Travelling at more than 17,000 miles an hour, the Upper Atmosphere Research Satellite is barreling toward Earth.
The 20-year-old research satellite will break into several pieces and there's little risk anyone would get hit with debris.
NASA scientists say the satellite will break apart upon entering the Earth's atmosphere, and 26 pieces, ranging from 1 pound to about 350 pounds, will rain down on Earth sometime between Thursday and Saturday.
The pieces are expected to cover an area 500 miles long.
"Once it hits a critical point, it will drop out of the sky, and we really won't know that until a few hours before it hits," said Dr. Patricia Reiff, director of Rice Space Institute.
Scientists said they'll have a better idea as to where it will hit about two hours before impact.
If you do come across what you suspect is a satellite piece, NASA doesn't want you to pick it up, because there could be sharp edges. Also, it's government property. It's against the law to keep it as a souvenir or sell it. NASA's advice is to report it to the police.
The Associated Press contributed to this report.