NASA should launch a shuttle mission to save the Hubble Space Telescope because its plan to use a robot to repair the instrument is unlikely to work, a panel of experts convened by the National Research Council recommended yesterday.
In a report commissioned by Congress, the group urged the space agency to fix and upgrade the world's premier observatory before breakdowns turn it into space junk - which could happen as early as 2007.
"A shuttle mission is the best option for extending the life of the Hubble telescope, and ultimately de-orbiting it safely," said committee Chairman Louis J. Lanzerotti, a consultant for Lucent Technologies and a professor at the New Jersey Institute of Technology.
After months of study, his panel of scientists and engineers concluded that a shuttle flight to Hubble - the fifth since 1993 - would be only slightly more risky than the manned missions NASA is scheduling to complete the International Space Station.
They also found that a robotic rescue mission under review by engineers at NASA's Goddard Space Flight Center is unlikely to fly before 2010 - three years later than Goddard expects and too late to prevent breakdowns that would cripple the observatory.
An internal analysis by a NASA contractor that came to light earlier this week drew much the same conclusion.
After the breakup of the shuttle Columbia in 2003, which killed seven astronauts, NASA canceled a manned Hubble tuneup mission planned for 2005, a decision that would have left the telescope dead in space within three years.
But pressure from scientists, Congress and ordinary citizens who have marveled at Hubble's spectacular images forced the agency to reconsider - the main question being how to keep Hubble alive.
There was no indication that the committee's report would change NASA Administrator Sean O'Keefe's decision to pursue a robotic rescue because of his conviction that a manned mission is too risky.
Lanzerotti said members of his group met this week with O'Keefe and found him willing to consider the committee's arguments. "His comments ... were that they would take the report and look at it very carefully and do an analysis," Lanzerotti said.
But NASA spokesman Robert Mirelson said the agency is still convinced by the conclusions of the Columbia Accident Investigation Board, which wants a "safe haven" available if a shuttle is damaged in flight. Although astronauts sent to the International Space Station could take refuge there if problems occur, a shuttle mission to Hubble provides no such haven.
"Safety remains the top priority, Mirelson said.
Even so, scientists were relieved that the committee gave Hubble's survival a high priority. Steven V.W. Beckwith, director of the Space Telescope Science Institute in Baltimore, said it was "good news for science" that both NASA and the National Research Council believe the telescope is worth rescuing - whatever the means.
On one hand, he said, a robot rescue would be difficult and risky, but it would advance the technology NASA needs for future missions. On the other hand, "We know that shuttle servicing works - we don't know that robotic servicing works."
Michael E. Brown, an astronomer at the California Institute of Technology and a Hubble client, said the cost of a robotic rescue could divert funds from other worthy science missions. But he said he has qualms about a manned flight, too:
"I'd have a hard time telling somebody that I'd like to use the space telescope to do something, and therefore I want you to risk your life to do it."
Lanzerotti's panel includes two Nobel laureates, three former astronauts and a who's-who of distinguished scientists, engineers, corporate and military leaders and risk-management experts.
It was convened last spring by the National Research Council, a private, nonprofit society of the nation's top scholars created to advise the federal government on science and technology.
Its final report endorsing the shuttle option throws a new spotlight on NASA's struggle to get the aging shuttle fleet flying safely again. The shuttle's lifting capacity is critical to America's international commitments to complete the space station. The first flight is now expected no sooner than May 2005.
The Orlando Sentinel reported this week that NASA believes it can now prevent large chunks of debris from falling off the shuttle's external fuel tank during launch. One of those pieces punctured Columbia's wing and doomed the crew. Future astronauts will also be able to inspect the shuttle for damage, but the agency said there's still no way for the crew to repair it.
On the issue of a "safe haven" for astronauts, the Lanzerotti committee said NASA could have a rescue shuttle ready to fly if Hubble repairmen get into trouble. In 1995, they noted, NASA launched flights less than two weeks apart.
Retired Adm. Richard H. Truly, a former NASA administrator and member of the Lanzerotti panel, said the difference in risk between missions to Hubble and the space station is "very small" and Hubble's value is worth the risk. The panel said NASA could add a Hubble mission after the sixth or seventh flight, sometime in 2007, which would still be in time to save the instrument.
The committee estimated that a robotic mission would have only a 30 percent chance of extending Hubble's useful life by three years, whereas shuttle astronauts would have an 80 percent chance.
Hubble was launched in 1990 and was repaired and upgraded by astronauts on four missions between 1993 and 2002. After canceling the final servicing mission for safety reasons, O'Keefe authorized a $300 million design review to determine by next summer whether a robot can be developed fast enough to fix Hubble and keep it operating for a few more years.
An outside contractor hired by NASA - Aerospace Corp. - concluded last summer, much as the Lanzerotti panel has, that the robot solution runs a high risk of failure, either because it won't work or because it can't be flown before Hubble breaks down.
Nevertheless, people close to the robotics design review under way at the Goddard Space Flight Center are confident it can work. The technology is farther along than outside critics think, they argue, and they believe they can have a mission ready within three years.
That will be key, said George Bekey, a University of Southern California robotics expert who reviewed portions of the Lanzerotti report. He said nothing on its scale and complexity has been attempted before.
Hubble relies on gyroscopes and fine guidance sensors to point it reliably at its celestial targets. Their expected failure - as early as 2007 - would end scientific observations. Battery failure, likely by 2009, would allow internal temperatures to fall and cause irreparable damage.
Sen. Barbara A. Mikulski announced plans yesterday to hold a Senate hearing in February to review the recommendations from NASA and the Lanzerotti committee. The Maryland Democrat, a longtime supporter of NASA and the Hubble telescope, commended the Lanzerotti panel for an "outstanding" report.
"NASA has the experience, the technology and now it has the money," she said in a news release yesterday. "It's time to fix Hubble - Congress and the American people expect nothing less."
Sun staff writers Michael Stroh and Dennis O'Brien contributed to this article.