WASHINGTON - NASA should seriously consider funding two more space shuttle missions to upgrade the Hubble Space Telescope (HST) even as the agency prepares for the possibility that it will be unable to send astronauts back to add instruments to the hugely popular orbiting observatory, a NASA-appointed advisory panel has urged.
But even if NASA concludes an extra Hubble servicing mission is feasible, officials should hold a competition to determine whether the funds for such a mission should instead be used for other scientific activities, such as spacecraft under the Explorers or Discovery programs, according to the report from the HST-JWST Transition Plan Review Panel, released by NASA on Thursday.
NASA appointed the panel to examine its plans for removing Hubble from service as it prepares for the launch of the James Webb Space Telescope (JWST) to a deep space Earth orbit as soon as 2011.
The panel convened a well-attended public hearing in Washington July 31 at which astronomers urged NASA to find a way to add more instruments to Hubble and keep it in operation beyond the inauguration of the James Webb Space Telescope, which some astronomers believe may not occur on time.
NASA has planned for awhile to conduct one more Hubble servicing mission, likely in 2005 or 2006, to add capabilities to the telescope and equip it with rockets to guide it into the atmosphere in 2010, when it is due to be removed from service.
Anne Kinney, director of NASA's Astronomy and Physics Division, which oversees the HST and JWST programs, said she will give "serious thought" to accommodating the science community's request that NASA devote additional resources to Hubble, including a possible second shuttle mission.
Kinney has said in the past that astronomers have to understand that NASA does not have the funds to continue supporting the aging Hubble telescope, which was launched in 1990. The scientific community should understand that Hubble must give way to the newer James Webb facility.
The report "reminds us that we have to be flexible and be thinking fairly deeply about all the different options," she said in an Aug. 14 interview with SPACE.com.
The Hubble report concludes that NASA has three options to consider as it ponders the future of Hubble:
- The "worst-case scenario," which would occur if NASA cannot send a shuttle to Hubble again even once, would mean rethinking how the telescope is used to ensure it lasts as long as possible without repairs or upgrades.
If this were to happen, NASA would have to send an unmanned rocket to somehow install boosters on the observatory so it can later be placed on a safe trajectory towards Earth. NASA wants to be sure portions of the telescope that do not burn up in the atmosphere hit the ocean without incident.
The report urges NASA to consider a stand-alone mission to launch new instruments designed for Hubble in the event there are no more Hubble servicing missions. Such a launch could occur by 2010 and use funds that would be freed if the already-planned servicing mission could not occur.
- The second option would be a single shuttle servicing mission, to occur by the end of 2006, which would allow NASA to add some instruments to Hubble and equip it with rockets to send it into the atmosphere. This concept is in line with what NASA has planned for some time.
- The best option, in the panel's view, would be to send two shuttles to Hubble to improve its capabilities and increase its longevity. Under this scenario, the first mission would occur around 2005 and the second about 2010.
This would allow more advanced instruments to be developed for installation during the later visit to Hubble, but the second mission would be weighed by a team of experts against other scientific proposals unconnected to Hubble.
Kinney described the panel's report as "intelligent, thoughtful and well thought out." But she said it would be challenging for NASA to determine whether an extra Hubble servicing mission is more worthwhile than other, non-Hubble scientific activities.
"We want to compete apples versus apples, and it gets very difficult if you compete apples versus oranges. A Hubble servicing mission is very big, and it would be decades worth of the Explorers budget line," she said, referring to the program under which NASA launches relatively inexpensive scientific spacecraft that take less time to develop and deploy than larger projects such as Hubble.
Before NASA can prepare for even one more shuttle mission to Hubble, the space agency has to receive clearance to return the space shuttle fleet to service following the February loss of Columbia as it reentered the atmosphere, Kinney said.
"I can do all the planning I want, but there are larger considerations in this agency that have a real impact" on Hubble's future, Kinney said. "Determining Hubble's fate is not critically urgent."
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