Space debris in near-Earth orbit

Debris: Cosmos 2251

Fragments of the derelict Russian satellite Cosmos 2251, which collided with Iridium 33 in February 2009 - the first accidental collision of two intact satellites

On 10 February 2009 the derelict Russian communications satellite Cosmos 2251 collided with the working Iridium 33 at about 790 km - the first accidental collision of two intact satellites, and the event that turned orbital debris from a projection into a thing that had happened. Cosmos 2251 was the heavier of the two and left the larger cloud.

Further reading: orbitaldebris.jsc.nasa.gov