Earth Planets Space, Vol. 60 (No. 4), pp. 283-292, 2008
Kazunori Ogawa1,2, Tatsuaki Okada1, Kei Shirai1, and Manabu Kato1
1Department of Planetary Science, Instutute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1 Yoshinodai, Sagamihara, Kanagawa 229-8510, Japan
2Department of Earth and Planetary Sciences, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550, Japan
(Received April 21, 2007; Revised September 10, 2007; Accepted October 22, 2007; Online published April 9, 2008)
We conducted a numerical estimation of lunar X-ray spectra, which is applicable for lunar X-ray fluorescence observations using an X-ray spectrometer (XRS) onboard the SELENE orbiter, with an improved simulation model. We investigated the integration times of measurements for six elements (Mg, Al, Si, Ca, Ti, and Fe) to achieve signal-to-background ratio of over 10 under various solar conditions. The results of these calculations indicate that expected along-the-track spatial resolutions of a single orbital path for Mg, Al and Si will be <90 km and 20 km under normal and active Sun conditions, respectively. Ca, Ti and Fe will be also detectable with a spatial resolution of 20 km during the periods active solar flares over M1 class happen to occur.
Key words: Lunar X-ray, numerical simulation, X-ray spectrometer, XRS, SELENE.