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The Associated Press September 26, 2006

Cosmic Debris -- Littering Heavens Are Old Satellites, Loose Glove, Ham Sandwich

The next time you're looking skyward, pointing out a shooting star during a romantic moment, look again. What you're about to make a wish upon might not be a celestial body at all. It could very well be garbage.

Yep, outer space is filled with the detritus of spaceflight, be it a spent booster rocket, an orbiting satellite or a bolt dropped by a spacewalker. The shuttle Atlantis' return to Earth was delayed a day so astronauts could determine whether several mysterious objects found floating nearby did any damage to the orbiter. After an exhaustive inspection, NASA gave the crew the all-clear on Wednesday.

Details

How much? There are nearly 10,000 trackable objects (those at least the size of a softball) floating around in that great dumping ground we call space, according to the space control center at Air Force Space Command.

Small but dangerous: There are also an estimated 100,000 smaller items that can't be seen by radar and telescopes - items as small as a fleck of paint that can scratch the window of the shuttle. At 15,000 mph, even the tiniest piece of dirt can do some damage.

NASA program: Space debris poses enough concern to scientists that NASA has an office dedicated to the topic: the NASA Orbital Debris Program Office. It defines space junk as "any man-made object in orbit about the Earth which no longer serves a useful purpose."

And as Mark Matney, a NASA scientist, bluntly puts it, "Every spacecraft is destined to become debris."

How it got there

Why is there so much junk circling our home when the first man- made object to orbit Earth was launched less than 50 years ago?

It's not litter: Despite the highly publicized dropping of two bolts into the void last week during extra vehicular activity, very little space debris is the fault of messy astronauts, says John Pike, director of GlobalSecurity.org, an intelligence Web site.

Rocket waste: The bulk of the mess is from launches. Debris is created when a spacecraft separates from its booster rockets and when a rocket explodes into hundreds of fragments.

Satellites: A defunct satellite is debris, too. And there are about 2,000 inert satellites - compared with 819 active ones - orbiting the Earth, according to the Union of Concerned Scientists.

Shooting stars? "If you were to go out in the early evening or early pre-dawn morning and look up in the sky, of the fast moving objects that you see, maybe half of them are going to be active satellites, and maybe half of them are going to be derelict satellites," Pike says. "Those will be the largest pieces of space debris."

Slippery fingers

Oops: Astronauts have left a wide variety of items in space, mostly by accident.

The first spacewalker, Ed White, dropped a spare glove. That was in 1965. Last July, Piers Sellers dropped a spatula. "Spatsat" should fall into the atmosphere and burn up sometime next month.

Pike says a ham sandwich was once lost in space.

On purpose: Matney says NASA purposely released a space suit (SuitSat) this year for research purposes, and it re-entered the Earth's atmosphere on Sept. 2. And Russian cosmonauts living on the space station Mir used to toss their trash bags overboard.

What happens

Burn up: Objects in lower orbits, a couple of hundred miles above Earth, will likely burn up in a short time because of atmospheric drag, Pike says. The bolts lost by the Atlantis crew this week will probably last six months, Matney says.

Hang around: But objects at higher orbits, in the 1,000-mile range and up, could float friction-free for hundreds of years.

Cleaning up

Pack in, pack out: It's been U.S. policy since 1988 to minimize the amount of junk put in space. Russia, Japan, France and the European Space Agency have similar policies as well. One thing these countries have agreed to do, Pike says, is to design upper-stage rockets that vent their residual fuel, which keeps them from exploding.


Copyright 2006,The Associated Press