Spacewalk wrapping up; not enough time for shuttle-related task

Two NASA spacewalkers are getting ready to head back inside the International Space Station after successfully completing a three-spacewalk effort to replace a failed coolant pump.

But managers decided to forgo plans to tackle one more job that would have helped prepare for shuttle Discovery's arrival in November, concerned that it might keep Doug Wheelock and Tracy Caldwell Dyson outside dangerously long.

"We're going to call it a victory" and leave that task for later, Oscar Koehler, a spacewalk officer in Houston, radioed to the spacewalkers.

The decision was made about seven hours into a spacewalk that was scheduled to last six-and-a-half hours.

Wheelock and Caldwell Dyson had reported their condition as "Alpha," meaning they felt great. But it took them longer than expected to clean up from the higher priority tasks.

The key "consumable" being watched was the ability of spacesuits' metal oxide canisters to scrub carbon dioxide exhaled by the crew members.

Another spacewalk is likely to be scheduled before the shuttle mission to route a power extension cable between modules. NASA also wants to move the failed ammonia pump from a temporary storage location to a pallet where spare parts are stored.