ROSAT (satellite)- likely to impact within the next several hours

ROSAT has lost 10 miles (16 KM) altitude in the past five hours.   At the point it enters the atmosphere, it will begin to free fall (~75 miles)  Scientists expect 30 pieces to survive re-entry and debris will be spread over 50 miles.

http://www.spaceflight101.com/rosat-re-entry-information.html