Physical properties of Phobos' regolith.

The paper presents results of two experiments on board of the PHOBOS spacecraft: spectrophotometry in the range 300 - 600 nm and thermal radiometry (intrinsic thermal emission in the range 6 - 50 μm). Thermophysics of the regolith is similar to that of the Moon. The reflectivity of the Phobos regolith is heterogeneous along the studied traces and depends mostly on features of the relief, first of all on craters and their age. In all cases the albedo which is low by its absolute value rises from 350 to 600 nm. Among the closest analogs of the surface there are optically modified mafic rocks. The awaited similarity of the reflected spectra with carbonaceous chondrites is not confirmed.