Most parts of the minivan-sized ROSAT research satellite were predicted to burn up as they hit the Earth's atmosphere at speeds up to 280 mph.
However, up to 30 fragments weighing a total of 1.87 tons could have crashed, the German Aerospace Center said.
Jonathan McDowell of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass., said the satellite appears to have gone down over Southeast Asia. He said two Chinese cities with millions of inhabitants each, Chongqing and Chengdu, had been in the satellite's projected path during its re-entry time.
U.S. military data and calculations indicate that satellite debris must have crashed somewhere east of Sri Lanka over the Indian Ocean, or over the Andaman Sea off the coast of Myanmar, or further inland in Myanmar or as far inland as China, said McDowell.
The satellite entered the atmosphere between 0145 GMT to 0215 GMT Sunday (9:45 p.m. to 10:15 p.m. Saturday EDT) and would have taken 15 minutes or less to hit the ground, the German Aerospace Center said. Hours before the re-entry, the center said the satellite was not expected to land in Europe, Africa or Australia.
The satellite used to circle the planet in about 90 minutes, and it may have traveled several thousand miles during its re-entry, rendering exact predictions of where it crashed difficult.
The Associated Press contributed to this report.