Spacewalk's Success Hinges on Bolt
Stuck Fastener Is Hurdle as Hubble Gets New Camera

By Joel Achenbach
Washington Post Staff Writer
Friday, May 15, 2009

Four astronauts with four PhDs, backed by the collective brainpower of NASA and riding a multibillion-dollar spacecraft, came face to face yesterday with what appeared to be an immovable object: a bolt.

The bolt secured the celebrated Wide Field and Planetary Camera 2 to the inside of the Hubble Space Telescope. For almost 16 years it had kept the camera in place. And it had no intention of relenting at this late date, no matter how much the astronauts wanted to swap the old camera for a new one.

If the bolt didn't budge, the old camera would not budge, either, and the new, more sensitive replacement, capable of probing even farther into the depths of space and time, would return to Earth as a $132 million piece of ballast. All of this made for high drama during the first of five scheduled spacewalks in five days to service the Hubble.

Spacewalkers John Grunsfeld (doctorate in physics) and Andrew Feustel (doctorate in geological sciences), who will be a team on three of the spacewalks, began their seven-hour, 20-minute extra-vehicular scramble at 8:52 a.m. Feustel stood on the end of a robotic arm operated from within the shuttle by Megan McArthur (doctorate in oceanography). Feustel's and Grunsfeld's movements were coordinated by Mike Massimino (doctorate in mechanical engineering).

"Too cool!" Feustel said as he came out of the airlock. "Hoo-hoo!"

The first major task was the removal of the Wide Field and Planetary Camera 2, the instrument that took many of the Hubble's most famous images. The astronauts needed to replace it with the Wide Field Camera 3.

Feustel used a hand-held socket wrench with an extension to try to loosen the bolt, which was hidden from sight but accessible via a hole in the camera's exterior. But it remained stuck.

Grunsfeld retreated to the airlock to fetch a new tool for Feustel, but that one didn't work, either.

Feustel went back to the socket wrench, which had been designed to apply only a certain amount of force before slipping, a precaution against breaking the bolt and trapping the old camera inside the telescope.

"Still slipping," Feustel reported time and again.

The astronauts had one final option: more elbow grease. They could remove the constraints on the wrench to permit Feustel to put as much force on the bolt as he wished.

"What are the implications if I over-torque and break the bolt?" Feustel asked.

The answer from Grunsfeld: The old camera would stay in the telescope forever.

Feustel made a final effort -- carefully, trying not to overdo it.

"It turned, it definitely turned," he suddenly said. Much exultation ensued among the fellow astronauts and at Mission Control.

"I'm five years older now than when I came to work this morning," said Hubble senior project scientist David Leckrone, who watched from the Johnson Space Center. "I don't know, I just hope the rest of the mission is a little bit smoother."

With the robotic arm retreating and Feustel, still riding the end of it, gripping the WFPC2, the old camera slid from the telescope like a drawer coming out of a dresser. The astronauts had no trouble installing the Wide Field Camera 3.

The old instrument, which scientists sometimes call the "camera that saved Hubble," will be brought back to Earth and sent to the Smithsonian. It was designed to compensate for a manufacturing flaw in the Hubble's primary mirror that had left the telescope with blurry vision when it was launched in 1990.

The two astronauts also completed several other tasks, including replacing a science data-management unit that broke down last fall and installing a docking ring that will allow a robotic craft to latch on and guide Hubble into the Pacific sometime in the future.

In today's spacewalk, astronauts Massimino and Michael Good will replace batteries and gyroscopes.

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