful of the new batch of smallsat launch companies so far. With just four launches in 2018 and six in 2019, they hope to get to a fortnightly pace soon, if they can streamline and automate enough manufacturing steps. They’re only hoping for a monthly pace in 2021, and haven’t gotten there yet. But even the minimal pace they’ve got so far is enough to position them solidly as the leading brand among new small-launch companies.

And now, after CEO Peter Beck saying they would never pursue reusability, Beck has officially announced that he is eating his hat (shredded with a blender) and starting a reuse project. The plan is to put a para-wing in the interstage, and as a drogue, a small balloon which will add drag at high altitudes during reentry. (Beck says they might also look at air brakes on the bottom of the stage.) They will not burn any fuel to slow down the booster — they’ve got none to spare. They will have some tiny cold-gas thrusters to keep it straight, but these are only needed at subsonic speeds. Before that, surviving the reentry heat is going to be quite a challenge, but they already had a lot of heat shielding on the bottom just to protect the parts from the rocket flame. The plan is to pluck the para-wing out of the air with a helicopter, which is a fairly well-understood technique that the Air Force was doing fifty years ago. Though chutes and balloons are lightweight, with a rocket so small that weight becomes significant, so even the lightest possible approach does take a bite out of their payload capacity. Fortunately, weight on the first stage imposes only a fraction of the cost that second stage weight does, so from what Beck says, the capacity penalty may be well under thirty kilograms.

The whole purpose of reuse is not to launch cheaper, but to launch more often — without reuse, their manufacturing process is currently keeping them stuck at a cadence of at most one launch a month.

In early versions the total payload capacity was only 150 kilograms, but soon they raised it to 225, and in 2020 they got it up to 300 by improving some components and lightening the batteries.

Another thing Beck said they wouldn’t do is develop a larger rocket. But in 2021 they announced the forthcoming Neutron, which will have an eight ton capacity... and be human rated. But he says it will be mainly intended for launching swarms. Their customers are still people with small satellites, but some of them want to launch them in batches. The Neutron’s first stage will do vertical landings like a Falcon. The engines for it are not developed at all yet, and will use conventional turbopumps, as the electric pumps in the Rutherford don’t scale up to that size very well. There will be four of them in the booster. They won’t launch these from New Zealand, but only from Virginia.

Recently Beck was accused of abusive management. As the company grows and matures, he still expects people to work tons of overtime as if it were still a little startup, promising big rewards later for “key contributors”. Words like “culture of fear” and “toxic” were used. Some of the pressure may be because the company is still losing money every year.

Electron: mass 10.5 t, diam 1.2 m, thrust 160 kN, imp 3.0 km/s (vac), type Mk, payload 0.3 t (2.8%), cost $20M/t, record 18/1/2.


In 2004, a suborbital spaceplane called SpaceShipOne won the Ansari X Prize by being the first privately funded craft to take a human pilot to 100 km in altitude, and then do it again within a week. This generated huge publicity. The vehicle was designed by legendary airplane builder Burt Rutan (now retired), and built by his company Scaled Composites, with funding from Paul Allen. It launched from under a specially made carrier plane, the White Knight. It used a hybrid rocket motor, with solid fuel and liquified oxidizer, namely nitrous oxide. (This is the same approach the Mythbusters used to make cheap crude rockets out of plumbing parts and the like, burning assorted fuels from candle wax to gummy bears to salami.)

After winning the prize, they formed a joint venture with Richard Branson’s Virgin Galactic, which started preselling tickets for suborbital flights. This generated even more hype, but nothing happened for years. Scaled Composites started developing the larger SpaceShipTwo, but in 2007 an engine test killed three engineers and injured three more with shrapnel. They got it flying (or at least gliding) in 2010, but in 2014 it broke up, killing one pilot and throwing the other into open air with numerous injuries.

That same year, they fired Sierra Nevada Corporation as their engine subcontractor and took engine development in-house. They kept the hybrid approach but changed the fuel formula from a rubber-based mix to nylon... and then changed it back.

Branson continued to insist that it would be ready for paying passengers real soon, and planned to ride it himself shortly. But in the meantime, Blue Origin had their New Shepard ready to sell suborbital tourist seats around the same time, and they offer bigger windows, possibly lower prices, and (so far) a record free of accidents. But Virgin will offer a longer and more interesting flight, lower G forces, and windows in more directions.&ensp:Branson did finally ride the thing, reaching about 86 kilometers altitude (which counts as space in America but not internationally) in 2021, nearly seventeen years after winning the X Prize, and fifteen after Branson started accepting money for tickets. They did this just days ahead of Jeff Bezos riding in his New Shepard, which itself had been in development for around fifteen years. They both finally got there just a couple of months ahead of SpaceX sending tourists on a multiday orbital flight.

So in the meantime Virgin took a stab at orbital launches. Not with a spacecraft, but just with a little carbon fiber rocket which is also launched from under a carrier plane. So it’s basically similar to a Pegasus in concept, but liquid fueled. They have a long way to go before they can ever take tourists to orbit... and now they might not even pursue that.

The LauncherOne rocket is a two stage expendable kerosene burner with fins at the back, with an engine they call the NewtonThree on the first stage, and a smaller NewtonFour on the second. NewtonFour is restartable. Newtons One and Two never flew — they were inadequate. Those were pressure-fed; the new ones have turbopumps. And woops, with the larger engines it turns out to be too heavy for their White Knight Two carrier plane, so they’re sticking it under a used 747 from the Virgin Atlantic fleet, which they’ve dubbed (sigh) “Cosmic Girl”. For now they’ll take off from Mojave and do polar orbits only, but that limitation shouldn’t last long.

They began work on upgrading the NewtonThree engine to a more powerful version called N3.2, even as the original had yet to fully prove itself over multiple launches. They also started work on a kick stage... and are now looking at first stage reuse via parachutes. The new push was fueled by the cash raised from going public.

Branson had previously worked on a deal to bring Saudi money into Virgin Galactic and Virgin Orbit — a billion bucks — but after one too many high profile human rights abuses by the Saudi government, he called it off and told them to keep their money.

They say they’re looking at ways to reuse the first stage. Don't hold your breath on that, but even in expendable mode they’re already way underpricing the Pegasus, and have presold lots of flights. They say that having no launchpad will allow them to quite easily ramp up to a rapid launch pace. Of course, they might well face stiff price competition from other new launchers such as Electron, if they also succeed in ramping up production. Virgin Orbit hopes to do about six launches in 2022, which is the same pace that Rocket Lab managed in 2020 and 2021.

One advantage of launching from under an airplane is that the whole operation is portable. They’ve “trailerized” their ground support equipment and made a mobile mission control, so their whole launch operation can move around the world to any available airport, including ones near the equator. They can also launch in worse weather than other rockets.

But their ability to price launches competitively faces extra difficulty because they have spent several times as much money on initial development as their competitors (Rocket Lab, Astra, Firefly, etc) have spent, and that money will be tough to get back. They’ll need to either outdo Rocket Lab on cadence and convenience, or find a profit margin while matching their prices.

They finally attempted their first test launch in 2020. The drop and ignition went fine but it failed early in the first stage burn when an oxygen pipe broke under pressure. They achieved orbit on the second attempt, early in 2021, and got their second success in mid-year with their first commercial launch. And even better, this little orbital rocket probably won’t get anyone killed.

LauncherOne: mass unknown, diam 1.6 m, thrust 330 kN, imp unknown, type Gk, payload 0.5 t, cost $24M/t at first, record 2/0/1.

ASTRA — USA, 2021

While most New Space ventures try to drum up as much hype as possible, this one has tried to keep its doings as far out of the public eye as it can. For the first three years its hiring page on LinkedIn only said “Stealth Space Company”. It was reported that the actual name of the company is Ventions LLC, but this turns out to have been a past venture by one of the founders, Adam London. (The other founder is Chris Kemp, who is mainly a software entrepreneur but has held a post at NASA. He’s the CEO.) It was also widely reported that the company’s current name is now ASTRA Space, this being short for Atmospheric and Space Technology Research Associates... but this is false. That is a separate unrelated company, with different people, a different location, and different specialties. And note also that neither of them is to be confused with Ad Astra Rocket Company, which is working on ion propulsion and the microwave-powered VASIMR engine. I’m starting to think that once they go public, it would be a prudent idea to change the company’s name to something less overloaded than “Astra” is. It doesn’t help that the rocket itself has no official name yet, so the company name is the only thing we can call it. They just designate their current design with a version number, such as “Rocket 3.1”.

While keeping publicity to a minimum, they attempted two suborbital launches from Alaska. These apparently consisted of test flights of their first stage with a dummy second stage, and neither of them managed to get clear of the spaceport grounds before falling back. Once they felt ready to attempt orbit, they went a bit more public. Unfortunately that attempt failed — they scrubbed a minute before launch, and then while pumping the fuel out, problems cascaded and the rocket was lost in a fire. This sent them back to the shop for months, after which they managed to get part way through the first stage burn before going off course and being forced to self-destruct, again failing to clear the spaceport grounds.

They build their rockets in Alameda, at the former Navy base there. They picked the spot because one of the old buildings is set up for testing engines indoors. This lets them iterate rapidly without having to schlep parts between a high-tech hub and an empty desert for testing, as most rocket companies need to do. The result is that they hoped to be setting a speed record for how quickly a small rocket startup could actually reach orbit, but that hope was dashed.

What they are working on is an orbital rocket which will be smaller than the Electron, with a 200 kilogram payload capacity. This small size was confirmed by paparazzi photos which have shown their booster being toted around with a forklift. The idea is to make it cheap, simple, and mass-producible, with no carbon composite or 3D printing, so once they have it working, they can quickly ramp up to producing and launching a rocket a day, if sufficient demand exists (which it probably won’t for many many years). They regard the Electron as over-engineered, and are hoping that their aluminum rocket will only cost a third as much, even in small production volumes. Once they start making them in bulk, there’s talk of bringing the cost down to six digits.

When their second test flight experienced a Rapid Unplanned Disassembly shortly after liftoff, we heard that the booster uses five engines... all of which failed together, apparently, due to a fire that destroyed the wiring. Even after they’ve emerged from stealth, some of our best further technical detail came from information released by NASA about R&D payments made to the company. These describe particular development tasks which include a kerosene-burning engine with electric pumps, similar to the Electron’s Rutherford engine, but apparently of lower performance. They also mention work on thrusters for satellites, probes, and interplanetary landers. Yep, they’re apparently involved peripherally in developing sample-return probes for the moon or even for Mars.

Anyway, the rocket is a stubby two-stage design in which the booster has five engines with rather small bells, and the second stage appears to be very small — the interstage and fairing just about swallow it from both ends, leaving us with (as yet) no picture at all of it out in the open on its own. Apparently it consists of two ellipsoidal tanks with only a narrow band of cylindrical hull on the upper one. It weighs maybe one ton fully fueled. The fairing is small enough that each half can be easily lifted into place by one guy. The enclosed payload volume looks like maybe one cubic meter. It appears that the tapered interstage comes off in halves, like the fairing. Eventually we we learned that the booster engine is named “Delphin” and the upper stage one is called “Aether”. The Aether is pressure-fed.

They are building this little rocket in respose to the Pentagon’s desire for a rapidly responsive launch capability, because the military services are tired of needing to schedule launches months in advance. Astra tried to get a $12 million prize from DARPA if they could make a launch with only a few weeks notice, and then a second launch within a few weeks after that. The prize also required that they do not require a fixed launchpad. They say they’ve got portable launching gear that they can set up on any flat piece of concrete, and the rocket itself can be transported in a shipping container. The DARPA prize expired, but they’ve already got about fifteen flights booked, with rockets for them already semi-assembled. They mean to transition quickly into outright mass production of these babies.&ensp:They also want to start building satellite buses, and have bought up a small outfit that makes ion engines. And they’ve gone public.

But first the rocket has to work. With the fourth test flight, they finally reached space and nearly reached orbit, which meant their goal of reaching orbit in three tries looked likely. All they needed to do was fix a mixture issue that made the upper stage run out of fuel with lox left over. But flight attempt five — the first with a real payload — was a step backwards, with the fuel hose spilling propellant and starting a fire, which made the rocket lose an engine, so it ended up wallowing sideways before starting to gain altitude. At least they got it over the ocean, with the majority of the fuel gone, before aborting. In November 2021 they finally had success with flight six, but it had no satellite, only an instrument package which stayed attached to the upper stage in order to monitor it. Maybe soon they will put up an actual satellite.

I hope they make it; they’re local to my area, and it would be great if launches could be done as inexpensively as they’re aiming for. But maybe orbital launching just doesn’t work if you’re this cheap.

But wait, what are they doing now? They just signed a deal with Firefly to license their Reaver engines and build them in their Alameda factory. This was signed shortly after both companies had test launches fail due to one booster engine quitting early. I don’t see what use Astra has for a larger engine with about the same level of reliability as the engine they’re already using. News stories are mentioning a possible Astra rocket with two Reavers in place of five Delphins, without making it any bigger, but I don’t know if that’s just speculation or is an actual plan. If it is something they plan to try, I do not see the point of the change.

Astra Rocket: mass <10t, diam 1.2m, thrust 140 kN, imp unknown, type Mk, payload ~0.2t, cost hopefully <$5M/t to $10M/t, record 0/5/1 (or 0/1/5).

ALPHA (α) — USA, 2021?

Firefly Space Systems had ambitious plans to build a small rocket called the Alpha with an aerospike engine, like NASA was trying in the VentureStar program that some say got killed by Dick Cheney. They went bust in 2016, thanks in part to a lawsuit by Virgin Orbit, claiming that Firefly’s original CEO Tom Markusic, who had worked at Virgin, took trade secrets with him. But now they’ve been revived as Firely Aerospace by a new owner, Noosphere Ventures. (That sounds like a perfect name for a bunch of egotistical coke-snorting vulture capitalists who think they’re building the future, but what do I know?) The new company is ditching the aerospike idea for traditional kerosene turbopump propulsion, which ironically makes them more likely than before to be using the same technology as Virgin Orbit. They’re also making the rocket bigger than it was in the original plan... which I suspect might not be all that good an idea, as they’re trying to compete on cheapness. This means that many of their small-sat customers will still have to settle for sharing rides, which will be cheaper on a big rocket. Firefly now has many more employees than before, including a branch in Ukraine, the homeland of Noosphere boss Dr. Max Polyakov, who has sunk some $150 million of his own cash into the venture.

Polyakov’s Ukrainian parents were both aerospace engineers. His goal, beyond making a profit, is to revive Ukrainian high-tech industry, which is a shambles now that the Crimean invasion has made cooperation with Russia impossible. To this end, Polyakov has founded a new engineering school there. But Polyakov doesn’t just do aerospace: his first successful venture was a company that ran disreputable dating websites which got accused of fraud, leaving him with a lot of distrust from the western financial world, which adds to the distrust they already have of entrusting sensitive awrospace work to Ukraine.

