NASA's best bet is that the space junk landed in the Pacific Ocean sometime between 11.23pm on Friday and 1.09am on Saturday morning, Eastern Standard Time. UARS circled the earth diagonally, starting on the east coast of Africa, before passing over the Indian Ocean, the Pacific Ocean, Canada and then West Africa. NASA said the descent was mostly over water.

It was originally predicted that the satellite could land anywhere between 57° south latitude and 57° degrees north latitude, or, put simply - the entire populated world. An estimated 26 pieces of debris would have survived re-entry into the atmosphere, with the largest estimated to weigh around 150 kilograms. But the odds of a segment hitting just one person in the world were about 1-in-3,200.

The satellite, known as The Upper Atmosphere Research Satellite, or UARS, was launched in 1991 to track climate change and completed its mission in 2005. Ever since, it's floated in space - gradually losing altitude.

A piece of space junk the size of UARS hits the Earth about once a year, with 20,000 pieces currently in orbit. In 1979, NASA's 68 tonne Skylab station crashed into Western Australia, and the Russians guided one of their 122 tonne satellites into the Pacific Ocean in 2001.