Astronauts install fresh batteries on spacewalk

CAPE CANAVERAL -- Astronauts outfitted the international space station with fresh batteries in an extra-long spacewalk Friday, moving slowly and even loitering at times to avoid a repeat of the suit trouble that cut short the previous outing.

Despite their dawdling pace, Christopher Cassidy and Thomas Marshburn managed to install all four new batteries.

Before the spacewalk, Mission Control had requested Cassidy and Marshburn to take their time heading out to the far end of the space station, where the critical battery changes awaited them.

It was difficult dealing with all the stiff bolts, and the men paced themselves accordingly as they pulled out 9-year-old batteries and plugged in new ones.

The last time Cassidy went out, on Wednesday, he was so gung-ho and moved so fast that the air-cleansing canister in his suit could not keep up. That resulted in rising carbon dioxide levels that forced an early end to the spacewalk.

"He's a Navy SEAL, he's in great shape, and so we really needed to tell him, 'Hey, we know you can do this really well and really fast ... just slow down a little and take your time,"' explained flight director Holly Ridings.

The spacewalkers took the advice to heart. But despite Cassidy's effort to stay relaxed, his metabolic rate was a little high at times and Mission Control urged him to take it easy. Marshburn, in fact, took on some extra chores early on to give his partner a break.

Six-and-a-half hours into the spacewalk, Mission Control reported that carbon dioxide levels were rising slightly in Cassidy's suit. The astronauts were advised to start wrapping everything up and be back in the air lock by the seven-hour mark.

"OK, guys, come back nice and steady," Timothy Kopra called from inside the shuttle-station complex.

Two of the four new batteries assigned to Cassidy and Marshburn should have been installed Wednesday. Only two fresh batteries were hooked up during that shortened spacewalk.

The extra work pushed the length of Friday's spacewalk past the usual 6 1/2 hours. It was the fourth spacewalk, over the past week, for shuttle Endeavour's visiting crew.