Astronaut Heidimarie Stefanyshyn-Piper may accidentally have committed the most high-tech act of littering in history. But the Earth's atmosphere has cleaned up after her.
In November, while she was on a spacewalk outside the International Space Station, she accidentally let go of a tool bag. The bag is believed to have burned up harmlessly in the Earth's atmosphere, probably in the last day or two.
It was an expensive little mishap -- the specialized tools in the bag were worth something on the order of $100,000. And Stefanyshyn-Piper conceded that after the bag slipped from her grasp, there was really nothing she could do about it.
"There was that split-second thinking that maybe I can go jump for it and grab it. Then I realized that it would just make everything worse and then we'd have two floating objects -- one of which would be me," she said in an interview from orbit the day after the spacewalk. The better part of valor being discretion, she watched the bag go.
Off it went, slowly drifting away from the station, more than 200 miles out in orbit. Slowed by friction with the minimal amount of air that exists even at that altitude, it gradually descended until it fell from orbit.
The bag -- roughly the size of a kid's school knapsack -- would weigh about 30 pounds on Earth. Spacewalking astronauts normally keep all their equipment tethered, but the half-open bag worked its way loose while Stefanyshyn-Piper was trying to clean up a leaky lubricating gun inside it.
Stefanyshyn-Piper, who visited the station during a flight of the shuttle Endeavour and is now a veteran of two space shuttle flights, has since retired from NASA and returned to the Navy in Washington, where she holds the rank of captain.
The U.S. Air Force tracks 19,000 pieces of space junk that are at least 10 cm (about 4 inches) across. NASA is grateful that there is one less to worry about.
They're not terribly concerned about stuff landing down here, since the atmosphere provides very good protection. But they say they're increasingly worried about stuff up there.
While they don't call it outer space for nothing, the space in low orbit around the Earth is getting crowded. A few times a year, a space shuttle is ordered to fire its thrusters to nudge itself out of the way of a known piece of debris from some previous launch -- and, on occasion, shuttles have come home with minor dents from pieces of debris too small to track.
"A particle as small as a fraction of an inch can disable or disrupt spacecraft operations," said Nicholas Johnson, NASA's chief for orbital debris, in an interview with ABC News.
So far NASA's luck has been pretty good. But two unmanned satellites actually hit each other in February, and both were pulverized. In March, the crew of the Space Station was ordered to take shelter in their Soyuz escape capsule, while a piece from a 15-year-old space probe whizzed by a few miles away.
The chance of a catastrophic accident is considered very small -- but it's a small chance of a really big thing.