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Astronauts take 2nd spacewalk to hook up plumbing

A pair of spacewalking astronauts floated back outside last night to hook up plumbing on the newest room of the International Space Station and bring it alive with power.

Robert Behnken and Nicholas Patrick had to route extra-long hoses that were fashioned right before space shuttle Endeavour's trip to the space station. The original ammonia coolant lines failed tests, and so engineers had to put together replacement hoses from shorter spares that were welded together.

The hoses are 4.3 meters to 5.5 meters long and, along with a protective blanket, cumbersome to work with.

"It certainly is longer than I remember it being," Patrick said as he got started.

It was the second excursion in three days for Behnken and Patrick. They have one more spacewalk to finish installing the Tranquility room and its attached observation deck, the last major building blocks of the 11-year-old space station. Endeavour carried up the pieces last week.

Once ammonia coolant is flowing through the hoses, Tranquility will begin surging with power. Its systems cannot be turned on unless there is a way to get rid of the heat generated by the equipment inside.

It was unwieldy work because of the extra-long hoses and potentially hazardous because of the ammonia coolant.

In fact, frozen bits of ammonia shot out at Patrick as he undid a connection. He said the ammonia was solid by the time it bounced off his visor and right glove, and he assured his colleagues there was no residue on him.

"It was about the kind of quantity of stuff that you would expect if you didn't empty the straw at the end of your drink bag," Patrick reported.

"Yeah - if you were drinking ammonia," astronaut Stephen Robinson said from inside. Patrick had a good laugh.

Mission Control said slight leakage was expected. As a precaution, the spacewalkers were instructed to check their suits at the end of the plumbing job.

The US$400 million-plus Tranquility and lookout - supplied by the European Space Agency - will hold life-support systems as well as exercise equipment and a toilet.

The domed lookout is essentially an enormous bay window that will provide breathtaking views of Earth. Its seven windows include the largest ever flown in space: a round one nearly 80 centimeters across.

While preparing the observation deck for its planned move to another side of Tranquility, the astronauts could not put on an insulating cover at the hatch. It simply did not fit; something interfered with the lock-down bars.

Late yesterday, the space station's commander, Jeffrey Williams, reported that bolts seemed to be causing the interference. He removed two of the bolts and said he thought the cover would fit, but that the clearance would be tight.

The cover is needed to protect a seal and docking mechanisms from getting too cold when that port is unoccupied.

Mission Control had some good news for the six shuttle astronauts before the spacewalk got under way: They will get to spend an extra day at the orbiting outpost.

Mission managers yesterday added a 14th day to the mission to give the crew time to move water-recycling equipment into Tranquility. NASA wanted to see if repairs to the broken urine-processing machine worked before moving the equipment. They apparently did.

Endeavour is now scheduled to return to Earth on Februay 21.

 

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