Repairs on Hubble going well

December 06, 1993|By Ann LoLordo | Ann LoLordo,Staff Writer

The Doctors Goodwrench repairing the Hubble Space Telescope tossed one of the spacecraft's faulty solar panels overboard last night and replaced it with a new one during the second of five planned spacewalks. The work followed a successful first day under the hood that secured the telescope's pointing ability.

Astronauts Tom Akers, an Air Force lieutenant colonel, and Kathryn C. Thornton, like their two predecessors on the first spacewalk, left the shuttle Endeavour's cabin more than an hour ahead of schedule.

"The epic continues," said the commander, Air Force Col. Richard O. Covey.

Barely an hour later, Ms. Thornton had tossed out one of Hubble's two solar panels, and set about with Colonel Akers to stow the second panel and to replace both with improved models.

"It looks like a bird, Tom. Look at it," she said, after releasing the gold-colored, partly furled panel somewhere over Somalia. As Colonel Covey carefully eased the shuttle away, the astronauts watched as the first solar panel wheeled and drifted away.

The panel, found to have a kink in its stainless steel frame when NASA's $1.6 billion telescope was brought aboard the shuttle for servicing early Saturday, failed to retract completely. Since it couldn't be brought home in that condition, a decision then was made to jettison it.

For about a year, the panel will be one of some 6,700 pieces of sizable space junk tracked by the U.S. Space Command. Then it should drop into Earth's atmosphere, where it will break up and burn, according to NASA officials.

About 2 1/2 hours into the second spacewalk, due to conclude before dawn, Colonel Akers, 42, and Ms. Thornton, 41, had completed installation of the first of two replacements for Hubble's jittery solar panels -- 40-foot-long winglike structures that extend on either side of the telescope. The work seemed to go with little difficulty.

NASA found that the temperature changes caused the original solar panels to flex nearly 20 inches, setting up a shudder that was transmitted throughout the spacecraft, affecting Hubble's ability to stay pointed at its astronomical targets.

The new pair, provided by the European Space Agency, was redesigned to eliminate the shakes.

To set the crimped solar panel adrift, Ms. Thornton had to grab the partially rolled-up solar panel with a 2-foot-long, Y-shaped handle. Then she was lifted above Endeavour on the end of the shuttle's mechanical arm, appearing suspended below the panels like a hang glider pilot beneath the wings of her craft.

When she got permission to release it, she simply let go.

The panels -- blankets of solar cells that roll up like window shades -- were retracted early yesterday, after the first (x spacewalk. The walk began late Saturday night and lasted 7 hours and 54 minutes. The record -- 8 hours and 29 minutes -- is held by the trio of astronauts who captured a satellite with their gloved hands in 1992.

For Endeavour's first spacewalkers, Story Musgrave and Jeffrey A. Hoffman, it was a hard day's night. But it was "a 100 percent success," pronounced Milton Heflin, the chief flight director.

Mr. Musgrave and Mr. Hoffman worked for hours on end, in darkness and light, some 360 miles above the Earth, in the most ambitious mission attempted by NASA since men landed on the moon.

Few rough spots

Sweating in white, bulbous space suits, they wrenched bolts free, changed fuses and installed sensitive electronic equipment the painstaking slow-motion of space as cameras recorded their every move and word. They struggled with doors that wouldn't shut and latches that wouldn't close, in the mirrored reflection of a silvered space telescope named for the 20th-century astronomer Edwin Hubble.

In the end, they accomplished their mission for the day. Hubble had two new pairs of gyroscopes that will enable the telescope to point and track objects in the universe, two new electrical units that drive the gyroscopes, and eight new fuses. Checks by the Goddard Space Flight Center in Greenbelt, which controls ++ the telescope operations, verified that the units were receiving power.

"Jeff and Story have definitely earned their Dr. Goodwrench certificates," said David Leckrone, a Hubble project scientist at Goddard who is serving as an adviser at Mission Control in Houston. "We're dead in the water without three working gyroscopes."

The success of the first spacewalk "has to be a big boost for their overall mental attitude," Mr. Heflin said of the seven-member Endeavour crew.

So far, so good

So far, the Endeavour mission has gone off without a hitch. It was an auspicious beginning to an 11-day mission on which NASA is betting to restore the acuity of Hubble, found to have a misshapen primary mirror two months after the telescope was launched in April 1990.

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