US ambitions of returning to the moon by 2020 and then heading to Mars risk being grounded because of "unrealistic" funds allocated to NASA, said Senator Bill Nelson, a former space shuttle astronaut.
"NASA simply can't do the job it's been given -- the president's goal of being on the moon by 2020," Nelson told the first public meeting of the Review of US Human Space Flight Plans Committee in Washington.
Nelson, a senator from Florida -- home to the Kennedy Space Center -- said that for years NASA's budget has been too small for its tasks.
"And that has led us to the point where we are now: with a space shuttle that's going to shut down but without the new rocket developed in time to pick up where the shuttle leaves off," Nelson said.
When President Barack Obama unveiled the federal budget last month, he ordered a review of the problem-plagued, budget-busting rocket that NASA hopes will be on launch pads by 2015 to replace its shuttle fleet, due to be retired next year.
The cost of the next-generation rocket has ballooned from an initial 28 billion dollars to about 44 billion due to technical troubles and cost overruns.
Nelson said that Congress last year authorized six billion dollars for NASA's space exploration program in 2009, a sum "well above what the president requested" in the budget.
Obama's budget proposal would leave the US space program with "a four or five year gap with no American human-rated launch system and that would expand to six, seven, possibly eight years," said Nelson.
With no US means to get to the International Space Station -- in which the United States has invested 100 billion dollars, according to Nelson -- US astronauts would have to hitch a lift into space with the Russians for several years.
"I don't think anybody wants us to continue in the circumstance where the only way to get to the International Space Station ... would be in a multi-year period dependent upon the Russians," Nelson said.
"It's my hope that our foreign relations with the Russians are going to get better, but who knows what the geopolitics are going to be later in this decade."
(c) 2009 AFP
Explore further: Mice, gerbils perish in Russia space flight