Computer Snag Delays Hubble Release Into Orbit

Astronauts delayed freeing the $1.5-billion Hubble space telescope from its orbiting dry dock until early today, while ground controllers investigated a faulty electronic circuit inside the observatory.

NASA officials said late Thursday that the problem involved a tiny computer switchboard that helps relay data from the Hubble’s main computer to other electronic systems aboard the telescope. The telescope has had this problem before, said engineers trouble-shooting the computer system.

NASA officials said the problem did not involve any of the systems repaired by the astronauts during five record-breaking spacewalks this week. Agency officials hope the repairs will enable the Hubble to view the universe with what will be new eyes.

Once the Hubble is released successfully from the shuttle Endeavour, it will be more than six weeks before NASA scientists can be sure the telescope’s refocused main mirror can see more clearly.

“We are ready to get on with finding out if the corrected optics are all we think they are,” Joseph Rothenberg, Hubble flight projects director, said Thursday at the Johnson Space Center.

Space experts said the $629-million shuttle mission was the most demanding orbital service call since Soviet cosmonauts revived a frozen and derelict orbiting Salyut 7 space station more than a decade ago. No previous U.S. space mission has had more than four spacewalks.

During more than 35 hours of extra-vehicular activity (EVA) in space this week, crew members from the shuttle Endeavour made critical repairs to the defective observatory, fitted it with corrective lenses and installed an advanced camera system.

In a final “roller-coaster” spacewalk early Thursday, payload commander F. Story Musgrave and mission specialist Jeffrey A. Hoffman pried loose the 25,000-pound telescope’s new, wing-like solar power panels, after motors failed to lower them into position.

The astronauts’ flawless performance, and the resulting dramatic, live television images it produced, is giving NASA a much-needed boost after a series of setbacks that called its competence and its luck into question, including the disappearance of the $980-million Mars Observer spacecraft, which vanished as it made its final approach to Mars earlier this year.

Sen. Barbara A. Mikulski (D-Md.), chairwoman of the Senate appropriations subcommittee that oversees NASA spending, predicted that the mission will go a long way to restoring congressional confidence in the agency.

“If they had not pulled this off, they would have been in very serious political trouble,” said John Pike, space policy director at the Federation of American Scientists in Washington, D.C. “They clearly needed to put something in the ‘win column’ and they did, on one of the more challenging and complex missions they have ever had.”

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Unlike many satellites, the Hubble was designed to be “spacewalk friendly” so it could be easily serviced and repaired in space by astronauts operating from the shuttle. But the NASA planners who designed the shuttle system more than 15 years ago underestimated the difficulty of working in orbit.

“It looks easier on paper than when you do it,” said John Logsdon, director of the Space Policy Project at George Washington University.

NASA officials and onlooking agency astronomers were elated by the week’s events, as ground-based controllers were poised to coax the refurbished observatory to a new level of performance once it had left the shuttle.