Live in Orbit: Spacewalk extended for batteries

Though running about two hours behind schedule, two Atlantis spacewalkers are forging ahead with their final task of the day, the installation of a fresh set of batteries in the Hubble Space Telescope.

Mission specialist Mike Massimino paused for about five minutes to recharge his oxygen supply at the space shuttle airlock, or he wouldn't have had enough to finish the job expected to take about 95 minutes.

Spacewalking partner Mike Good's battery power was the next concern, but he was told he has three hours remaining.

"We think we've got plenty of time," said Dan Burbank, an astronaut communicating with the Atlantis crew from NASA's Mission Control Center in Houston.

"I'm willing to give it a try," Good said.

"I'm OK," said Massimino.

The spacewalk was scheduled to last six hours and 30 minutes. But it took five hours and 45 minutes to replace three sets of gyroscopes and close the doors to the first work site.

To allow for the extra-long spacewalk, mission controllers plan to push back by an hour the time the crew goes to sleep and wakes up on Saturday.

Massimino and Good will replace the first of two battery modules, each holding three nickel hydrogen batteries and weighing 460 pounds.

The new batteries will replace originals launched with Hubble in 1990, which have far exceeded their design life.

The second set is scheduled to be replaced on the mission's fifth and final spacewalk, planned Monday.

Here's a fact sheet with more background on the batteries.