Astronauts John Grunsfeld and Richard Linnehan began repressurizing the shuttle Columbia's airlock at 11:06 a.m. EST today, officially ending a seven-hour 20-minute spacewalk, the crew's fifth and final excursion devoted to servicing the Hubble Space Telescope.

During five-back-to-back spacewalks, Grunsfeld, Linnehan, James Newman and Michael Massimino installed two new solar arrays, a new flywheel assembly to help the telescope move from target to target and a new power control unit to more efficiently route electricity to the observatory's subsystems.

The astronauts also installed a new $75 million camera Thursday and a high-tech refrigerator today to revive a dormant infrared camera-spectrometer that ran out of coolant in 1995. All mission objectives were accomplished.

With the conclusion of today 's spacewalk, Columbia's crew logged 35 hours and 55 minutes servicing Hubble, setting a new single-flight shuttle spacewalk record by 29 minutes.

Grunsfeld and Linnehan marked the moment by floating together in front of Hubble and addressing the engineers, flight controllers, mission managers and astronomers who made the complex repair job possible.

"Up here on Columbia on STS-109, we've just finished five days of spacewalking," Grunsfeld said. "We've given Hubble a new power system that will take it off into the next decade of discovery. We've given it new eyes to see deeper into the universe than it's ever been able to see before. And I think you'll see that people at the Space Telescope Science Institute, universities all around the world, amateur astronomers young and old will be able to enjoy the beauty and inspiration that these new pictures from Hubble will bring.

"I'm convinced that the next (garble) incredible discovery is one that's probably months if not years away," he said. "And the work that we've done up here on Columbia is just a small part of what has brought us to the point of being able to make those discoveries.

"Part of it, though, is the people. It's people up here servicing spacecraft like Hubble and being able to make it better that's really the incredible story. And although there's seven of us on orbit, there's a huge team on the ground ... with maybe thousands of people who have worked on this mission, tens of thousands, to get Columbia into the wonderful shape it's in for us to go to orbit."

Linnehan then thanked the engineers and technicians who prepared their spacesuits.

"I just still can't believe that I'm here," he said. "It's been a wonderful experience. My physics teacher in high school, if he's listening, he used to tell me the only thing I'd ever be good at was taking up space. So I guess I made it, big time."

Grunsfeld, who holds a Ph.D. in astronomy, closed out the spacewalkers' remarks by saying "HST is definitely an icon of science, but also the peaceful use of space."

"And so to all the people above us on planet Earth, may there be peace on Earth and thanks very much for helping us with STS-109."

A few minutes later, engineers at the Goddard Space Flight Center sent commands to re-deploy Hubble's two high-gain Ku-band antennas to permit high-speed telemetry and commanding prior to the observatory's release Saturday at 5:03 a.m.

All together, 14 astronauts have now logged 129 hours and 10 minutes in 18 spacewalks devoted to Hubble servicing.