What Goes Up Must Come Down

It seems the stuff of science fiction and Hollywood – satellites crashing to Earth – but rather this is the result of years of scientific and commercial ventures in outer space, and the subsequent creation of space junk.

NASA's Upper Atmosphere Research Satellite (UARS) has fallen out of orbit and is falling towards the Earth. NASA has confirmed that UARS is expected to re-enter the Earth's atmosphere on the afternoon of 23 September, Eastern Daylight Time. This re-entry will occur six years after UARS ended its productive scientific life when it ran out of fuel in 2005. In other words, UARS is now uncontrollable space junk.

Most of UARS is expected to break or burn up before reaching the Earth, but scientists have identified 26 separate pieces of the satellite that could survive the fall through the atmosphere, and NASA estimates that debris could therefore fall to Earth over an area 500 miles long. The largest piece of debris is expected to weigh over 150