This rocket is somewhat like the electron, but not nearly as small. It has two carbon fiber stages, both burning kerosene, with four “Reaver 1” engines (yeah, we know what their favorite TV show is) on the booster and a single little “Lightning 1” on the upper stage. Both engines employ a tap-off power cycle, which is rarely used — the pump turbine is powered from a hole in the side of the main combustion chamber. The four first-stage engines each gimble on one axis only.

They planned to follow it up with a Beta (or β as they prefer to spell it), which would be basically an Alpha Heavy, with three boosters side by side. But then they told people that the Beta would have a larger core and use the Aerojet-Rocketdyne AR1 engine — the staged-combusion kerosene burner which was originally intended to replace the Russian RD-180 in the Atlas and Vulcan. But Firefly’s website still shows the version with three Alpha boosters. I wonder what kind of deal Firefly was given by Aerojet-Rocketdyne... who farted around for years, procrastinating on making the AR1 despite increasingly urgent Congressional mandates, only to find that by the time they finally started getting serious with it, Blue Origin had beaten them to the punch and stolen their main customer, ULA. (At one point, they even offered to buy ULA entirely! Apparently $2 billion was too low an offer. A few years later the shoe was on the other foot, and they got bought out by Lockheed.) The AR1 has enough power that the Beta might have a capacity of eight tons, whereas the triple Alpha would do at most four.

In January of 2020, they managed to get a completed booster onto a stand for a static fire test. Unfortunately it caused a fire which wasn’t quite static — flames in the engine compartment due to a fuel leak — which prompted a rapid evacuation of surrounding neighborhoods. The test immediately aborted itself and extinguishers automatically blew out the fire, with no real damage done.

(That’s a much better situation than rival company Rocket Crafters suffered around the same time, in which an “overpressure event” during an engine test punched holes in their roof and started grass fires outside. They were trying to make a hybrid engine called STAR3D, in which the S was supposed to stand for “safe”.

They hoped to get to orbit within six months after fixing whatever caused the leak. It took eight to get a successful run on the test stand, but that left them thinking they could go for orbit within weeks. It was not to be... even after the rocket arrived at Vandenberg, the expected launch window passed by with no word from the company for months after. It wasn’t until the following September (thanks in part to covid) that they finished the updates to the launch pad, completed a static fire on it, and launched. It looks like it lost an engine early, and managed to keep flying for about two more minutes before it went sideways and they had to blow it up. (In such cases they usually want to get it as far as they can from the launchpad, with as little remaining fuel as possible, before pushing the boom button.)

Firefly is also eyeing the lunar landing market, which NASA is trying to fund commercial development for. They’re working on a small lander which they call Genesis — no, now they’re calling it Blue Ghost — and an Orbital Transfer Vehicle with an ion engine. That will use the same Aerojet-Rocketdyne hall-effect thruster that is used on the secret X-37B spaceplane, and the Genesis will license some technology developed for Israel’s Beresheet lander, which crash-landed on the moon in its maiden flight. They are aiming for a capacity of 85 kilograms for a lunar surface instrument payload.

Finally, they’re talking about their Gamma (γ) rocket being a spaceplane. That is of course many years away.

Meanwhile, they’re also willing to sell engines, it seems, or license them. They signed a deal with Astra to let them build Reaver engines for use in their own rockets. The purpose of this is not clear, as Astra’s own Delphin engines, though smaller, seem to be about as ready and reliable as the Reaver is. This deal was made just after both companies, at nearly the same time, had test launches fail because one engine gave out.

α: mass 54 t, diam 1.8 m, thrust 740 kN, imp 2.9 km/s, type Tk, payload 1.0 t (1.9%), cost hopefully $15M/t, record 0/1/0.

NEPTUNE — USA, no estimate

Interorbital Systems is yet another startup with a little rocket for launching cubesats and such... but their approach is different. They’ve designed a simple disposable booster core which cuts lots of corners to be super cheap — it burns turpentine hypergolically with nitric acid, it uses pressurized tanks instead of pumps, it uses ablatively cooled nozzles, and so on — and then they designed them to be used in parallel. Tell us how big your payload is and we’ll tell you how many booster cores to put under it. Like real-life Kerbal players, they just stick more and more side boosters on until your payload flies. Common configurations they describe include five in a plus-sign layout, and seven in a hexagonal one. More recently they tested with four in a square pattern. They have planned a setup with five clusters of seven; by adding up thirty-five little boosters, they might be able to put a whole ton in orbit. These rockets could be launched at sea, hence the name. Or, with smaller bundles, a flimsy little trailer is all that’s needed. They claim the whole system is so simple that two people and one laptop could perform a launch.

The whole idea is derived from a German company called OTRAG, which tried to put together a similar rocket made of cheap disposable pressurized modules back in the seventies and eighties. One of the designers was none other than Werner von Braun. Their venture didn’t fail: it was forced to quit by political pressure from neighboring countries which didn’t want Germany to have rockets. The remnants of OTRAG are now advisers to Interorbital. But the new group is led by people unaffiliated with the earlier effort, most notably CEO Randa Milliron, one of very few women to run a rocket outfit, and someone familiar with doing things in a cheap DIY way from experience playing in a punk rock band. Her husband Roderick, who was also in the band, is the company’s CTO. As amateur hobbyists they once built a cryogenic engine for under a thousand bucks.

The company has announced ambitious plans to put an instrument package on the moon, as part of the competition for the Lunar X Prize. But unfortunately, they seem to be having plenty of trouble just getting the damn thing to fly. Their target dates just keep slipping, year after year, and as yet they’re still working on mastering the shortest suborbital hops. Very little has been heard from them since 2018, but they still make noises like they’re trying to compete with the likes of Astra for DARPA prizes.

Neptune N5: mass unknown, diam 1.9 m (0.6 per core), thrust 1300 kN? (330? per core), imp unknown, type Pv, payload 0.03 t, cost unknown, record 0/2/0.

— failed plans, 2017-present —   [Show]

— not flown yet —   [Hide] 

This section may include some projects with more hype than hope. Small startups continue to work on new innovative launchers: the Bloostar and Miura from Spain, the Haas from Romania, the Prime from Britain, the New Line and Nebula from China, the Hapith from Taiwan, the Blue Whale from South Korea, and the RS1 and Terran from the USA. India’s space agency is also working on a small solid-fueled launcher. Argentina and Brazil hope to join the orbital club as well, as does Turkey. Among larger rockets, Blue Origin’s forthcoming New Glenn looms like a colossus, and Britain’s Skylon has the potential to make orbital costs fall through the floor. The traditional aerospace giants struggle to keep up with the pace of innovation, with plans such as the Phantom Express and the Omega falling by the wayside, and only the Vulcan still moving toward deployment. And SpaceX wowed us all again as we watched them build the incredible Starship, which if it really flies will be both the most powerful and the most revolutionary rocket of all time, capable of opening up the whole solar system. Meanwhile, Congress has pumped billions and billions through NASA into the bloated SLS program, which has no reusability and no chance of commercial application.

HAPITH — Taiwan, 2021?

The name Hapith means “flying squirrel” in the language of the Saisiyat, one of several peoples who were indigenous to Taiwan before the Chinese took over. About five thousand of them still live there. TiSPACE, the company building the Hapith rocket series, has in the past faced protests from indigenous peoples, but seems to have worked out a better relationship with them now.

The rocket itself is of a somewhat crude type, a hybrid using solid fuel and pressurized fluid oxidizer — to be specific, rubber and nitrous oxide. This kind of design can waste a lot of oxidizer, but they claim theirs is less wasteful than a solid rocket, as well as of course being safer since it’s possible to shut it off, and it’s supposedly impossible for a hybrid rocket to explode. (Tell that to Rocket Crafters) It’s deeply throttleable, and also restartable.

The Hapith V needs three stages to reach orbit (their suborbital Hapith I has two — it looks like the V without the bottom stage). The first stage uses five “Lelien 1C” motors, which can steer through liquid injection. The skinnier second stage has four Lelien 1B motors, which gimbal. The top stage, which is skinnier yet, has a single gimballed Lelien 1A. All use carbon fiber construction. All in all, it’s about twice as big as an Electron and offers similar capacity.

Their launch facility is is a relatively undeveloped area on Taiwan’s southeast coast, and they plan to expand it considerably if they are successful enough, but first they want to find another site in Scandinavia or Australia, as the local one doesn’t have a clear pathway for sun-synchronous launches, which is one of their main target markets.

Some souces say that the Taiwanese government would have loved to invest more directly in rockets, and developed the capability much sooner, but they were held back by diplomatic pressure based on fear of antagonizing mainland China. South Korea experienced some of that preseure too. In particular, the USA wanted both countries to not have solid fuel first stages, as these are ideal for building ICBMs with. With that kind of inhibition... an outfit like TiSPACE is what’s left.

Hapith-V: mass 23 t, diam 2.2 m, thrust 640 kN, imp unknown, type H, payload 0.3 t (1.3%), cost unknown.

RS1 — USA, 2021?

ABL Space Systems is working on a rocket quite similar to the Firefly Alpha, with three kerosene engines on the booster and a tiny one on the upper stage. It aimed to carry 1.2 tons, which is on the high side for a smallsat launcher, but if someone has a sat that size, it gives them a spot in the market with no competition from the other startup companies. They raised that goal to 1.35 tons once their engine performed better than planned. They quote a flat price per launch of $12 million, which is not that low compared to some of the other outfits. Rocket Labs sells Electron launches for significantly less, and Astra is promising they will dramatically undercut the Electron’s price. And heck, there’s a Russian/Spanish company called SpaceDarts which, if they can be believed, might someday be able to put something tiny in orbit for under $50,000 if you buy in bulk. Of course, they all have lower capacity.

Like many other smallsat companies, they are trying to leverage 3D printing to make an expendable rocket engine cheaply. But they use it only for selected components, such as the combustion chamber; for a lot of parts, they stick to copying designs already known to work dependably. Their whole philosophy is that innovation means nothing unless you know it will work, so proven reliability trumps all other goals. The rocket body is traditional aluminum. And like several other American builders of small rockets, they are trying to fulfill the Pentagon’s desire for a launcher which can be deployed very quickly. They plan to launch it from a heavy truck, like a Chinese ICBM. Furthermore, their long term plan is to so thoroughly automate the launch process that no live human being needs to be present at the site; someone can just push a button remotely and up it goes. They’re getting some Air Force Space Force money to pursue that goal. The Pentagon wants this to be doable from “austere” locations — like maybe they’re thinking of camouflaging the truck and keeping the launch site hidden.

The founders are former SpaceX engineers, notably Harry O’Hanley and Dan Piedmont, who are now CEO and CFO. And in 2021 they somehow sold Lockheed on a deal in which the larger company would hire them for dozens of launches. Nice work if you can get it, and quite a vote of confidence in a rocket that is far from ready.

RS1: mass unknown, diam 1.8 m, thrust 560 kN, imp unknown, type Gk, payload 1.35 t, cost hopefully $9M/t.

SSLV — India, 2021?

The Indian space agency’s PSLV has been a considerable success, but clearly they have to bring launch prices down. Although they are working on a reusable launch vehicle, for the short term the way to do it is the way everyone else has been doing it: by building a cheap solid rocket with minimal capacity.

They’re talking up plans to have fifty or more launches a year, bringing in lots of revenue. But given the large number of direct competitors this rocket will have, especially in China, I am doubtful of it finding that much business.

SSLV stands for Small Satellite Launch Vehicle, and they say it will cost a tenth of what the PSLV costs, despite its not being all that tiny. This rocket is as uninteresting as most of its small solid peers. The bottom stage is called the S85, which makes it smaller than the core booster of the PSLV, but not a lot smaller. The second stage is the S7, which is the third stage on the PSLV. Atop that goes the S4, which is basically the same thing but shortened. Finally, a liquid-fueled kick stage is used for orbital trimming. It has open mesh interstages like an old Russian rocket — a feature which seems pointless when solid fuel is used, as its main benefit is to allow ignition of liquid stages while under thrust, obviating the need for separate ullage motors.

Detailed specs are scant as yet. The most interesting bit might be the kick stage, and I have no idea what fuel it uses, or anything.

The rocket has been subjected to extensive delays. First, all work on it was paused so that ISRO could concentrate on their Chandrayaan 2 moon shot (which crashed on the lunar surface, like Israel’s Beresheet). Then the following year, the whole space center pretty much shut down due to covid-19.

SSLV: mass 120 t, diam 2.02 m, thrust unknown, imp unknown, type S, payload >0.5 t (0.4%), cost hopefully $8M/t.

VULCAN — USA, 2021?

The United Launch Alliance, having been caught somewhat flat-footed by the new competitiveness in the launch market, and by tensions with Russia which may halt the supply of Atlas V motors, is now putting together a modern rocket of its own to replace Atlas: the Vulcan. Uncle Sam is contributing to the development effort, yet people have been noticing the ULA Board of Directors dragging its feet on fully committing to the project. Hopefully that hesitation is in the past now. The intent is to cut the Atlas’s launch cost in half. They may want even more badly to replace Delta, which they now say is too expensive to make, except for the few who are willing to cough up for the Delta IV Heavy, which is the only Delta model they still offer, and which will probably lose its market once bigger rockets come into regular use. For that matter, once the Vulcan is given a full complement of strap-on boosters, it should pretty nearly match the capacity of the Delta IV Heavy.

ULA partnered with Blue Origin (see the New Glenn article) to use their BE-4 staged combustion methane engine, which may now be ready for full production... or maybe not; a government report just said that issues with the engine may be threatening the readiness of the Vulcan, and therefore risking noncompliance with the federal mandate to stop using Russian engines for national security launches by 2022.

They’re calling this a codevelopment effort, but I have not heard of any engineering contribution coming from the ULA side. Aerojet Rocketdyne was lobbying to have their proposed AR1 engine used instead (and yes, “lobbying” meant they were getting members of Congress to try to put a thumb on the scale in the selection process), but their experience with expensive engines such as those in the Space Shuttle has apparently left them ill-prepared to compete on cost per flight, so they don’t have a suitable motor anywhere near as ready as the BE-4 is... the Air Force has paid Aerojet-Rocketdyne around a quarter billion to develop one, and after years of pressure to stop American companies buying from Energomash, their AR1 replacement still had yet to be test fired. It was to be a fairly direct replacement for the RD-180, being a high performance staged combustion kerosene burner, but it would be two separate engines instead of a single unit with two nozzles. But in the fall of 2018 ULA finalized their choice to use two BE-4 engines instead. Either one would give it a capacity upgrade over the Atlas, but the BE-4 has the edge in thrust, and presumably in specific impulse as well.

