DAVID G. AGRESTI, Professor

(205) 934-8032, agresti@phy.uab.edu

The Chemical and Mineralogical Composition of Extraterrestrial Bodies

My work focuses on materials of extraterrestrial origin and their terrestrial and laboratory-produced analogues. With Physics faculty colleague Edward Wills and collaborators at NASA Johnson Space Center, my group is involved in the development and evaluation of a soft-drink sized backscatter M ssbauer spectrometer (BaMS), a nuclear gamma-resonance device designed to be placed on the surface of Mars, the moon, or an asteroid. BaMS will yield information about the chemical and mineralogical composition of iron-containing surface materials and hence help in the understanding of the history of these extraterrestrial bodies and support their eventual visit by humans. As part of the project, my group is studying how data statistics and extent of mixing of mineral phases affect the ability of BaMS to determine the mineralogy of a planetary surface. Development of a library of spectra of possible Martian surface materials is underway. With UAB astrophysicist Tom Wdowiak, we are investigating material from bacterial colonies associated with deep-sea volcanic vents to determine whether BaMS might provide a way to search for early life on Mars. This work is supported by grants from NASA headquarters and Marshall Space Flight Center.

Instrumentation:

• Mössbauer spectrometers: including sample oven (to 1,000K)
• APD closed-cycle refrigerator (12K)
• Bench-top research electromagnet (2T)
• For sample preparation and evaluation: Lindberg tube-furnace (1500 C); Mettler balance
• Other instruments: fast-Fourier transform spectral analyzer, pulse amplifiers, scalers, multi/single channel analyzers

• Dr. Thomas J. Wdowiak
• Johnson Space Center
• Arizona State University

Recent Publications:

• Hot springs on early Mars: implications of a Mössbauer investigation of iron-rich terrestrial hydrothermal vent systems. Wade, M.L., Agresti, D.G., Wdowiak, T.J., Armendarez, L.P., and Farmer, J.D., 1998. Submitted 8/8/98 to JGR (Planets).

• In-situ resource assessment and process control with laser-Raman spectroscopy. Agresti, D.G., et al, at In Situ Resource Utilization (ISRU II) Technical Interchange Meeting (Lunar and Planetary Institute, Houston, November 18-19, 1997).

• Mössbauer spectroscopy of thermal springs iron deposits as Martian analogs. Agresti, D.G., et al, in Conference on Early Mars: Geologic and Hydrologic Evolution, Physical and Chemical Environments, and the Implications for Life, eds. Clifford et al. (LPI, Houston), LPI Contribution No. 916, 1-2, 1997.

• Prototype backscatter Mössbauer spectrometer (BaMS); instrumentation summary and conclusions. Shelfer, T.D., Morris, R.V., Nguyen, T.Q., Agresti, D.G., and Wills, E.L., Lunar and Planetary Science 27:1185-1186, 1996.

• A Mössbauer investigation of hot springs iron deposits. Agresti, D.G., Wdowiak, T..J., Wade, M.L., and Armendarez, L.P., Lunar and Planetary Science 26:7-8, 1995.

• Mössbauer spectroscopy as a tool in the search for evidence of past life on Mars. Agresti, D.G., Wdowiak, T.J., and Wade, M.L., Hyperfine Interactions 91:523-528, 1994.

• Extraterrestrial Mössbauer spectrometry. Agresti, D.G., Morris, R.V., Wills, E.L., Shelfer, T.D., Pimperl, M.M., Shen, M.-H., Clark, B.C., and Ramsey, B.D., Hyperfine Interactions 72:285-298, 1992.

• Mössbauer spectroscopy for mineralogical analysis on planetary surfaces. Morris, R.V., Agresti, D.G., Shelfer, T.D., and Wdowiak, T.J., in Proceedings, Pathfinder Sample Acquisition, Analysis, and Preservation Instrument Technology Workshop (Johnson Space Center, Houston, November, 1988).