DREAM CHASER — USA, 2024?/2026?

A company called Sierra Space (a spinoff of Sierra Nevada Corporation), which has gathered a lot of aerospace experience behind the scenes making subcontracted parts of other companies’ projects, is building a lifting-body spaceplane out of carbon fiber. They don’t make boosters — it would be launched atop a Vulcan. Long term, any other rocket of comparable size might do, as the wings of the cargo version can fold to fit inside a five meter fairing. (The crewed version would not have a fairing around it, and will use rigid wings.) These wings and its aerodynamic bottom, would decelerate it early during reentry and let it have lift to stay higher longer, allowing it to subject passengers and cargo to well under two gees, they say, whereas a capsule such as a Starliner or Dragon will load you up with about seven.

The cool part is it would land on a runway. This means that, like the Shuttle, it has to pop out landing gear through the heat shield. And the nose of the craft has no room for a wheel, so in front it just pops out a hardened steel skid plate. This has raised a bit of concern among those who maintain runways, especially the exquisitely smooth giant runway that was built at Kennedy Space Center for shuttle landings.

It could seat up to five people (early plans said seven, as they were aiming for the capacity of a shuttle). The volume of the passenger compartment might be as large as sixteen cubic meters, and the mass is supposed to be around nine tons, making it exceptionally light and roomy if those numbers hold up. Of course they will start their ISS operations by doing uncrewed cargo deliveries first. They say it could carry 5.5 tons up and 1.85 tons back down. They hope to get fifteen flights out of each vehicle. The initial fleet is two cargo craft which they are dubbing Tenacity and Reverence. (Boeing and SpaceX follow a NASA tradition and only give craft names when people ride them, but other outfits have named cargo spacecraft before, including the European Space Agency.)

The passenger version would have rocket engines on the back for emergency launch escape. After considering a pair of hybrid engines (solid fuel and liquid oxidizer), they settled on eight smaller motors which react propane with nitric acid, sourced from a company called Orbitec, which Sierra acquired. These might be used for orbital maneuvering as well as for emergency escape. The reaction control thrusters use a fuel based on ethanol... and might be snall hybrid motors? It isn’t clear. Anyway, all of these chemicals are safe enough that the thing could land at an ordinary airport, which is not the case with the hypergolic propellants normally used on spacecraft, which require ground crews to use special equipment and careful procedures to sniff for toxic leakage.

The major nozzles are placed well to either side on the back end; in the middle is the hatch to access the interior. Yep, it docks to the space station with its butthole. And that’s the only door, so since docking hatches are only 80 centimeters wide, this means that going in and out on the ground has to be done by crawling. Sierra has a set of mockups that they use just for training people in the awkward process of loading the inside through that narrow door.

The heat shield is made of tiles, like on the Shuttle. And as on the shuttle, each tile is uniquely cut to fit in one specific place. But there are only about two thousand of them rather than twenty thousand, and they don’t seem to be delicate, so the operation of shaping them and gluing them all on isn’t taking prohibitively long.

It will have a sort of service module thing on the back, but this is considered optional. It’s mainly just extra space for cargo, both pressurized and unpressurized, though it would also give the craft some solar cells. It can also have active instruments bolted to the outside, which it supplies with power and data connections; these devices can then be transferred to the outside of the station, or popped loose into their own orbits. They dubbed this add-on module “Shooting Star” — a poetic way of saying it burns up on reentry.... if it doesn’t get repurposed as a satellite in its own right, which it’s quite capable of supporting. And the Shooting Star has another trick up its sleeve: it can also be equipped with an ion engine, and with that, the Dream Chaser can fly all the way to the Lunar Orbital Platform-Gateway, inexpensively and reusably supplying it with several tons of cargo. (Not people, because the ion engine would take forever to get there.) The 5.5 ton cargo figure is only valid if the Shooting Star is used. It’s pretty substantial in size — four and a half meters long and over three wide at the back end — comparable to a moderately sized box truck. The Dream Chaser itself is nine meters long, with a wingspan of seven. When loaded up, they’d keep a clear passageway through the middle, with everything strapped to the sides. They say it can use the Shooting Star on crewed flights without interfering with launch abort — presumably it gets left behind.