The rest of the Vulcan will apparently be a mishmash of existing Atlas and Delta parts, some of which are to be updated later. They are planning to use up to six small solid boosters around the base to augment lift when needed. Though positioned primarily as a replacement for Atlas, which is much more heavily used than Delta is, it might be some Delta IV tooling which gets repurposed to make the Vulcan’s core stage, which is slightly bigger around than the Delta’s five meter diameter. Cost savings relative to the Delta should be huge.

Is it going to be rated for human passengers? Yes. Is it going to be reusable? A little bit. The plan is that the engine section would detach itself from the first stage, reenter with an inflatable heat shield, and descend on parachutes. If all goes well, it would then be snatched up by helicopters before it hits the ocean. If successful, this would be relatively inexpensive to build — a lot less complicated than the Ariane 6 or 7’s winged landing system, and more fuel-efficient than landing the entire booster, though the helicopter operation would certainly have some expense, and losing the rest of the booster would allow it to save only about two thirds of the cost of the first stage. Two thirds isn’t bad, but on the other hand, they aren’t going to put this capability into the first Vulcan version. And that heat shield is going to have its work cut out for it, as the Vulcan booster, like that of the Atlas before it, will get to unusually high speeds and altitudes before cutting the second stage loose. The reentry would take place many times further out to sea than those from, say, a Falcon 9.

The whole program is designed to evolve incrementally away from the Atlas one step at a time; using the BE-4 engines and methane tanks is one big step, but lots of smaller ones will be done later, such as replacing the Centaur second stage, which is undersized for it. They want the new one to be able to remain fueled and active for weeks rather than hours after it reaches orbit. The working name for the new one is ACES, and it isn’t scheduled to fly until 2023. It has a modular design so it can be made in various lengths, with one, two, or four engines. The motor they use would, at least for a while, be some version of the venerable Aerojet Rocketdyne RL10 hydrogen-burner, like they’ve been using all along for their Atlas and Delta second stages, but they might switch to the Blue Origin BE-3U (which has quite a bit more thrust than the RL10).

Or not. They now say that their ACES plans are being scaled back. The new upper stage will now be called Centaur V, and though it will use many ACES ideas to increase its endurance, fuel capacity, and reusability, it will not be a full ground-up redesign. They still say it might eventually be able to do missions with 500 times the duration that the old Centaur could handle.

One odd feature of the ACES is that it would meet its needs for electric power not with solar panels or fuel cells, but with a six cylinder internal combustion engine which burns the vapors from the hydrogen and oxygen tanks. (A piston engine has never gone into space before.) The engine’s heat would be used for keeping the fuel pressurized. It’s part of a system which is designed to eliminate many of the secondary fluids and energy sources which other rockets have to lug around with them to make all the little parts work. I don’t know if this idea will be used in the Centaur V... to me a fuel cell would make a lot more sense.

With a bigger upper stage and six side boosters, they think a Vulcan could hoist up to 36 tons — enough to compete very directly with the Falcon Heavy and the New Glenn. There’s been some loose talk of them making a triple-booster Vulcan Heavy, but no such plan will be pursued for many years yet. If they do build one, it would be a lot more capable than the Falcon Heavy. Even the single-stick Vulcan looks to be fairly competitive with the Falcon Heavy in both capacity and cost... unless SpaceX cuts their prices, which they probably could.

They’re also tackling reusability from another angle. For missions beyond low orbit, rockets usually need a third stage added, but they envision avoiding this by making the ACES or Centaur V reusable, which would give them something they call a “space truck”. A few of them could be parked in low orbit, and the launch vehicle would rendezvous with one, fuel it, hand over the payload, and tell the truck where to take it. After completing the job, the truck could return to its parking place. This would not only save building expendable third stages, it would save the weight of lifting it along with large payloads; you’d only need to lift the fuel. But the fuel is the heaviest part (or to be more exact, the lox is), and this system would be of little use in cases where a lower orbit is the final destination of the payload, as it quite often is... and orbital transfer just isn’t the costly part of the average mission. So this plan might not have much impact for most commercial work, though for lunar or interplanetary missions, this sort of refueling might yield extra delta-V. On the other hand, if you want to bring the truck back to low orbit, that increases the fuel requirement again, so its weight may be no better than sending up an expendable stage.

But it sounds like the real point of ACES is that they are making a long term bet on the possibility that someday they will have a facility for making hydrolox fuel away from Earth, such as at the lunar south pole. ULA has called for the government to work toward this goal, which if achieved would give ACESes the ability to go anywhere.

The Russians, on the other hand, are hoping to build an orbital truck with nuclear-powered ion engines. They’ve had plans for this on paper for about a decade. It would be covered on the sides with big hinged radiators to disperse about three megawatts of heat. They call it the Transport and Energy Module. This would move slowly because it would only have about 18 newtons of thrust, but it would cut the mass of needed propellant down to a tiny amount, like no heavier than the payload. This thing could, like, make repeated trips to Mars orbit and back, or explore asteroids.

Unless the government gets more heavily behind this, I don’t know if ULA will even hold together... they’re laying off workers, though apparently they are still turning a profit. And in May 2018, their machinists’ union went on strike against them. Even if they succeed with this project, a 50% price drop may not save them. Some governmental launch customers, such as the Air Force, have requirements that there be two American providers for any rocket they need, so they might prop up ULA for a while (as they are currently propping up the Delta 4 Heavy though ULA would rather drop it)... but if one of the other startups qualifies, ULA might eventually be out in the cold. But on the other hand, it may turn out that none of the upstarts is capable of building something as good as the Vulcan, and its prices may be reasonable for its quality level. This rocket might end up a real winner. Their Atlas V has been the safest and most dependable large rocket ever built, and if they can continue that record with the Vulcan, it may not matter much that SpaceX underprices them. And Blue Origin’s New Glenn may not be any cheaper, nor ready anywhere near as soon at the rate they’ve been going.

Vulcan 401 (no side boosters): mass 430 t?, diam 5.4 m, thrust 9800 kN, imp 3.1 km/s?, type ZOm, payload 10.7 t (2.6%?), cost hopefully under $5M/t.


Of all the entries on this page, this is the most updated and revised, due to the frequent and public changes to the design of the proposed rocket. And also due to the fact that of all the rockets listed here, this one is the most truly revolutionary. If it works, it will expand human access to the solar system in a fundamental way that no other rocket can match. There may be other big rockets which on paper could launch a hundred ton spaceship, but no others have a way of then loading that ship with a thousand tons of fuel. And once you’re up in space with that much fuel... you can go anywhere.

SpaceX may not have announced anything to compete with the New Glenn, but what they’re working on now is a leap right past it: the most ambitious rocket design ever budgeted. Its goal is no less than to enable colonization of other planets! This rocket would start with an enormously powerful methane-burning reusable booster, far larger than the New Glenn, and on top of it, they plan to put a huge passenger-carrying spacecraft. In their original 2016 proposal, this spacecraft would have been twelve meters wide and 49 long — big enough to swallow the entire first stage booster of a Saturn V (10.1 by 42 meters) except for the finned fairings — but in 2017 they scaled it down to only nine meters wide. Since then that diameter has remained unchanged, though there have been constant changes to the height, the expected weight, the number of engines, the aerodynamic surfaces, and even the construction material. The expected dry mass has varied too; the latest definite number I have is from 2019, when they said they’d shoot for about 110 or 120 dry tons for the ship part. (Their initial rough prototype, which never flew, weighed about 200.) In early flying prototypes the bare fuselage is somewhere around 50 tons, I think, at just under 4 mm thick. Later versions may use thinner metal in selected areas. But areas near the bottom which support a heavy vertical load have to be reinforced with a corrugated inner layer, which more or less doubles the thickness, adding many tons beyond the weight of the skin alone.

This spacecraft would have its own engines, which would act as the second stage, thereby eliminating the last part of a rocket stack which previously had to be expendable, and getting them much closer to the dream of a spacecraft which can be reflown for only the cost of the fuel.

To go to Mars or wherever, this spacecraft would put itself in orbit with passengers aboard, and then dock with a tanker for refueling. The tanker would just be another Starship, but with the partitions between the fuel tanks moved closer to the nose to increase its capacity (though just leaving the front empty might leave nearly the same amount of fuel unburned). The passenger ship’s tanks can hold about twelve hundred tons of propellant (the lox being most of the weight), so it will take many tanker flights to fill up the passenger vessel. At first they claimed the payload would be 150 tons, then they said 100, and now they only say it will end up somewhere between those two numbers. Fewer tanker loads will suffice if you don’t need the maximum delta-V. The tanker could be launched by another flight of the same booster, which is designed to be reused rapidly with minimal maintenance. They’ve talked about eventually doing tanker launches as rapidly as three times a day with one booster, which to me sounds very optimistic, and certainly won’t happen in the short term. One part of this hope is the idea of landing the booster right back onto the launchpad, or close enough that it can be swung back into launching position with a simple crane built into the tower. Obviously this is a risky strategy, as a slip could destroy the launch complex. The latest variant of this idea is that the pad would have a C-shaped support ring near the top which the booster’s grid fins would come to rest on, so the bottom end doesn’t touch the ground.

And this is where we start to see what a gamble the Starship plan is. Any launch beyond low orbit, whether to the Moon or the Gateway or Mars or Pluto, would absolutely require the ability to launch multiple tankers within a span of just days. If they get spread out over weeks, the fuel might be lost from the orbiting ship as fast as they can bring up more. And this rapid cadence also depends on being able to land the boosters and tankers right next to the pad, which means landing them where there’s a maximum of risk that a crash could stop the whole operation for months. Rapid reusability has to be completely nailed down as a safe, commonplace, routine operation before it will become possible to get any use out of the Starship for distant destinations, especially if passengers are on it.

Once fully fueled, the passenger ship would then cruise to Mars, possibly at speeds high enough so the trip might take as little as three months (but I doubt it). Slowing that flight down might save some tanker loads, but on the other hand it could also increase the passengers’ radiation exposure.

To come back from Mars... well, they haven’t fully worked that out yet. As presently designed, it has enough fuel to land there but not to take off again. They are planning to devise a means for people on the surface of Mars to manufacture their own methane and lox out of carbon dioxide and water (2 H2O + 1 CO2 → 1 CH4 + 2 O2) via the Sabatier process, which involves splitting the water and then reacting the hydrogen with the CO2 via a metallic catalyst such as nickel. They hope to land machines for this purpose on an unmanned flight, and it’s conceivable they might be able to start filling up tanks of return fuel before the human passengers set off... but I think it’s likely that human beings might have to get the machine running after they arrive, as it will be hard to automate a process to dig up the ice it needs, which does exist on Mars but is not abundant or easily accessible, except at the poles.

And not only will they be faced with the daunting prospect of mining huge amounts of ice, but they will also need about a megawatt of electric power to run the process, which will not be easy to generate. Solar cells for that much power would have to be made very thin and lightweight... and therefore very fragile. Plus they would be subject to dust storms. All in all, the plan to get people back to Earth when or if necessary definitely needs work. Some have proposed making a mini-starship to make returns feasible.

It is this ability to refuel in orbit, 100 or more tons at a time, which turns a rocket into a spaceship. Without that, it’s just a second stage with a nonremovable fairing, but with it, it gains a level of delta-V never previously available to heavy deep-space missions — up to about eight km/s depending on payload — making any body in the solar system reachable with a bit of gravity assist. Of course, if you put people in it, voyages beyond Mars are still implausible due to the time it would take, but the ship itself can get there. Give it a smaller rocket as a payload, and it should be no problem to perform feats of delta-V such as soft-landing a probe on the surface of Io or Mercury, or flinging something past Voyager 1.

Though on paper they had what looked like a complete design as early as 2016, first under the name “Interplanetary Transport System” and then the placeholder name “BFR”, very little of this was built or tested until 2019 except for the “Raptor” engines. These are not all that much heavier than their existing Merlins but produce twice the thrust — about three fourths as much as Blue Origin’s far larger BE-4. These new motors get a much better specific impulse from methane than the Merlin now gets from kerosene, thanks in part to an exceptionally high combustion chamber pressure: 250 bar for the near term, and hoping to get past 300 later on. In 2017 they already had a two-thirds scale test engine working well at 200 bar (the pressure of a scuba tank) — already high enough to raise some eyebrows even in an expendable motor. By mid-2020 one test engine had survived 330 bar. (The BE-4’s target is 134 bar, a safer value which might lend itself to a longer reuse lifespan, but still outdoes the Merlin. The Space Shuttle’s main engines, which were the most advanced of the 20th century, reached 206 bar.) The first full-scale Raptor was completed and fired early in 2019, apparently with substantial changes from the smaller version, and later that year they started flying it in a low-altitude test vehicle. That version did have issues with durability, producing what is sometimes called “engine-rich exhaust”, but apparently it fully met its ambitious goals for power and thrust. A year later they had the engine flying with no such issues... except when fuel-pressure problems made it run too lean. (Meanwhile, whatever testing Blue Origin is doing on the BE-4 has been out of sight and we have no idea what progress they have made, but they appear to be satisfied with it, as they are now constructing their engine factory.)

Even as they were building test articles, fundamentals of the rocket’s overall construction kept undergoing deep changes. For instance, the intent had originally been to build the ship out of carbon composites, until in late 2018 Musk suddenly said they were moving toward metal construction. They decided that the most weight-efficient material that could survive re-entry might be, of all things, stainless steel! It can be polished to reflect away most radiant heat (which, astonishingly, scales with the eighth power of speed during reentry), and it can be cooled from the back with piped fluids — or in the tank sections, perhaps just by splashing the cryogenic fluid against the interior walls. At one point they said they would also put tiny pores in it so the coolant fluids (i.e. extra propellant) boil out to produce a gaseous protective layer... but this idea was fraught with risks, so they wisely backed away from it. They then developed a thin ceramic tile to put over the steel, getting it to re-emit as much radiant heat as possible, which means it’s near black in color. Because steel can tolerate far more heat than aluminum or carbon fiber, the tiles don’t have to deflect the entire heat load, which means they can be quite thin and light compared to previously used materials such as the Space Shuttle’s tiles, or a traditional ablative heat shield. They can even have little gaps between them. Any hot gases leaking through will first encounter a thin blanket of insulating fibers, and then the shiny steel surface.

