Cosmic Log

Alan Boyle, Science Editor NBC News

11 hours ago

Nearly two weeks after a faulty coolant valve crippled the International Space Station, two NASA astronauts took on a rare Christmas Eve spacewalk to get things back to normal.

During Tuesday's seven-hour, 30-minute repair operation, spacewalkers Rick Mastracchio and Mike Hopkins installed a refrigerator-sized coolant pump module with an assist from Japanese astronaut Koichi Wakata, who operated the 58-foot-long (18-meter-long) robotic arm from inside the space station.

NASA commentator Rob Navias said the new module passed an initial pressure test. "We have a pump that is alive and well," he reported on NASA TV.

The only other time NASA conducted a spacewalk on Christmas Eve was during a Hubble repair operation in 1999. The timing lent a holiday spirit to Tuesday's proceedings. "It's like Christmas morning, opening up a little present here," Mastracchio joked as he checked his tools.

PhotoBlog: Santa never had a view like this!

Two and a half hours into the job, Hopkins stood at the end of the robotic arm and steadied the 780-pound (355-kilogram) pump module as it was swung into position for installation. "Mike Hopkins taking a special sleigh ride on this Christmas Eve," Navias observed.

The spacewalk didn't always go as smoothly as Santa's rounds, however: After the astronauts slid the boxy apparatus into place and secured it with bolts, they had some trouble switching the cooling system's fluid lines. They had to tap and pry at one of the interim fluid-line connections to free it up, and in the process they set off a mini-blizzard of toxic ammonia "snowflakes."

Follow this link:

Spacewalkers finish crucial space station repairs in time for Christmas