Sunday, April 11, 2010

Spacewalkers To Defer Work After Struggle With Coolant Tank

A lengthy struggle to bolt a coolant tank into place outside the International Space Station will keep two spacewalkers from finishing all planned work today.

Discovery mission specialists Rick Mastracchio and Clay Anderson will not have time to hook up nitrogen pressurization lines and ammonia coolant lines to the tank. They also are going to skip the retrieval of a couple of space debris shields. All that work now will have to be picked up on a third and final spacewalk planned by the two early Tuesday.

Mastracchio and Anderson were breezing through their work until it came time to bolt a new ammonia coolant tank into place on the starboard side of the station's central truss. They were about 40 minutes ahead of schedule, but it took much longer than planned to drive four bolts in place, and they now are hooking up electrical connections.

Mission managers decided the astronauts would not have time to remain outside and "bake-out" in the event of a toxic ammonia leak during coolant line hook-ups. Procedures call for astronauts who come in contact with ammonia to remain outside until any trace of the substance sublimates, or turns into a gas. The astronauts would not want to reenter the closed-loop environment inside the space station with any ammonia on their suits.

The two did get a great view of Anderson's home state, Nebraska. They flew right over it about five and a half hours into their excursion.

"Hello, down there, my Husker friends," Anderson said.

"Clay makes working with bolts look like a can of corn," joked crewmate Dottie Metcalf-Lindenburger, a reference to baseball lingo for catching an easy fly ball.

Anderson said maybe he'd have some corn for dinner. Mastracchio said the arduous spacewalking work left him hungry enough to devour a steak.

"Well, we'll fix you guys up some good food when you come back in," Metcalf-Lindenburger said.

The astronauts should be back in the Quest airlock within the next hour or so.

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