Sunday, May 22, 2011

Astronauts top off coolant in leaking loop

Outside the International Space Station, Endeavour spacewalkers have successfully recharged a solar array cooling loop that has a slight leak.

Drew Feustel and Mike Fincke finished routing jumper cables between a tank near the center of the station's structural truss and the loop serving solar arrays on the far left end.

"Everything's looking good," radioed Steve Swanson, an astronaut communicating with the crew from Houston, as the ammonia began to flow.

It took about 10 minutes to top off the system with five pounds of ammonia, a process controlled from the ground. The loop's full capacity is 55 pounds.

Feustel will now vent and remove the jumper cables that have been hooked up for the job. He'll be watching out for potential ammonia leaks that could contaminate his spacesuit.

Meanwhile, Fincke has begun work to lubricate the 10.5-foot diameter joint that allows the four solar array wings on the station's left side to turn continuously to track the sun.

It turned out quick hands were needed to remove bolts on a series of covers being removed to gain access to the joint.

Fincke reported a bolt that needed an extra turn to release unexpectedly "popped up and popped off."

"The good news is I caught it," he radioed.

"Good catch, Mike," said Feustel.

"It was a little bit of a surprise," said Fincke.

The same thing happened on several more bolts.

Once the covers are off, Fincke will take pictures, wipe up samples of the existing lubrication and then use grease guns to apply fresh grease.

The only other snag so far: A camera Feustel was using to catalogue his work stopped working about an hour into the spacewalk.

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