BREAKUP
Iridium 33 / Cosmos 2251 collision (February 2009)
Tue Feb 10 2009
The first major accidental satellite collision in history. Active Iridium-33 collided with defunct Cosmos-2251 at 789 km, producing ~2,200 cataloged fragments.
Iridium-33 (operational) and Cosmos-2251 (defunct) collided at a relative velocity of ~11.7 km/s. Both were in nearly polar LEO orbits at 789 km altitude. The event proved that even well-tracked objects could collide, and led directly to today's industry-wide investment in conjunction-screening services.