Opportunities for X-ray remote sensing at Mercury

Mercury is the little known innermost terrestrial planet. A number of signi ficant questions remain unanswered. We describe areas in which a compact im aging X-ray spectrometer could make a valuable contribution. It can provide high quality spectroscopic analysis of Mercury, using the fluorescence tec hnique. A solar monitor is required to provide the calibration of the illum ination necessary to produce a global map of absolute Hermean elemental abu ndances. In the case of Mercury studies of the surface and the magnetospher e form a single linked problem. The intense level of the radiation observed by Mariner 10 suggests that the auroral zone, where the energetic radiatio n interacts with the surface, is a potential intense source of X-rays. We e stimate the fluxes. The solar wind may also contribute to X-ray generation, if it can reach the surface during highly excited periods. We describe bri efly the instrument characteristics that could produce these observations. (C) 2001 Elsevier Science Ltd. All rights reserved.