Lunar gamma-ray observation by kaguya GRS

Nobuyuki Hasebe, N. Yamashita, Y. Karouji, S. Kobayashi, M. Hareyama, Shinichi Komatsu, K. Hayatsu, K. Nemoto, K. Iwabuchi, Y. Takeda, H. Nagaoka, K. Tsukada, J. Machida, O. Okudaira, S. Sakurai, E. Shibamura, M. N. Kobayashi, Mitsuru Ebihara, T. Hihara, T. AraiT. Sugihara, H. Takeda, C. D'Uston, O. Gasnault, B. Diez, O. Forni, S. Maurice, R. C. Reedy, K. J. Kim

    Research output: Chapter in Book/Report/Conference proceedingChapter


    The high precision Gamma-Ray Spectrometer (GRS) was carried on the first Japan's large-scale lunar orbiter, SELENE (KAGUYA). The GRS employed a Ge detector with high energy resolution. Since the regular observation by the KAGUYA GRS started on December 14, 2007, gamma-ray data had been accumulated over the Moon. Many elements were identified: O, Mg, Al, Si, K, Ca, Ti, Fe, Th and U. The regular GRS observation at 100 km altitude let us create global distribution maps of chemical abundances on the lunar surface, which showed considerable regional variations. Special operations were conducted in December 2008 in order to measure background gamma rays from materials of the spacecraft body and the GRS detector itself, and to anneal the Ge crystal for about two days at 85 ± 5 degrees Celsius in order to recover the resolution of the Ge crystal that had been degraded due to radiation damage in space. Its energy resolution was improved to the level at the initial phase of the mission. Results from the special operations and regular observation of the Moon are described.

    Original languageEnglish
    Title of host publicationAdvances in Geosciences: Volume 19: Planetary Science (PS)
    PublisherWorld Scientific Publishing Co.
    Number of pages12
    ISBN (Electronic)9789812838162
    ISBN (Print)9812838155, 9789812838155
    Publication statusPublished - 2010 Jan 1

    ASJC Scopus subject areas

    • Earth and Planetary Sciences(all)

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