Computer simulation and beam experiment on the identification of elements for planetary exploration

Abstract

The remote sensing from the orbit is very effective for exploring the surface of satellites and planets with no or little atmosphere. The surface material of planets are irradiated by the cosmic-ray, producing neutron with a wide variety of energy as a result of nuclear interaction. These neutrons then react again with surface material and lose energies, while some of them excite the nuclei. As a result, the decay of excited nuclei emits gamma-rays with characteristic energy, and their leakage flux is dependent on the abundance of the elements on the surface. The information such as chemical abundances and the determination of volatile/refractory element concentration will provide the very important data to restrict the theory for the origin and evolution of a planet. However, in order to determine the absolute chemical concentration on a planet, highly precise ground-based experiments and computer simulation is needed to derive such information from the mission data. In case of the moon, Apollo data provides 'ground truth,6apos; but those are only for limited point of the entire surface to be observed. For other planets, there would be no such reference data. Therefore, computer simulation will play very important role in determination of concentration and its consistency has to be verified with the ground-based experiments.