To be more specific, the material they plan to use in mature versions of the vessel is a special new chromium steel which is treated at cryogenic temperatures. Apparently it was the breakthrough which made this new stainless steel available which caused them to change their minds about using carbon fiber. They call it “30X” for now. Besides tolerating heat, this new steel also likes cold: it doesn’t turn all glassy and brittle when chilled to the temperature of liquid oxygen, as many materials do — in fact, it’s actually stronger cold than at room temperature, which for steel is kind of bizarre. Insulation for the tanks will essentially be nonexistent: the idea is to make the tank wall and the outer hull a single piece to avoid redundancy, but since steel is much more thermally conductive than carbon composite is, keeping things cool will be a problem, especially in the atmosphere. It looks like the current plan is to just accept the extra boiloff. Whether this might affect the capacity to keep fuel available on months-long missions may still be an open question, as liquid oxygen can produce a vapor pressure far beyond the capacity of the fuel tanks to contain, long before getting near room temperature.

Even after sending prototypes on hop tests they kept making design changes. Musk’s philosophy is to have no attachment to sunk costs, to have no reluctance to ask other engineers to change their part if it’s making your part difficult, and that if a design turns out to be difficult to implement, that means the design is flawed and should change. The result that this philosophy arrives at may turn out to look amazingly simple and crude, belying the amount of sophistication that went into pursuing complex alternatives. He intends to keep pursuing rapid iteration and revision as they build and launch numerous Starships, so that in a year or two they arrive at something much better than what they’ve got now. They are free to do this because so far, almost nobody is actually paying them to launch on one, so the only thing these test flights will be used for is putting up their own Starlink satellites.

Unlike the Merlin, the Raptor uses “full flow staged combustion”. That enormous 250+ bar chamber pressure is applied to all of the fuel and all of the oxidizer, as each is preburned with a minimal amount of the other to power the pump on its side. (On the methane side, the mostly unburned result is then used as coolant on the outside of the bell and combustion chamber.) This means it doesn’t lose specific impulse by having a separate low-pressure exhaust pipe coming out of the turbopump, as the Merlin does. The BE-4, by contrast, uses oxygen-rich partial staged combustion, which is the same approach preferred by Energomash. This puts it ahead of the Merlin in efficiency, but may actually be less safe, as it requires the turbine parts to withstand hot oxygen at high pressure. Hot oxygen is what makes a cutting torch eat through steel in seconds, so handling this is not easy. The mitigating factor is that it’s not nearly as hot as fully combusted exhaust would be. (Blue Origin’s BE-3U hydrogen engine, by contrast, does have an exhaust pipe... it uses an open expander cycle, dumping cold unburned fuel.) The full-flow cycle shares this issue of hot oxygen but it might allow the heat level to be somewhat more moderate in the turbines. SpaceX originally claimed “long life through... more benign turbine environments”, and said they have a new oxygen-resistant alloy to make the turbine from. But they may be walking that back a bit: Musk’s latest hints imply that instead of keeping the internal conditions benign, they will instead push this new alloy even harder, and raise the pressure in the engine to even more unheard-of levels. And to have 300 bar in the chamber, the pressure in the turbines is at least double that, maybe reaching as high as a thousand bar — a rather inconceivable number. Both Energomash and Aerojet Rocketdyne have experimented with full flow, but no such engine has flown before. Staged combustion of any kind is rare in American engines, the RS-25 Space Shuttle Main Engine (which used a fuel-rich cycle) being the outstanding example.

One possible issue I’ve heard mentioned is that it might be tricky and complicated to start the Raptor up. That’s an issue with partial staged combustion too; it’s why the Space Shuttle’s hydrogen engines had to be started seven seconds before lighting up the solid boosters. The Raptor has multiple turbine stages to produce all that pressure, making the issue even trickier. Even the simpler Merlin has to be started by first running helium through the turbine to get it turning. (Historical note: in the Apollo, the initial flow to get the pumps turning was powered by gravity. The rocket was so tall that even standing still, the fuel entering the engine was under quite a bit of pressure.) I have no idea how they start the Raptor; with (as I understand it) two separate sets of turbines on independent axles, I can only guess that they might have to blow both fuel and oxygen through it unburned, which would risk an explosive “hard start”. But despite this, their test flights have demonstrated that the Raptor can, as claimed, be started up very quickly. This would need to happen if, for instance, the Starship suddenly has to detach from a failing booster. The escape plan in this case is mostly to trust the ship’s steel hull to protect it from the booster’s fireball for a second or two, rather than to try to outrun it completely as you would have to with something like a solid-fuel booster. But even so, you still need thrust right away.

SpaceX also plans to develop reaction-control thrusters that burn gaseous methane and oxygen, replacing the hypergolic “Draco” thrusters that the Dragon capsules are equipped with, as well as the very inefficient compressed-nitrogen jets that they now use to steer Falcon boosters during re-entry. Musk says they’ll have quite a lot of thrust. I presume that these will be turbineless, and use electric pumps or heat to pre-pressurize their fuel so they can start instantly... but reliably igniting a gas mixture when surrounded by vacuum is a tricky challenge in itself, so it’s understandable why most makers of deep space thrusters would rather use hypergolics, or even monopropellant. They also plan to eliminate the helium tank that the Falcon uses to pressurize its kerosene, since methane and oxygen can be pressurized enough to feed the turbopumps (about five bar) just by backfeeding some heat from the engines, if ambient warmth hasn’t already given you all the pressure you can stand. Since they also plan to use spark plugs for ignition (like the Space Shuttle’s main engines), instead of the pyrophoric igniter fluid that the Merlin uses, this would eliminate the need for any other consumable chemical to be supplied — an important consideration if your journey is starting from someplace other than Earth. But this may have to wait for a future version. In today’s version they will, for instance, still use cold nitrogen thrusters, and the first high-altitude flight of a Starship prototype (SN-8) crashed because the autogenous pressurization didn’t work for the small “header” tank that stores fuel for the landing burn. This is positioned between the two main tanks, and the lox header is up in the nose of the ship to balance the weight during reentry, so getting hot gas into them is not so simple. For a short while, they went back to using helium pressurant, but this caused a new failure mode so they switched back. And time will tell whether a spark igniter can be reliable enough for reaction-control thrusters... they’ve had some issues with spark ignition dependability in ground tests of the Raptor.

The number of engines per stage has changed repeatedly. By 2020 they had settled on six engines for the ship, and dropped the number on the booster to 31, saying they might go as low as 28 if they can get the thrust high enough. In mid-2021 the current plan is for 29. This high degree of numeric redundancy means that even if several booster engines have issues at once and shut down, they could still reach orbit just fine. It also means that propulsive landings would be safer, as they could also survive an engine failure. They now plan to burn three engines when landing the ship, and be prepared for any one of the three to fail. (Falcon booster landings traditionally depend on the central engine alone, even if two additional ones were sometimes used for part of the landing burn.) Unlike Blue Origin, they feel that keeping the engine relatively small and (by rocket standards) mass-produced will be the secret to cheapness.

The booster engines will be nongimballed except for a central cluster of nine (originally seven). The fixed outer engines will have higher thrust than the central ones. The outer three engines on the spaceship would have large bells optimized for vacuum, about 2.4 meters in diameter, and likewise be nongimballed. These are the engines they’d use for orbital maneuvers, such as sending the vehicle from Earth orbit toward Mars, and for the lion’s share of second stage boosting in the upper atmosphere. The inner three have small bells, about the same as the engines on the booster, and can gimbal widely and quickly. These would be used for landing, and I think for takeoff from Mars. Those large-belled outer engines (called “R-Vac” for short) would have a claimed specific impulse of 3.7 km/s, possibly even 3.8.

At any diameter, they hope to give these engines the unusual ability to throttle down to just 20% of max thrust. The only current engine I’m aware of with such a range is the BE-3 hydrogen burner in the New Shepard, which needs to go that low in order to hover before landing. One issue is that low throttling at sea level is supposed to be incompatible with even a moderately large bell size. But this low throttling probably only needs to be used in low gravity and little or no atmosphere, not on Earth.

Throughout most of 2017 and 2018, I kept hoping that at some point they’d budget some time and attention to giving this “BFR” project a real name, like Condor or Pterodactyl or something, instead of Big, uh, Falcon Rocket. I took to just calling it “the Beef” for short. This allowed me to ask regularly where it is. Then late in 2018 they decided to name the upper stage “Starship”, and the lower stage “Super Heavy Booster”. These names are disappointing, since “Starship” manages to be both blandly generic and preposterously overblown, and “Super Heavy Booster” is just a category name that could be used by anyone.

Of course, this Mars colonization scheme may go nowhere, but if so, the Raptor should still be a very competitive engine or other uses. They could use it to make a cheaper Falcon with fewer motors, or make a new rocket in the fifty ton payload class, or make a compact model with one Raptor. Musk had said that he hoped that the Raptor can make a reusable second stage possible for the Falcon; the Air Force was helping to fund some development for second stage use, and it sounded for a while like that was probably where the engine would first fly. Maybe that was one reason why they were testing the engine at two thirds size: because this would fit into a Falcon second stage. (There don’t seem to be any exact figures available on what size this smaller engine is; it may be more or less comparable to a Merlin, which weighs about half a ton and, with the sea-level bell, is about the size of a phone booth. The mature Raptor is apparently a little over one ton.) Lots of uses are possible; after all, once you’ve got the engines working, you’ve done two thirds of the development work — the rest of the booster is simpler stuff and takes less time, so all kinds of body designs are possible.

But they have now dropped plans for a raptorized or reusable Falcon second stage. Instead, they announced plans to start making some second stages into small BFR testbeds, so they can try out heat shields and reentry techniques, but even that ended up being dropped, as far as I know. They no longer want to invest any new technology into improving the old Merlin system. Since the Starship has no presold customers except one billionaire who is paying for a flight around the moon, they are tightening their belts and trying to cut as many financial corners as possible until they complete a working rocket. Musk has said that the goal is to get out to the moon as quickly as possible, presumably on the assumption that at this point they’ll start getting paying customers.

But while such uses might all be profitable, Musk is threatening to dedicate his life and fortune to promoting a Mars colonization effort involving thousands of ships, at a hoped-for cost of around $200,000 per colonist. Personally, I don’t see the need to rush. But here’s how seriously he takes the idea: he now says the plan is to replace their entire fleet of Falcons and Dragons with these new rockets, so that astronauts will ride a Beef — er, Starship to the space station, and commercial satellites will be launched from a Starship with a huge cargo bay that opens like an alligator jaw. This makes me envision the thing making stops at a dozen different orbits to drop off payloads, like a mailman doing his rounds... but just as likely, this means that a lot of flights are going to leave the Starship’s payload area mostly empty.

Hey, maybe they could fit the interior with some kind of catapult, to help fling the satellites into different orbits. It might be a good use of all that available space, and would save fuel. Telescoping rails, perhaps? If it can unfold to forty meters long, then with 5G of acceleration it could impart 44.7 m/s of orbital change velocity; with 10G, you’d get 63.2 m/s — enough to save at least one ton of fuel per change of orbit.

Anyway, this easing of space constraints would be a big relief to satellite builders, who grumble about the “tyranny of the fairing”. (One area where the Falcon 9 does lag behind its competitors is in fairing size.) This roomy cargo bay would particularly enable the deployment of big telescopes.

And of course with refueling, a Starship could also take a substantial load to the moon, which is a destination that has been getting a lot of renewed interest lately, and is definitely on Musk’s list. He says they are officially budgeting all post-Falcon R&D to building the Starship and its booster. The idea is that using it for their regular business of orbital launches will allow the entire Mars scheme to pay for itself. Their bet is that using an absurdly oversized rocket to launch ordinary satellites will make economic sense because the 100% reusability will make each flight so cheap... but that might not work unless the market for heavy cargo expands considerably as prices drop. If they can’t do large volume business, these savings may remain elusive... but mass-producing ships out of sheet steel does look like a good start on keeping them inexpensive. But if they pull it off, then maybe once the competition also has high reusability, at that point a smaller launcher would save money again. A Mini-FR that scales this design back down to, say, a thirty ton capacity might someday end up being the even cheaper way to carry satellites and astronauts.

Because of these priorities, Musk’s plan is now to devote most of the development effort to the ship rather than the booster, since it’s a much more complex task and requires far more innovation. They’ll be sending prototype ships on suborbital hops before the booster has even started being built. He says the heat shield is particularly challenging, due to the high velocities it’ll be asked to handle. But I bet that’ll be nothing compared to the million details it’ll take to go from a usable unmanned Starship to one that can carry passengers safely for months. I would not be surprised to see more than five years go by between the first uncrewed commercial launch, and the first crewed one. (Their proposed schedule is to cover this gap in just two years.)

Whereas most super-heavy rockets are exotic expensive beasts that launch only a few times, Musk wants the Starship to be mass-produced. That’s the only way to have a fleet big enough to colonize Mars, after all, and I suppose he hopes that if the flights are cheap enough, it will catalyze a boom in demand for other uses. Even as they build the earliest prototypes (and quite often destroy them in tests, because they have fully embraced the principle of “fail fast”), they are looking at every stage for ways to make the process scalable to high volume assembly line production. Musk is talking about increasing the human race’s orbital lift capacity by about two orders of magnitude within a decade or so, if they really do start making these in large numbers. That could be enough to build whole cities in orbit, and large bases on the Moon. Longer term, a full-sized Mars fleet might make that three orders of magnitude. And he’s considering making future Starships of a size far larger yet.

One factor which Musk has basically ignored — and which NASA seems to be turning a blind eye toward as well — is the possibility that there is already life on Mars. The Viking tests back in the seventies are difficult to explain by other means, and strange color blooms have been seen in certain patches of soil in moist areas near the equator... if such life exists, colonizing on top of it could be a bad look, and possibly even mortally dangerous. The fact that NASA has sent multiple probes after Viking but has never been willing to follow up on biological experiments is a strange omission.

The silliest proposal for the system is to use Starships for rapid transportation here on Earth: build spaceports around major cities (most likely out in the ocean), and fly passengers to the far side of the world in 45 minutes. Can you imagine the regulatory nightmare that would be, and what a tempting target it would be to use one for a terror attack? And as someone once said of this sort of ballistic passenger transportation scheme when it was first dreamed of fifty years ago, “For half of the flight you can’t get to the toilet, and for the other half it’s out of order.” Well, it’s not as unrealistic as Musk’s “Hyperloop” plan.

Since Musk is always thinking about the project after next as well as the next project... what would come after Starship?&ensp:What he’s talked about as a successor is the same thing only bigger — a fat Starship. They’re considering increasing the diameter, perhaps as big as 18 meters. Even if there is little increase in height (and I don’t think raising the height would be easy), that would give us a rocket weighing around twenty thousand tons, with a payload capacity of several thousand cubic meters.

