date: 2012 December 12 (Wed) 15:00-16:00
room: CPS Conference Room
speaker: Ryosuke Nakamura (AIST)
organizer: Hiroshi Kimura
title: Differentiation of the Moon's Magma Sea and Vesta's Magma Ocean
abstract: Recently, Dawn spacecraft confirmed the direct link between asteroid Vesta and HED ("howardite?eucrite?diogenite") meteorites.
Diogenites are dominated by low-Ca pyroxene (LCP), while eucrites have higher plagioclace fraction and howardites are regolith breccias consisting of eucrite and diogenite fragments. The visible and near-infrared spectra of Vesta indicated that most of Vesta's surface is covered by materilas similar to eucrites and howardies.
The biggest Rheasilvia basin around the south pole shows more mafic-rich composition like diogenite.

We have conducted similar hyperspectral surveys of the Moon by using KAGUYA Spectral Profiler (SP). It was found that the LCP-rich exposures are concentrated around the Imbrium, Southe-Pole Aitken and Procellarum basins. The standard impact theories predict that these huge basins were once filled by tremendous amount of impact melt.
The spatial scale of such "magma sea" would be comparable to those of Vesta's magma ocean. In this presentation, we discuss their possible common solidification sequence. The presence(absence) of olivine-rich exposures on the Moon(Vesta) could be a key to understand their differentiaion process.
keywords: Moon, asteroid, meteorite, infrared spectra, magma ocean