2008 Joint Meeting of The Geological Society of America, Soil Science Society of America, American Society of Agronomy, Crop Science Society of America, Gulf Coast Association of Geological Societies with the Gulf Coast Section of SEPM

Paper No. 2
Presentation Time: 8:15 AM

New Insights into the Composition and Texture of Lunar Regolith Using Ultrafast Automated Electron-Beam Analysis


RICKMAN, Doug1, WENTWORTH, Susan J.2, SCHRADER, Christian M.3, STOESER, Doug4, BOTHA, Pieter W.S.K.5, BUTCHER, Alan R.6, HORSCH, Hanna E.6, BENEDICTUS, Aukje6, GOTTLIEB, Paul6 and MCKAY, David7, (1)Marshall Space Flight Center, Code VP61, NASA, 320 Sparkman Drive, Huntsville, AL 35802, (2)ERC/ESC Group, JE23, NASA Johnson Space Center, 2101 NASA Parkway, Houston, TX 77058, (3)BAE Systems-MSFC, 320 Sparkman Drive, Huntsville, AL 35802, (4)Central Region Mineral Resources Team, USGS, Mail Stop 973 Box 25046 DFC, Denver, CO 80225, (5)ARMC, Intellection Corporation, 10955 Westmoor Drive, Suite 400, Westminster, CO 80021, (6)Intellection Pty Ltd, 27 Mayneview St, Milton, Queensland, 4064, Australia, (7)Astromaterials Group, NASA Johnson Space Ctr, Mail code SN, Houston, TX 77058, doug.rickman@nasa.gov

Sieved grain mounts of Apollo 16 drive tube samples have been examined using QEMSCAN® - an innovative electron beam technology. By combining multiple energy-dispersive X-ray detectors, fully automated control, and off-line image processing, to produce digital mineral maps of particles exposed on polished surfaces, the result is an unprecedented quantity of mineralogical and petrographic data, on a particle-by-particle basis.

Experimental analysis of four size fractions (500-250 µm, 150-90 µm, 75-45 µm and < 20 µm), prepared from two samples (64002,374 and 64002,262), has produced a robust and uniform dataset which allows for the quantification of mineralogy; texture; particle shape, size and density; and the digital classification of distinct particle types in each measured sample.

These preliminary data show that there is a decrease in plagioclase modal content and an opposing increase in glass modal content, with decreasing particle size. These findings, together with data on trace phases (metals, sulphides, phosphates, and oxides), provide not only new insights into the make-up of lunar regolith at the Apollo 16 landing site, but also key physical parameters which can be used to design lunar simulants, and compute Figures of Merit for each material produced.