Super Heavy and Starship: mass 4850 t, diam 9 m, thrust 72000 kN, imp 3.5 km/s, type Z2m, payload 100‒150 t (2.0‒3.0%) with reuse, cost maybe $2M/t at first (and less later). Yipe!

(...How does 4850 tons compare to the biggest historical rockets? Apollo was just under 3000 metric tons, N-1 (the failed Soviet moon rocket) was 2750 tons, the Energia was 2400 tons without payload, and the Space Shuttle was 2000 tons. As far as I am aware, those are the only rockets that have ever been bigger than a New Glenn or Falcon Heavy. The SLS will be about 2500 tons in its initial version.)

(The original 2016 BFR design was expected to be 10,500 tons. If you think that was absurdly gigantic, well, it still isn’t as big as the legendary “Sea Dragon” which was designed in the early sixties but never built — a very basic but very large rocket designed to make heavy lifting as cheap as possible for the time. It would be built out of sheet steel in a shipyard, and use a simple pressure-fed motor on each of its two stages. That thing would have weighed eighteen thousand tons, and the two engine bells were well over twenty meters wide — large enough to fit comfortably over my house. And Boeing once proposed a far bigger rocket called the Large Multipurpose Launch Vehicle, with a core stage so huge that it could use ten strap-on solid boosters that were each the size of an Apollo. The heaviest configurations might weigh thirty thousand tons, and lift almost two thousand tons to orbit.)


I’m beginning to wonder if the reason Lockheed and Boeing spun off ULA is so that the parent companies would be insulated from its coming bankruptcy (though since that time, the Vulcan is now looking pretty promising). NASA’s forthcoming Space Launch System reinforces that suspicion, as is built not by ULA, but by Boeing as the primary contractor. It’s a setup with two huge solid boosters on the sides and four hydrogen-burning engines in the middle, with both the solid boosters and the hydrogen motors being copied from those previously used in the Space Shuttle. Even the main fuel tank of the first stage is based on the shuttle’s external tank. As in the Shuttle, that big hydrogen tank is able to place itself just short of orbit, requiring only a tiny circularization burn for the upper stage to avoid reentry. This leaves most of the upper stage’s fuel available for interplanetary destinations.

It’s intended for strictly noncommercial use, lifting governmental payloads too large for existing rockets. It’s expected to lift 70 tons to low Earth orbit in its most basic configuration, with later enhancements planned to bring the capacity up to 105 tons by giving it a much larger upper stage, and then to 130 tons with taller side boosters — a figure that pretty much matches the Saturn V. No announced commercial system is aiming for this capacity, except for SpaceX’s “Starship”. Musk is doing all he can to aggressively speed up the timeline for the Starship to be able to reach the moon, without clarifying what the hurry is, though part of the reason might be so they can win a NASA contract for flights that otherwise would require the SLS.

The “Interim” upper stage is based on the five meter wide upper stage of a Delta IV, with stretched tanks and some improvements for human rating. It has one RL-10B2 engine — a variant of the venerable expansion cycle hydrogen burner which has been used for decades because of its unmatched efficiency. It will be replaced later by the “Exploration” upper stage, which will be 8.4 meters wide like the SLS main tank, and have four engines, maybe the RL-10C3 variant. This will raise the payload capacity for a lunar transfer orbit from 26 metric tons to 40.

In contrast to other bold new rockets, the SLS is not intended to be reusable at all. For this reason, they plan to use the classic shuttle-derived main engines, which are reusable, only for a limited number of early flights, and then switch to a cheapened version if the rocket continues in service. Why no reuse? Well, they don’t plan to launch much more often than once every two years or so. In fact, the idea is that the first few rockets will be built largely from the inventory of spare shuttle parts which have been sitting in warehouses. Aerojet Rocketdyne has about ten leftover RS-25 main engines, for instance — many of them being ones which have already flown multiple shuttle missions and were swapped out for various reasons. This is a bit awkward as some SLS stages will be made with engines that don’t match each other, with some being of earlier revisions and some being later, with slightly different performance.

The side boosters are subcontracted to Northrup Grumman, which bought out Orbital ATK, which bought out Thiokol, the original contractor for the Shuttle boosters. This reinforces my suspicion that Boeing and Lockheed spun off their Delta and Atlas businesses because they expected them to be money losers. On the other hand the SLS, being a traditional aerospace contract with no competition, is comparatively risk-free profit. Even if the whole SLS project gets cancelled, which is an option that some of the people in charge of funding it are starting to discuss in louder voices, Boeing will do just fine. Some say that maybe the whole SLS program is just being milked for jobs and kickbacks — why else would something built from spare parts have turned out so expensive? About $14 billion has gone into it so far. SpaceX and Blue Origin are both developing all-new superheavy rockets for far less. The difficult part, apparently, has been the core stage, and the launchpad; the boosters and upper stage were ready around the beginning of 2020. And if money is being milked, it looks like Boeing’s work on the core stage is where most of that has happened. It’s been the costliest and the longest delayed of the main components. How could it take six billion dollars just to integrate existing engines onto big tanks? Some say NASA administrator Jim Bridenstine lit a fire under them and got them to finally stop farting around, though of course that doesn’t recover any of the lost money. Bridenstine seems to have earned a decent level respect as head of NASA, which is a surprisingly positive thing to see given his beginnings as a right wing hack politician who denied global warming.

NASA had a previous project named Ares, which was cancelled. The SLS is pretty close to what the Ares V would have been, with a bit less power and weight — the core stage of Ares V would have had five shuttle engines instead of four. The $14B figure above does not even include the earlier Ares expenditures. (See “OmegA”, in the cancelled section, for the tale of the Ares I.) What do they plan to use this Saturn-like capacity for? For one thing, a space station orbiting the moon, called the Lunar Orbital Platform-Gateway, or LOP-G — a base that would allow astronauts to make multiple trips to different parts of the moon, going up and down practically at will... so long as they can be supplied with fuel, which is the difficult part. The SLS would have the grunt to move thirty-plus tons at a time to this remote location — enough to get the core of the station in place, at which point the Russians and others might add further modules to it with smaller rockets. That new station would be where future Mars missions set off from, in NASA’s current plans. But if SpaceX gets to Mars first, or Bigelow sets up a lunar space station before the Gateway is ready, that whole plan might be abandoned. And on the other hand, if Blue Origin builds a New Armstrong, some version of NASA’s Mars plan might be able to go ahead without the SLS.

There are plenty of people who’d like to see the SLS program die, but unfortunately, certain powerful politicians, most notably the senators from Alabama, are determined to keep the pork barrel rolling at any cost. This has led some to dub the project the “Senate Launch System”. More than one administration has tried in vain to staunch the budgetary bleeding, but Congress has always managed to keep the flow going. Some senators and representatives have even tried to write overt unnecessary make-work into the SLS program, which would have to be done in their home states. They also mandated that the Europa Clipper probe would have to be launched on one, even if the Falcon Heavy can do the job at far lower cost with far less harsh vibration... but common sense prevailed and the Heavy got the job.

In the absence of extravagant dream rockets like the Starship and the New Armstrong, could the Gateway be built without the SLS? Could the Falcon Heavy or New Glenn do the job cheaper? It’s tempting to just say “of course”, because loads could be split up: instead of lifting a big habitat to orbit along with a stage to push it to the lunar altitude, just lift them separately and then dock them. Two to four SpaceX flights would certainly be cheaper than one SLS launch... but there’s a hitch — apparently the SLS was already going to split up loads that way. So it may be that some pieces, as currently envisioned, are just too big. Or maybe it would just take a third trip to give it enough propulsion. Since the design is still in flux, I think it could be worked out. And if the Falcon Heavy is insufficient, the New Glenn might be more capable for those distant orbits, especially once they give it a third stage. I think if the New Glenn does what it promises, it should be sufficient to make the SLS largely unnecessary and obsolete, even though it would take something the size of the Starship to fully match the planned capability of the SLS, and once it evolves to its final form (if that is ever budgeted — the White House is now trying to defund that later part of program) maybe even the Starship would fall short, unless it’s used expendably.

If you’re wondering why there’s a need to build a lunar space station before NASA can go to Mars... well, you’re not alone. There are good reasons why some are disparaging the idea by calling it the “lunar tollbooth”. Any inquiry into building the Gateway by other means also has to question whether it ought to be built at all. If the LOP-G is omitted from the program, there would be no clear need for a rocket as gigantic as the SLS, and New Glenn will probably be sufficient. And indeed, the latest NASA plans are apparently de-emphasizing the gateway in favor of going directly to the lunar surface for the short term, in a program now dubbed Artemis (which the previous administration wanted to fund by raiding social programs). Blue Origin is developing a lander named “Blue Moon” so that the Glenn could handle this program, presumably with a lot of savings over using the SLS... though maybe not so much, as the Blue Moon is not reusable. And SpaceX is trying to prove that a Starship will be viable for lunar missions on a similarly quick schedule... though again, this is problematic because though it is reusable, its enormous dry mass makes its fuel consumption rather extreme. But if we foresee moving heavy payloads on and off the surface, the size makes sense.

If we want a small lander, an alternative does exist: the third proposal is lightweight, highly reusable, and has lots of clever ideas, such as maybe putting wheels under the habitable section so it can leave the rocket and drive around. It’s from Dynetics, with contributions by two dozen other companies, prominently including Sierra Nevada. It’s called ALPACA — Autonomous Logistics Platform... forget it, the acronym is too tortured to be worth expanding here. It would have eight small methane engines. In 2021, NASA decided that of these three, the Starship would be their lander of choice for Artemis, though the others might get a shot at followup missions. The Starship is certainly the one with the most potential to scale up operations in the future... and specifically, to have no long term need for the SLS. The reason for picking the Starship was mostly just because they needed less money... and the ALPACA proposal, though it sounded very attractive on paper, was reportedly in trouble due to the lander being overweight, though I’ve also heard that the weight issue had already been resolved at the time, and is further improved now. The less solvable problem is the price, which would be something like $9 billion to develop all the novel components — quite a bit more than the National Team asked, and waaay more than SpaceX asked.

The final proposal — and until recently, the one that everyone thought would be most favored by the establishment — was built on a variation of the Blue Moon lander. It would have a Blue Origin descent stage, a Lockheed ascent stage and passenger capsule, and a Northrup orbital transfer stage. Of these, only the crewed ascent part would be reused. One weakness that this shared with the Dynetics proposal is that it would require a refueling rendezvous in lunar orbit, whereas the Starship, though its refueling requirements would be enormous, could do it all in low Earth orbit.

It does now appear that in the struggle between the budget-cutters and the pork barrelers, the LOP-G is now being de-emphasized, so it looks likely that the Artemis program won’t depend on it, though they do still plan to build it in parallel with the Artemis lunar program. If the gateway slips any further, there goes about half of the justification for building the SLS. The other half would be a NASA manned Mars program, and that is also not within any current budgeting. So what we’re left with is a giant super-expensive rocket whose only stated purpose is a few moon flights, in which role it may well be obsolete within the next few years.

The SLS needs a better name. Either “Ares” or “Artemis” would have done nicely.

SLS (base “1A” configuration with small upper stage): mass 2500 t, diam 8.4 m, thrust 37000 kN (core 7400), imp 3.6 km/s, type ZFh+S, payload 70 t (2.8%), cost ~$8M/t.

NEW GLENN — USA, 2022?

The other American tech-billionaire space startup, usually mentioned in the same breath as SpaceX, is Blue Origin. It’s run by Jeff Bezos, the founder of Amazon who somehow made that company into a wild success story without managing to consistently show a net profit, even in the days when the company was underselling everyone by failing to charge sales taxes. (It still evades a lot of taxes today, via offshore bullshit.) The all time net revenue earned by Amazon is, in fact, far smaller than the billions that Bezos has ended up with in his own pockets. Bezos has now become the world’s richest man, while Amazon warehouses remain among the toughest places in America to earn $12.50 an hour. With this personal wealth, he has bought such toys as the Washington Post, as well as some neat rockets.

His company developed the suborbital New Shepard for short tourist flights, and finally put people on it (including Bezos) in 2021, just days after Richard Branson took a similar joyride on his SpaceShipTwo. This stubby little one-stage rocket burns hydrogen in a single engine called the BE-3, which they developed in-house. We have no clear specs on this rocket; we don’t even know its exact external dimensions. Its noteworthy feature is that it can do a soft landing for reuse. It doesn’t do these landings anywhere near as smoothly as a Falcon does, but that’s intentional, and even their concept animations for the New Glenn show it hovering and drifting like a manually piloted helicopter just before touching down. They might prefer to do it this way for the sake of increasing safety margins. (The Falcon is actually unable to hover because its engines can’t throttle low enough, so they were forced to use the “suicide burn” approach. They don’t call it that, of course: their official term is “hover-slam”, in which both words are completely bogus.) As Blue Origin likes to point out, it was the Shepard, not the Falcon, which was the first rocket in the world to return from space to make a successful vertical landing. And one of their Shepard test rockets made five flights long before any Falcon booster could.

That suborbital craft may not be important to us here (unless they add a second stage to it for smallsats, which is something Bezos says they are considering), but the much larger New Glenn is coming along right behind it. In its basic configuration the Glenn originally was to consist of two stages, both burning methane. Some are calling liquid methane “the fuel of the future” because it’s almost as good as kerosene at sea level and almost as good as hydrogen in vacuum, while being cleaner than the former (kerosene gets soot on everything) and easier to manage than the latter, and cheaper as well. The first stage will use seven of their big BE-4 engines — quite a contrast to the puny set of two that ULA’s Vulcan would use — and in the original plans, the second would have a single one with an enlarged bell. A third stage would be optional — it would burn hydrogen in a BE-3U (a vacuum version of the Shepard motor), and be capable of escaping from Earth orbit. But now they’ve changed their minds, and both the second and third stage will use hydrogen. The two upper stages were originally going to be the same height, but now the second stage will be taller, and have two independently gimballed BE-3U engines to provide sufficient thrust, while the third stage is now apparently going to be small, and ride inside the fairing instead of beneath it. They say that using hydrogen will extend the range of orbits that the rocket can reach without needing a third stage. So they’re going to skip developing a vacuum version of the methane engine.

Actually, the BE-3U differs significantly from its sea-level progenitor: rather than just changing the bell, they are switching the turbopump power cycle from a tap-off system to an open expander cycle, which will require a lot of reworking. In this form, it no longer has the deep throttling capacity of the original BE-3, but it might be easier to restart in space.

The BE-4 methane engine, on the other hand, uses oxygen-rich staged combustion, like an Energomash engine. This makes it more advanced and efficient than most American engines, including SpaceX’s Merlin. By contrast, the BE-3U’s expander cycle design is as old as the hills. Even the venerable Centaur uses a closed expander, and avoids dumping unburned fuel, though the closed cycle does limit it to much lower power and thrust.

