Live In Orbit: Spacewalkers Give Hubble Final Hug

LIVE IMAGES: Refresh this page for periodic updates and the latest still image from NASA TV. Click to enlarge the NASA TV screen grabs below.

Spacewalking astronauts John Grunsfeld and Drew Feustel are safely back inside shuttle Atlantis after winding up the last of five back-to-back spacewalks that have left the Hubble Space Telescope at the apex of its scientific capability while extending the observatory's orbital life an anticipated five to 10 years.

Grunsfeld and Feustel switched their spacesuit batteries off and started pressurizing the shuttle's airlock at 3:22 p.m., marking the end of a seven-hour, two-minute spacewalk.

During the past five days, Grunsfeld, Feustel and two other spacewalkers -- Mike Massimino and Mike Good -- installed two state-of-the-art science instruments, repair two others and equipped the observatory with new batteries, gyroscopes and other gear that should extend observations until at least 2014.

Grunsfeld was thoughtful and poetic as the $887 mission enters the home stretch.

"This is a really tremendous adventure that we've been on, a really challenging mission. Hubble isn't just a satellite. It's about humanity's quest for knowledge," he said.

"The only way of finding the limits of the possible is by going beyond them into the impossible. And on this mission we tried some things that many people said were not possible." he added.

Among them: Repair the Space Telescope Imaging Spectrograph and the Advanced Camera For Surveys. Both comatose instruments were resuscitated. Many thought it would be impossible to finish all the work.

"But we've achieved that, and we wish Hubble the very best," Grunsfeld said.

"It's truly a sign of the great country that we are able to do things like this on a marvelous spaceship like space shuttle Atlantis. But I've convinced that if we can solve problems like repairing Hubble, getting into space, doing the servicing we do, traveling 17,500 mph around the Earth, that we can achieve other great things like solving our energy problems and our climate problems," he said.

"I want to wish Hubble a new set of adventures, and with the new instruments that we installed, that it may unlock further mysteries of the universe."

NASA astronaut Dan Burbank radioed congratulations up from the Mission Control Center in Houston.

"There's a lot of happy folks down here on the ground," Burbank said.

"We just look back and kind of marvel at the last five days and all the amazing work -- electronic brain surgery, and I don't know how else you can put it -- that you guys accomplished on that telescope. And Hubble's never had it better. It's never been more capable, and it's just been a marvel to watch you guys do this," he said.

Atlantis mission commander Scott Altman urged Grunsfeld -- an astronomer-turned-astronaut who has served on three Hubble repair missions -- to seize the day.

"John, remember take a moment here. This is it spacewalk on Hubble and maybe our last visit to space. so enjoy this. you earned it," Altman said.

"Thanks for those kind words," Grunsfeld replied. "We really have achieved a lot out here."

NASA astronauts have performed 23 spacewalks servicing Hubble, tallying 166 hours and six minutes of work on the observatory. Hubble launched in April 1990.