At MIT, Ostro was advised by Gordon Pettengill and Irwin I. Shapiro and studied the radar scattering properties of Saturn's rings and the Galilean satellites using the Arecibo Observatory.

[4] From August 19 to 22 of 1989, Ostro and Scott Hudson observed the contact binary 4769 Castalia from the Arecibo Observatory, producing the first resolved radar images of an asteroid, which they later used to construct a model of the object.

Following the further development of imaging and shape reconstruction techniques by Ostro, Hudson, and Christopher Magri, and the upgrade of Arecibo in the mid-1990s, the number of radar observations increased dramatically.

To explore the dynamical implications of these observations in detail, Ostro collaborated with Steven Chesley, Jon D. Giorgini, Scott Hudson, Jean-Luc Margot, and Daniel J. Scheeres.

Radar observations of Mars' moons, Phobos and Deimos, have refined knowledge of their orbits and show that their surfaces are coated with very low density (~1 g/cm3) material, most likely fine-grain dust, to a depth of several meters.