Abandoned 6-ton Upper Atmosphere Research Satellite (UARS) entered the earth's atmosphere early on Saturday and crashed in the North Pacific Ocean, the Californian Joint Space Operations Center said.
On Friday, officials predicted the satellite would be passing over Canada, Africa and Australia, and vast areas of the Pacific, Atlantic and Indian oceans.
The UARS was the biggest piece of U.S. space junk to fall in 30 years. NASA stressed there was a "very remote" risk to the public from the 26 fragments of the UARS which were expected to survive the fiery re-entry into the atmosphere.
NASA said it was still trying to determine the precise re-entry time and location. Unconfirmed reports on Twitter suggested some of the debris may have fallen near a town south of Calgary in western Canada.