We know Arecibo Observatory for its 305-meter (1000-foot) diameter telescope and its appearances in Goldeneye and Contact. Aside from battling Bond villains and driving red diesel Jeeps around the telescope (grousing at the site director about the funding status of projects is optional), several hundred hours a year of telescope time at Arecibo go toward radar studies of asteroids. Tasked to “find asteroids before they find us”, a group of us four planetary radar astronomers at Arecibo (as well as collaborators and colleagues at institutions outside of Puerto Rico) observes asteroids for NASA’s Near-Earth Object Observation program. We study the orbits and surface properties of our rowdy neighbors, near-Earth asteroids.
How do we transmit and receive radio waves using the klystrons and radio receivers at the observatory, and how do we turn these into images of asteroids? Read more on my guest post at the Planetary Society on how planetary radar at Arecibo Observatory works.
Sondy!
Another great post on Arecibo. Back in the day (this was in the late 70’s) Don Campbell was performing reflectivity studies of the surface of Mars. He used another much smaller radio telescope nearby to form an interferometer, in order to disambiguate reflections from the two Martian hemispheres.
These maps of Mars were then printed out on long sheets through the lineprinter. Copies of these were so plentiful that I once used a reflectivity map odf mars to wrap a birthday present for a friend…