International Space Station has close shave with space debris

Our perception of space as a vast expanse of emptiness is changing, especially the region near to our planet. With several satellites currently in orbit around the earth, accompanied by the remnants of even a larger number of inactive ones, space is gradually becoming a global junkyard.

Orbital debris has become a major problem for space-faring nations. Scientists estimate that there are tens of millions of pieces in orbit, including more than 17,000 bigger than a grapefruit. (See: The great junkyard in outer space)

The danger of this debris was brought perilously close yesterday as a dangerous chunk of debris bore down on the $100-billion International Space Station (ISS) forcing the three-member crew comprising of Commander Michael Fincke, Flight Engineer Yury Lonchakov, and Flight Engineer Sandra Magnu to take temporary refuge in the attached Soyuz capsule lifeboat.

If the 5-inch piece of a spent rocket motor were to hit when the crew were in the main part of the space station, they would have had only 10 minutes of safety, mission NASA control told them. A hole in the space station could mean loss of air, loss of pressure and eventual loss of life.

The crew 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." Matney, who has been with NASA since 1992, said it was the closest call he could remember.

The debris missed. Engineers still don't even know by how much and may never get a good figure. It could have been a few hundred feet or a couple miles. Ten minutes later, with the danger over, the crew returned to the space station.

Soyuz has been used for shelter at least five times in the past, NASA spokesman Josh Byerly said. And the crew may have to use it again soon because this orbiting hazard could return. "It's still crossing the station orbit, so there's a probability that it could threaten the station in the future," said Gene Stansbery, programme manager for NASA's orbital debris office in Houston.

NASA officials said that the piece of space junk came from an upper-stage rocket that helped launch a US military global positioning satellite in 1993. They described it as a "portion of a spent satellite motor."

Stansbery added that NASA had so little warning that the space junk was approaching because it moves in an unusual orbit, ranging from 89 miles above Earth to almost 2,500 miles. Each time it whips through the fringes of Earth's atmosphere, it slows somewhat, making it hard to track.

The trash is even worse in the orbit of the Hubble Space Telescope. The February satellite crash increased the risk of junk hitting the space shuttle when it repairs Hubble. NASA is still calculating whether it's safe enough to do the repairs later this year.

Smaller space debris often falls into lower orbit and eventually burns up as it returns to Earth. But David Wright, a physicist with the Union of Concerned Scientists, said, "some of the big things will be up there for centuries and those are the ones that can really wreak havoc."

The problems of space junk hit world headlines earlier this year when a working communications satellite collided with a defunct Russian satellite, destroying both of them. (See: Space crash destroys Iridium-owned satellite)