The chairman of the House Science Committee said Congress needs to decide whether the 14-year old telescope, renowned for its inspiring snapshots, is worth the cost of repair - estimated to be as much as $2 billion.
"We have to make hard choices about whether a Hubble mission is worth it now, when moving ahead is likely to have an adverse impact on other programs, including quite possibly other programs in astronomy," said Rep. Sherwood Boehlert, R-N.Y.
Hubble hovers about 375 miles above the Earth, circling the planet every 95 minutes, and has seen galaxies that are more than 12 billion light years away.
While NASA has sent several repair missions, experts say an additional one is needed because the batteries and gyroscopes probably will fail between mid-2007 and 2010.
But with the crash on Feb. 1, 2003, of the space shuttle Columbia, a manned mission to repair Hubble is not worth the risk, said Rep. Dana Rohrabacher, R-Calif.
"Some people just want to dive back in and use the shuttle as if these catastrophic accidents didn't happen. ... To the degree that we don't have to use the shuttle, we shouldn't use the shuttle," he said.
Experts also are divided about the best course of action.
NASA caused an uproar among scientists last year when the agency said that the safety of astronauts should not be put at risk in order to repair Hubble.
A National Academy of Sciences committee concluded in December that NASA should use astronauts, not a robot, for a repair attempt.
"The crew risk of a single shuttle mission to Hubble is very small," the chairman of that committee, Louis Lanzerotti, a professor at the New Jersey Institute of Technology, told lawmakers Wednesday.
But Dr. Paul Cooper, an executive at the company asked by NASA to create a Hubble-repairing robot, said such a trip could be of huge scientific benefit in future repairs of U.S. satellites, particularly for the Defense Department.
The goal of any repair mission to Hubble would be to install fresh batteries, gyroscopes, fine-guidance sensors, and two powerful new cameras that could make the telescope more productive than ever.
NASA has agreed that failing all else, it will use a robotic spacecraft to steer Hubble into the ocean by 2013.
By Devlin Barrett