15:45 〜 16:00
[PPS06-14] Distribution of the volatile spectral signals observed at the lunar polar regions
キーワード：月、揮発性成分、極域
Recently, the water condensation at the lunar polar region has been suggested by multiple datasets. However, distribution, amount, form, and origin of the water are not clear. To solve these problems, we have been investigating spectral signatures of the water observed at the lunar polar regions by analyzing Spectral Profiler (SP) data onboard SELENE (Kaguya) and reported clear evidence of water ice and other volatile components both on the north and south polar regions. Also, we interpret that the signals are likely originated from the dust and volatile mixture lofted in space and reflecting the solar light.
In this study, we investigated the identified spectral signals at the polar region (> ±80° in latitude) to understand mechanism of the volatile lofting by generating distribution map of the lofted volatile components among all SP data. The derived distribution map was compared to the previously reported water-equivalent-hydrogen (WEH) map (Sanin et al., 2017) obtained by the Lunar Exploration Neutron Detector instrument (LEND) onboard the Lunar Reconnaissance Orbiter and the water ice map (Li et al., 2018) obtained by the M3 instrument onboard the Chandrayaan-1. The results revealed that majority of the identified signals in our study matches well to the WEH map by LEND while it mismatches to the water ice map by M3. In the map reported by Li et al. (2018), water ice locates mostly in the permanent shadowed regions (PSRs) while our data indicates majority of the signals locate non-PSR. This evidence suggest that the identified signals are volatile materials sublimated mainly from the non-PSR where theoretically sublimation can occur in short term (during operation of the SELENE) if sufficient volatile materials are stored in a buffer. And the WEH distribution map of LEND possibly correspond to the location of such a buffer.
Reference:
Sanin et al., Icarus, 283, p20-30, 2017.
Li et al., PNAS, Proceedings of the National Academy of Sciences, 115, p8907-8912, 2018.
In this study, we investigated the identified spectral signals at the polar region (> ±80° in latitude) to understand mechanism of the volatile lofting by generating distribution map of the lofted volatile components among all SP data. The derived distribution map was compared to the previously reported water-equivalent-hydrogen (WEH) map (Sanin et al., 2017) obtained by the Lunar Exploration Neutron Detector instrument (LEND) onboard the Lunar Reconnaissance Orbiter and the water ice map (Li et al., 2018) obtained by the M3 instrument onboard the Chandrayaan-1. The results revealed that majority of the identified signals in our study matches well to the WEH map by LEND while it mismatches to the water ice map by M3. In the map reported by Li et al. (2018), water ice locates mostly in the permanent shadowed regions (PSRs) while our data indicates majority of the signals locate non-PSR. This evidence suggest that the identified signals are volatile materials sublimated mainly from the non-PSR where theoretically sublimation can occur in short term (during operation of the SELENE) if sufficient volatile materials are stored in a buffer. And the WEH distribution map of LEND possibly correspond to the location of such a buffer.
Reference:
Sanin et al., Icarus, 283, p20-30, 2017.
Li et al., PNAS, Proceedings of the National Academy of Sciences, 115, p8907-8912, 2018.