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© Stan Nelson
On April 2nd, ham radio operator Stan Nelson of Roswell, New Mexico, was listening to the radar's signals when the International Space Station and a meteor passed through the beam in quick succession.

The slowly descending tone at the beginning of the soundtrack is the radar's doppler-shifted reflection from the ISS. It sounds like the whistle of a train racing past a stationary bystander. Indeed, the basic physics of the doppler shift is the same in both cases.

The rapidly descending tone near the end of the soundtrack is the radar's doppler-shifted reflection from a meteor. Because meteors travel through space some two to ten times faster than Earth-orbiting spacecraft, their radar reflections are much more sharply doppler shifted.

Click on the dynamic spectrum to listen.

On April 22nd you might hear both kinds of reflections as Lyrid meteors and various Earth-orbiting satellites pass over the radar facility. Tune in!