Arecibo Observatory

Artist's impression of a signal being received at the Arecibo Observatory

This would have just been the pic-of-the-day, but then I found that Arecibo Observatory has just gotten a big fat grant to go looking for possibly troublesome asteroids.

Map showing estimated path of incoming asteroid

Meanwhile, the University of Hawaii has an asteroid detection program. One recently detected asteroid actually came to visit and was also picked by an infrasound detector at Arecibo. This asteroid was only about 4 meters in diameter, so would probably have burned up before it hit the ground.