With NASA's ambitious Constellation program apparently on the verge of termination, the US space agency - anticipating that the wrapping up of the program will be no mean feat - is already feeling the strain of its elaborate plans.

To close down Constellation, a project for returning astronauts to the Moon by 2020, NASA will have to steer through an essentially self-weaved political and financial tangle; and it is reportedly trying to assemble all information about what it owes to the contractors.

Meanwhile, as per the 2011 budget proposal, $2.5 billion will probably be assigned for payment to Constellation contractors, so as to stall any ongoing work on the Ares rockets, Orion capsule and Altair lunar lander.

That the assigned amount will be far from adequate is evident from the fact that NASA has already signed contracts worth over $10 billion for designing, testing and building the Ares I rocket and Orion capsule. Furthermore, the costs of the contracts have supposedly risen by almost $3 billion since 2007 owing to design and agenda changes and technical issues.

About the proposed $2.5-billion figure, NASA administrator Charles Bolden, who is himself unclear about the total cost figure, said: "I think we took what was an estimate from what industry said, what our analysts said. It's a ballpark figure. Hopefully, it's something that's extreme."