Hubble's outlook uncertain with delay in flight schedule

July 28, 2005|By Frank D. Roylance and Gwyneth K. Shaw | Frank D. Roylance and Gwyneth K. Shaw,SUN STAFF

NASA's decision to ground the shuttle fleet could have dire consequences for the future of the Hubble Space Telescope.

Observers said late yesterday that the grounding makes the race to repair the telescope before it fails that much more difficult. And, it could dampen the willingness within NASA to send a shuttle to Hubble.

Astronomers have been counting on NASA Administrator Michael D. Griffin to order astronauts to fly a fifth and final servicing mission, to extend the telescope's useful lifetime and upgrade its instruments.

Without a repair flight, failing batteries or gyroscopes could cripple the telescope as early as 2008.

Griffin has expressed support for such a mission. But he has said he won't consider it until two post-Columbia shuttle missions have been safely flown.

That prospect dimmed yesterday as photographs revealed evidence that Discovery's external fuel tank shed a substantial chunk of foam insulation during its launch Tuesday.

Although there was no evidence Discovery was seriously damaged, it was the same problem that punctured Columbia's left wing and precipitated its destruction during re-entry Feb. 1, 2003, killing all seven crew members.

The persistence of the issue despite 2 1/2 years of troubleshooting prompted NASA yesterday to order the shuttle fleet grounded until the problem can be fully evaluated and resolved.

"Griffin would not make a positive decision to service Hubble until two shuttle flights have met their technical goals," said Steven V.W. Beckwith, director of the Space Telescope Science Institute in Baltimore, which manages Hubble observations.

Asked whether this flight would qualify, Beckwith said, "I really have no idea."

Louis J. Lanzerotti, who headed a National Research Council panel that recommended late last year that NASA use the shuttle to service Hubble, said last night that the latest setback could change the thinking on just how risky such a mission would be.

"I would say that it looks somewhat problematic" based on the fragmentary information available, Lanzerotti said. "This is not a good omen."

The NRC panel found that a shuttle mission to Hubble would not be much more dangerous than a mission to the International Space Station, which affords astronauts a place to take refuge if there is a problem in orbit.

But if new information emerges that the shuttle is less safe than previously thought, it almost certainly would affect the thinking about a Hubble mission, Lanzerotti said.

For now, NASA is preoccupied with a new round of analysis and repairs. Agency spokesman Steve Nesbitt said shuttle officials don't know whether a solution to the debris problem is weeks or months away. Any changes to equipment typically undergo rigorous, and often lengthy, testing to ensure that the fix doesn't make things worse.

"The bottom line is, it's way too early to tell what effect it will have on future flights," Nesbitt said. "We just don't know what kind of schedule impact there might be."

The bad news threw a damper on the space telescope institute barely a day after what looked like a successful launch.

"During the launch people were just elated; it's sort of a miracle," Beckwith said. "I think people believe NASA will have the will and the foresight to service Hubble. We'll just have to await their analyses."

Even if Griffin orders a repair mission, an extended grounding of the shuttles would increase the risk of critical gyroscopes and batteries on the observatory breaking down before astronauts can replace them.

"The window for that servicing is clearly ASAP," said James B. Garvin, chief scientist at NASA headquarters, speaking earlier this week before the shuttle grounding.

If there were delays, Griffin could make up some of the lost time by reshuffling the sequence of shuttle flights once they resume, Garvin said, delaying an early flight to the space station and inserting a Hubble mission in its place.

Griffin had previously ordered that planning continue at the Goddard Space Flight Center for Hubble servicing, and for the installation of new scientific instruments. When and if a repair flight is ordered, Garvin said, "they will be prepared."

In the meantime, scientists and engineers at Goddard and the space telescope institute have been working out ways to continue Hubble's scientific work using just two of the telescope's remaining four gyroscopes, instead of the three once thought critical.

Although using just two gyros makes it more difficult to plan observations, "the pointing performance once you're on target is indistinguishable between two- and three-gyro mode," Beckwith said. "It's a total surprise."

He said Hubble will shift to two-gyro operations late next month. "By doing that we preserve the lifetime of the other gyros. ... That will extend the scientific lifetime of Hubble by at least a year."

The observatory's batteries, meanwhile, are expected to last until 2010. "Right now I assume that we can keep operating Hubble until at least 2008, and maybe 2010," he said.

There's one more trick up Hubble's sleeve, Beckwith said.

One of the tasks planned for shuttle astronauts sent to Hubble will be the attachment of a de-orbiting rocket. That's needed so that the telescope can make a controlled re-entry into the atmosphere when its work is done.

Scientists are reassessing estimates of how long the observatory can stay aloft on its own. If re-entry is further off than previously estimated, Beckwith said, development and installation of the de-orbiting rocket could be delayed. The repair mission might then be able to fly without it, and lift off sooner.

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