Spacewalkers easily pull off tricky Hubble fix

— -- It was supposed to be one of the toughest spacewalks in history.

Instead, two astronauts nimbly polished off an unprecedented and tricky job on Saturday's outing into space: fixing a priceless Hubble Space Telescope camera that broke in 2007.

Astronaut John Grunsfeld said before his mission that repairing the camera, the Hubble's most valuable, would be a "nailbiter." But he pulled off the repair at a rapid-fire pace, without so much as a pause. He and spacewalking partner Andrew Feustel worked so quickly that they got an hour ahead of schedule.

During their spacewalk, Grunsfeld and Feustel also breezed through the installation of the new Cosmic Origins Spectrograph, which will allow scientists to study the composition and structure of the universe.

"Nice work, guys. Congratulations," said the spacewalkers' commander, Scott Altman, as they wrapped up their work.

Grunsfeld, Feustel, Altman and four other astronauts blasted into space on space shuttle Atlantis Monday to pay the fifth and final call on the Hubble. Because they'll be the Hubble's last visitors, it's up to them to leave the telescope in good enough shape to last another five to 10 years.

The ease with with Grunsfeld and Feustel dispatched their assignments Saturday was in sharp contrast to the labors of the mission's first two spacewalks. NASA officials had characterized the first two outings as routine, but instead they turned into marathons of frustration and exertion:

•On Thursday, an old Hubble camera refused to budge from its slot, leading Mission Control to fear that its $132 million replacement would have to return to Earth. In the end, Feustel and Grunsfeld succeeded in exchanging the cameras, thanks to new tools and brute strength.

•On Friday, spacewalkers Michael Massimino and Michael Good could not slide a new gyroscope into place on Hubble despite repeated tries. They ended up having to put a spare, refurbished gyroscope in its place.

No such trouble plaugued Grunsfeld and Feustel Saturday. The new $88 million spectrograph glided into place, after the astronauts removed its outdated predecessor without incident.

Then came time for Grunsfeld to fix the Advanced Camera for Surveys, which has snapped many of the Hubble's most famous pictures. Among them are the famous "Ultra Deep Field" shot depicting galaxies forming shortly after the Big Bang.

Relying on a bagful of specially designed tools, Grunsfeld had to cut off a grate, remove 36 tiny fasteners and pull out four circuit boards — all while wearing stiff, heavily padded space gloves.

Making Grunsfeld's work more difficult, the repair site is dark and accessible only at an odd angle. Grunsfeld had to reach around a corner to unfasten the screws, and a pillar made his small workspace even smaller.

"Somehow I don't think brain surgeons go 'Woo hoo!' when they pull something out," Grunsfeld said, just after removing some miniature screws.

"Mabye they should," said Good, who was supervising the spacewalk from inside Atlantis.

The flawless spacewalk proved the foresight of Hubble senior scientist David Leckrone. On Friday, Leckrone noted that Hubble had thrown curveballs on the first two spacewalks, which had been billed as straighforward.

"We've always said EVA 3 is going to be the most difficult," Leckrone said, using the shorthand for "extravehicular activity," NASA's term for a spacewalk. "I predict it's going to go more smoothly than any other EVA on this mission … (through) some version of Murphy's Law."

Listeners laughed, but Leckrone got the last laugh.