October 27, 2006
Decision Expected Today on Fate of the Hubble
By Frank D. Roylance
The future of the Hubble Space Telescope hangs in the balance today in Washington as top NASA managers weigh the feasibility and risks of sending shuttle astronauts on a fifth and final servicing mission to the observatory.Michael Griffin, the agency administrator, is scheduled to announce Tuesday at the Goddard Space Flight Center in Greenbelt whether he'll order the mission.
"There is talk about very little else at the moment. Everybody wants to know what's happening," said Matt Mountain, director of the Space Telescope Science Institute in Baltimore, which manages Hubble science. "This is basically going to renew the telescope that is so very critical to us."
If Griffin says "go," the mission could launch as early as 2008, providing 7,000 astronomers worldwide with five more years of access to the famous telescope -- along with better instruments to explore the depths of the universe and its evolution.
But a Hubble mission would also be the only flight before the shuttle's retirement in 2010 that could not reach the International Space Station in case of emergency. That scenario has worried NASA since 2003, when the shuttle Columbia was damaged by debris on liftoff and burned up during re-entry. All seven crew members perished.
Griffin has said he might support a manned Hubble repair, but only after two safe post-Columbia missions. NASA has now flown the shuttle safely three times since then. The agency has also reduced the shedding of insulating foam -- debris that damaged and doomed Columbia. In addition, crews have proved they can inspect and repair minor damage to their heat shields in orbit.
Still in question -- and a likely topic of today's meeting -- is whether NASA could launch a second shuttle on short notice to rescue a crew marooned on a Hubble mission. Like the foam issue, that was a recommendation of the Columbia Accident Investigation Board.
Griffin's predecessor, Sean O'Keefe, canceled further servicing missions in 2004, concluding that the scientific reward was not worth the risk to astronauts' lives.
So Griffin's choice "is not an easy decision, not a slam-dunk by any stretch," said Preston M. Burch, Hubble program manager at the Goddard Space Flight Center.
But he said, "The scientific community has high expectations that the effort that's been invested so far in Hubble will be used. So if we were not to do it, it's going to be a huge disappointment."
Astronomers are eager for astronauts to install two new scientific instruments and to revive a third.
Built at a cost of $167 million, the new Cosmic Origins Spectrograph and the Wide Field Camera 3 would improve Hubble's view of dark matter and the earliest galaxies that formed after the big bang by factors of up to 100, scientists say.
And repair of the observatory's Space Telescope Infrared Spectrometer -- the most advanced spectrograph ever flown in space -- would revive an instrument idle since 2004.
Just keeping Hubble alive a few years longer would allow scientists to capture the unexpected, said Mario Livio, a senior astronomer at the space telescope institute. "If we do not have a telescope like Hubble, with its sharp vision and sensitivity, we may miss out on some very important cosmic events," he said.
A series of scientific panels -- convened after O'Keefe's cancellation -- concluded Hubble was worth preserving. But it was Griffin's 2005 appointment that turned the tide. As a physicist and engineer who had moved to NASA from the Johns Hopkins Applied Physics Lab, he seemed more attuned to the scientists' pleas.
"Everybody has enormous respect for Mike Griffin," Burch said. "He is probably technically the most astute administrator NASA has ever had, and he will be making a very thoughtful and highly reasoned decision, based on the technical aspects of whether or not to fly."
Said Livio: "If he will decide not to service Hubble, it will probably be for some very good safety reason. Clearly, we will not only accept, but respect any decision he will reach."
While others at NASA worked on the shuttles' defects, Griffin revived preparations for a manned repair mission, not wanting to lose time if it became feasible.
Since then, teams at Goddard and Houston have choreographed the tasks that crew members would perform, designed specialized tools and rehearsed a team of six astronauts.
The priority would be replacing Hubble's six gyroscopes, which hold the telescope steady. Installation of new batteries, the new instruments, thermal blankets and other hardware would follow.
But by far the most challenging task, on the fourth of five spacewalks, Burch said, would be the five-hour spectrograph repair -- the first time astronauts have ever opened a Hubble science instrument in flight.
Goddard engineers had to invent a special plastic cover to capture each of 111 screws as they come out. They turned out another tool to help astronauts -- in bulky spacesuits and cramped quarters -- replace a faulty STIS circuit board, whose fasteners were designed to stay put.
If Griffin drops the ax, Goddard engineers will have to nurse the observatory along until it fails. Controllers have already learned to do science with just two gyroscopes, holding two in reserve.
And the telescope's 17-year-old batteries are holding their own since Goddard revised their management routines. "We've had to do a lot of care and feeding from the ground," Burch said.
If the decision is "no-go," he said, "it'll be very disappointing. But right now we are very hopeful that we're going to fly."