月クレータ中央丘表面岩相の検証

抄録

Scaling relation of craters indicates that the lunar central peak material can be related to the lower crust of the moon. Craters, ranging in diameter from 40 to 180 km, are believed to have exhumed material from 5-30 km beneath the surface to form the peaks. Therefore, the craters which have central peaks are selected as probable candidates for a landing site in the future Japanese lunar mission. Tompkins and Pieters (1999) investigated the central peaks of 109 impact craters across the Moon and classified lithologies of central peaks into eleven kinds of plutonic rocks using Clementine UVVIS five-color spectra.
In order to verify the estimated lithologies, influences of space weathering, photometric condition, and quenched glass phase on the estimation were examined by detailed spectral data analysis. The relation between crater diameter and central peak lithologies was also examined.
As a result, we conclude that the estimated mafic lithologies at the sunny side of central peaks are probable. Aristillus, Bhabha, Birkeland, Bose, Bullialdus, Finsen, Fizeau, Jackson, King, Maunder, Stevinus, Tsiolkovskiy, Tycho, Vitello, White, and Zucchius are suitable sampling sites for finding lower crust rocks among 109 central-peak craters. Additionally, we searched out olivine bearing lithologies at the central peaks. The central peaks of Jackson and Tsiolkovsky were regarded as suitable sampling sites for finding olivine bearing lithologies among 109 craters. Strange crater walls, which have more mafic lithologies than their central peaks, were found in Aristarchus, Burg, and Plinius. They suggest the existence of an unknown factor which changes the spectral properties to be more mafic.