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article imageExpedition 24: Astronauts complete space station repair

By Kim I. Hartman     Aug 16, 2010 in World
Houston - Flight Engineers Doug Wheelock and Tracy Caldwell Dyson finished this mornings spacewalk to install a spare ammonia pump module on the S1 Truss. The successful spacewalk took 7:20 hours to complete and was the 150th maintenance walk for the space station.
The Expedition 24 crew will enjoy some well deserved downtime after the completion of a third contingency spacewalk today to replace a failed ammonia pump module. The spacewalk began at 6:20am est. and continued for just over seven hours ending at 1:40pm est.
The failed pump module that provided cooling for the International Space Station’s systems was removed from the S1 Truss during Wednesday’s second repair spacewalk which lasted 7 hours, 26 minutes. It was temporarily stowed on an external stowage platform adjacent to the Quest airlock. The first repair spacewalk took place Saturday, Aug. 7 and lasted a record 8 hours, 3 minutes.
Flight Engineer Shannon Walker assisted the space-walkers on each spacewalk from inside the station by operating the Canadarm2, the station’s robotic arm. Specialists on the ground carefully plotted the robotic maneuvers necessary for Walker to move the space-walkers into their work positions. The procedures were sent up for her to practice in between spacewalks.
After the original pump module failed two weeks ago ground controllers powered down numerous station systems and readjusted them to provide maximum redundancy. Mission managers and astronauts on the ground also quickly began choreographing the contingency spacewalks and planning repair procedures. The spacewalks were planned several days apart to give crew members time to rest and managers on the ground time to review data and make necessary adjustments, said a NASA spokesman.
During a post-mission press conference that was held at Johnson Space Center today, NASA officials answered questions and explained Monday’s spacewalk. The entire press conference can be seen on NASA TV where it was broadcast live this afternoon.
Courtenay McMillan, Expedition 24 spacewalk flight directer said, "The 780-pound spare pump module was removed from an external stowage platform by Wheelock while working from the Canadarm2. The module was successfully installed on the S1 Truss after Wheelock attached four bolts and Caldwell Dyson mated five electrical connectors."
"Ground controllers confirmed the module was in healthy condition when it began receiving power. After a pressure check and more fluid cable connections, the module was filled with ammonia. The pump was tested at 1000 rpm's and functioned satisfactory," said McMillan.
She added, "The cleanup activities met their objectives and by tonight they would be able to conclude that the new pump was working properly. It will take almost twenty-four hours to boot and power up all systems back to their original configurations prior to the pump module system failure."
Kirk Shireman, of Mission Control, when asked what caused the failure, said "We are pouring over the data now and will continue to look at every detail in determining the cause of the system failure. If the pump was returned to Earth it would simplify this effort allowing forensics to check the entire system and carry-out diagnostic tests to develop preventative measures to see it wouldn't happen again, but that will not happen as they not expected to return the failed pump on any future flights."
Shireman said they are looking forward to getting back to research projects, now that this repair was complete, with over 66 hours of studies designated next week for the International Space Station's crew.
David Beaver, Expedition 24 spacewalk officer, said the crew was in high spirits and excited to have completed today's repairs. They are ready for the rest they earned following this, the 150th spacewalk, in support of space assembly and maintenance aboard the international space station. Beaver said, "all lines are hooked up, everything went smoothly, all parts were installed. critical cleanup was completed and everything was back to work and life, as usual."
"It was a long day and great work was done." Beaver added. "Consumable limits had been reached and the space repair team of Wheelock and Dyson were safely instructed to return to the space station.
The spacewalk was the 242nd in NASA history and the fourth for the crew of Expedition 24.
Video shown is of the second spacewalk that took place on Wednesday.
More about NASA, Spacewalk, Expedition, Pump module repair, International Space Station
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