Endeavour's station stay extended one day

Endeavour's planned 13-day mission has been rounded up to a full two weeks.

NASA mission controllers alerted the six shuttle astronauts of a one-day mission extension when the crew awoke around 4:15 p.m. Eastern time.

"Hey, that is great news," said mission specialist Steve Robinson. "There's cheering going on onboard. Thanks for the extension."

The extension was anticipated before Endeavour launched early Monday. The extra time allows the crew to help transfer racks holding the International Space Station's life support systems into the newly installed Tranquility module.

The racks that recycle urine and condensation into drinkable water have been running since Endeavour docked early Wednesday, bringing replacements for failed parts.

NASA wanted to be sure a large enough sample of water could be processed for testing back on the ground before moving the racks. Evidently, enough water has been produced for managers to go-ahead with the relocations.

The station crew could have done the work later if necessary, but the shuttle crew was trained in the procedures and they were always intended to be part of the shuttle mission timeline, assuming the systems were operating properly.

The main task for the day ahead is the second of three spacewalks by mission specialists Bob Behnken and Nick Patrick, who spent the night "camping" in the Quest airlock at a reduced air pressure, a procedure that reduces the chance of experiencing decompression sickness.

Behnken and Patrick will tackle a critical and potentially dangerous task, the installation of four ammonia coolant cables between Tranquility and the station.

The module can't be activated without the connections to the station's cooling system.

The spacewalk is scheduled to begin at 9:09 p.m. EST.

Other work today will include continued outfitting of Tranquility from the inside, and transfer of supplies, equipment and experiments between the station and Endeavour -- an activity alluded to in the wake-up song played for Robinson: "Too Much Stuff," by Delbert McClinton.

Mission speclialist Kay Hire and pilot Terry Virts will also troubleshoot a problem placing a protective cover over the Tranquility hatch now covered by the windowed cupola, which is scheduled to be relocated on Sunday evening (Flight Day 8).

The mission's extension means the crew's earliest targeted return to KSC is now slated for 10:16 p.m. Sunday, Feb. 21.