NASA's Ares V cargo launch vehicle (CaLV) and Altair lunar lander design contracts worth hundreds of millions of dollars have been put on hold until the conclusion of a human spaceflight study that was ordered by president Barack Obama's administration and will finish its work by August.
The study, announced 7 May, will assess whether NASA's Constellation programme, which is developing the Altair, CaLV, Ares I crew launch vehicle (CLV) and Orion crew exploration vehicle, can on its present course deliver a replacement for the Space Shuttle fleet that is being retired next year.
"I have been inclined to hold off on [the contracts] because I don't want to presume the outome of the [Obama human spaceflight] review," says NASA exploration systems mission directorate associate adminstrator Doug Cooke, speaking at the roll out of the space agency's fiscal year 2010 budget on 7 May.
Asked about alternatives to Orion and Ares Cooke, whose directorate runs Constellation, said he could not see an alternative that would meet the 2015 target date for manned flights using the Shuttle replacement system.
He added that on safety grounds he thought the Constellation vehicles were safer than any of the alternatives offered. Those alternatives include using US Air Force Evolved Expendable Launch Vehicles such as the United Launch Alliance Atlas V.
Under the FY2010 budget published on 7 May CLV gained an additional $348 million over the 2009 funding while Orion lost $3.7 million but clawed back over $210 million through the American Recovery and Reinvestment Act 2009.
This Obama administration macro economic stimulus act gave NASA $250 million for its Constellation programme.