Rockets of Today

DREAM CHASER — USA, 2024?/2026?

A company called Sierra Space (formerly 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.) The cool part is it would land on a runway. This means that, like the Shuttle, it would have to pop out landing gear through the heat shield. It will 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 would start their ISS operations by doing unmanned 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 passenger version has two rocket engines on the back for emergency launch escape. After considering a hybrid engine (solid fuel and liquid oxidizer), they settled on motors which react propane with nitric acid, sourced from a company called Orbitec. 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 small reaction control thrusters also burn a safe fuel, namely alcohol. The two abort nozzles are placed well to either side on the back end; in the middle is the hatch for the astronauts. 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 interior 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 could 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. The Dream Chaser itself is nine meters long, with a wingspan of seven.

The basic design of the craft is derived from work done in the nineties by Lockheed-Martin on spaceplanes called the HL-20 and HL-42, which were in turn inspired by a Russian prototype from the eighties. 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. 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.

The cargo version has wings that fold in, so it and the Shooting Star can fit inside a five meter fairing. The crew version has non-folding wings and would launch with no fairing around it. It can still use the Shooting Star without interfering with launch abort, they say.

And if NASA isn’t interested in flying people in it, they might find customers in other countries. There is talk of this becoming a spacecraft option for the ESA (flying on an Ariane) and for JAXA as well (on an H-3).


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’re getting built so far is a scale model 60 centimeters wide and weighing around 40 kilograms, dubbed “Bikini”, which will be thrown overboard from a satellite launch to see how it handles reentry. After that will come a 1.6 ton mid-scale test article 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 quite optimistic. And unfortunately, once they completed the first cargo vessel (named “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.