Japan Geoscience Union Meeting 2016

Presentation information


Symbol P (Space and Planetary Sciences) » P-PS Planetary Sciences

[P-PS13] Lunar science and exploration

Sun. May 22, 2016 1:45 PM - 3:15 PM 104 (1F)

Convener:*Hiroshi Nagaoka(Waseda Univ.), Tomokatsu Morota(Graduate School of Environmental Studies, Nagoya University), Chikatoshi Honda(The University of Aizu), Masaki N Nishino(Institute for Space-Earth Environmental Research, Nagoya University), Chair:Hiroshi Nagaoka(Waseda Univ.), Ryuhei Yamada(National Astronomical Observatory of Japan, RISE project)

2:30 PM - 2:45 PM

[PPS13-16] On-site isotope laser spectrometry aiming underground lunar water

*Chihiro Yamanaka1, Ko Hashizume1, Naoya Tasaka1, Shigeki Tokita2 (1.Graduate School of Science, Osaka University, 2.Institute of Laser Enginerring, Osaka University)

Keywords:lunar water, isotope, Laser isotope measurement

It has been long believed liquid water cannot exist at the Moon's surface. However, it is also true that water is continuously supplied to the moon by meteorites or comets and a few studies indicated the existence of water in the moon1). Actually, lunar volcanic glass showed a trace amount of water2-3). Water may also survive in cold permanently-shadowed craters at poles4) or deep underground which is not affected by diurnal variation of solar heat5). Now, lunar water is a big concern among researchers.
It is also important to know the origin of the water on the moon. On-site isotope measurements are essential because contamination of terrestrial water should be avoided.We are planning to fabricate a light-weight laser isotope measurement system about several kg in weight. Light weight DFB laser or Er-doped (Er:ZBLAN) fiber laser are candidates, which emit at desirable absorption bands for water isotope around 2.7 Another concern is a sample cavity which consists of a cell and mirrors. In order to resolve the small amount of isotopes, a long path length about km of laser beam must be achieved. In Mars Science Laboratory by Nasa, Curiosity includes the Laser isotope spectrometer with a Herriot cell, while commercial devices using a cavity enhanced cell with ultra-high reflectivity. Our concept and preliminary experiments will be presented.
1) Feldman et al., Science 281. pp.1496 (1998)
2) Saal, et al., Nature 454. pp.192 (2008)
3) Saal et al., Science 340. pp.1317 (2013)
4) Binder, Science, 281. pp.1475 (1998)
5) Hashizume, private comm.