— Michael Lopez-Alegria will disconnect fluid-filled cooling lines in an area NASA refers to as the "rat's nest" – he will be prepared for a potentially dangerous leak of ammonia coolant (Illustration: NASA)
Michael Lopez-Alegria and Sunita Williams will retract unnecessary radiators on the ISS (Illustration: NASA)
Two astronauts aboard the International Space Station (ISS) will embark on an unprecedented three spacewalks in nine days beginning on Wednesday.
Space shuttle crews often do this many spacewalks during a short flight, but this will be a first for the station without a shuttle docked there. So far, there have only been five US-led spacewalks from the ISS without the shuttle.
Current ISS crew members Michael Lopez-Alegria and Sunita Williams will perform the spacewalks. But it has been about six months since they last trained together in a gigantic swimming pool that simulates microgravity.
So they have been preparing for the gruelling excursions onboard the station, exercising for two hours a day, as required for all astronauts on the station.
But NASA is not concerned about their ability to carry out the extra-vehicular activities, or EVAs. Back on the ground, Williams runs marathons, and Lopez-Alegria is set to become NASA's most experienced spacewalker.
"I think there's a little bit of competition bet the two of them on who can be the most fit," says Glenda Laws, NASA's lead spacewalk officer for this mission.
The December 2006 shuttle mission added a permanent cooling system to the ISS, so the spacewalkers will disconnect the temporary system that had provided cooling for lab equipment inside the ISS up to that point.
For the first and second spacewalks, scheduled for 31 January and 4 February, Lopez-Alegria will disconnect fluid-filled cooling lines in an area NASA refers to as the "rat's nest" because of its jumble of cables and lines. Williams will watch from nearby to ensure that Lopez-Alegria does not get entangled.
During these activities, NASA is prepared for a potentially dangerous leak of ammonia coolant. Astronaut Robert Curbeam experienced this first-hand while connecting ammonia lines on a space shuttle mission in February 2001. Ammonia contaminated his suit and he had to stay in the sunlight to bake off the material, which could be hazardous to crew members if it were brought back inside the space station.
'Bundle of laundry'
Later in the spacewalk, ground controllers will send commands to retract two radiators that are no longer necessary.
During the second spacewalk, Lopez-Alegria will remove a sunshade that is no longer needed on a docking port because the station has changed its orientation. He will toss this beneath and behind the ISS so that it will quickly burn up in the Earth's atmosphere.
On the third spacewalk, expected to take place on 8 February, the pair will remove two thermal shrouds larger than king-sized bed sheets on the P3 segment of the truss. The truss is the backbone for the station's solar arrays and cooling system. They will wad these shades up and toss them overboard again.
"We do expect it to look like a large bundle of laundry," Laws says.
At the end of these three spacewalks, Williams will hold the record for the most spacewalks by a US woman four.
Not to be outdone, Lopez-Alegria will embark on a fourth spacewalk on 22 February with cosmonaut Mikhail Tyurin to help free a stuck antenna. After that spacewalk, he will have made 10 spacewalks in his career, making him the most spacewalked US astronaut in terms of the number of spacewalks and hours spent outside the airlock.