Without repair, the Hubble telescope is expected to fail by the end of 2007. Its backup steering gyroscopes are not working and its batteries are weakening. But the space agency, NASA, canceled a maintenance visit by shuttle astronauts planned for last year after the 2003 shuttle Columbia disaster. It says it will not jeopardize crew members' lives with a mission whose goal is other than completing international space station assembly.
Instead, NASA has backed an unmanned Hubble servicing mission using untested robotic technologies now being developed. But some experts say astronauts would be more reliable. Others argue for replacing Hubble with a new platform designed to do the same thing, and still others say Hubble's mission is outdated by a new generation of orbiting telescopes being planned.
The chairman of the U.S. House of Representatives science committee, Sherwood Boehlert, says it's going to be a tough call. "On the one hand, everyone acknowledges that the Hubble has been a sparkling jewel in the crown of American science, but on the other there is disagreement about how and whether to save it. 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 in astronomy," he says.
NASA has sent four shuttle crews to maintain and upgrade the Hubble since 1993. A National Academy of Sciences panel studied the issue at the request of Congress and says this is still the best way because it would use proven methods and allow immediate human intervention if a problem arises. Panelist Charles Bolden, a former astronaut, counters NASA's concern that a shuttle visit is too risky. "There is no human safety concern more from a Hubble Space Telescope mission than there is from an individual international space station mission," he says.
But an official of the company developing a mechanical arm for a robotic mission to Hubble bridles at the academy panel's assertion that unmanned repair technology is less reliable than people. Paul Cooper of M.D. Robotics says tests show the technology works. "We relentlessly took a real robot operating on real mock-up hardware and we have now executed every single task that's necessary to do the servicing and upgrade operations. In short, we can do this and we think it's the right thing to do," he says.
A third option being promoted is a replacement of the Hubble with some of the new instruments intended for it. Those who favor it say it would not have to be rushed into orbit before a Hubble failure and that its more capable technology could quickly make up for any scientific losses incurred in the time between such a failure and the launch of the new platform.
But Princeton University astrophysicist Joseph Taylor says the loss of Hubble would not set back astronomical research. Mr. Taylor co-chaired a National Academy of Sciences committee that decided future research priorities in astronomy. He points out that new observatories to be launched by 2011 can better serve the new priorities because they will be able to look into the farthest reaches of the universe with instruments Hubble does not have. "We concluded that answers to many of the astrophysical questions most ripe for scientific progress in this decade are likely to be found at spectral wavelengths outside the Hubble telescope's capabilities. It is very difficult for me to say that knowledge of the premature loss of the Hubble would have significantly altered our priority list," he says.
Still, there are those in Congress who think the telescope should be rescued. Science Committee Chairman Boehlert, who is one of them, says he is concerned about news reports that NASA has cut funds for a repair mission from its 2006 budget to be released Monday. "I would dearly love to save the telescope. It has outperformed everyone's fondest hopes and has become a kind of mascot for science, maybe even for our planet. One can't help but root for it," he says.
If nothing is done to save Hubble's scientific capabilities, NASA says it will still dispatch a robotic mission to deorbit it safely by 2013 at the latest.