JOHNSON SPACE CENTER, Houston--Spacewalkers David Wolf and Christopher Cassidy were told to cut short their space station battery replacement work and head back to the lab's Quest airlock today because of a problem with the carbon dioxide removal system in Cassidy's spacesuit.
The astronauts made it back to the airlock without incident and the five-hour, 59-minute spacewalk officially ended at 3:31 p.m. CDT, about a half hour earlier than planned.
Dave Wolf's helmet cam view, showing crewmate Chris Cassidy just outside the space station's Quest airlock module before ending a five-hour 59-minute spacewalk.
(Credit: NASA TV)"Hey, like I said, we were looking at the LIOH (lithium hydroxide) trend in Chris's suit," Aki Hoshide radioed from mission control around 2:52 p.m. "We do see it trending up. This is probably not by working hard, but it seems like the canister itself is experiencing some problems. So at this point, we would like to start cleaning up. How copy so far?"
"I think I copied, the canister may be having problems, it's not a metabolism-related issue?" Wolf asked.
"And that is correct."
"Interesting," Cassidy said.
"Um hm," Wolf agreed. "Do you see the possibility of an imminent canister failure? We're cleaning up, by the way."
"And yeah, it's not an imminent failure," Hoshide said. "We do still have some time, we just wanted to make sure that you guys are back in the airlock.
"OK."
A few moments later, however, flight controllers told Cassidy to head on back to the Quest airlock module without delay. Cassidy's carbon dioxide levels were near NASA's safety limit at that point, but they dropped back down before he entered the airlock.
The goal of Wednesday's spacewalk was to replace four of six 375-pound batteries in the International Space Station's far left solar array. When the astronauts were told to wrap up their work, two new batteries had been installed and a third old battery had been removed from the solar array's integrated electronics assembly. The old battery was left attached to a temporary mount.
The Endeavour astronauts plan two more spacewalks, Friday and Monday. The rest of the batteries presumably will be installed during those excursions, but it's not yet clear if the astronauts will be able to complete all their planned work in the final two EVAs.
This was the 128th spacewalk devoted to station assembly and maintenance since construction began in 1998, the ninth so far this year and the third of five planned by Endeavour's crew. Total station assembly EVA time now stands at 798 hours and 30 minutes.
