A 40-ton Soviet space station the size of a railroad freight car tumbled into the Earth's atmosphere over Argentina before dawn Thursday and "burned out of existence," the official news agency Tass said.

There were no reports of any debris hitting the ground.Tass said Salyut-7 and an attached spacecraft re-entered the atmosphere over a sparsely populated area of central Argentina at 12:47 a.m. local time (8:47 p.m. MST Wednesday).

The U.S. Space Command in Colorado Springs, Colo., said the spacecraft was traveling about 17,000 mph at re-entry.

Salyut-7 was put into orbit in April 1982. Tass said it should have stayed in orbit for several more years but a sudden increase in solar activity in 1988 caused it to descend sharply.

Soviet officials said the space station, powered by solar energy and chemical batteries, contained no nuclear fuel or other dangerous substances.