Two crewmen aboard the International Space Station on Thursday prepared for a spacewalk during which more than 730 kg (1600 pounds) of obsolete gear will be tossed overboard and left to burn up in Earth's atmosphere...
Their tasks include jettisoning a refrigerator-sized device containing ammonia that was part of the station's first cooling system. NASA upgraded the station's power and cooling systems and no longer needs the 635-kg (1400-pound) tank...
The discarded equipment is expected to remain in space for at least 300 days before friction from the atmosphere drags them down towards Earth.
The camera stand is expected to burn up completely, but chunks of the ammonia tank as heavy as 17.5 kg (39 pounds) could survive re-entry and fall to Earth.
NASA said that while the debris is most likely to land in an ocean, there is about a 1 in 5000 chance it will hit a populated area.
The agency said tracking radars will follow the objects until they are about two hours away from atmospheric re-entry. Warnings would be issued if the debris seems likely to pose a threat.