Nuclear Selenology by KGRS by
Prof. Hasebe N (Research Institute for Science and Engineering, Waseda University, Shinjuku, Tokyo, Japan)
Seminars Tuesday 23 November 2010
High energy cosmic rays constantly create neutrons and characteristic gamma-rays as nuclear reactions products with lunar surface material. The measurement of their nuclear radiation from lunar orbit provides a powerful method for remotely determining the absolute abundances of elements in the surface material of the Moon. Kaguya Gamma-Ray Spectrometer (KGRS) with a high energy resolution onboard Lunar polar orbiter, SELENE (Kaguya), measured many nuclear gamma-ray lines emitted from the lunar surface and determined the elemental composition in the subsurface down to about 20-30 cm. Global maps of their elements such as natural radioactive elements and major elements were made by the KGRS, which verified that nuclear spectroscopy is a powerful method for chemical analysis of the lunar surface material from orbit. In the near future, sophisticated nuclear instrument actively combined with pulsed neutron generator would be carried on lunar landing and roving missions, which greatly improves the scope of measurable elements, the shortening of accumulation time, and the increased preciseness. The KGRS results of radioactive nuclides and future prospect of lunar exploration in Japan will be presented.