Of a pair of satellites?

Of a pair of nuclear subs?

http://www.guardian.co.uk/uk/2009/feb/16/nuclear-submarines-collision-investigation

http://www.aviationweek.com/aw/generic/story_generic.jsp?channel=awst&id=news/aw021609p2.xml&headline=Orbital%20Collision%20Won%27t%20Be%20The%20Last