Dr. Eshleman will use the radar capabilities of the telescope at the Arecibo Observatory to conduct detailed studies of the surfaces of Europa, Ganymede, and Callisto (large, ice-clad moons of Jupiter). The data will be compared to theoretical predictions from models of the surfaces of these moons. The emphasis will be on the geophysical significance of the results. Ice and icy surfaces are ubiquitous in the outer Solar System. One potentially important source of information about these surfaces is from radar experiments. Radar echoes have been obtained from Europa, Ganymede, and Callisto, from the particles in Saturn's rings, from several dozen asteroids, and from five comets. The icy moons are the best studied of these, and they have radar echoes profoundly different from the well-understood returns of the rocky planets and our Moon. Dr. Eshleman will obtain new radar observations of the icy moons of Jupiter to better understand reasons for the anomalous radar characteristics of these objects.