The Shuttle Gets a Go

Flotsam and jetsam in Earth orbit, most of it the residue from old satellite explosions, is so profuse that former astronaut John Glenn, on observing the sun glinting off the pieces, once likened it to flying through a cloud of lightning bugs. But given NASA's heightened safety awareness since the 2003 loss of Space Shuttle Columbia, one piece of debris — caught on video and measuring just 2 inches by 5 inches — was enough to cause another high-profile hitch in a series of operational setbacks for Space Shuttle Atlantis.

NASA on Wednesday cleared Atlantis to land in Florida at 6:21 a.m. Thursday — one day late — after astronauts performed two extra inspections of the shuttle's critical heat shield using a camera mounted atop the craft's 100-foot robotic arm and boom. No damage was found.

The piece of junk trailing the shuttle, and several others seen floating by the shuttle's windows, might never be definitively identified. Astronauts described the objects variously as a plastic baggie, some copper wire, two ring-shaped items and a piece of foil or shimmering cloth. NASA is guessing the largest bit was a piece of pliable plastic used as a tile shim, which could have dropped off the shuttle during a test firing of the shuttle's maneuvering jets.

NASA officials say similar space junk has probably followed previous shuttles home, unnoticed and unscrutinized. But on a mission whose departure was beset by a fuel cell malfunction, a lightning strike on the launch pad and an approaching hurricane, the delay caused by the debris threatened to mar what has otherwise been a successful mission. After a four-year delay following the destruction of Space Shuttle Columbia, astronauts have finally resumed the construction of the International Space Station, installing 35,000 pounds of solar arrays and trusses. Fourteen more missions are needed to finish the job by 2010, when the shuttle will be retired.

"With each of these missions that are coming up, you're going to see more of the same awe-inspiring activities. And surrounding those awe-inspiring activities are going to be a lot of tedium and detail," says Elliot Pulham, CEO of the Space Foundation. "There's a lot of tedium and detail in this and I think we're just seeing a lot more of it than we have in the past." With tens of millions of bits of space junk orbiting Earth — including 11,000 larger than 10 centimeters in size — more such encounters with the shuttle are hardly out of the question. Occasionally in the past, the shuttle has had to dodge a significant piece heading its way. Although most of the junk eventually burns up in the atmosphere, an average of one piece of space debris a day actually makes it back for a landing on Earth.