Updated

Two astronauts used brute force to free a stubborn bolt Thursday during the first of five spacewalks planned to upgrade and repair the Hubble Space Telescope.

John Grunsfeld and Andrew Feustel also swapped out an old camera for a new one the size of a baby grand piano, the first step to making Hubble more powerful than ever.

"Let there be light," quipped Grunsfeld as ground controllers switched on the power to the new camera.

Grunsfeld and Feustel also replaced a data-handling unit that broke down last fall.

In a foreshadowing of Hubble's eventual fate, they hooked up a docking ring so that a robot spacecraft can "de-orbit" the telescope by steering it into the Pacific at the end of its useful life in a decade or so.

• Click here for more photos of Atlantis and its crew.

• Click here for some of Hubble's most spectacular images.

• Click here for NASA's live video feed.

• Click here to follow astronaut Mike Massimino's Twitter feed.

• Click here to visit FOXNews.com's Space Center.

The repair job — all the more dangerous because of the high, debris-ridden orbit — got off to a slow and rocky start.

Grunsfeld and Feustel had trouble removing the old camera from the telescope because a bolt was stuck. They fetched extra tools, but none seemed to work.

Finally, Mission Control urged the astronauts to use as much force as possible, even though there was a risk the bolt might break.

If that had happened, the old camera would be stuck inside, leaving no room for its souped-up replacement.

"OK, here we go," Feustel said. "I think I've got it. It turned. It definitely turned." And then: "Woo-hoo, it's moving out!"

Atlantis and its crew are traveling in an especially high orbit, 350 miles above Earth, that is littered with pieces of smashed satellites.

A 4-inch piece of space junk passed within a couple miles of the shuttle Wednesday night, just hours after the shuttle grabbed Hubble. Even something that small could cause big damage.

For the first time, another shuttle is on standby in case it needs to rush to the rescue.

Once the sticky bolt was freed, Feustel pulled out the old camera, the size of a baby grand piano.

"This has been in there for 16 years, Drew," said Grunsfeld, "and it didn't want to come out."

The spacewalkers followed up with the installation of the replacement camera. From inside Atlantis, spacewalk overseer Michael Massimino congratulated Grunsfeld and Feustel for "adjusting to the curve ball that was thrown at you."

The newly inserted wide-field and planetary camera — worth $132 million — will allow astronomers to peer deeper into the universe, to within 500 million to 600 million years of creation.

The old one was installed in December 1993 during the first Hubble repair mission, to remedy the telescope's blurred vision.

It had corrective lenses already in place and, because of the astounding images it captured, quickly became known as the camera that saved Hubble.

It's also been dubbed the people's telescope because its cosmic pictures seem to turn up everywhere.

The camera — which has taken more than 135,000 observations — is destined for the Smithsonian Institution.

Massimino was corrected when he said it was awesome to get the new wide-field camera in "to unlock the secrets of the universe."

"More of the secrets," responded Grunsfeld, an astrophysicist.

Grunsfeld, the chief repairman with two previous Hubble missions under his work belt, took the lead on the camera and data-handling device replacements.

He sounded awe-struck as ever. "Ah, this is fantastic," he said as he floated outside, the bus-size telescope looming overhead.

Hubble's original data handler, which was launched with the telescope 19 years ago, failed in September, just two weeks before Atlantis was supposed to take off on this fifth and final servicing mission.

The breakdown caused all picture-taking to cease and prompted NASA to postpone the shuttle flight.

Flight controllers managed to get the telescope working again, but NASA decided to replace the faulty computer unit. The goal is to keep Hubble running for another five to 10 years.

Another two-man team will venture out Friday for the second spacewalk.