WASHINGTON — Companies working on commercial crew transportation services to and from the international space station reported milestones in their efforts even as a NASA official warned that the agency likely will have to order more Russian Soyuz crew capsules to keep the orbital outpost fully occupied.

Phil McAlister, director of commercial spaceflight at NASA headquarters, told an advisory panel Dec. 9 that the agency may have to order another batch of Soyuz crew capsules from Russia unless Congress funds NASA’s Commercial Crew Program at the $800 million-plus level sought by the White House. 

“I think that’s going to be a topic of a lot of debate in the next year or so,” McAlister told a panel of the NASA Advisory Council.

The debate, McAlister hinted, might be more about how many seats to buy, rather than whether to buy the seats at all. 

NASA’s current contract with the Russian space agency, Roscosmos, covers astronaut transportation to and from the space station through 2016, and emergency crew rescue services through June 2017. 

The White House is seeking $821 million this year for the Commercial Crew Program, under which Boeing Space Exploration, Sierra Nevada Space Systems and Space Exploration Technologies Corp. (SpaceX) are working on U.S. alternatives to the Soyuz. The U.S. government is currently operating under a six-month continuing resolution, set to expire Jan. 15, that funds the program at $525 million.

“We really do want these systems available by 2017 if possible,” McAlister said. However, “Our ability to accommodate lower-than-expected budgets is getting [to be] much less.”

A week after McAlister’s remarks, Sierra Nevada Space Systems announced that it had received the full payment from NASA for an October flight test of its prototype Dream Chaser crew taxi that ended with a crash.

The full-scale engineering test article was dropped by a helicopter from an altitude of about 4 kilometers at Edwards Air Force Base, Calif. The shuttle-like craft made a smooth, automated approach to the runway, touched down dead-center, but crashed after its left landing gear failed to deploy.

Sierra Nevada maintained that the crash had not stopped the company from gathering the data the test flight was designed to generate, and NASA evidently agreed.

“After extensive post-flight analysis by NASA, [Sierra Nevada] received the full award value for the milestone,” the company said in a Dec. 16 press release. The milestone, the last under the company’s $102 million, second-round Commercial Crew Development contract, was worth about $8 million. 

“After the post flight evaluation, the vehicle was deemed to be fully repairable and a schedule to return it to flight has been created,” Mark Sirangelo, head of Sierra Nevada Space Systems, wrote in a Dec. 17 email. The company expects to test the vehicle “upgraded with additional capability in 2014,” he said.

Meanwhile, Aerojet Rocketdyne of Sacramento, Calif., wrapped up development testing on a pair of launch-abort engines for the CST-100 space capsule Boeing is developing under the Commercial Crew Program.

The latest tests took place near Mojave, Calif., during the second half of October. A pair of engines, each capable of generating about 39,000 pounds of thrust, were fired for a combined 29.7 seconds, Boeing spokeswoman Kelly George wrote in a Dec. 16 email. The successful development tests clear the way for qualification tests, in which each engine will be fired for 11 seconds — double the design requirement, George said.

 The engines are for CST-100’s pusher-style abort system. In the event of a launch mishap, four such engines would propel CST-100 and its crew to safety. In a normal launch, the system will be carried to orbit, where its fuel could be used to pad margins for the rest of the mission, Boeing said in a Dec. 16 press release. 

Pusher abort systems are different from tractor-style abort systems — such as the one used on the Saturn 5 rocket for Apollo missions and the one planned for NASA’s Space Launch System — which are discarded shortly after liftoff during a nominal launch.

SpaceX is working on a similar pusher abort system for its Dragon space capsule. The Hawthorne, Calif., company now expects to test its launch abort system sometime before June. 

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Dan Leone is the NASA reporter for SpaceNews, where he also covers other civilian-run U.S. government space programs and a growing number of entrepreneurial space companies. He joined SpaceNews in 2011.Dan earned a bachelor's degree in public communications...