American space agency NASA has released more information about the satellite that will crash to Earth by sometime on Friday.
It says most of the Upper Atmosphere Research Satellite (UARS) will disintegrate and burn up as it enters the atmosphere.
But NASA warns more than 20 large chunks, weighing in total 500kg, will survive re-entry and land somewhere on Earth. It says the risk to life from the satellite is 1 in 3200, the BBC reports.
The UARS satellite was deployed in 1991 from the space shuttle Discovery on a mission to study the make-up of Earth's atmosphere, particularly its protective ozone layer.
Nasa has warned members of the public not to touch any pieces of the spacecraft which may survive the re-entry, urging them to contact local law enforcement authorities.