Space junk threat worries space station

March 12, 2009 12:54:02 PM PDT
The crew of the international space station had a close call with space junk Thursday. The three astronauts briefly took refuge inside a Russian escape capsule before returning inside the space station. Officials were worried that the orbiting outpost might get hit with a small piece of passing space debris. Tiny pieces of debris could cause a fatal loss of air pressure in the station.

"We've cleared," station commander Mike Fincke radioed to Mission Control in Houston as he prepared to go back inside after an 11-minute stay in the capsule.

The debris, part of a mechanism to put a satellite in proper orbit, measured about 5 inches, a size that "will wreck your whole day," said Mark Matney, an orbit debris scientist for NASA.

"We were watching it with bated breath," Matney told The Associated Press. "We didn't know what was going to happen." Matney, who's been with NASA since 1992, said it was the closest call he can remember.

NASA usually tries to move the space station out of the way of space junk, but they got this warning Wednesday night when it was too late to move the station, NASA spokesman Kyle Herring said. Instead, NASA sent the crew to the Soyuz capsule.

A Soyuz capsule is parked at the space station to serve as a lifeboat if needed for the station's residents. The capsule has been used for shelter at least five times in the past, said NASA spokesman Josh Byerly. There was a scare last September, but at the last moment NASA called off using Soyuz because new calculations showed much lower risk.

Thursday's debris was expected to come within the 2.8 mile box of space around the station that makes up NASA's danger zone, Herring said.

"We were looking out the Soyuz window," Fincke radioed to Houston. "We didn't see anything of course. We were wondering how close we were."

Because the U.S. Strategic Command, which monitors space debris, could not get a good enough look at the debris, NASA may never know exactly how close it came, said Byerly. It was traveling 5.5 miles per second - about 20,000 mph, he said.

The debris is likely a small weight followed by a 39-inch string or strand that was used to stabilize a global positioning satellite placed in orbit in May 1993, said Harvard astrophysicist Jonathan McDowell, who tracks all objects in orbit.

One of the reasons NASA got such late warning on the debris is that it is an unusual orbit that keeps dipping into the atmosphere and changing, McDowell said. It was in the worst kind of orbit to track, Matney said.

The GPS satellite went out of daily use in January, McDowell said.

Fincke is one of two Americans living aboard the space station; the third resident is Russian.

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On the Net:

NASA: http://www.nasa.gov

NASA is reporting that the crew has been put inside a Soyuz capsule. A spent motor that helped put a satellite into orbit was passing close the the space station.

The space shuttle Discovery was set to blast off last night for the space station, but a hydrogen leak scrubbed the mission. A Sunday launch had been scheduled by NASA.

Crew members are entering their Soyuz TMA-13 capsule and soft-locking the hatches, in case the debris should affect the space station and they are required to undock. The closure of the hatches ensures the safety of the crew and the ability to quickly depart the station in the unlikely event the debris collided with the station causing a depressurization.

The time of closest approach of the debris to the station is 12:39 p.m. EDT. Once the object is clear of the station, the crew will exit the Soyuz and reopen the hatches.


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