After wrestling a bulky new cooling pump into place aboard the International Space Station Monday, astronaut Doug Wheelock raised his left wrist to the camera attached to his helmet. The message for Mission Control, written large across a cue card, was succinct: 'Game over!' NASA appears to have won this game, played 200 miles above Earth in free fall, by completing the removal of a failed cooling pump and replacing it with a spare. Since the failure of the pump, a critical system, Wheelock and his colleague Tracy Caldwell Dyson have conducted three spacewalks, totaling nearly 23 hours in space. The station's system to cool its critical components in the sun's direct light has two loops through which ammonia coolant is pushed. The failure of one of the two pumps on July 31 forced the station to shut down non-critical systems and shelve many ongoing science experiments. NASA had stashed spare cooling pumps, which weigh 780 pounds on the ground, aboard the station. And when the original pump failed it set into motion plans laid long before. 'People over the years have thought about this failure, and when it happens you just go execute those plans right away,' Shireman said. All went well until the first spacewalk 10 days ago, when Wheelock struggled to remove one of four ammonia lines leading to the old pump. When it finally came free it sprayed ammonia into space. After the original attempt to free the old pump failed Wheelock and Caldwell Dyson successfully removed it last week during a second spacewalk, and then the pair had a relatively smooth time of it Monday installing the new pump. By this morning NASA intends to turn the new pump on for good, and begin restoring full power to the station. eric.berger@chron.com XXX - End of Story3D 