Heads Up! Space Station Trash To Plunge To Earth Sunday

The National Aeronautics and Space Administration and the US Space Surveillance Network are tracking a 1,400-pound tank of toxic ammonia coolant jettisoned over a year ago from the International Space Station. During the last year, the ammonia tank's orbit has slowly degraded due to gravity and atmospheric drag.

Expected to re-enter Earth's atmosphere Sunday afternoon or evening, the exact location where the refrigerator-sized tank will land remains unknown. In a recent interview, NASA space station program manager Mike Suffredini said, "This has got a very low likelihood that anybody will be impacted by it. But still, it is a large object and pieces will enter and we just need to be cautious."

NASA expects as many as 15 pieces of the tank to survive the intense heat of re-entry, ranging in size from about 1.4 ounces to nearly 40 pounds, according to MSNBC. The largest piece of orbital trash ever tossed overboard, the Early Ammonia Servicer coolant tank was discarded by NASA astronaut Clayton Anderson during a July 23, 2007 spacewalk. An unneeded 212-pound video camera stand was jettisoned at the same time, burning up harmlessly in its descent through the atmosphere earlier this year, Suffredini said. The tank was originally used as a coolant reservoir, boosting the Space Station's cooling system in the event of leaks. Last year's upgrades to the station made the tank obsolete, but engineers were doubtful it could withstand a ride back to Earth aboard a NASA space shuttle. "As a matter of course, we don't throw things overboard haphazardly," Suffredini said. "We have a policy that has certain criteria we have to meet before you can throw something overboard."

While astronauts have accidentally lost a tool or two during spacewalks, the planned jettison of larger items is done with the utmost care to ensure the trash doesn't hit the station or any other spacecraft as it circles the Earth, Suffredini said. Engineers also make sure the risk to people on Earth is low.

Should re-entry occur over land, NASA advises that the public should contact local authorities, or the US Department of State via diplomatic channels if outside of the US, if they believe they've found the remains of the tank.