The cooling system in cosmonaut Alexander Kaleri's spacesuit malfunctioned during a planned five-and-a-half-hour spacewalk today, forcing flight director Vladimir Solovyev to order an early end to the excursion.

"I have rain inside the helmet," Kaleri told Russian flight controllers shortly after 7 p.m. "I have water inside the visor."

"How much water? Could you estimate?" a controller asked.

"Well, quite some amount, a significant amount," Kaleri said. "It felt like rain."

Telemetry indicated a malfunction in Kaleri's sublimator, a device used to prevent water from condensing inside the suit. He recycled power, but the cooling system did not recover and Solovyev ordered Kaleri and Michael Foale to return to the station's Pirs airlock module.

"Everything had been proceeding by the book and on schedule until about 40 minutes ago when Alexander Kaleri reported that a couple of drops of water had formed on the inside of his visor and that his suit temperature was increasing slightly as well, not to a particularly uncomfortable level but to the point where additional humidity was beginning to form within the suit and within his visor," said NASA spokesman Rob Navias.

"Russian flight controllers are indicating an apparent failure of a sublimator cooling device, which maintains cooling and regulates humidity within the suit itself."

Foale and Kaleri had completed all but two of their planned tasks, swapping out experiment packages and mounting an instrumented dummy torso on the station's hull to measure the radiation environment faced by spacewalking astronauts. They were heading toward the aft of the Zvezda service module to swap out another experiment package and to relocate reflectors needed for future dockings by European supply ships when the EVA was called off.

The spacewalk began at 4:17 p.m. EST and officially ended at 8:12 p.m., for a duration of three hours and 55 minutes. Thirty eight NASA astronauts, eight cosmonauts, one Frenchman and one Canadian have now logged 322 hours and 32 minutes of spacewalk time building and maintaining the international space station in 52 excursions. The most recent was April 8, 2003.

Today's spacewalk left the space station vacant in the first such outing since crew sizes were reduced in the wake of the Columbia shuttle disaster.

Foale and Kaleri, known by his nickname "Sasha," have seven earlier spacewalks to their credit.

"Sasha and I have both performed spacewalks before, on previous flights, and I have also done a spacewalk in a Russian suit on board the space station Mir," Foale said last month. Today's spacewalk is, "in our minds, anyway, pretty much a routine or regular, if any spacewalk can be, EVA to replace some science experiments from Japan and from Europe and Russia on the outside surface of the service module and to bring in some experiments that were placed out there already by previous crews for return to Earth eventually.

"This EVA is different for the international space station ... because we will not have a third person on board the space station watching over the station systems while Sasha and I are outside in our suits," he said. "But really, my take on this is not one of alarm but one of this is something we all must get used to. Just as the Apollo astronauts, when a pair of them would land on the lunar surface and venture out of their lunar module, many miles even on their rover, just the two of them in their suits with no one back in the lunar module, I think we will be in no different a situation. In fact, we will be in a much better and safer situation, less risky. To that extent, I feel we can conduct this EVA safely."

The station normally is staffed with three crew members, one of which remains inside during spacewalks to monitor station systems and to assist in case of problems that might affect the safety of the astronauts outside. But following the Columbia disaster last year, NASA and the Russian space agency were forced to reduce the station crew size to two until shuttles can resume flights.

Some at NASA initially questioned the wisdom of conducting spacewalks with just two station crew members, but those concerns were resolved last year. For their part, Russian cosmonauts routinely conducted such outings on the old Mir space station.

Video coverage for subscribers only:
   VIDEO: ANNOUNCEMENT OF EARLY END TO SPACEWALK QT
   VIDEO: ANIMATION SHOWS SPACEWALK TO-DO LIST QT
   VIDEO: COMMANDER FOALE DISCUSSES THE SPACEWALK QT
   VIDEO: SPACEWALK PREVIEW NEWS CONFERENCE QT
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