Seems you've heard of this idea before. I just heard of it yesterday. This certainly seems far more feasable than a robotic repair mission to Hubble. But of course, far more expensive than a simple, old-fashioned, Shuttle repair mission to Hubble.
Here's an article from Astronomy magazine yesterday:
http://www.astronomy.com/default.aspx?c=a&id=2862
Replacing Hubble
Instruments destined for the venerable space telescope could form the basis for its replacement.
Francis Reddy
February 3, 2005
The Hubble Space Telescope, it seems, just can't catch a break. Sooner or later, aging batteries and failing gyroscopes will put a stop to the tremendous flow of science from Hubble, which astronomers have lauded as the most productive telescope since Galileo's.
NASA canceled the final shuttle servicing mission last year, citing safety considerations following the Columbia tragedy in 2003. Then, the space agency became intrigued by the possibility of repairing Hubble with a robot. Both a National Research Council panel and the world's largest group of astronomers back servicing the telescope by some means — preferably with the shuttle. But sources in the White House have indicated that NASA's 2006 budget, to be unveiled next week, will not include the estimated $1.5 billion for either repair option.
Now, an international team led by Johns Hopkins University astronomers suggests an alternative: create a new space telescope, called the Hubble Origins Probe (HOP), that would carry instruments built for the canceled servicing mission. "Though we support any option that will maintain the Hubble mission, the Hubble Origins Probe is the best choice not only for continuing that tradition of discovery, but also for taking it one step further," said Colin Norman, one of the team leaders, in testimony before the U.S. House of Representatives Committee on Science yesterday.
HOP would replicate design of the original Hubble but use a much lighter mirror and a modern spacecraft. The new mirror would not contain Hubble's mission-threatening optical flaw, which astronauts fixed in 1993 during the telescope's first servicing mission by installing "contact lenses." HOP would include two instruments destined for Hubble that have been built already — the Cosmic Origins Spectrograh (COS) and Wide Field Camera 3 (WFC3).
HOP can be developed quickly at significant savings and low risk, according to Norman, by replicating a successful design and using existing instruments. The spacecraft bus, which provides power, data handling, pointing control, and communications, is based on the Spitzer Space Telescope's. One of HOP's fine guidance sensors, which are crucial for tracking cosmic targets, will come from Hubble's own spare parts, but two others will be designed using modern technology.
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