15:30 〜 17:00
[PPS06-P08] First High-Resolution Geological Map of the South Polar Region on the Moon
キーワード：月、南極、かぐや、マルチバンドイメージャ
To generate a geological map of the polar region of the Moon in high spatial resolution has been difficult. It is mainly because in the polar region, the lunar surface is in a shadow for a longer period compared to the low latitude area. To obtain reflectance spectra of this region with accurate positional information, mosaicking of multiband or hyperspectral images obtained in different timing is required. And mosaicking images of the polar region is difficult due to the higher percentage of shadows within the images.
Recently, a mosaic of the lunar south polar region of the Moon was generated from Multiband Imager (MI) datasets by updating the orbital information of the satellite and re-calibrate and re-calculating reflectance from the original MI datasets (Sato and Ohtake, 2022). The MI on the Selenological and Engineering Explorer (SELENE) has a high spatial resolution (20 m/pixel in visible or 62m/pixel in near-infrared wavelength at the nominal altitude of 100 km) and has 9 observation bands. By using this newly created MI mosaic, we generated high resolution geological map of the south polar region of the Moon as a first time by conducting analysis of spectral shape, FeO/TiO2 abundance, and absorption strength.
In this study, we focused on analyzing the South Pole-Aitken (SPA) basin, which expands from the 15°S to the south pole and is the biggest basin (larger than 2000 km in diameter) on the Moon. Because of its large size, the SPA basin is estimated to excavate and exposed part of the lunar mantle. A previous study of the SPA basin based on the MI data up to 60 °S (Ohtake et al., 2014) observed that Low-Ca pyroxene dominant rocks are widely distributed within the SPA basin and its surroundings, and this is the most abundant rock type in this region. And from the analysis, it is suggested that this rock type is the major component of the lunar mantle, at least in the excavation depth by the SPA basin. However, previous studies could not analyze the southern part of the SPA. Therefore, we focused on analyzing the southern part of the SPA basin. As a result, multiple olivine-rich sites near the southern limb of the SPA inner ring were found in the generated geological map. The previous study by Yamamoto et al. (2010) identified olivine-rich sites within the inner ring of the SPA basin only at the central peak of Zeeman, which locates southern part of the SPA basin. The newly identified olivine-rich sites within the basin may suggest concentrated exposure of the olivine-rich material at the southern part of the SPA basin.
Recently, a mosaic of the lunar south polar region of the Moon was generated from Multiband Imager (MI) datasets by updating the orbital information of the satellite and re-calibrate and re-calculating reflectance from the original MI datasets (Sato and Ohtake, 2022). The MI on the Selenological and Engineering Explorer (SELENE) has a high spatial resolution (20 m/pixel in visible or 62m/pixel in near-infrared wavelength at the nominal altitude of 100 km) and has 9 observation bands. By using this newly created MI mosaic, we generated high resolution geological map of the south polar region of the Moon as a first time by conducting analysis of spectral shape, FeO/TiO2 abundance, and absorption strength.
In this study, we focused on analyzing the South Pole-Aitken (SPA) basin, which expands from the 15°S to the south pole and is the biggest basin (larger than 2000 km in diameter) on the Moon. Because of its large size, the SPA basin is estimated to excavate and exposed part of the lunar mantle. A previous study of the SPA basin based on the MI data up to 60 °S (Ohtake et al., 2014) observed that Low-Ca pyroxene dominant rocks are widely distributed within the SPA basin and its surroundings, and this is the most abundant rock type in this region. And from the analysis, it is suggested that this rock type is the major component of the lunar mantle, at least in the excavation depth by the SPA basin. However, previous studies could not analyze the southern part of the SPA. Therefore, we focused on analyzing the southern part of the SPA basin. As a result, multiple olivine-rich sites near the southern limb of the SPA inner ring were found in the generated geological map. The previous study by Yamamoto et al. (2010) identified olivine-rich sites within the inner ring of the SPA basin only at the central peak of Zeeman, which locates southern part of the SPA basin. The newly identified olivine-rich sites within the basin may suggest concentrated exposure of the olivine-rich material at the southern part of the SPA basin.