Television observations of Phobos

IN February and March 1989 the Phobos 2 spacecraft took 37 television images of the moon Phobos from a distance of 190-1,100 km. These images complement the data from the Mariner 9 and Viking missions by providing higher-resolution coverage of a large region west of the crater Stickney (70-160° W) and by providing disk-resolved measurements of surface brightness at a greater range of phase angles and wavelengths. The data are being used to update the three-dimensional model of Phobos, to provide improved determinations of its density and orbital dynamics and to study its surface colour, composition and texture. Here we present preliminary findings, which include different integrated photometric behaviour in visible and near-infrared bands, observa-tion of a region immediately west of Stickney which is relatively free of large grooves, the prevalence of bright rims on grooves and younger craters and low bulk density.