HR: 08:00h
AN: P31A-01    [Abstracts]
TI: What do we know of Mercury's composition?
AU: * Robinson, M S
EM: mrobinson@asu.edu
AF: Arizona State University, School of Earth and Space Exploration Box 871404 , Tempe, AZ 85287-1404, United States
AB: Little is known of Mercury's bulk composition and the range of petrologic diversity within its crust and mantle. Our best constraint on the planet's bulk composition is an inference from its high-uncompressed density - Mercury has the highest metal to silicate ratio of all the terrestrial planets. However we do not know if this ratio is original or due to a catastrophic redistribution of materials early in its history. At a smaller scale Mariner 10 and Earth based telescopic data indicate that Mercury's crust may have compositional and mineralogic affinities with the lunar crust. The same data allow the tenuous interpretation that Mercury's mantle contains relatively low ferrous iron. Intriguing observations of Mercury's surface bound exosphere show a relatively high concentration of sodium, a finding not easily reconciled with other evidence that Mercury is the most refractory planet. This paper will review our knowledge of Mercury's composition and preview the MESSENGER mission's first flyby of Mercury that will occur in January of 2008.
DE: 5410 Composition (1060, 3672)
DE: 5455 Origin and evolution
SC: Planetary Sciences [P]
MN: 2007 Joint Assembly