CAPE CANAVERAL, Fla. (AP) -- The cabin pressure aboard the international space station dropped again Friday as the crew ruled out a Russian-made air purifier as the possible cause of the mystery leak.
Cosmonaut Alexander Kaleri found the carbon-dioxide removal unit to be airtight, and the search for the culprit widened. Flight controllers in the United States and Russia planned to have Kaleri and astronaut Michael Foale close the hatches on compartments one at a time beginning this weekend.
Mission Control stressed that even though the pressure was now down to 14 pounds per square inch, it was still safe for the crew and station operations. However, some pieces of equipment can begin to fail at 13.9.
The normal air pressure aboard the space station is 14.7 pounds per square inch, a level not seen since before Christmas. Flight controllers zeroed in on the air purifier earlier this week as the possible source of the problem.
If no leak is found this weekend, the space station will be replenished with nitrogen Monday, bringing the pressure to 14.3 pounds per square inch, Mission Control said. Then on Wednesday, the American side of the complex will be sealed off from the Russian side to pinpoint the source of the drop in pressure. The two sides would remained barricaded for four or five days, a major inconvenience.
Space station managers are going through the list of equipment that is susceptible to falling pressure, Mission Control said. The main item in question is a monitor for air contaminants that is certified for use only above 13.9 pounds per square inch.
In emphasizing the lack of immediate danger, NASA noted that the current level of 14 pounds per square inch is equivalent to the atmospheric pressure in Oklahoma City. There are plenty of places on Earth where people live with much lower air pressure, a Mission Control commentator said, citing Las Vegas at 13.6, Denver at just over 12, and Mexico City at less than 12.
Nevertheless, Mission Control offered up sympathy to the spacemen and commended them for their hard work and patience in tracking the pressure and other problems over the past week.
``Mike, I don't know if you remember the TV show `McGuyver,' but that was the guy who could take a couple of paper clips, a dry eraser and a pipe wrench and build an airplane out of it. Well, you guys are like McGuyvers to us now,'' Mission Control said.
``I'll explain that to Alexander because he's the McGuyver one,'' Foale replied. ``He hasn't built a spacecraft out of a paper clip -- yet.''
Foale, the commander, and Kaleri are supposed to remain on board until the end of April. They arrived in October as the eighth set of full-time residents.
NASA has reduced the number of space station residents from three to two for the foreseeable future because of the grounding of the shuttle fleet in the wake of the Columbia disaster.
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