Publications

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Journal Article
Ike, D, Bada JL, Masters PM, Kennedy G, Vogel JC.  1979.  Aspartic-Acid Racemization and Radiocarbon Dating of an Early Milling Stone Horizon Burial in California. American Antiquity. 44:524-530.   10.2307/279550   Website
Skelley, AM, Scherer JR, Aubrey AD, Grover WH, Ivester RHC, Ehrenfreund P, Grunthaner FJ, Bada JL, Mathies RA.  2005.  Development and evaluation of a microdevice for amino acid biomarker detection and analysis on Mars. Proceedings of the National Academy of Sciences of the United States of America. 102:1041-1046.   10.1073/pnas.0406798102   AbstractWebsite

The Mars Organic Analyzer (MOA), a microfabricated capillary electrophoresis (CE) instrument for sensitive amino acid biomarker analysis, has been developed and evaluated. The microdevice consists of a four-wafer sandwich combining glass CE separation channels, microfabricated pneumatic membrane valves and pumps, and a nanoliter fluidic network. The portable MOA instrument integrates high voltage CE power supplies, pneumatic controls, and fluorescence detection optics necessary for field operation. The amino acid concentration sensitivities range from micromolar to 0.1 nM, corresponding to part-per-trillion sensitivity. The MOA was first used in the lab to analyze soil extracts from the Atacama Desert, Chile, detecting amino acids ranging from 10-600 parts per billion. Field tests of the MOA in the Panoche Valley, CA, successfully detected amino acids at 70 parts per trillion to 100 parts per billion in jarosite, a sulfate-rich mineral associated with liquid water that was recently detected on Mars. These results demonstrate the feasibility of using the MOA to perform sensitive in situ amino acid biomarker analysis on soil samples representative of a Mars-like environment.

Beaty, DW, Miller S, Zimmerman W, Bada J, Conrad P, Dupuis E, Huntsberger T, Ivlev R, Kim SS, Lee BG, Lindstrom D, Lorenzoni L, Mahaffy P, McNamara K, Papanastassiou D, Patrick S, Peters S, Rohatgi N, Simmonds JJ, Spray J, Swindle TD, Tamppari L, Treiman A, Wolfenbarger JK, Zent A.  2004.  Planning for a Mars in situ sample preparation and distribution (SPAD) system. Planetary and Space Science. 52:55-66.   10.1016/j.pss.2003.08.016   AbstractWebsite

For Mars in situ landed missions, it has become increasingly apparent that significant value may be provided by a shared system that we call a Sample Preparation and Distribution (SPAD) System. A study was conducted to identify the issues and feasibility of such a system for these missions that would provide common functions for: receiving a variety of sample types from multiple sample acquisition systems; conducting preliminary characterization of these samples with non-destructive science instruments and making decisions about what should happen to the samples; performing a variety of sample preparation functions- and, finally, directing the prepared samples to additional science instruments for further analysis. Scientific constraints on the functionality of the system were identified, such as triage, contamination management, and various sample preparation steps, e.g., comminution, splitting, rock surfacing, and sieving. Some simplifying strategies were recommended and an overall science flow was developed. Engineering functional requirements were also investigated and example architectures developed. Preliminary conclusions are that shared SPAD facility systems could indeed add value to future Mars in situ landed missions if they are designed to respond to the particular requirements and constraints of those missions, that such a system appears feasible for consideration, and that certain standards should be developed for key SPAD interfaces. (C) 2003 Elsevier Ltd. All rights reserved.