Third Spacewalk Finishes Installation Of Spare Ammonia Pump

Flight Engineers Doug Wheelock and Tracy Caldwell Dyson completed the third contingency spacewalk to install a spare ammonia pump module on the S1 Truss at 1340 EDT Monday. Flight Engineer Shannon Walker assisted the spacewalkers from inside the International Space Station and operated the Canadarm2.

NASA Image

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.

Wheelock and Caldwell Dyson were outside during the third repair spacewalk for 7 hours, 20 minutes. On Wednesday they were outside during the second spacewalk for 7 hours, 26 minutes. The first repair spacewalk took place Aug. 7 and lasted a record 8 hours, 3 minutes.

After the original pump module failed July 31 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.

The spare ammonia pump installed was delivered aboard space shuttle Discovery and stowed on an external stowage platform in July 2006. STS-121 Mission Specialists Piers Sellers and Mike Fossum performed the transfer work during a 6-hour, 47-minute spacewalk.

FMI: www.nasa.gov