SPACE TRASH: IS A 'JANITOR' NEEDED?

Spent satellites, burned-out rocket boosters, and bits of other space trash create a floating junkyard that could destroy a space shuttle or satellite.

Kumar Ramohalli, a University of Arizona professor of aerospace and mechanical engineering, says he has invented a ''space janitor'' that could clear the space lanes of the most dangerous debris.

The Autonomous Space Processor for Orbital Debris would automatically catch errant satellites or bits of space junk with robot arms, cut off reusable parts like solar panels with a solar-powered torch, and dump the rest in a hopper. When it filled up, the satellite would either be emptied by a space shuttle, dive into the atmosphere and burn up, or splash down in the ocean for recovery. Mr. Ramohalli, formerly of National Aeronautics and Space Administration's (NASA) Jet Propulsion Laboratory, has developed his invention since 1988 with the help of students and a $17,500 annual grant from the Universities Space Research Association Advanced Design Program. He estimates that his satellite would cost up to $5 million to build and $15 million to deploy.

Orbiting trash is no joke for NASA. Officials have estimated there's a 1-in-5 chance the planned space station would be hit by junk if it were launched. Satellites have been hit by debris. Space shuttles have been hit many times by smaller bits, and shuttles Discovery and Atlantis have had to steer around larger pieces.

''It's not a minor issue as far as the space station is concerned,'' says Donald Kessler, senior scientist for orbital-debris research at NASA's Johnson Space Center in Houston. But NASA officials aren't ready to turn to Ramohalli's approach, he says.

NASA and the US military have used radar to catalog about 7,000 objects in orbit that are softball-size or larger. There are many times more objects too small to detect.

Rather than sweep up debris, NASA is concentrating on preventing the buildup of more space trash, Kessler said. The agency is working with other spacefaring nations to ensure that satellites and boosters are programmed to spiral into the atmosphere and burn up harmlessly.

It might be 10 years or so before NASA takes a serious look at retrieving space junk, Kessler says, adding: ''It'll always be nice if some people have done some advanced thinking along those lines.''