Hubble in Trouble, But It Could Have Been Double
(Via Wired)Wired said:The Hubble Space Telescope has experienced an epic fail on orbit that has shut the instrument down, but the timing of the problems couldn't have been better.
A long-planned final service mission to the Hubble was scheduled for October 14. With the phase-out of the Shuttle program, no repairs would have been possible from a later flight. So, when a central scientific data controller broke on Saturday, Hubble's operators weren't distraught, they were relieved.
"Think if it had happened two weeks after the service mission... We could have lost the mission in six, twelve, eighteen months," said Ed Weiler, associate administrator of the Science Mission Directorate at NASA. "If this had to happen, it couldn't have happened at a better time. We're very lucky."
Now the service mission has been delayed until February to allow for a replacement system — long in storage on the ground — to be included in the mission.
The Hubble mission has experienced its share of ups and downs. In 1990, weeks after it launched, astronomers discovered a major error in the scope's optics and pronounced it stillborn. A heroic engineering effort fixed the problem and led to a string of discoveries via some of the most beautiful highest-resolution images of space ever seen. Hubble, initially deemed a failure, has turned into one of the most successful NASA missions in the post-Apollo age.
The new problem does not appear nearly as severe as the optical problem. The malfunctioning unit — the Control Unit/Science Data Formatter — was built with a redundant system on board. NASA engineers will attempt to switch to the built-in backup this week, and will use it until the full replacement unit can make the trip in February.
NASA's Hubble managers don't anticipate any problems with the built-in backup unit, and believe that scientific operations will resume soon.
"It was checked out extensively on the ground," said Preston Burch, Hubble manager at NASA's Goddard Space Flight Center in Greenbelt, Maryland. "We are pretty confident it should work."
After that, however, the Hubble will have no redundancy in that controller, and that's why NASA wants to fly the entirely new control unit into space on the now-delayed service mission.
Despite the optimism at NASA, there could still be major problems for the Hubble. For example, neither backup unit has been used or tested for almost 20 years. It remains to be seen whether the old systems can shake off the dust they've accumulated and perform to specifications.
If the on-orbit backup doesn't function properly, scientific observations could be delayed until the February mission. If the replacement system stored on the ground doesn't properly check out, the Hubble and all its expensive gadgetry will be running through a computing system with no backup.
And then there is the nightmare scenario: neither backup system works properly. If that happens, NASA engineers would be staring down an ignoble end to an otherwise brilliant mission. Asked about that scenario in a media teleconference, Weiler dismissed the possibility and countered that the Hubble mission had "been here before," dealing with unanticipated hardware failures.
"This whole program was declared dead in 1990," Weiler said. "Not only did we survive it, we came back as the great American comeback story."
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