NASA outlines why it passed over Sierra Nevada

October 10, 2016 – 12:30 am

A prototype of Sierra Nevada's Dream Chaser space plane conducted a taxi and approach and landing test campaign in 2013 at Edwards Air Force Base, California. Another landing test is planned for March. Credit: NASANASA cited the complexity of Sierra Nevada’s Dream Chaser space plane and an uncertainty of when the proposed crew transport craft would be ready to fly astronauts to the International Space Station as the primary reasons the agency picked Boeing and SpaceX for lucrative contracts to develop commercial space taxis.

Sierra Nevada’s Dream Chaser spacecraft, which would take off on top of a United Launch Alliance Atlas 5 rocket and land on a runway like the space shuttle, is not as far along in development as the competing CST-100 and Crew Dragon capsules proposed by Boeing and SpaceX, according to a source selection statement signed by Bill Gerstenmaier, head of NASA’s human exploration and operations directorate.

“A winged spacecraft is a more complex design and thus entails more developmental and certification challenges, and therefore may have more technical and schedule risk than expected, ” Gerstenmaier wrote in the selection statement.

NASA wants to have the commercial crew capsules operational by the end of 2017 to end U.S. purchases of astronaut seats on Russia’s Soyuz ferry craft. Before NASA permits its astronauts to fly on the CST-100 and Crew Dragon, each spaceship will go through ground testing and complete unpiloted and crewed test flights.

NASA released the document late Friday outlining the rationale for its selection of Boeing and SpaceX in a competitive procurement to develop and build spacecraft to ferry astronauts between Earth and the space station in low Earth orbit.

The space agency announced the Boeing and SpaceX contracts on Sept. 16, but officials initially withheld the reasoning for the agency’s decision over concerns about the release of information considered proprietary by each company. A review by the Government Accountability Office sparked by a protest of the Boeing and SpaceX deals by Sierra Nevada, which was shut out of a contract, further delayed the release of the source selection document, according to a blog post on NASA’s website.

The statement describes why Boeing and SpaceX received contracts worth $6.8 billion to complete development of the CST-100 and Crew Dragon capsules.

The Commercial Crew Transportation Capability, or CCtCap, contracts cover the design, testing and certification of the CST-100 and Crew Dragon spacecraft. The contracts guarantee each company at least two full-up operational missions to rotate crews on the space station, with options for up to six flights through 2019.

The spaceships will accommodate up to seven astronauts — or a smaller crew mixed with supplies — and stay attached to the space station for up to 210 days, serving as a lifeboat back to Earth in case of an emergency.

The CST-100 capsule will launch on ULA’s Atlas 5 rocket, while the Crew Dragon vehicle will take off on SpaceX’s Falcon 9 booster. Both spaceships will launch from Cape Canaveral.

If NASA exercises all the contract options, Boeing’s deal is worth up to $4.2 billion, and the value of SpaceX’s contract is $2.6 billion.

Gerstenmaier acted as the selection authority and made the final decision on which companies won the CCtCap contracts after advice from an evaluation board.


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