I’m unsure about the materials the rocket is constructed from. I think the upper stages are using a carbon fiber fuselage, but the tanks of the booster are stir-welded aluminum. Not sure whether both stages use the same materials for either the tanks or the fuselage. If they do, presumably the carbon fiber part is the one that supports all the weight against however many G’s of acceleration, while the aluminum one just has to contain a bit of pressure, and a layer of thermal insulation could be put between the two if desired. This is in contrast to the steel Starship, where the outer wall is a single layer of conductive metal despite having reentry heat on one side and cryogenic liquid on the other.

The upper stage or stages will be expendable, but the first stage will soft-land itself on legs for reuse, just as the Shepard does. Blue Origin points out that with six legs, it will be able to land even if one fails. (This is a dig at SpaceX, which once lost a Falcon when a leg failed to latch down.) They hope to get 25 uses out of each New Glenn booster (they originally said 100). It’s big — it would be by far the largest nongovernmental rocket ever, if it weren’t for the Starship being developed at the same time. Overall, the New Glenn amounts to about half a Saturn V. The booster appears to be at least the equivalent of the three boosters of the Falcon Heavy combined into one, and the second stage is many times bigger than the Falcon’s. Despite this size, they do plan to land the booster at sea, just as SpaceX does. The landing boat is apparently a converted freighter with a widened deck, rather than the simple barge SpaceX uses. They say they’ll be able to land on it while it’s moving, and handle rougher seas than a barge can.

Note that the sixty ton payload commonly quoted for the Falcon Heavy is for expendable mode, but Blue Origin’s forty-five ton figure for the Glenn is with reuse, so though it may sound like it has less capacity than the Falcon Heavy, it actually has more. I figure this is probably in large part because of the much bigger second stage. The New Glenn will be the world’s second most powerful commercial rocket, after Starship, assuming both get off the ground. And for higher orbits, the advantage over the Falcon Heavy just gets bigger — between the larger second stage, the use of hydrogen, and the option of adding a third stage, the capacity of the New Glenn to send stuff to the moon and beyond might be double or triple what the Falcon Heavy can do. Also, the fairing capacity dwarfs that of the Falcon, offering about four times as much room inside. Of course, you’ll also probably pay a lot more for all that expendable stage capacity. And again, this all sounds awesome compared to older rockets, yet the Starship is poised to make it instantly obsolete, and may actually fly before the New Glenn does.

But Bezos has a plan to fight back. For a later version of the New Glenn, they will try to build a reusable second stage. The plan is apparently to use the same approach pioneered by SpaceX, and make that stage out of stainless steel covered by a thin heat shield. Without reuse, the large size of their expendable upper stage will probably make it impossible to compete with SpaceX on price, but with it, they’ll be in a much better position. This attempt at a reusable second stage is called Project Jarvis, and apparently they have taken serious measures to insulate it from the company’s normal management practices... which gives you some idea of how well-run the rest of the company is.

And speaking of the Moon, in 2019 Bezos announced a lunar lander called “Blue Moon”, which is essentially a rocket platform that any desired payload can be bolted to the top of, with davits to lower rovers and such to the lunar surface. Yes, he wants to offer moon landings as a commercial service! The lander weighs fifteen tons with fuel, and has four legs which will fold up to fit into the seven meter New Glenn fairing. It has exposed spherical tanks... which led Elon Musk to mockingly nickname it “Blue Balls”. The capacity is 3.6 tons of cargo, and they later proposed a stretched version for human landings, raising the capacity to at least 6.5 tons. Any capacity to return to orbit will be left to the payload to implement for itself. The basic lander will use a single engine: a new hydrogen-burner called the BE-7, which is quite a bit smaller than the BE-3U. It runs on a dual expander cycle, is restartable, and supports deep throttling. The human version would have two or three engines — it’s not clear which.

This stretched lander is part of the “National Team” proposal for a human landing system for the Artemis program. This would carry a crew capsule and ascent stage built by Lockheed, with its interior and electronics based on the Orion capsule. It was regarded as the front runner in the competition, despite how neither of the other proposals it was up against (the Dynetics ALPACA and the Lunar Starship) would leave big expendable stages behind on the lunar surface. But then Congress cut the budget and only SpaceX bid low enough. The other two both lodged formal protests. Congresspeople started arguing to raise the budget again to restore competition, and others (notably Bernie Sanders) decried this as a “Bezos bailout”. In response, Bezos offered to defray up to $2 billion of the cost himself, if his lander was chosen — a controversial move that blurs the line between charity and bribery. Blue Origin also formally protested Nasa’s selection (as did Dynetics, the lead company of the other losing team), but the Government Accounting Office rejected the appeal. Bezos then sued, because he is an asshole.

The question that’s begged by the size of the Glenn is, of course, who will have a use for that much rocket. The Falcon Heavy has found far fewer customers than it was expected to when it was first planned, and the trend lately across the industry has been toward smaller and smaller satellites. Bezos has said that all of their future rockets are going to be even bigger than the New Glenn, but they may have to change their minds about that. Unless NASA revises its current plans and decides it doesn’t want the SLS but does want the Lunar Orbital Platform-Gateway, I don’t know who out there would need such a big rocket. Maybe they’re just hoping that if really big satellites are cheaper to launch, someone will come up with a use for one. We could imagine, for instance, super-powerful communications satellites that enable cell phones to work without towers... but I don’t think that’s likely. Sending things to the lunar surface might be almost the only mission where the New Glenn is the most cost-effective choice.

One way they’ll get some use for that capacity is to stack two full-sized sats into a single fairing, like the Ariane V does. The additional juice in the second stage should be able to put the two into substantially different orbits. This would cut the launch price in half for cases where the logistics work out for both customers, and might go a long way toward making it competitive in cost. But for any load that doesn’t make use of that huge capacity (which at its debut is not only likely to be the heaviest payload capability commercially available, but by far the largest fairing volume as well, assuming the Starship is not in service yet), I bet a Falcon will always be able to underprice it because less is thrown away, so I don’t know how the Glenn will manage to get a lot of business, unless they eventually get that reusable second stage working.

Of course they could, like SpaceX, make their own work by putting up satellite swarms. Amazon does indeed have a swarm in the works... and will launch the first nine batches on Atlases as the New Glenn is still far from ready. They have also announced a partnership with Sierra Nevada to launch their proposed space station, which would need a Glenn as each module is huge, but once up it would be mostly serviced by smaller rockets.

They also plan to sell tourist seats on it at some point. Aside from these options for creating their own markets, there aren’t many customers with payloads over twenty tons. I wouldn’t be surprised if only a modest number of New Glenns end up being built, while cheaper Falcons roll off an assembly line by the dozens... and for the short term, at least, this is explicitly Blue Origin’s plan, because they hope to get so many reuses out of each one. (If this works they could give each one a name, like a ship.) Despite the lack of mass production, I guess it’s possible that the Glenn’s larger scale may eventually make it a cost winner against the Falcon, particularly against the Heavy. So far, though, it sounds like Blue Origin has a long way to go before they can bring costs down that far, and SpaceX seems to be at little risk of losing their lead.

Blue Origin has opened their factory near Cape Canaveral, which they say will have the world’s biggest carbon fiber wrapping machine... but their fuel tanks will be aluminum, and apparently so will the outer body of their booster stage. The factory will, they hope, be mostly used for making the expendable upper stages, if their boosters prove as reusable as they expect. As usual, I will note that the rocket business is rather prone to dashing such hopes.

As of 2021 this factory is still mostly empty and idle. One insider described the whole company as a dysfunctional Potemkin village which puts up a fake appearance of productive industriousness. The company’s performance got so frustrating that Bezos stepped down from running Amazon in order to manage Blue Origin full time.

For now Blue Origin is not cutting costs anywhere near as aggressively as SpaceX is, and this is for a very good reason — not just because they’ve embraced a cautious “slow is fast” design philosophy, in contrast to SpaceX’s fail-forward approach. They have a coat of arms which emphasizes this, as it features two tortoises and the motto “Gradatim Ferociter”. Ironically, some other insiders say that the reason Blue Origin stayed stuck in suborbital flight for most of two decades is because Bezos wouldn’t follow his own philosophy, and insisted on trying a large reusable rocket right away instead of solving easier steps first. On the other hand, he did hire old-line aerospace veterans who are accustomed to slowness and caution and minimizing risk, but there ain’t any slow-is-fast in that tradition, only just plain slow.

Another reason for not cutting costs aggressively is that while Musk is undercutting the traditional space market for lifting satellites and probes and professional astronauts, Bezos is trying to create a new one for space tourism, and eventually, to open up cislunar space as a place for regular people to have jobs. For this game, where their intended market is civilian passengers, safety is paramount, so it makes some sense that Blue Origin is moving at a much more careful pace than SpaceX is.

But on the other hand, maybe SpaceX is developing safety and reliability in the best way, by practicing lots of real launches. By occasionally losing a Falcon, they may be gaining more practical safety knowledge than Blue Origin’s low-risk approach can, even if their overall approach can be criticized for sometimes being too hurried to get things right... as shown by for instance the Falcon Heavy, which ended up with four years of delays because their initial plans were naive. Back on the first hand, it’s also possible that SpaceX’s performance goals for their future spacecraft are too aggressive and they are cutting safety margins too thin — a bad habit from their early days when they always had to work exhausting hours and push the deadlines just to stay solvent. It may be that Blue Origin will be able to sustain more safety and reliability over the long term. That’s what Bezos believes.

Neither company has gotten anyone killed by a rocket yet, but inevitably the day will come when one of them does. Rockets are dangerous, period. It’ll be interesting to see to what extent the public is willing to accept and support this from a private venture. If it’s traditional astronauts that die, I suppose things will resume after a year or two, as has happened in the past, but if it’s tourists, that might mean the business goes bust. Even the loss of an unmanned rocket can be very costly: when a Falcon once blew up on the pad, the direct and indirect loss to the company over the following months was something like $700 million, and repair work on the pad facilities took more than a year. Virgin Galactic and Scaled Composites, which are focused on the suborbital tourist business, have in fact killed a test pilot, and this may have been a factor in the company now leaning away from plans to develop tourism to the orbital level, and instead pivoting toward conventional launch services — a market where the existing work they’d done on suborbital passenger flight was of little use, and they had to start from scratch.

In any case, Bezos is betting that as the space business expands and gets more affordable, people are going to want to move heavier loads to orbit, and the future will belong to big rockets. He says they only plan to build even larger stuff in the future. If he’s right, the traditional space companies are going to be out of the game for years. If New Glenn can fly at a price competitive with the Falcon Heavy, or turns out to be safer, and works better than the Starship, it could be the dominant space vehicle of the next decade. But if he’s wrong... whoever makes the smallest reusable rocket might be the one who really cleans up. There are a lot of competitors in the small-sat market now, and none of them have figured out reuse... whoever does might end up doing the majority of the world’s launches.

Where next for Blue Origin? After New Glenn, they say they’re going to try a New Armstrong, to scale up their capacity for lunar and interplanetary missions. But they might need to also scale down — they might find a lot more business below five tons than above fifty tons.

I note that even though the Shepard is flying today, we still don’t have exact specs for it. Blue Origin has in general been much less public about its doings than SpaceX has. But one thing they have said is that their long term plan is to build some kind of base on the lunar surface, in the next decade. Their vision over the even longer term is to enable a future where there might be a million people living and working in orbit or on the moon. (He has also shown concept art for what appears to be a luxury space habitat for rich people. That actually looks like a more likely goal for the shorter term.) Bezos has not shown any particular interest in going to Mars. I guess he figures that people will get there eventually, once it’s no longer so difficult.

So maybe in Bezos’s mind, it doesn’t matter that there won’t be a lot of customers for launching forty ton satellites. Maybe, like SpaceX with their StarLink system, if nobody else wants that much launch capacity, he’ll find a use for it himself. If he envisions thousands of people living and working in orbit, it’ll require hundreds of heavy launches to put the habitats up. Maybe he’s eventually planning on building a private city up there. And in the shorter term, orbital space tourism will probably do a fairly good business... the Glenn could hoist a much larger capsule than any current rivals, able to accomodate rich people in comparatively luxurious conditions, or take twenty or thirty people on a shorter flight.

On a more mundane level, they say that besides providing BE-4 engines to ULA for the Vulcan, they will gladly sell their motors to anyone else who’s interested. They could end up competing with engine builders such as Energomash and Aerojet Rocketdyne as much as they do with ULA and SpaceX. As of late 2020, it sounds like the engine is ready for full production.

New Glenn (two stage): mass unstated (1500 t?), diam 7 m (8.5 at base), thrust 17100 kN, imp ~3.4 km/s?, type ZOm, payload 45 t (3%?) with reuse!, cost unknown.

BLUE WHALE — South Korea, 2021?

As the South Korean government wonders aloud whether there’s any point in pursuing a space program and building a successor to the Naro rocket, a tiny company called Perigee Aerospace (페리지항공우주) has been working toward a private rocket since 2012. Now emerging from stealth and backed by Samsung money, they have a rocket called the Blue Whale 1. Ironically for something named after the world’s biggest animal, the rocket is absurdly tiny. Under two tons! Some of its competitors, which are still considered small, can launch payloads as big as this entire rocket.

They intend to mainly go for sun-synchronous orbits, and in that role their max payload would be 50 kilograms. Like most rocket companies, they also say that later on they’ll make something much bigger. In their case, that means something about the size of the Electron.

So how can something so tiny get the job done? With an advanced engine — a kerosene burner with an oxygen-rich staged combustion cycle, like an Energomash engine. The most unbelievable part of the story may be the plan to build an engine this complex and advanced into a rocket that costs only two million dollars. How did they pull this off? How does it work? We have no idea. Details and technical data are very sparse. For instance, I have no information at all about the upper stage. The company’s website is nearly content-free, and the usual places that collect rocket info don’t even know how its name is spelled in Korean. (푸른 고래-1?). It might be made of carbon composite, but there’s nothing definite about that.

They won’t be launching it from Korean soil. Because they want to launch frequently, they need a spot with little nearby air traffic. They found their spot on the south coast of Australia, at a place called Whalers Bay on the Eyre Peninsula. It’s under construction.

Blue Whale 1: mass 1.8 t, diam 0.76 m, thrust unknown, imp 3.5 km/s, type ZOk, payload 0.07 t (4%), cost ~$28M/t.

TERRAN — USA, 2021?

Relativity Space was a venture I was ignoring, until they signed a launchpad lease at Cape Canaveral, and let it be known that they had already logged a lot of engine firing time on the test stand. They are taking an approach similar to a number of other New Space rockets, in that they have a bottom stage with multiple “Aeon 1” engines (nine) and a second stage with a single vacuum-bell version of the same engine. Unlike any of the others, they’re using methane as a fuel right from the beginning — something that other companies have considered only after they’d gotten themselves well established.

