Atlantis Astronauts Do the 'Impossible,' Complete Last-Ever Hubble Spacewalk

The last humans to ever touch Hubble in space finished up the telescope's final repairs today.

After more than 7 hours, Atlantis astronauts John Grunsfeld and Drew Feustel completed the mission's fifth and final spacewalk. The 19-year-old Hubble Space Telescope will never again undergo a servicing mission in space.

VIDEO: Final spacewalk for Atlantis astronautsPlay

"We have been on a challenging mission," Grunsfeld said. "Hubble isn't just a satellite. It's about mankind's quest for knowledge. The only way to find the limits of the possible is to go beyond the impossible. Many people said we could not do this. We have achieved this and we wish Hubble the very best."

His partner Feustel also had some final words.

"I'm just really proud to have been a part of this," he said, thanking his wife, children, crewmates and NASA colleagues on the ground.

Cmd. Scott Altman congratulated his crew, saying, "The sign of a great crew is that the commander doesn't have a lot to do. I appreciate all of the work we've had together. … It's been a great thrill. I'm very proud of the crew and the whole team."

NASA: 'Hubble's Never Had it Better'

Feustel and Grunsfeld started work this morning an hour early. During the spacewalk, the duo installed a new set of batteries, a Fine Guidance Sensor that helps aim the telescope and protective steel-foil sheets on the telescope's exterior.

As they worked, the crew appeared to be in good spirits.

"Rollin', rollin', rollin," astronaut Mike Good sang from inside the cabin, as Grunsfeld used a roller to help the steel blanket stick to the telescope's exterior.

Before the astronauts could re-enter the shuttle, they had to thoroughly clean off the debris from their gloves. Specialists on the ground were concerned that gold foil sticking to Grunsfeld's gloves (from when he removed old insulation) would contaminate the shuttle's interior.

As the astronauts were preparing to re-enter the shuttle, Grunsfeld's backpack bumped into an antenna. Mission Control sent them back to re-adjust the end cap of the antenna to make sure it was working. Once they were sure that antenna was in good shape, the astronauts and specialists on the ground gave their last remarks.

"Hubble's never had it better. It's never been more capable," spacecraft communicator Dan Burbank said. "It's just been a marvel to watch you guys do this."

Thanks to the astronauts repairs, the telescope should be able to photograph the cosmos for another five or more years. NASA expects to launch the more advanced James Webb Space Telescope in 2014. When Hubble retires, this new telescope will pick up from where it left off.

The astronauts will release the Hubble Space Telescope Tuesday and, after additional tests and preparations, are scheduled to return on Friday.

Scientists Will Know Outcome of the Repair Mission in Three Months

It will be three months before scientists know how well all of the new instruments work. The Goddard Space Flight Center in Maryland will unveil the new discoveries after Hubble's renovation Sept 7. In total, this Hubble mission costs more than $1 billion.

"We fought against tremendous odds to fly this mission, and we succeeded beyond our wildest dreams,"said Chief Hubble Scientist Dave Leckrone, after the spacewalk was over.

On Sunday, Astronauts Mike Massimino and Good were tasked with installing the steel New Outer Blanket Layer Sunday, but were unable to accomplish it because the spacewalk fell three hours behind.

The team was asked to fix a spectrograph that can, among other things, measure the chemical composition of distant objects in the cosmos. To accomplish this, Massimino had to remove more than 110 small screws which, with huge space gloves, proved to be a tedious, time-consuming task.

At one point, Houston sent Massimino back to the space shuttle's airlock to refill the oxygen in his backpack. In the end, the astronauts wrapped up what was scheduled as a 6½-hour spacewalk after eight hours.

Previous Spacewalk More Successful

On Saturday, astronauts Grunsfeld and Feustel whipped through what was supposed to be the toughest spacewalk of the mission with remarkable ease.

The two replaced an old instrument with the new Cosmic Origins Spectrograph, and then repaired a broken camera deep inside the telescope, removing blown circuit boards that were never meant to be taken off in orbit.

Massimino and Good were working on the telescope's Space Telescope Imaging Spectrograph, or STIS. They had the very challenging task of replacing a low-voltage power supply board, which contains a failed power converter. That meant taking out the 110-plus very small screws -- and not letting any of those screws float away -- to accomplish the repair.

STIS has been in "safe mode" since August 2004, when its power supply failed. Massimino, during training on the ground, managed to perform the task in 40 minutes.

The spacewalkers also were scheduled to install one of two new protective thermal insulation panels to protect Hubble from space junk.

Spacewalking Is Hard Work

Spacewalking to fix the Hubble Space Telescope is hard work, especially when the shoe doesn't fit. If your feet hurt nothing is fun. Ask any woman who has to smile while wearing 4-inch heels.

Good struggled with an ill-fitting boot on his first spacewalk last week, and a team on the ground at Mission Control sent up suggestions to adjust the fit.

"Once pressurized, you should be able to pull your foot back in the boot away from the pressure point on the top of the foot," wrote astronaut Rex Walheim to Good.

Walheim said he has chased boot pain issues in spacesuits for more than seven years.

A fifth and final spacewalk is set for Monday, and the Hubble telescope will be released Tuesday from Atlantis, with a landing planned, if weather cooperates at the Kennedy Space Center Friday.

The new discoveries from the improved Hubble Space Telescope won't be revealed for months. This last mission to Hubble cost more than $1 billion.