A U.S. mobile communications satellite has collided with a non-operational Russian communications relay station creating a cloud of orbiting debris, according to the U.S. space agency NASA.

One of nearly 100 satellites that support Iridium Satellite LLC's satellite telephone operation collided Tuesday with the Cosmos 2251 491 miles above northern Siberia, said Nicholas Johnson, NASA's chief scientist for orbital debris at the Johnson Space Center in Houston, according to CBS News. The cause of the collision, the first by two big objects, was unknown, according to Johnson.

The U.S. Strategic Command, the agency responsible for space surveillance, initially detected some 600 pieces of debris caused by the collision of the 1,485-pound Iridium satellite launched in 1997 and less than one ton Russian craft sent into orbit in 1993.

Iridium admitted that its satellite was disabled but assured that its service will not be disrupted as other satellites will take over the function of the lost craft.

Johnson said the International Space Station, which is in a lower orbit at 220 miles above Earth, is not immediately in danger of getting hit by any debris from the collision. NASA will also check if the debris pose danger to its space shuttle scheduled to fly on Feb. 22 with seven astronauts aboard.

He said other debris will be tracked to determine its threat to other satellites while pieces that will fall to Earth will disintegrate in the atmosphere.