Russians Discount Threat of Drop in Space Station Air Pressure

American and Russian astronauts on the orbiting International Space Station were unable Tuesday to determine the cause of a slow, steady drop in air pressure, but the problem poses no threat to their safety, Russian officials said.

“There are dozens of different gaskets, collars and seals on the International Space Station, some of which run through the spacecraft skin, so it is quite possible that some of these gaskets or seals are leaking,” said Sergei Gorbunov, spokesman for the Russian Aviation and Space Agency. “But in any case no one is panicking and no one should be panicking. It is yet another working situation in space and there is nothing horrible about it.”

U.S. Mission Control first noticed the drop in pressure Thursday, and informed astronaut Michael Foale and cosmonaut Alexander Kaleri about it just before their bedtime Monday, assuring them that no immediate action on their part was required, NASA said.

The men checked valves leading to the vacuum of space, but as of Tuesday evening, they had not found the presumed leak, Russian space officials said. Foale said the valves on the U.S. side of the space station checked out fine.

The still-unfinished station is a $100-billion project of the United States, Russia, Japan, Canada and Europe. NASA said U.S. engineers have determined that the leak began Dec. 22.

“Experts believe that the air pressure drop in the station might have been caused by a faulty valve or a leak at the junction of the Russian cargo ship docked to the complex, therefore the crew has to do enormous work to check hundreds of valves and sensors,” said Pavel Vinogradov, an executive of Energia Rocket & Space Corp., the main manufacturer of Russian spacecraft.

He told Russian news agency Itar-Tass that similar problems had occurred several times on Russia’s Mir space station but were dealt with successfully.

Despite the extra workload, communications sessions between the astronauts and their families planned for today -- Orthodox Christmas -- will proceed as scheduled, state-run Russian television reported.

Alexander Lazutkin, a veteran cosmonaut, also was reassuring in comments on state-run television.

“Both the crew and the specialists are ready for something like this,” he said. “The pressure drop has not been that dramatic. It is not happening so fast that it is time to cry, ‘Help! Run for your lives!’ ”

Russian officials gave conflicting reports Tuesday on the air pressure level, but placed it in a range of 715 millimeters to 750 millimeters of mercury. Reports from NASA and the Russians placed the pressure loss since Thursday at slightly less than 2 millimeters per day. The safe pressure range is considered 610 to 880 millimeters, Vinogradov said.

Gorbunov said it is also possible that there is no leak and pressure gauges have given inaccurate readings.

According to standing instructions, the astronauts would be required to evacuate the station in their Soyuz escape craft if the pressure fell to 550 millimeters, said Igor A. Marinin, editor in chief of Novosti Kosmonavtiki magazine, Russia’s leading space journal.

He noted at the current rate it would take about three months to reach that level, but added that delivery of more oxygen is scheduled this month. It would be possible to deliver enough oxygen to operate the station permanently with continuous pressure loss of this scale, so “it is clear that the situation is far from being critical,” he said.

“What is happening today is nothing compared to the problems that Russian cosmonauts had to face in the past,” Marinin said. “The only problem is that on the International Space Station such a situation has emerged for the first time, hence, this great attention to the issue.”

Marinin added that in his view “the most significant factor here is the Americans -- they tend to make a sensation out of anything, really.”

“They even told the crew about the leak just when the astronauts were about to go to sleep. That was a very non-Russian thing to do -- the Russians would never do anything like this to a Russian cosmonaut,” he said.

Gorbunov, the Russian space agency spokesman, said that “some people on the American side are stirring up all this -- I hate to say it -- panic.”

He attributed the U.S. sensitivity to the February breakup of the space shuttle Columbia and the deaths of its crew.

“These people must have obviously not gotten over the Columbia shuttle accident yet,” he said. “They must be thinking that the shuttle perished because someone had not reported something he was supposed to report. So, the logic is, ‘Let’s report every single thing, no matter how insignificant and petty it is.’ ”

Marinin also said U.S. space officials were overreacting but offered a different explanation: “In our opinion, NASA uses every opportunity that presents itself to draw public attention to itself and its space programs. Sensations like this reflect NASA’s know-how of making sure it gets its share of the U.S. budget pie.... Sensations like this keep the interest of Congress and the U.S. public in space programs hot.”

Both Gorbunov and Marinin said they are sure that the leak, if one exists, was not caused by an incident in November when a tiny object may have hit the space station, causing a metallic noise.

On Nov. 26, station Commander Foale reported hearing a sound like a crunching tin can or flexing sheet metal coming from the rear of the module that serves as living quarters.

The noise raised concerns that the ship may have been hit by a meteoroid or a piece of space junk.

Alexei V. Kuznetsov of The Times’ Moscow Bureau contributed to this report.