MOSCOW (AP) - This time, the scare didn't come from Mir's own aging equipment or a crew member's error.
A U.S. satellite zipped by the space station, coming within 500 yards of Mir and forcing its three occupants into an escape capsule because they feared a collision, Russian officials said Tuesday.
In a reversal of roles, American space officials played down the Monday night incident and said the defunct satellite was twice that distance from Mir. "It wasn't anything major. ...This happens every month," said John Lawrence, a spokesman for the U.S. space agency.
Vera Medvedkova, spokeswoman at Russia's Mission Control, said it was the Mir's closest brush with an unrelated spacecraft in its 11 years in orbit. If two airplanes pass at 1,000 yards in U.S. airspace, it is considered a near-miss.
Near-collision or not, the incident provided a reminder of the hazards of space traffic - and the deadly potential of a crash of objects crisscrossing at a sharp angle at 17,500 mph.
"At orbital speed, even a grain of sand carries the impact of a .38-caliber bullet," said James Oberg, an American space engineer who tracks the Russian program closely.
Though Russian officials spoke matter-of-factly about it Tuesday, the rare decision to send the Russian-American crew into the Soyuz capsule as a precaution showed how serious they considered the risk.
"They did the prudent thing," said Oberg, who called satellite's pass-by "closer than usual."
"Had it hit the structure, you're talking about a catastrophic failure (of Mir functions). The shock wave would have hit anything else in there," he said by telephone from Houston.
The Mir already has been dented by one cosmic collision - a June 25 docking exercise in which a cargo craft bashed into the Spektr module.
Still living with the effects of that crash, the crew had barely finished fixing the Mir's cranky main computer Monday night when they were warned that an object was approaching the station.
It was a 370-pound research satellite traveling on a perpendicular orbit - inoperative since shortly after its 1994 launch by the Ballistic Missile Defense Organization, an arm of the U.S. Defense Department. At the Mir's altitude, objects in orbit typically burn up within a year or two.
The U.S. Space Command in Colorado Springs, Colo., had informed NASA of the close approach about 30 hours beforehand, and NASA in turn informed the Russians.
The Russian-American crew spent 30 minutes in the Soyuz until the danger passed, Medvedkova said.
Oberg said the incident illustrated a difference between the U.S. and Russian space programs. The Russians don't maneuver Mir out of the way of approaching objects - especially since distance estimates are inexact. U.S. officials already have decided that the international space station, a much bigger orbiting target, will use thrusters to try to dodge them.
Either way, space officials must be alert to the risks of some 6,000 to 8,000 tracked objects orbiting Earth - anything bigger than the size of a pack of cigarettes. These objects are mostly fragments from payloads and rocket bodies.
The June collision was the worst ever in space, and by far the most serious of a string of accidents plaguing the Mir all year. The aged space station's hapless performance in recent months has raised concerns in the United States about the safety of American astronauts taking part in the collaboration.
But NASA officials on Tuesday defended their decision to send an American replacement astronaut to Mir this month and said it would be unprecedented to call off or change the upcoming mission based on political pressure.
"I'd be surprised at something like that," said Frank Culbertson, manager of NASA's shuttle-Mir program.
The House Science Committee is holding a hearing Thursday to discuss the mission.
During a briefing at the Johnson Space Center in Houston, Culbertson stressed that the Mir is safe for those aboard. Reviews of Russian safety standards have "found them, with some minor exceptions, to be perfectly compatible with U.S. standards," he said.
"I believe they have very strict standards that everybody here is very comfortable with, that meet our standards if not exceed them," Culbertson said. The hazards, he added, are well understood and well-controlled.
The Mir crew was keeping watch Tuesday on the effects of Mir's latest malfunction - a computer breakdown Sunday that led the team to turn off lights in all but two of the Mir's six modules.
The orientation system was still down, forcing the crew to fire thrusters to point the spaceship in the right direction. But the jury-rigged computer was back on line, and most or all systems were expected to return to normal within a day, Medvedkova said.
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