Radar Detection of Phobos

Science  24 Mar 1989:
Vol. 243, Issue 4898, pp. 1584-1586
DOI: 10.1126/science.243.4898.1584


Radar echoes from the martian satellite Phobos provide information about that object's surface properties at scales near the 3.5-cm observing wavelength. Phobos appears less rough than the moon at centimeter-to-decimeter scales. The uppermost few decimeters of the satellite's regolith have a mean bulk density within 20% of 2.0 g cm-3. The radar signature of Phobos (albedo, polarization ratio, and echo spectral shape) differs from signatures measured for small, Earth-approaching objects, but resembles those of large (≥100-km), C-class, mainbelt asteroids.