But that’s not what makes them really stand out. The unique thing about the Terran 1 is that they intend to 3D-print the entire rocket. Lots of other companies use 3D printing to make complex engine parts, but nobody else is considering printing the fuselage, fuel tanks, and so on. At first blush, the idea seems ridiculous. A printed material is never going to be competitive on, for instance, optimizing the strength to weight ratio for tank walls. But they say that by printing everything, they can make an Aeon engine with fewer than 100 parts, and a whole rocket with fewer than 1000. (Most traditional rockets have tens or even hundreds of thousands of parts.) In fact, they have said that some versions of their engine have just three parts.

That’s only the beginning of their ambition. The reason they want to 3D print the entire thing, even if it doesn’t result in optimal properties, is so the process can be automated from beginning to end, so they can make a rocket by pushing one button, with no skilled labor required. It would still take weeks for the build to be completed, but that should certainly achieve some reduction in costs.

We're not done. It can’t actually save money to require no human workers at all — there are diminishing returns there, for sure — so why do they want to do it? Well, so the entire factory can be dropped on Mars, and build rockets there. That’s the end goal of this odd approach. It’s also why they picked methane as the fuel. Maybe when they start building it there, they’ll call it the Martian 1 instead of the Terran 1.

This begs the question of what raw materials the printer would use. They mentioned nickel, so it sounds like they might plan to make a lot of parts out of the same inconel alloy which is widely used for the high temperature parts of engines. Inconel mixes are generally at least half nickel, sometimes three quarters, and nickel should be reasonably easy to find on Mars. The crucial second ingredient of inconel is chromium... and it looks like this may also be fairly abundant. Aluminum and titanium are not rare either, and their tanks and frame are mostly aluminum.

Their giant superduper 3D printer is named Stargate. For the large parts such as tanks, it rotates them on a turntable as it builds up the metal on the top edge. (The results look rather rough and grainy in the video they’ve released so far.) Apparently it not only incorporates some proprietary metallurgy, but also some kind of artificial inteligence features, to help make it autonomous. They claim it will learn to build faster as it gains experience. They are now happy enough with the prototype that they are building several more.

Their first rocket, which they claim will in the future be scaleable to different sizes, is fairly small: bigger than an Electron but not bigger than much else. They claim they’ll sell them for $10 million each. The engine itself will probably have to scale in numbers, rather than size, as it uses an expander cycle — a rare choice for a booster engine, but a good fit for 3D printing, as it uses complex plumbing but does not make severe demands on the materials. From pictures, it looks like it’s a semi-closed design which dumps the unburned turbine propellant into the bell... and does it with a single fat pipe, rather than a ring of little holes such as most people would use for the purpose.

This vision has somehow attracted tons of investor capital — a lot more than many of their competitors. As with Virgin Orbit, it’s questionable how it will be possible to make all that money back.

And as every small-launch company eventually seems to do, they announced that they will follow the Terran 1 with a bigger rocket. They will call it the Terran R, for reusable. This one intends to even have a reusable upper stage, looking like a mini Starship. And it would be a big rocket, bulkier than a Falcon or Vulcan. The booster would have seven engines, adding up to around 9.5 meganewtons of oomph. I’m guessing these planned bigger engines will not use the expander cycle.

Terran 1: mass unknown, diam unknown, thrust 621 kN, imp ~3.5 km/s, type ENm?, payload ~1 t, cost $10M/t.

NEW LINE (新干线, Xīn Gàn Xiàn) — China, 2021?

China is full of companies large and small, old and new, which are developing small orbital rockets based on the solid fuel technology that China has long used for ballistic missiles. But one company stands out from the pack: LinkSpace (or 翎客航天, “Líng-kè Aerospace”). They are building a small liquid-fueled booster which will land vertically for reuse. It very openly draws inspiration from the Falcon 9. Like the Falcon, it will burn kerosene. Like the Falcon, it will have four triangular landing legs folded against its sides, and four grid fins at the top. But it won’t have nine engines on the bottom, like the Falcon or the Electron — only four. This may mean that the upper stage has more spare thrust than the Falcon has (with full tanks, the Falcon upper stage can’t even pull one G).

They have not given out much detail on the engine, such as what its power cycle is or how it will be constructed. Perhaps they aren’t all that far along with it yet. But they do have something flying: they’ve released video of a skeletal single-engine “hopper” rig lifting off from a metal pad, hovering, moving itself sideways, and landing in the middle of a different metal pad. More recently they’ve done a 40 meter hop with a more rocketlike test vehicle, then a 300 meter hop, and they aim to try a 1 kilometer hop soon. But these hoppers do not use the kerosene engine yet; they’re powering these short flights with ethanol.

They say they’re even going to pursue trying to reuse the upper stage — an idea that SpaceX has dropped for the Falcon. This would probably wait for a later rocket with more spare payload capacity.

New Line 1: Mass 33 t, diam 1.8 m, thrust 0.4 MN, imp unknown, type unknown (k), payload >0.2 t (0.6%) in expendable mode, cost <$22.5M/t.

PRIME — Britain, 2022?

Britain, though notorious for being the only government to achieve orbit and then cancel its space program, is not without a substantial aerospace industry, and it’s starting to produce its share of New Space startup companies. One of them is called Orbex, and their promised rocket is rather interesting in that it burns a fuel that nobody else uses: cryogenic propane. And one thing they like to emphasize is that they source it from people who produce it as a biofuel, so the whole rocket is almost carbon-neutral. Propane doesn’t burn as clean as methane, but it’s pretty close. One advantage of propane is that it can be stored as a liquid at room temperature without having to use a lot of pressure, yet it can also be chilled to the temperature of liquid oxygen without freezing. In the latter state it gains density. Their stages actually put the propane tank inside the lox tank. Maybe the intent is to make sure that if something boils off, it will be the oxygen. The tanks are carbon composite.

The engine is 3D-printed, as is becoming commonplace nowadays. They claim it’s the largest 3D-printed engine in the world, though that record probably won’t stand for very long. They’ll use the same engine on the first and second stages, with a large bell on the upper one. The lower stage will have six engines. They have not clarified what power cycle the engine uses, though they have stated that it’s not pressure-fed — it does have a turbopump of some kind. The engines are being developed in Denmark, while the rest of the rocket is made in Scotland.

They also claim that the first stage will be reusable. No details have been given about how it will land or be recovered, or when they plan to try to get that process to work. I do think there’s a bright future ahead for whoever can be the first to regularly land and reuse a small orbital booster, so it’s nice to see a few people saying they’re going to make the effort at it. A couple of others going for it are the Miura from Spain’s PLD Space, and the New Line 1 from China’s LinkSpace. Rocket Labs is also planning to attempt it with the Electron, though the rocket was not originally designed for reuse. It sure would be nice to see a couple of them succeed, and start making solid fuel rockets obsolete. That could do a lot to reduce the environmental impact of satellite launches, along with the cost.

One place they might launch is from a complex in the Azores, similar to the one in the Canaries that the Spanish companies are planning to use. But they are also working on constructing a small launch complex on the north coast of Scotland, at a place called A’Mhòine. It looks like that would be used for polar or sun-synchronous orbits only... but the plan could be in trouble because the location is environmentally sensitive. If built, the Scottish site would probably also be used by any other British companies that produce a small launcher, such as Skyrora. (Well, they’re partly British, being divided between Scotland and Ukraine.) That company does not yet have its own entry. They were apparently nostalgic for Britain’s Black Arrow program and aimed to revive its technology, including the use of peroxide instead of lox, though this approach is rather primitive. But they are using modern techniques such as 3D printing, and their engine’s power cycle is a unique hybrid between archaic and modern — they power turbines by decomposing peroxide, like a Soyuz, but it then drains into the main chamber as in a staged-combustion design. They have yet to fly anything above ten kilometers.

The interesting thing Skyrora has done is that they are trying out a kerosene substitute made from waste plastic, which they call “ecosene”. They have started testing the fuel in a small upper-stage engine.

Prime: mass 18 t, diam 1.3 m, thrust unknown, imp unknown, type M?v, payload 0.15t (0.8% — unknown if reusable mode), cost unknown.

NEBULA — China, 2023?

This rocket was supposed to be ready quite soon, so I knew I had to write it up, but for a long time I couldn’t because there was just nothing to say. Finally I just went ahead with what little I could find. I have no idea whether the company is even legit enough to be worth the effort. The company’s name is Shēnlán Hángtiān (深蓝航天), or Deep Blue Aerospace.

Most of the more technical info I could gather is from the company’s website, which has a “中文|EN” language button that does nothing. All I could gather between that and news reports is that the Nebula-1 will be a two stage smallsat launcher with maybe nine 3D-printed kerosene engines on the first stage, with a thrust of 360 kN apiece in vacuum. The engine is called the 深蓝雷霆-20 (Shēnlán léitíng-20, Deep Blue Thunder-20), and as best I could tell it looked like a gas generator, but that may be wrong. The upper stage apparently uses the same engine, presumably with a vacuum bell.

Then the site also illustrates a Nebula-2 model, which is shown as a Nebula-1 with landing legs photoshopped on. So yeah, they plan to try for reuse with vertical landings. They also a Thunder-100 engine with 1000 kN of thrust. Apparently this will be for the Nebula-2, which will be larger, with a capacity goal of 4.5 tons. I think the picture showing a group of nine engines applies to this rocket.

Some journalists are saying that they will attempt reuse on the Nebula-1, but I have no source for the origin of this assertion.

So far all they’ve built is a small Nebula-M test vehicle. In the fall of 2021 this did a hop test, rising 100 meters and then landing on legs. So they are apparently going for reuse up front. This hopper had electrically pumped engines.&enso;Not bad, but these guys might still be years from reaching orbit, let alone doing so reusably with a bigger rocket. But that didn’t stop them from claiming in 2020 that they would launch by the end of that year.

Nebula-1: Mass unknown, diam 2.25 m, thrust 2.7 MN?, imp unknown, type unknown, payload ~0.7 t, cost unknown.

HAAS — Romania, 2022?

ARCA originally stood for Asociația Română pentru Cosmonautică și Aeronautică, and was founded in Romania as a nongovernmental organization — essentially, a nonprofit — in 1999, by Dumitru Popescu and pals. They made some progress with suborbital rockets and stratospheric balloons, going through several small models of rocket... with some design choices apparently having been made in ignorance of the “pendulum fallacy” which bit Robert Goddard back at the beginning of rocketry. And they started building a spaceplane in pursuit of the Ansari X Prize, which was won by Scaled Composites.

Then in 2015, they moved most of the outfit to New Mexico, as the for-profit ARCA Space Corporation. And for some reason, Popescu got arrested for fraud, but then was cleared on all charges by the grand jury. Apparently some guy that Popescu was talking up for a deal decided he was being scammed, but failed to prove it.

They started working on the first Haas rocket in 2008, with the nominal intention of competing for the Lunar X Prize. It’s named after Conrad Haas, a rocket pioneer who lived in medieval Romania.  They weren’t starting on a very strong footing for this, because their engines at that time were based on using hydrogen peroxide to burn solid bitumen. After a series of annoying failures they decided to bite the bullet and use a proper kerosene/lox engine.

The first Haas was to be launched from under a balloon, using three bitumen/peroxide stages. Then they decided that they couldn’t reliably handle balloons, and decided to launch from a plane. The second Haas was designed around a kerosene/lox engine called the Executor, which was to be made of carbon composites and ceramics and use an ablatively cooled nozzle, and which despite its nonmetallic design had a turbine, producing a chamber pressure of 45 bar. The Haas 2 was apparently designed to make some use of the turbine exhaust for steering, and would have had two stages, each with one Exector, with the second having an enlarged bell. The plan was to follow this up with a larger Super Haas which would have multiple engines.

The carrier plane would be ARCA's IAR 111, a supersonic seaplane powered by another Executor. It would carry the Haas 2 to about 17 or 18 km altitude, at a speed of up to 0.9 km/s — mach 2.6. So far, only a partial fuselage has been assembled.

They intended to flight-test the Executor in a single stage rocket called the Haas 2CA, which they believed should be light and efficient enough to reach orbit without a second stage, with up to 100 kg of payload.

But then things got interesting. They decided to try making an aerospike engine, and as far as can be determined from their current promotional content online, they found this so exciting thay they are shelving the previous Executor engine.

What the heck is an aerospike? It’s a piece of aerodynamic trickery that replaces the bell part of a rocket engine with a concave point or wedge shape which confines the rocket exhaust on only one side, with confinement on the other side being essentially provided by ambient atmospheric pressure. This has two claimed advantages: first, that unlike a bell, it self-adjusts to work optimally at many different altitudes, and second, that at low altitudes it needs less fuel. But how the heck is it supposed to be any good in full vacuum?

Many space outfits have experimented with aerospikes, because on paper they offered the tempting possibility of getting to orbit with a single stage. They were even considered for the Space Shuttle’s main engines, but nobody ever quite got to the point where they judged the result preferable to a conventional rocket engine. Then the VentureStar program was going to use one for a replacement shuttle, which would have made a single-stage rocket make sense (without reusability, there’s not much point)... but both Lockheed and the NASA administrator of the time overpromised how cheap and easy it would be, and the program ended up getting cancelled over issues which, in hindsight, were probably quite solvable. Aerospikes have largely been sitting unused ever since, but now ARCA thinks the time is right.

Their new plan for the Haas 2CA is for a “linear” aerospike — that is, a wedge with a straight back edge as used in VentureStar, as opposed to a ring shape or a single point, as in some other proposed designs. It will have eight little combustion chambers on each side of the wedge. Throttling the ones near the corners provides steering. Oddly, they’ve regressed to using peroxide instead of lox, though the fuel is still kerosene. They’ve also regressed to using pressure-fed combustion. They now claim that this engine is what the Executor name refers to. But the really bold claim is that they expect this thing to launch small satellites for just $1 million per flight. Maybe the regression is justified by extreme cheapness.

Or maybe they never had the capability of building a cryogenic engine, and the original Executor was a paper fantasy. I have found no evidence to the contrary. I would be a lot more excited about this innovative and futuristic rocket if the company had even once succeeded at anything else it tried.

If you want to follow their progress, they put out a Youtube series called The Flight Of The Aerospike, which is already over twenty episodes. So far, this shows them building a “Demonstrator 3” suborbital aerospike, which is based on using peroxide as monopropellant — a reaction which doesn’t even produce temperatures hot enough to require metal nozzles. In short, the fabrication work they’re now doing has almost nothing in common with making the promised orbital engine! I do not have much confidence in this company. They are obviously many years away from building anything orbital.

