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An Iridium communications satellite and a defunct Russian communications satellite going at right angles to each other crashed into each other, a first for the worlds' space programs!
So the velocity of impact was halfway between (about) being together in the same orbit in the same direction and velocity, or practically zero and hitting headon at a combined speed of some 50,000 Km/hr. So it was like each one slamming into a brick wall at about 25,000 Km/hr. Needless to say, both the US and Russia are monitoring the debris, hundreds of pieces:
http://www.newsdaily.com/stories/tre51a8ia-us-space-collision/