Rockets of Today


A company called 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 can fold to fit inside a five meter fairing. The cool part is it would land on a runway, with little wings which are folded over the body during launch. 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). 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 thing will have two small rocket engines on the back for orbital maneuvering. After considering a hybrid engine (solid fuel and liquid oxidizer), they settled on a motor which reacts propane with nitric acid. 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 two nozzles are placed well to either side; in the middle is the hatch for the astronauts. Yep, it docks to the space station with its butthole.

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.

The crewed version will have a disposable launch abort motor, I think.

It could have a sort of service module thing on the back, but this is strictly 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 recently dubbed this add-on module “Shooting Star” — a poetic way of saying it burns up on reentry. But 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 perhaps 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.

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. As things stand today, the Dream Chaser project seems to be moving quite slowly, but it looks like they might finally be getting ready to fly.

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).