One problem with aerospikes is that it’s difficult to cool the nozzles and combustion chambers. The best mitigation for this may be to build the engine on a very large scale. But ARCA intends to keep this engine small, and so far, they are just avoiding the heat issue by using weak-ass propellant. This makes them even more unprepared.

Lately they’ve started hyping yet another novel idea: an optional booster stage to increase the capacity of the Haas. This stage wouldn’t use any chemical fuel — it would simply use steam! Apparently the water would be heated electrically before launch. They call this the Launch Assist System, or LAS.

Haas 2CA: mass 16.3 t, diam 1.5 m, thrust 225 kN, imp 3.1 km/s, type Pk*?, payload 0.1 t (0.6%), cost hopefully $10M/t.

BLOOSTAR and MIURA (and TRONADOR) — Spain, 2024?

It’s an old idea: the “rockoon”. Since rockets lose a lot of energy by fighting their way through the atmosphere, and engine bells which work well at high altitude can’t be used at sea level, use a balloon to lift the rocket up into the stratosphere before it even starts firing. It doesn’t impart some horizontal velocity like an airplane does, but on the other hand, helium balloons can reach a higher altitude than any affordable plane. The makers of Bloostar, a Spanish company called Zero 2 Infinity (or 0II) already have balloons that can lift instrument packages to altitudes of thirty kilometers, where the air density is only a fiftieth of what it is at sea level. At such altitudes, rockets can use large vacuum-optimized bells even on the first stage. And they’re building such a rocket. They tout that this balloon-based approach significantly lowers the environmental impact of a launch. The rocket is quite small — no bigger than the Vector would have been, if you don’t count the balloon, but with (they hope) twice the capacity.

Bloostar has three stages, but it doesn’t look like any other three stage rocket. It’s wider than it is tall! From the side, with the fairing up, it looks a bit like a VW Beetle. The stages are not cylinders stacked end to end, but toroid shapes — the first two stages have hollow centers. The first stage is a ring with six small “Teide 2” engines (which I presume they’ve made in-house) spaced around it. (Teide is the name of a volcano in the Canaries.) They burn liquid methane with lox. They’re fed by pressurized tanks, which keeps them simple and cheap because they don’t need any turbines, but does limit the performance, because the combustion chamber pressure cannot exceed the remaining tank pressure. In fact, they are currently planning to limit the chamber pressure to a measly 10 bar (about the pressure of a skinny bicycle tire). The second stage is a smaller copy of the first, which nestles inside the outer ring. It has six “Teide 1” engines, which are about half the size of the first stage engines, also burning methane. These engines stick out of the hole in the center of the first stage. Finally, the third stage is of a conventional shape, and has a single Teide 1 engine. It weighs under half a ton, and is about the size of a wine barrel balanced on a wastebasket.

The fairing is attached to the outer ring of the first stage, and opens like an eyelid, with accordion pleats. They say that since it’s common for satellites to be wider than they are tall, this shape helps satellite makers avoid having to do as much folding and unfolding as they usually need to do.

Why this crazy donut shape? Well, it allows them to run all three sets of engines at the same time. Others have talked about using propellant crossfeed, or “asparagus staging”, but they’ve actually gone and done it. (Or maybe this counts more as “onion staging”.) When the rocket lights up, all 13 engines ignite, but the fuel comes only from the first stage tanks. When it drops off, the second stage tanks are still full. And likewise, the third stage engine burns fuel from the second stage tanks until it drops off. Why bother with all the plumbing and valves required for this trick? I guess the answer is that the Teide 2 engines just don’t have enough thrust, because of their low pressure. But they claim there is enough thrust so that if an engine outage occurs on either the first or second stage, and the engine on the opposite side has to shut down to balance it out, it can still reach orbit.

Both the balloon and the rockets may be reusable, though they’re not counting on it. They’ll put parachutes on the first two stages, and hope to recover them both. One advantage of the fat torus shape is to slow down faster on reentry. The balloon would be set loose at sea, probably from near the Canary Islands (which belong to Spain), so the parts will come down at sea and they can have boats waiting.

Their only test flight that’s been done so far consisted of taking up the second stage with no first stage under it, dropping it, and firing it just long enough to make sure that it could aim itself correctly, then recovering it after it descended on chutes. A long time later, I learned that this test didn’t even use the Teide engines: they just stuck a solid motor on it to simulate them, so the only test was of the guidance stuff. And unfortunately, it seems the company has gone rather quiet since that test. Some say they are now concentrating on their profitable balloon business and putting rocketry plans aside for a while. It’s sounding more and more like this company is long on hype and short on hardware.

They also plan to offer tourist rides to the stratosphere in a capsule carried by a really big balloon. This craft is simply named “Bloon”. It won’t fly as high as a New Shepard or a SpaceShipTwo, but it can spend hours at high altitude rather than just a few minutes.

There’s another Spanish company in the game now too, called PLD Space. They are working on a single stage suborbital rocket which was to be called Arion 1 but has now been renamed as Miura 1, to be followed by an Arion 2 Miura 5 version a few years later. They’ve got a kerosene/lox engine more or less working, they say. It was called “Neton 1”, then “Teprel-1B”, but now it’s called “Teprel-B”. The Miura 5 will graduate to a “Teprel C”, and add two more stages (and I would guess multiple engines) to create a rather conventional small-satellite lifter roughly the size of the Electron. (The Miura 1 is much smaller — just 2.5 tons. It might fly in 2021.) The B engine is pressure-fed but they plan to go gas-generator for the C. So far they have only gotten the B into operational condition on the test stand.

The launch pad is to be built in the Canaries. They also hope to recover the booster by parachute, and this is something they hope to perfect with the initial Miura 1 suborbital rocket. They are telling customers that they will retrieve and return their suborbital payload. (They also claim they will work on propulsive landing in the future.) This venture is getting some support from the European Space Agency, as well as backing from private investors. The first orbit might come around 2022 under ideal circumstances. The Miura 5 will get its own section at some point, if it moves forward as hoped and develops more definite specs. All I know so far is that their planned payload capacity is between 300 and 500 kilograms. So far they have done drop tests for the splashdown and recovery, but have not shown a working booster, or even its engine. Once again, the company seems to be going rather quiet.

There are a lot of companies entering the competition to launch small satellites cheaply, but none of them are counting on reusability, which is the one thing that would allow them to separate from the pack and avoid the coming shakeout as the less successful companies fail. This simple addition of parachutes by Bloostar and Miura is the nearest we’ve seen to a reuse plan from any of these startups. Bloostar also say that one reason they’re using methane instead of kerosene is that the absence of soot would make it easier to clean up and reuse a stage, should they manage to recover it.

(One other small company which is taking the rockoon approach is called Stofiel Aerospace. Brian Stofiel is a home inventor who says he has come up with a formulation that will allow him to 3D-print a rocket motor out of plastic!)

The one company that was really working on a highly reusable small launcher was not any disruptive new startup, but Boeing, with the Phantom Express spaceplane they were building for the Pentagon. Unfortunately, they abandoned the project.

ULA plans to recover Vulcan engines by snagging the parachute out of the air with a helicopter. It occurs to me that when the rocket is small enough, the same technique could work for the entire booster. That simple approach, involving no new technology, could be what lets someone disrupt the small launch market in the same way that SpaceX disrupted the large one. It could finally bring prices down to a level well below those of solid-fuel missiles. But it wouldn’t produce any semi-monopolies, as the barriers are much lower than with propulsive landings. If the technique works, it could be applied to other little rockets — and indeed, Rocket Lab now says they will try it with their Electron.

PLD Space is going for an even cruder approach with the Miura boosters: they plan to let them hit the ocean, and just add reinforcement and waterproofing so they can survive the splashdown. The chute would be on the back end so the nozzles don’t absorb the impact. That’s a better plan for reusability than most of their competition has, but there’s room for improvement where some other company could have lower reuse costs.

Speaking of people who speak Spanish, the government of Argentina is also working on a kerosene-burning launcher, with a three engine booster and a hypergolic second stage. They call it Tronador (Thunderer) II. This is larger, like 67 tons, though still with only a half ton target capacity — a less ambitious figure than many solid rockets in that size range.

They hope to do better than Brazil, which after decades of effort (with some Ukrainian help) built a big solid-fueled satellite launcher called VLS, but never managed to reach space with it. They suspended the program after the rocket blew up in 2003, killing 21 workers and destroying their launch complex... but recently they said they plan to resume the effort, and also work on a smaller rocket called VLM. The VLS had four solid rockets as the first stage while the VLM will use just one. The project is controversial because it involves pushing a large group of poor rural people off their land — not a great look for a dictatorship already in trouble for utterly failing to manage covid. But now maybe they’re backing down and just hiring Virgin Orbit.

Another hopeful country, which doesn’t fit anywhere else, is Turkey. Their UFS national program is developing a liquid-fueled engine for a small launcher with side boosters, known during development as Mikro Uydu Firlatma Sistemi... or maybe for its successor. They’ve previously built a solid-fueled sounding rocket.

Bloostar: mass 5 t, diam 2.9 m, thrust 90 kN, imp 3.4 km/s, type Pm, payload 0.14 t (2.8%), cost unknown.

(no specifics yet for Miura 5)

SKYLON — Britain, no estimate

A company called Reaction Engines Ltd is hoping to build a true orbital spaceplane — a vehicle which can go from runway to orbit to runway without any stage separations. As yet there is not even any funding to start building the plane, but they are making good progress on the propulsion system which would make this possible, which they call SABRE, for Synergistic Air-Breathing Rocket Engine. (Yeah, the word “synergistic” in there is kind of gratuitous.) This motor is based on a trick whereby they scoop up air like a ramjet, but then they subject it to very rapid cooling, which greatly increases its density. They then turbopump it into a rocket combustion chamber, along with liquid hydrogen which has been warmed by the incoming air (but not directly — there’s a complicated intermediary loop filled with helium which also gets involved with the preburner and turbopumps). Some excess hydrogen which was used for the cooling gets burnt separately in a set of ramjet-like nozzles arranged in a ring around the four nozzles of the rocket engine; this happens at medium speeds and altitudes where the amount of fuel needed for cooling exceeds the amount burned by the rocket. The result is a rocket which, for its initial boost phase, needs no onboard oxygen and gets much of its lift from wings, thereby saving tons of propellant. Then, once they get up near 2 km/s speed (to be more precise, mach 5) and 26 km altitude, they close the intakes and start using lox, making it a conventional rocket from then on.

The middle of this single-stage craft would have a cargo bay, in which they could put a passenger capsule for space station taxi service. They say they might pack up to thirty people in there, if there’s anywhere for that many to go. It would not have any windows or any pilot’s seat.

The SABRE engine is apparently fairly far along in development, at least in incomplete small-scale form. They’re testing the high speed phase in the blast of jet engine exhaust, and those tests reached mach 5 successfully in 2019. Unlike a ramjet, the SABRE can produce quite strong thrust at high speeds, and it can also operate from a standing start. It might be the one engine which works in all phases of airplane and rocket flight. If Skylon succeeds, it could make giant boosters obsolete, except for the biggest payloads.

But we’re not going to reach orbit with something all that much smaller than a conventional rocket; it’ll still need fairly enormous tanks of liquid hydrogen, and they’re thinking that despite the savings, the finished plane would be many times the size of a Space Shuttle, with a length exceeding eighty meters — nearly as big as a New Glenn, though much lighter. But at reentry time, this large size will be an advantage: because it weighs little in comparison to its size, especially with empty tanks, it can lose a lot of speed in the upper atmosphere without subjecting its ceramic skin to much heat. Their proposed design has the fuselage tapered to a point at both ends, with two stubby wings each bearing a SABRE nacelle, and some control fins at the tips. They’ve also got a conventional rocket nozzle of a much smaller size at the back end, for low-thrust orbital maneuvering. Most of the weight would be in the middle: the wings, engines, and cargo bay are right at the center, with the lox tanks abutting the bay fore and aft. The majority of the plane’s length consists of nothing but hydrogen tanks.

We don’t know yet if the Skylon plane will ever be built, but the SABRE engine has an interested customer in the US Air Force, so it’ll probably get used in some way. Meanwhile, a group in China is working on an engine that sounds similar.

The company claims they have solved the most obvious problem with the design, which is the accumulation of ice on the air cooler, but are not yet revealing the solution to the public. Personally I have grave doubts as to whether this issue is really solvable.

Though the SABRE engine might make a single-stage spaceplane possible, that doesn’t mean that the single-stage approach is the correct one to use. A more sensible approach would be to make a suborbital spaceplane powered by SABREs, and then drop a conventional rocket stage from it. The plane might be able to release a second stage with both an altitude and a speed that could exceed that provided by a conventional first stage booster, and by doing so, put up a substantially larger payload than the single-stage version of the plane would be able to lift. That upper stage might be made recoverable by giving it a heat shield, and if not, it might be quite small, like not much heavier than its payload. Lately, Reaction Engines Ltd has been mumbling that yeah, they’ll approach two stage designs first, before trying to build anything like the Skylon. However, the Skylon is the approach for which we have a clear design and specs, so that’s what we’re documenting here.

One question which interests me is what the SABRE’s specific impulse would be in the atmosphere in different parts of the flight. On the one hand, like an airplane engine it ought to have an impulse many times the exhaust velocity, since it only takes a small mass of hydrogen to propel a large mass of air out of the back, but on the other hand, as it speeds up, the refrigerated air scoop may rob it of more than half of its thrust. I would bet that the cutoff for when to close the intakes is determined not by how thin the air is, but by how close they are to the point where the exhaust velocity can no longer exceed the intake speed. It’s in these conditions that a scramjet has the advantage, on paper, because it doesn’t need to slow down the incoming air before burning it. Some of Reaction Engines’ figures suggest that the specific impulse in air-breathing mode might range from 40 to 90 km/s; I would guess that the higher number (if achievable) applies at minimum speed and altitude. That big number means that not only does it benefit from saving the weight of lox, it also benefits from consuming hydrogen at a lower rate for the same thrust, because the reaction mass is multiplied due to all the nitrogen and other gases which get pushed through the rocket along with the hydrogen and oxygen. Hopefully the engines run rich, like most hydrogen rockets, or they might end up producing nitrogen oxide smog. (And hopefully by then we will be seeing a decrease in higly toxic rocket fuels, especially solid fuel.)

Skylon: mass 325 t?, diam 6.3 m?, thrust 5800 kN?, imp 4.5 km/s?, type Gh (sort of), payload 17 t? (5.2%?), cost unknown.

— crewed space vehicles —   [Show]

— space stations —   [Show]

— my forecasts —   [Show]

For some possible alternatives to chemical rockets, see this additional article.