A tool bag lost by a spacewalking astronaut last year met its fiery demise in Earth's atmosphere Monday after months circling ever closer to the planet.

The $100,000 tool bag plunged toward Earth and burned up as it re-entered the atmosphere, according to the U.S. Air Force's Joint Space Operations Center tracking it and more than 19,000 other pieces of space junk in orbit today from Vandenberg Air Force Base in California.

"Based on its size and composition, we expect the object to completely burn up before hitting the Earth," center officials said in a statement.

The tool bag was lost during a Nov. 18 spacewalk at the International Space Station. In addition to the Joint Operations Space Center, amateur skywatchers also tracked the bag as it silently circled the Earth.

Center officials did not immediately have a specific time and location for the tool bag's ultimate demise, but a Sunday report by the Web site Universe Today predicted the wayward space satchel would hit the Earth's atmosphere at about 9:16 a.m. EDT (1316 GMT) over the Pacific Ocean, just west of Mexico.

Lost in space

The tool bag weighed about 30 pounds (14 kg) and was about the size of a small backpack. It contained grease guns, trash bags and a scraper tool.

Former NASA astronaut Heidemarie Stefanyshyn-Piper lost the bag during a November spacewalk to repair a balky solar array joint on the International Space Station as part of NASA's STS-126 shuttle mission. A grease gun leaked inside the bag, which apparently wasn't secured properly, and it drifted free while Stefanyshyn-Piper was trying to clean up the mess.

"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," Stefanyshyn-Piper said in a televised Nov. 19 interview from space the day after losing the bag. "So the best thing to do was just to let it go."

Stefanyshyn-Piper, an active captain in the U.S. Navy, retired from NASA's astronaut corps last month to return to her Navy duties.

A look at junk in space

Space debris, in general, has been a growing concern for NASA and other spaceflight operators due to the unprecedented crash of a Russian and American satellite earlier this year. The Feb. 10 smashup in space created two new large clouds of debris that have been continuously tracked by the Department of Defense's Space Surveillance Network.

The network is currently tracking more than 19,000 pieces of space junk larger than four inches (10 cm) across, but an estimated 300,000 total objects bigger than a half-inch (1 cm) are thought to be in Earth orbit today, space debris officials have said.

Stefanyshyn-Piper's bag and other tools lost by astronauts in the past have typically posed little risk of coming back and hitting spacecraft in orbit. The tool bag, for example, circled Earth for more than eight months before finally destroying itself in Earth's atmosphere.

If a piece of space debris is expected to come close to satellites or manned spacecraft like NASA's shuttles or the International Space Station, the vehicles can be moved ahead of time given enough advanced notice.

The space station's most recent brush with a piece of space junk came on July 17, just hours after the space shuttle Endeavour arrived with a crew of seven astronauts during NASA's STS-127 mission. Astronauts fired Endeavour's thrusters to nudge the space station and move it clear of a piece of orbital debris that would have come within its safety perimeter, NASA officials said.

Endeavour's seven-astronaut crew landed in Florida Friday to end a successful 16-day mission that replaced a member of the station's crew, as well as delivered a new experiment porch and spare parts for the orbiting laboratory.

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