The basic design of the craft is derived from work done in the nineties by Lockheed-Martin on lifting body spaceplanes called the HL-20 and HL-42. The HLs are very similar in shape to the Dream Chaser, though different in size. It’s a good looking shape, even if from some angles it kind of looks like a shoe. When the design was first revived, the intent was just to make it a suborbital ride like SpaceShipTwo, but then they realized that their goal needed to be loftier.

At first, this design was out of the running as a Space Station passenger carrier; they entered NASA’s design competition against the Dragon 2 and the Starliner, and didn’t make the cut. Maybe next time; at least they got approved to participate in the second round of unmanned ISS cargo flights. (The first round went to the Dragon 1 and Orbital ATK’s Cygnus canister, described in the article on cargo capsules.) Or alternatively, some say that the European Space Agency may be interested in flying a Dream Chaser on a future Ariane booster — it’s quite a bit smaller than their cancelled Hermes spaceplane would have been, but that’s a lot bigger than having no spaceplane at all. There’s also been talk of flying it on an H3 for JAXA, the space agency of Japan. This would probably be a lot further along if they had someone with a budget backing the completion of the development. For a long time, the Dream Chaser project seemed to be moving quite slowly, but they’re now about ready to fly the cargo version. And they say that its little RCS thrusters are capable of reboosting the station’s orbit, like a Progress or a Cygnus.

But what’s this? Sierra Space now says there will be two Dream Chaser models, DC-100 and DC-200. The former is the shape we’re familiar with, whereas the latter will apparently be a new shape which is more of a flattened lifting body, with small “four-poster” control surfaces at the rear like a twin-tailed fighter jet, rather than any real wings. The new shape is simpler and not nearly as pretty. And apparently the plan now is that only the new DC-200 will get a crewed version? This means that the upper bulge at the front of the DC-100, which clearly was put there just so there could be pilot windows at the front, will now have no purpose. The illustrations they’ve provided for how they envision the DC-200 show no windows at all. But don’t make too much of that — they are only “studying” this twin-tailed lifting body design, and they may end up settling on something that looks quite different from these sketches. But one thing is clear from this: those who were hoping that a crewed Dream Chaser could replace the troubled Boeing Starliner for carrying NASA crews to the International Space Station are not going to get their wish. By the time this is ready, the ISS will probably be about due for deorbiting.

And unfortunately, once they completed the first cargo vessel, Tenacity, and got it ready for a maiden launch, Sierra laid off numerous workers. If that first flight goes badly, they may not get another chance. And then even after Tenacity was shipped to Florida to mate with a Vulcan, further little delays cropped up, and they missed their flight. And somehow these small delays stretched into much bigger ones, and what was supposed to be a loss of maybe three months ballooned into more like eight, just because that’s the soonest that the ISS will have a parking space available.

Nyx

Speaking of Europe, some ArianeSpace and Airbus veterans have founded The Exploration Company, which might provide an alternative to buying from Dream Chaser. They are working on a commercial spacecraft called Nyx, which is a traditional conical capsule with a service module. The design is rather modular, they say, so it can be configured for lots of different types of missions, from space station cargo in the earliest iteration to eventually, they hope, taking people to the moon. They even talk about making it into a lunar lander. The capsule would use “green” monopropellant (peroxide) for its thrusters, and they’re working on a methane engine called Huracan for the service module so it can reach cislunar destinations. They’re aiming for five reuses per capsule. They are also designing it to be refuelable in orbit.

The specific design is far from complete, so we can’t give any specs or stats for it. About all they’ve built so far is a scale model 60 centimeters wide and weighing around 40 kilograms, dubbed “Bikini”, which was to be thrown overboard from a satellite launch to see how it handles reentry. This went up with the maiden flight of Ariane 6, but the failure of the upper stage to do its final relight meant that the reentry test couldn’t be carried out. They’ll probably have to make another Bikini test article. After that will come a 1.6 ton mid-scale test vehicle with thrusters and a parachute, which can take a useful payload up and hopefully bring it back undamaged.

They are targeting 2026 to make the full sized capsule. That sounds optimistic.