"The Hubble Telescope has done nothing less than revolutionize astronomy and our understanding of the universe," said Bruce Betts, Director of Projects at the Planetary Society in Pasadena, California. "Its ability to peer into the distant universe is unparalleled."
Hubble, unlike most satellites, has no onboard propulsion system. Instead, it relies on gyroscopes and flywheels to point the telescope and maintain stability. The observatory is repaired during periodic service calls by a space shuttle.
Now, those repair visits are being reconsidered.
How long the Hubble will survive without further service missions depends on how long the gyroscopes keep working. Currently, four out of six are functioning; at least three are needed for the telescope to produce science.
Moving on to Webb
Left unserviced, the Hubble would eventually fall out of orbit and crash onto Earth, possibly in a populated area. That's why NASA is now instead planning a U.S. $300 million space tug that would launch on a Delta 2 rocket, grapple Hubble and guide the telescope into the Pacific Ocean.
NASA says the Hubble is in no immediate danger of falling, even if left unserviced, with one study predicting it would stay up until at least 2013.
"This is not a crisis or an urgent situation to deal with now," said Don Savage, a NASA spokesperson. "An independent scientific review will determine how it rates against other missions. The expectation is that they'll keep operating the Hubble as long as it's producing really good science."
While lauding Hubble's success, many NASA scientists are eager to move on to the James Webb Space Telescope, named after the NASA director who oversaw the Apollo missions. It is scheduled to launch in 2011.
The Webb telescope will be able to see farther away than Hubble, back toward to the beginning of time, because it's bigger and observes at infrared wavelengths, unlike Hubble, which sees in visible light and ultraviolet.
"With the Webb, we'll have a chance to see the very first things that lit up after the big bang," said John Mather, the Webb senior project scientist. "We have a lot of theories of what that might be, but almost no information."
Mather says the Webb is not meant as a replacement for Hubble, but should be seen as complimentary. In the future, a large, ground-based telescope could continue Hubble's work.
A Public Relations Dilemma
Paolucci, whose "Save the Hubble" campaign has attracted followers in the low thousands, recognizes the scientific need for the Webb telescope, but warns that Webb's infrared images will look less spectacular than the Hubble images.
By getting rid of the Hubble, Paolucci says, NASA is squandering a chance to expand public interest in space.
"They're not making the most use of the good will that has been built up around the Hubble," said Paolucci. "When you have this triumph that has captured the imagination of people, it seems they should look for ways to emphasize that and not dump the Hubble in the sea as if it's obsolete."
Other experts offer cautionary advice.
"NASA needs to carefully consider when to decommission Hubble," said Betts of the Planetary Society. "A working space telescope is a very precious asset. Clearly the decision to de-orbit Hubble should be dependent upon the successful start of operations of the James Webb Space Telescope, and even then shouldn't be entered into lightly."
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