2004 Annual Science Report
NASA Goddard Space Flight Center Reporting | JUL 2003 – JUN 2004
Characterization of the Early Bombardment Through the Investigation of Lunar Breccias
The initial phase of work to characterize the early bombardment of the inner solar system has consisted of selecting and separating pure melt rock from lunar highlands breccias. The purpose of this work is to fingerprint the late additions to the Moon using the relative abundances of the highly-siderophile elements that occur in generally high abundance in likely impactors, but extremely low abundance in the indigenous lunar crust. Towards this end, approximately 2g of two Apollo 17 breccias, 73215 and 73255 were requested and have been obtained from the Johnson Space Center curatorial facilities. In collaboration with Dr. Odette James, a longstanding expert on these rocks, Dr. Walker and his students have cleanly separated 13 chips from 73215 and 6 chips from 73255 for processing for Os isotopes and measurement of highly siderophile element abundances. At present (June, 2004), we are doing final checks on chemical blanks for the separation and measurement procedures to be used on these rocks. Analytical work consisting of powdering, dissolving, separating elements of interest, and mass spectrometric measurements will begin in July, 2004.
PROJECT INVESTIGATORS:Richard Walker
RELATED OBJECTIVES:Objective 1.1
Models of formation and evolution of habitable planets