Working 350 miles above earth to swap out the Hubble telescope's 900-pound camera, two astronauts struggled with a stubborn bolt and a grueling and potentially dangerous work schedule.
The repair job got off to a late start when the spacewalk started more than a half-hour late Thursday morning. Then, John Grunsfeld and Andrew Feustel ran into problems trying to loosen a bolt holding the old, grand piano-sized camera in place. They went back to space shuttle Atlantis for more tools, but there were concerns that too much pressure on the bolt could cause it to snap, making it impossible to pull the old equipment out.
As mission control watched, Feustel put his back into the effort.
"OK, here we go," he said. "I think I've got it. It turned. It definitely turned."
"Woo-hoo, it's moving out!"
Thursday's spacewalk was the first of five. In addition to replacing the telescope's 15-year-old, grand piano-sized camera with one that can peer deeper into the universe and beam images back to earth, two crews plan to replace a broken computer data device, batteries, gyroscopes and a pointing mechanism. They also will install fresh thermal covers on the telescope, along with a docking ring so a future spacecraft can guide the telescope into the Pacific Ocean sometime in the early 2020s.
But the big job was the camera exchange. Once the bolt was out, the old camera -- destined for the Smithsonian Institute -- came out and the new one went in.
"Let there be light," Grunsfeld said as ground controllers checked the power.
The new, $132 million camera will allow astronomers to peer deep into the universe, to within 500 million years of the Big Bang. After the repairs, NASA hopes to get another five to 10 years of dazzling views of the cosmos from Hubble.
The other two-man team will float out of Atlantis to work on the telescope on Friday.
Weighing on the astronauts were earlier reports of minor damage to the shuttle's heat shields and the fact that the orbit in which they are working is littered with space debris. The shuttle already has an ugly stretch of nicks from Monday's launch, but the damage is not believed to pose a safety threat.
NASA is readying another shuttle in case the damage proves worse than thought and requires a rescue.
It is the fifth time astronauts have gone to fix the 19-year-old Hubble, the last time being in 2002. Prior repairs were much less complicated, however. In all, Grunsfeld and his team will pull out 111 screws to get at and fix parts that were not designed for interstellar repairs.