Arecibo radar observations of Phobos and Deimos

In November 2005, we observed the moons of Mars using the Arecibo 2380-MHz (13-cm) radar, obtaining a result for the OC radar albedo of Phobos (0.056 +/- 0.014) consistent with its previously reported radar albedo and implying an upper bound on its near-surface bulk density of 1.6 +/- 0.3 g cm(-3). We detected Deimos by radar for the first time, finding its OC radar albedo to be 0.021 +/- 0.006, implying an upper bound on its near-surface density of 1.1 +/- 0.3 g cm(-3), consistent with a high-porosity regolith. We briefly discuss reasons for these low radar albedos, Deimos' being possibly the lowest of any Solar System body yet observed by radar. (c) 2006 Elsevier Inc. All rights reserved.