I'm kind of baffled by the concept of radar astronomy. Apparently this is one of two radio telescopes that can do radar astronomy [1], but I'm shocked it works at all since the inverse square law leads to such a falloff in power as distance increases. On the other hand, even radio amateurs can achieve moon bounce, so if you consider the enormity of the dish it makes sense that it can hear the radar bounce from much further away. The wiki says Arecibo was used for mapping rings of Saturn and surface features of Mars. Bonkers.
[1] https://en.wikipedia.org/wiki/Radar_astronomy