The first high-speed collision of large, intact spacecraft occured yesterday:
Two big communications satellites collided in the first-ever crash of its kind in orbit, shooting out a pair of massive debris clouds and posing a slight risk to the international space station. NASA said it will take weeks to determine the full magnitude of the crash, which occurred nearly 500 miles over Siberia on Tuesday.
the explosion resulting from the energy of impact would have been about the same as detonating 5 tons of TNT.
That’s a lot. It’s easily enough to totally destroy both satellites, and in fact the U.S. Space Surveillance Network has detected a substantial amount of debris, at least 600 pieces.
At the moment, that debris is expanding in a cloud, and is still too high to threaten the space station which orbits at less than half the height where the satellites collided… but eventually the debris will pass through the altitude of the ISS. It’s not clear yet how much danger the station is in. Satellites in similar orbits as the two that hit are in the most immediate danger, but again it’s unclear what will happen.
You'll be relieved to know that despite Mr. Plait's concerns (above quotation), the risk to the space station (with three astronauts aboard) is believed to be low, and that the collision is not thought to present a danger to the space shuttle set to launch February 22 with seven astronauts.
But it's been predicted for years that such a collision was inevitable. Worse, scientists have been worried about the cascade effect of space debris and space collisions: more debris means more collisions, and more collisions mean more debris ... you get the idea. Check out this site for illustrations of the space debris problem and more detailed information on just how much junk is out there.
Too much debris makes space exploration riskier and riskier, and even threatens satellite communications. Mitigation measures have been proposed (see above link); without them, conditions in space will only worsen in regard to collisions and space junk.
That was one hell of an explosion, and I hope there's some follow-up in the news at some point as to just how much debris was generated and how much of a threat it poses. The world depends a great deal on satellite communications, and seeing the danger of just letting space debris accumulate illustrated in this dramatic way should (should, but may not) cause scientists--and communications companies--to give the matter some serious thought.