An ammonia tank the size of a refrigerator was tossed by astronaut Clayton Anderson during a spacewalk in July 23, 2007, and it's expected to finally enter the Earth's atmosphere and hit either land or ocean.

The reservoir was used to store any possible leaks that the cooling system of the International Space Station might produce. Upgrades made it obsolete, and it now became one of the largest pieces of space debris orbiting the Earth.

The tank weights 1,400 pounds but it's likely that it will break into several smaller pieces, about 40 pounds in weight, traveling at about 100 miles per hour. "If anybody found a piece of anything on the ground Monday morning, I would hope they wouldn't get too close to it," said Mike Suffredini, space station program manager at NASA. However, he assured people that there is a very low likelihood that anybody will be impacted by the space junk.

NASA tried to avoid adding the tank to the debris that's already orbiting Earth, but without sufficient room on the remaining Space Shuttle missions, the tank could not be returned to Earth.