Spaceflight Now STS-109

New solar wing attached to Hubble during spacewalk
Posted: March 4, 2002

As seen from the shuttle's crew module, spacewalker Rick Linnehan carries the new solar array up to Hubble while riding on Columbia's robot arm. Photo: NASA TV/Spaceflight Now
Shuttle Columbia astronauts John Grunsfeld and Rick Linnehan removed the Hubble Space Telescope's starboard solar array this morning and installed a new, more powerful array during a successful seven-hour spacewalk.

It was the first of five consecutive days of spacewalks scheduled for Columbia's mission to rejuvenate the observatory. The excursion started at 1:37 a.m. and concluded at 8:38 a.m. EST.

"Hello Mr. Hubble, the telescope!" Grunsfeld called out after floating into the shuttle Columbia's cargo bay. "We're here to give you more power to see the planets, stars and the universe."

Grunsfeld, standing on a foot restraint mounted to the side of Hubble, rotated the array boom parallel to the body of the telescope. He then unhooked various electrical cables between Hubble and the array before releasing a clamp band holding the array to the telescope.

"Eight... nine... 10," Grunsfeld called, counting rotations of the nut holding the mast clamp in place.

"I feel it loosening," Linnehan commented.

"11... 12... 13... OK, Rick, you have the array," Grunsfeld said as the clamp released and the array mast pulled free.

Linnehan, riding on the end of the shuttle Columbia's robot arm, transported the array to a carrier in the payload bay to be stowed for the trip back to Earth.

The new solar array is opened up on Hubble. Photo: NASA TV/Spaceflight Now
This array and its twin on the other side of the observatory were installed during the first Hubble servicing mission in 1993. They weigh 339 pounds each and measure 40 feet long by 10.8 feet wide, delivering about 4,600 watts of power from silicon solar cells.

Due to the wear and tear of temperature extremes and normal space radiation, these flexible panels now provide just 63 percent of their original power. In addition, they suffer from structural problems and some shorted circuitry in the wiring connecting all the solar cells.

Hubble's new arrays are heavier -- 640 pounds per wing -- and more powerful, generating some 5,270 watts. But they are smaller than Hubble's flexible panels, measuring just 23 feet long and 8.5 feet wide.

The additional power generated by the new gallium arsenide solar cells will enable astronomers for the first time to operate all of Hubble's instruments simultaneously for multi-disciplinary observations. In addition, their smaller size will reduce the atmospheric drag that constantly acts to reduce Hubble's altitude.

The old array on the port side of Hubble will be replaced Tuesday.

After replacing the starboard array's diode box assembly, the new array was removed from its launch carrier and ferried up to the telescope by Linnehan.

The spacewalkers successfully attached the new array and then opened it like a book, exposing the solar cells.

A view of Hubble with its new, more powerful solar array. Photo: NASA TV/Spaceflight Now
Ground controllers later performed a series of tests on the array, which revealed all systems were working properly.

"We had a great day today," lead flight director Bryan Austin said. "It's just been marvelous watching the crewmen, the telescope and all the pictures coming down. It's been a really exciting day and I look forward to four more EVAs."

Today's spacewalk was the 14th dedicated to Hubble servicing since 1993.

Columbia's second spacewalk is scheduled to start at 1:27 a.m. EST Tuesday to replace the port side array.

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Mission specialist Rick Linnehan emerges from shuttle Columbia's airlock to begin his first ever spacewalk.
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Grunsfeld uses a power tool to loosen a clamp band and release the old starboard solar array from Hubble as seen by a video camera mounted to his helmet. Riding on the shuttle's robot arm, Linnehan then maneuvers the array away from the observatory.
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The starboard solar array that has been on Hubble since December 1993 is stowed on a carrier in shuttle Columbia's payload bay by the spacewalkers for return to Earth.
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The spacewalkers open up the newly installed starboard solar array on the Hubble Space Telescope. Although smaller in size, the array is more powerful than the one it replaced.
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Lead Flight Director Bryan Austin, HST Program Manager Preston Burch, Director of Astronomy and Physics Division NASA HQ Anne Kinney and Lead EVA Officer Dana Weigal brief the news media after the first spacewalk.
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