Space junk puts a scare into NASA, station crew

More close calls considered likely

WASHINGTON – A near miss of space junk yesterday was a warning shot fired across the bow of the International Space Station, experts said, and more are likely to come.

With less than an hour's notice, the three astronauts were told that they would have to seek shelter in a Russian capsule parked at the space station in case a speeding piece of space junk hit.

If it hit and they were in the main part of the station, they would have only 10 minutes of safety, Mission Control told them. A hole in the space station could mean loss of air, loss of pressure and eventual loss of life.

The crew members moved so fast that they may have left their instruction manual on the other side of a closed hatch. Inside the Soyuz, they waited for 10 minutes, ready to flee to Earth if the worst happened. On the ground, space-debris experts fretted.

“We were watching it with bated breath,” NASA space-debris scientist Mark Matney said. “We didn't know what was going to happen.”

The debris missed. Engineers still don't know by how much, and they may never get a good figure. It could have been a few hundred feet or a couple of miles.

In space, Cmdr. Mike Fincke said they watched out the Soyuz window.

“We didn't see anything, of course. We were wondering how close we were,” he radioed Houston.

Matney, who has been with NASA since 1992, called it the closest call he can remember.

It happened a month after two satellites collided in orbit, adding several hundred pieces to the space-litter belt. In the past few years, the problem of debris in space has gotten much worse with satellites destroyed on purpose.

“It's yet another warning shot that we really have to do something about space debris now. We have to do something on an international level,” said Harvard astrophysicist Jonathan McDowell, who tracks everything in orbit.

“As we continue to put stuff up there, the predictions are that the rate (of close calls) will increase,” added William Ailor, director of the Center for Orbital and Reentry Debris Studies at the Aerospace Corp. in El Segundo.

The U.S. Space Command tracks 13,943 orbiting objects 4 inches or larger. Only about 900 of those are working satellites, McDowell said. The rest is litter. There are thousands more smaller pieces of junk that can't be tracked as easily.

In space, size doesn't matter much after about 3 or 4 inches. Speed does. The object that put the scare into the space station was probably 5 inches, Matney said. McDowell figures it was bigger, maybe a foot: “a long, thin thing” with a thread or string attached.

It was traveling 5½ miles per second – about 20,000 mph, NASA spokesman Josh Byerly said.

At that speed, a 5-inch object “will wreck your whole day,” Matney said.

The object probably was a “yo weight” used to stabilize a Global Positioning System satellite placed in orbit in 1993, McDowell and Matney said. It's ejected when the satellite reaches its proper position.

Usually with enough warning, NASA will move the space station out of harm's way. But NASA didn't learn of the threat until Wednesday night. This piece was in an odd orbit that kept dipping into Earth's atmosphere, making it hard to track, Matney said.

NASA didn't notify the astronauts until a couple of hours after they woke yesterday because they wanted to get more information about the debris, NASA spokesman Kyle Herring said.

The space station and space shuttle have been hit by debris in the past. So far, the only holes have been in the station's solar panels and in the shuttle radiator, neither of them dangerous, McDowell said.

“It just needs to hit at exactly the wrong place and then you have a problem,” he said.

Separately, NASA said yesterday that it's replacing some space-shuttle connections in hopes of plugging a gas leak and launching Discovery to the space station Sunday, after delays of more than a month.

Discovery was supposed to blast off Wednesday night with a crew of seven and one final set of solar wings for the station. But hydrogen gas began leaking as the shuttle was being fueled, and NASA called everything off.

The leak occurred near the line that vents hydrogen gas out of the external fuel tank. Yesterday, workers were removing the quick-disconnect unit at that location and a pair of seals, and planned to replace the parts today.

NASA spokesman Allard Beutel said shuttle managers have “high confidence” that all repair work can be done in time to launch Discovery on Sunday night. That would lead to a slightly shorter mission in order to make way at the space station for a Russian Soyuz spacecraft scheduled for liftoff March 26.

The Soyuz is a higher-priority mission. It will deliver a fresh crew to the station.

If Discovery is launched Sunday, its mission will be reduced to 13 days from 14, and there will be three spacewalks instead of the planned four, Beutel said.

Because of the impending Soyuz mission, Discovery must be flying by Tuesday. Otherwise, the shuttle will have to wait until April.

Liftoff originally was targeted for mid-February, but NASA kept delaying the flight because of concern over hydrogen gas valves in Discovery's engine compartment. Extra tests were ordered to ensure that the three valves in Discovery were safe to fly and wouldn't break like one did during the last shuttle launch in November.