October 01, 2012
Credit: Credit: Bill Ingalls/NASA
Frank Morring, Jr. Washington
Sierra Nevada Corp. drew the short straw in NASA's Commercial Crew Integrated Capability (CCiCap) competition, winning only about half as much of the federal seed money to advance its Dream Chaser lifting-body crew vehicle as its two competitors received for their capsule designs.
At $212.5 million, the company's award is not exactly chump change, but the $460 million for Boeing and the $440 million for SpaceX would go a lot further in wringing out the questions that remain about Sierra Nevada's unique approach to flying humans to space. The half-portion grew out of congressional fears that NASA was spending too much to preserve competition in its commercial crew development effort (AW&ST June 18, p. 26).
In his source-selection document William Gerstenmaier, associate administrator for human exploration and operations, says the Dream Chaser design—based on the old NASA HL-20 testbed—poses “significant risks because of design complexity.”
“The winged vehicle offers a lot of advantages, even to customers, in terms of easier landing—you can land on a runway—lower gs, cross-range from deorbit, that's all called out in the document,” Gerstenmaier says. “But associated with that are more technology hurdles. You've got to look at aborts. They're a little more difficult. You've got thermal protection issues, the heat-shield kind of stuff we dealt with on shuttle protection on orbit, all those things. So there's a lot more complexity with a winged vehicle.”
As a result, the agency cut back on the milestones Sierra Nevada had proposed, commensurate with the lower funding level, and does not expect the Louisville, Colo., company to pass critical design review under CCiCap. “We kept enough in that we think we'll get really good insight into how well they can handle those technical challenges,” Gerstenmaier says.
Abort-testing is not on the new list of for Dream Chaser milestones, says Mark Sirangelo, head of Sierra Nevada's space systems unit, but the company plans to make a start anyway. The abort system uses the same hybrid-rocket engines designed for in-space maneuvering to fly off a failing Atlas V, which would be the initial Dream Chaser launch vehicle (AW&ST July 2, p. 37).
“We have plans to do a pad abort test in the coming months,” Sirangelo says. “Our vehicle has no black zones right now for abort from launch to orbit, and we can abort to a runway anywhere along the way. . . . None of the three of us has done any abort tests so far, and we need to all do that. We have that planned to retire that risk, not as one of the milestones but as work that we're doing separately.”