Astronauts Douglas Wheelock and Tracy Caldwell Dyson wrapped up a successful seven-hour 20-minute spacewalk Monday, installing a new ammonia pump to help recover from a failure July 31 that shut down half the International Space Station's cooling systems.

The spacewalkers had hoped to finish the excursion by installing a long extension cord between the Quest airlock and the Unity module that is needed before attachment of a cargo module during a shuttle visit in November.

But work to pack up tools and equipment used for the pump replacement work ran a bit long and the cable installation was deferred.

"We're going to call this a victory and go ahead and drop the J612 (cable) task and ingress the airlock," Oscar Koehler called from mission control.

The spacewalk began at 6:20 a.m. EDT and ended at 1:40 p.m., pushing the total time for three coolant system repair EVAs to 22 hours and 49 minutes. Wheelock's total through six career spacewalks now stands at 43 hours and 30 minutes, moving him up to 10th on the list of most experienced spacewalkers. Total EVA time for station assembly and maintenance stands at 944 hours and 24 minutes -- 39.4 days -- through 150 spacewalks.

Before repressurizing the Quest airlock, Wheelock asked for an update on the newly installed pump.

"The pump is looking good," Koehler reported.

"Oh, sweet," Wheelock replied. "I hope the day continues like this as we start everything back up and we've got our station back."

"Concur with that," Koehler said.

It will take flight controllers, working with the astronauts aboard the station, another few days to restore normal operations in the wake of the July 31 failure of the ammonia pump in coolant loop A.

With half the station's cooling system out of action, the astronauts had to install jumpers to transfer loads from loop A to loop B and to route additional power to the Russian segment of the station. All of that allowed the station to continue near normal operations with three of four stabilizing gyroscopes, life support systems and critical communications gear.

But with one loop out of action, systems in the Japanese Kibo module and the European Space Agency's Columbus module had to be powered down, along with several science racks in the U.S. segment of the station. And with only one coolant loop in operation, the space station had no redundancy in a critical system.

As a result, NASA managers decided to defer a spacewalk planned for Aug. 5, opting instead to stage two complex spacewalks to remove the failed ammonia pump and install a replacement. Four spare pump modules were available, stored on the station's main power truss as a hedge against failures.

During the first repair spacewalk Aug. 7, however, the astronauts ran into problems disconnecting one of four ammonia lines leading to the failed pump. Falling behind schedule, Wheelock finally released a quick-disconnect fitting only to report a significant ammonia leak.

Flight controllers told him to tighten the quick-disconnect and to leave the line in place while they considered a variety of options. They ultimately lowered pressure in the line by venting nitrogen and during a second spacewalk Aug. 11, Wheelock was able to remove the M3 connector. He and Caldwell Dyson then removed the failed pump and mounted it on an attachment fixture at the base of the station's robot arm.

During today's spacewalk, the astronauts had no major problems installing the replacement pump, the oldest of the four available spares. Flight controllers successfully activated the pump module and reported normal operation.

"And Wheels, just to confirm, we did not see any ammonia come out today, amazingly," Koehler radioed. "So if you can confirm you saw no ammonia during any of the QD ops we are go with no ammonia tests at the end of the EVA."

"OK. I did not, Oscar," Wheelock replied. "I did at one time, though, saw what I thought were just a couple of little snowflakes. But I'm not able to confirm that. There was no leak or anything."

A few moments later, Wheelock showed off a cue card on his spacesuit's left wrist that thanked flight controllers and ended with the words "Game over!"

But it will take until Thursday to restore the station's two coolant loops to normal operation. On Tuesday, flight controllers plan to briefly shut down hardware being cooled by loop B that is normally serviced by loop A.

"All the loads currently powered by a contingency jumper that has transferred loads from the loop A cooling loop to loop B since the failure of the pump module back on July 31, those loads will be powered off temporarily," said Rob Navias, NASA's mission control commentator.

"The crew inside the International Space Station will remove that lab-truss contingency jumper that was installed on the night of July 31 to transfer loads to loop B. Then the DC-to-DC converter units will be reactivated to power loop A and the pump module and other configurations will occur to bring back on line the Kibo Japanese module systems, as well as the European Columbus module systems."

By Thursday, Navias said, "all of the configuration activity will be complete and a final power jumper providing contingency power to the Russian segment of the International Space Station will be removed and we'll be back in business the way we were before the failure occurred July 31."

Additional coverage for subscribers:
VIDEO: AMMONIA HOSES ARE ATTACHED TO THE PUMP PLAY
VIDEO: POWER AND DATA LINES BRING PUMP TO LIFE PLAY
VIDEO: REPLACEMENT PUMP SECURELY BOLTED DOWN PLAY
VIDEO: PUMP INSERTED INTO SPACE STATION SLOT PLAY
VIDEO: SPACEWALKER HAULS PUMP OVER TO TRUSS PLAY
VIDEO: RETRIEVING THE REPLACEMENT PUMP PLAY
VIDEO: SPACEWALK NO. 3 BEGINS PLAY

VIDEO: POST-SPACEWALK NO. 2 STATUS BRIEFING PLAY
VIDEO: FAILED COOLANT PUMP REMOVED FROM THE STATION PLAY
VIDEO: ROBOT ARM MANEUVERS SPACEWALKER AROUND PLAY
VIDEO: POWER AND DATA LINES UNPLUGGED PLAY
VIDEO: TROUBLESOME UMBILICAL DETACHED PLAY
VIDEO: NO REPEAT OF AMMONIA LEAK PLAY

VIDEO: POST-SPACEWALK NO. 1 STATUS BRIEFING PLAY
VIDEO: PROBLEM CONNECTOR FINALLY FREED BUT THEN LEAKS PLAY
VIDEO: LEFT-HAND AMMONIA UMBILICAL COMES OFF WITH EASE PLAY
VIDEO: SKIPPING OVER PROBLEM CONNECTOR TO DO ANOTHER PLAY
VIDEO: TROUBLES AND ADVICE FOR STUCK AMMONIA LINE PLAY
VIDEO: PUMP'S SMALL COOLING LINE UNPLUGGED PLAY
VIDEO: SPACEWALKER DOUG WHEELOCK WORKS ON OLD PUMP PLAY
VIDEO: BRIEFING ON PUMP FAILURE AND SPACEWALKS PLAY
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