If the members of the space committee in the House were to get their way, there would be a single answer to the question of what will the astronauts ride to get to and from orbit: the Orion crew module planned as part of Constellation (renamed the Multi-Purpose Crew Vehicle by the Senate a few days ago), which they'd like to restore after the administration canceled it in February. It weighs much more, and has capabilities unneeded for the simple task of getting to space and back, because it is designed to go all the way to lunar orbit, and to enter Earth's atmosphere from almost escape velocity (about twice the energy needed to enter from low Earth orbit), which means it needs a more robust heat shield. It also has longer-duration life support, and toilet facilities. It is expected to cost several billion dollars to complete, and the jury is still out on the issues of both whether or not it will be reusable (much of the reusability was lost when Ares I performance issues required stripping weight out of Orion), and whether or not it will land in the water or on terra firma.

If the Senate compromise prevails (as looks likely), and Commercial Crew remains adequately funded, there will be several options.



(Photograph by jurvetson/Flickr) (Photograph by jurvetson/Flickr)

The one furthest along in development is SpaceX's Dragon capsule. It would go up on a SpaceX Falcon 9 rocket, the same type that launched a Dragon boiler-plate structural test article in early June. It is designed to carry both crew and cargo, and a pressurized version of it is planned to fly in September, with plans for one or more test flights that will rendezvous with the ISS, to occur next year. In order for it to carry passengers (up to seven), it will have to add a life-support system, and a launch abort system, either the "Tractor" type planned for Orion (in which a tower on top of the capsule fires a solid motor that pulls it away from a hazardous launch situation) or a pusher type, that lies underneath the capsule, and may be usable on nominal missions to help get into orbit, making it less of a waste of money and weight when (as usual) the ascent goes well.

It is designed to land in the water, with parachutes (a critical capability for aborts, since most of the ascent trajectory, at least to ISS, will occur over the Atlantic), though some think that it might also be capable of landing on land, at least eventually, which makes for an easier recovery. SpaceX has designed it to be reusable, but NASA plans to buy a new one for each cargo mission (and will presumably do the same for crew, if SpaceX gets a commercial crew contract), which means that SpaceX will have plenty of inventory for either lower-cost rides for commercial customers, or as small space stations in the form of what they call Dragon Lab. Because the Dragon Lab is designed for long duration, the Dragon could also serve as a lifeboat for the ISS, a function that is currently performed only by the Russian Soyuz (even if the shuttle continued to operate, it can only stay in orbit for a couple weeks or so). The company estimates that it could be flying passengers for a billion dollars in development cost, including abort tests and flight demonstrations to the ISS, in three years or so (by 2014).

Boeing

(Rendering courtesy of Boeing)

Boeing's entrant, a joint development with Bigelow Aerospace, is called the CST-100, presumably for Commercial Space Transport—Boeing had no comment when I asked what happened to CSTs-1 through 99. Actually, the Boeing press release says that it stands for a hundred kilometers—the distance from the ground to low Earth orbit (LEO). Unfortunately, it's a lot farther to LEO than that, which is only the altitude traditionally considered the beginning of space, so if that was the rationale, they really should have called it the CST-300.

Boeing is currently working on an $18 million contract from NASA on the Commercial Crew Development (CCDev) program. Boeing has the drawings for the Apollo capsule (having inherited them from its purchase of Rockwell International's space divisions in the nineties) and the capsule looks very much like one. It's larger than Apollo, and will be able to carry up to seven passengers, like Dragon, but it's smaller than Orion, because it doesn't need or have the deep space capability.

It's designed to land with airbags (probably at White Sands), though like Dragon, it is capable of a water landing as well, for aborts. For maximum flexibility, it will be able to be launched on a United Launch Alliance Atlas or Delta, as well as on a SpaceX Falcon 9, so (unlike Ares I/Orion) it will have redundant means of getting to orbit, in the event of a problem with one launcher type. Their abort system will be a pusher, using liquid hypergolic propellants (monomethyl hydrazine and nitrogen tetroxide, the same propellants as the Shuttle Orbital Maneuvering System and reaction control system use). It has high-thrust engines for aborts, with lower-thrust engines (similar to the shuttle RCS engines) for orbital maneuvering on nominal missions. It will base its automated rendezvous and docking (AR&D) system on the one successfully used for Orbital Express. Like the Dragon, it is being designed for at least a six-month orbital mission, allowing it to be a lifeboat as well. A final decision by Boeing to move forward with the project will depend on political events in Congress. Boeing has stated that they cannot close the business case for it with their own money absent some amount of NASA funding, and assurance that it won't have to compete with a taxpayer-funded Orion. With adequate funding, however, they believe that they can be flying it by 2015.

Lockheed Martin

(Photograph by Bernt Rostad/Flickr)

Bigelow Aerospace has partnered in the past with Lockheed Martin to build an "Orion Lite," based on the capsule being developed as part of Constellation, but without the deep space capability. No government funding has been provided for this concept to date, and it is tangled up with the politics of Orion's fate. At this point, it seems to be an unlikely contender.





SpaceDev

(Photograph via Wikimedia Commons)

Perhaps the most interesting, but longest-shot entrant is the Dreamchaser. The only non-capsule contender, it is a lifting body based on the old NASA HL-20 test vehicle. It actually has a heritage going back about twenty years, to the Personnel Launch System being considered by NASA Langley and Rockwell as a shuttle replacement for space-station crew support in the early nineties. It will be a vertical takeoff (currently designed for an Atlas V) vehicle capable of large cross-range and runway landing anywhere in the world. Like the other vehicles, it will carry up to seven passengers. It is being developed with $20 million of seed money from the CCDev program but, like Boeing, it will probably require much more NASA funding to move to full-scale development.





Bottom Line

For servicing ISS, there are several potential providers of crew services, all of which combined would likely cost less than going forward with the underfunded Orion/MPCV, providing redundancy. The main benefit of the latter is the capability to carry crew beyond LEO (though this is a goal for SpaceX's Dragon as well), and there is no funding or plans for landers and other things needed for the more ambitious missions, so such a vehicle might still end up all dressed up and no place to go, even if sufficiently funded. But as with all major NASA decisions, the fate ultimately lies with Congress.

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Orion

Dragon

CST-100

Orion Lite

Dreamchaser

Beyond Earth Orbit

Yes

Maybe

No

No

No

Launch System

TBD

Falcon 9

Delta IV, Atlas V, Falcon 9

Atlas V

Atlas V

Landing Mode

TBD

Chutes in water

Chutes/airbag on land

TBD

Runway landing

Abort System

Solid Tractor

TBD

Hypergolic Pusher

Solid Tractor

TBD

Mission Duration

Years

One Year

Six Months

TBD

TBD

Passenger Capacity

TBD

7

7

TBD

7

Earliest Operational Date

TBD

2014

2015

TBD

TBD

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