2:30 PM - 2:45 PM
[PPS13-16] On-site isotope laser spectrometry aiming underground lunar water
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.
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.