ROSAT, an x-ray telescope, finished its mission on Feb. 12, 1999 and ran out of fuel thereafter. Since then, it has slowly been descending toward Earth.
The German Aerospace Center estimated it would crash anywhere between Oct. 21 and the 25, but are uncertain of the estimate since the orbit could widen that range.
The agency also predicted that parts of the telescope would survive re-entry into the Earth’s atmosphere with pieces as heavy as 880 pounds. However, the largest piece to survive the fall will be the telescope’s mirror, the agency said.
Areas under ROSAT’s orbit could be affected, extending to 53 degrees northern and southern latitude, said the agency.