WASHINGTON - The Bush administration tried to reassure Congress yesterday that NASA's support for space science will continue even as the agency shifts its resources to fulfil President Bush's vision to return astronauts to the moon by 2020.
But there were no assurances that it will reverse a decision to consign the Hubble Space Telescope to an early demise.
Presidential science adviser John H. Marburger III said, instead, that new technologies for telescopes in space and on the ground will do as well as or better than Hubble in some key areas of astronomy.
While there will remain some things only Hubble can do, he said, "Hubble's uniqueness is diminishing."
The comments came during testimony by Marburger and NASA Administrator Sean O'Keefe before the House Science Committee, which is reviewing the president's space initiative and NASA's proposed budgets through 2009.
Several committee members worried that the renewed emphasis on manned space flight will starve other NASA activities. A committee report said the NASA budget plan calls for cuts to space science projects totaling $2.6 billion over five years, as others are added.
Rep. Nick Lampson, a Texas Democrat, said, "I am not prepared to do damage to NASA's other programs and activities" to accomplish the president's goals.
O'Keefe assured members that NASA will make increasing investments in the study of Earth's environment and global warming, continue robotic exploration of the solar system, pursue studies of the sun and the origins and evolution of the universe, and continue to work on aviation safety.
But Hubble's future remains in peril.
Last month, O'Keefe canceled a planned fifth space shuttle mission to service and upgrade the orbiting observatory. Scientists expect that will lead to a crippling malfunction by 2007, well short of the telescope's planned retirement in 2010.
Protests from astronomers, the public and some in Congress, however, prompted NASA to ask Adm. Harold Gehman, who headed the Columbia Accident Investigation Board, to review the decision. That review is pending.
Yesterday, Marburger echoed a National Research Council report in 2001 that said the Hubble telescope "has arguably had a greater impact on astronomy than any instrument since the original telescope of Galileo."
But the NRC report, he said, also noted that "tremendous progress has been made in improving the quality of ground-based telescopes" in the 14 years since Hubble's launch.
Adaptive optics - a technology that enables telescopes to compensate for much of the distorting turbulence in Earth's atmosphere - have enabled mountaintop observatories to see as well as or better than Hubble in infrared wavelengths, Marburger said.
Although ground-based telescopes are still more limited in their field of view and their sensitivity than Hubble, more advanced versions will improve both, Marburger said.
Steven V.W. Beckwith, director of the Space Telescope Science Institute in Baltimore, said he wrote the portion of the NRC report that Marburger cited. After watching a tape of the hearing, he said, "I think Mr. Marburger took [it] out of context."
It assumed Hubble would work until 2010, he said: "Our conclusions ... would have changed dramatically had we known NASA had plans to cancel Hubble halfway through the decade."
He said there are no plans to develop adaptive optics for the visible wavelengths that are Hubble's strength. And "it will take another 10 years before they [ground-based observatories] are competitive with Hubble even in the infrared. ... The whole calculus has changed."
Marburger said that adaptive optics is not a "killer argument here. ... But it's also true that Hubble's uniqueness is diminishing, and it is approaching the end of its design life."
Marburger said the safety issues surrounding the final servicing mission to Hubble "cannot be ignored." They played a key role in O'Keefe's decision to cancel the flight,
Rep. Vernon J. Ehlers, a Michigan Republican, reminded O'Keefe that "this is a hazardous enterprise. ... We can't encumber the program with such absolute requirements for safety that we price ourselves out of doing it."