Studies of Phobos polar illumination and thermal conditions

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We will analyze data from Mars Express obtained from 2012-2015 to update the current shape and rotation parameters for Phobos. We then use the new shape and orientation models to investigate the illumination and thermal conditions of the polar areas of this small Martian satellite.Owing to the tilt of the rotation axis with respect to the orbital plane of the Mars system, the polar areas enjoy daylight for many months during the summer seasons. Owing to the odd shape of Phobos we expect intricate patterns of illuminated areas and shadows. We will produce illumination maps, which will be compared with distribution of sunlight and darkness in images to possibly identify potential for improvement of our shape and illumination model.We also study thermal conditions near the surface of Phobos as a result of incoming sunlight and thermal radiation from nearby Mars. Owing to the slightly elliptic solar orbit of Mars and its satellites, thermal cycles over the year are expected to be quite different on the Northern and Summer hemisphere. We also consider the effect of short eclipses (with Mars blocking incoming sunlight). Using numerical models of heat conduction and applicable soil parameters, we study the penetration depth of the diurnal and seasonal heat wave, for nearside, farside, polar and equatorial areas, to constrain the minimum depths of suggested water ice reservoirs within Phobos. Our project will support missions to Phobos, which are being planned in the coming years and it will greatly improve our understanding of the daily and seasonal cycle of changing environmental conditions for different geographic areas on this small satellite.