Astronauts set for last spacewalk to repair Hubble

Monday, May 18, 2009 at 2:16 AM Posted by Beijing News


US astronauts are to embark on their final spacewalk under NASA's ambitious bid to extend the life of the Hubble Space Telescope for another five years at least.

After they venture outside the space shuttle Atlantis for the fifth and last time, the astronauts will equip the telescope with three more batteries, a pointing sensor and external shielding.

Astronauts Mike Massimino and Mike Good on Sunday overcame a string of frustrations while working aboard the shuttle to revive a long inactive science instrument inside Hubble.

That outing to recover the instrument that identifies super massive black holes was considered to be the most intricate of their spacewalk jobs.

It turned equally frustrating for the two men when they were forced to overcome a stripped bolt, a power tool with a dead battery and other obstacles that stretched their activities to more than eight hours.

"Oh, for Pete's sake," Massimino complained when the battery in the power ratchet he was holding died.

Later, the veteran astronaut cursed as he wrestled to discard the cover plate he'd pulled from the Space Telescope Imaging Spectrograph into a storage bag.

Massimino and Good focused all of their efforts on the imaging spectrograph, an instrument installed in the telescope by shuttle astronauts in 1997.

The spectrograph, which astronomers use to gather information about the chemical composition, temperature and pressure motions of celestial targets, was sidelined by a power failure in 2004.

In order to replace a failed power converter, Massimino and Good had to replace an internal circuit card. The extraction required Massimino to remove a protective cover secured by 111 small screws using an arsenal of custom-made hand tools.

But access to the cover and the many tiny fasteners was obstructed by a hand rail that had to be removed first. The rail was secured by four thin bolts, one of them badly stripped.

After several failed attempts to turn the bolt with wrenches, Massimino offered to snap the hand rail off by hand.

"Okay, here we go," said Massimino as he broke it away.

The two men then made quick work of removing a protective cover, replacing the bad circuit card and installing a new cover held down by a pair of latches rather than screws.

The spectrograph quickly passed an electrical test, the first step in a more thorough evaluation.

"Today was like a dream come true for the science community," said NASA astrophysicist Jennifer Wiseman, who predicted the revived spectrograph will experience heavy use.

"It has a very unique capability. That is why this is such a tremendous victory for us."

The shuttle's 11-day mission is scheduled to conclude Friday with a landing at the Kennedy Space Center in Florida.



A participant attends the 17th Life Ball in Vienna. AFP/Joe Klamar

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