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A.M. Di Lellis, M.T. Capria, S. Espinasse, G. Magni, R. Orosei, G. Piccioni (Istituto di Astrofisica Spaziale - CNR, Roma, Italy), C. Federico, G. Minelli, C. Pauselli (Dip. di Scienze della Terra, Univ. Perugia, Perugia, Italy), G. Scarpa (ENEA-Casaccia, S. Maria di Galeria, Italy)
MARE is an experiment for the measurement of the \beta and \gamma radioactivity in space and in the Martian soil, both at the surface and in the subsurface. This will be accomplished by means of a dosimeter and a spectrometer. The radiation dose rate to which crews will be exposed is one of the hazards that has to be quantified before the human exploration of Mars may begin. Data for evaluating radioactivity levels at Martian surface are of great interest for environmental studies related to life in general. The dosimeter will be able to measure the \beta and \gamma radiation dose received, with a responsivity which is very close to that of a living organism. The dosimeter is based on thermo-luminescence pills which emit an optical signal proportional to the absorbed dose when heated. Radioactive elements (40K, 235U, 238U and 232Th) can be used as a mean of tracing the evolution of a terrestrial planet. These radioactive elements are the source of the internal heat, which drives convection in the mantle. They have been redistributed in this process and they are now concentrated in the crust where they are accessible for study. Their different behavior during the fractionation process can be used as a mean to investigate the geochemical characteristic of Mars. The spectrometer, a scintillation radiation absorber system for single event counting, is capable of detecting \gamma photons with energies between 200 KeV and 10 MeV. The detected events will be processed in such a way to allow the recognition of the spectral signature of different decay processes, and thus the identification and the measurement of the concentrations of different radionuclides in the Martian soil.