COLLIDING SATELLITES: Experts are calling it an "unprecedented event." Two large satellites have collided in Earth orbit. Kosmos 2251 crashed into Iridium 33 on Tuesday, Feb. 10th, approximately 800 km over northern Siberia; both were destroyed. The resulting clouds of debris contain more than 500 fragments, significantly increasing the orbital debris population at altitudes where the collision occurred. The Air Force Space Surveillance Radar is monitoring the clouds as they pass over the radar facility in Texas. We, in turn, are monitoring signals from the radar and you may be able to hear debris "pings" by tuning in to our live audio feed. This is a story that will unfold in the days ahead as researchers study the evolution of the debris clouds and piece together the details of the collision. Stay tuned to http://spaceweather.com for full coverage.