Astronauts on Their Way to Set Spacewalk Record

CAPE CANAVERAL, Florida -- Small amounts of toxic ammonia leaked from a fluid line on Sunday as two astronauts conducted the second of what could be a precedent-setting three spacewalks in nine days, upgrading the international space station's cooling system.

The ammonia flakes did not appear to make contact with Michael Lopez-Alegria or Sunita Williams. Mission Control told the astronauts to continue their task of hooking up ammonia fluid lines from a temporary cooling system to a permanent one.

The astronauts looked over their spacesuits, gloves and helmets and found no ammonia residue. "I think we're happy with what we see," Lopez-Alegria said.

Mission Control told the astronauts to expose their spacesuits to the sunlight in an effort to "bake off" any ammonia residue that may have gotten on them. The astronauts experience a sunrise every 1 1/2 hours.

A leak occurred during a similar spacewalk by astronaut Robert Curbeam in 2001. During Lopez-Alegria and Williams' first spacewalk together Wednesday, four or five flakes of ammonia fell from a cooling line cap but did not touch the astronauts.

Nevertheless, Mission Control ordered the astronauts to take precautions against contamination since ammonia could cause respiratory problems for the three-person crew if enough of it got in the space station.

"They look like pinpoints," Lopez-Alegria told Mission Control on Sunday. "They don't look like what we saw the other day, but they are coming out with some velocity."

Lopez-Alegria and Williams planned to complete almost identical tasks to ones they did during their spacewalk Wednesday, hooking up the permanent cooling system and covering up an obsolete radiator.

The third spacewalk is set for Thursday, marking the first time three spacewalks will have been conducted in such a short time at the space station without a space shuttle docked to it. Lopez-Alegria plans to conduct a fourth spacewalk with Russian flight engineer Mikhail Tyurin on Feb. 22.

If the schedule stays in place, both U.S. astronauts would hold spacewalking records by the end of the month. Williams will hold the record for the most by a woman, and Lopez-Alegria will be the U.S. champion, surpassed only by Russian cosmonaut Anatoly Solovyov for the all-time record.