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Bada, JL, Ehrenfreund P, Grunthaner F, Blaney D, Coleman M, Farrington A, Yen A, Mathies R, Amudson R, Quinn R, Zent A, Ride S, Barron L, Botta O, Clark B, Glavin D, Hofmann B, Josset JL, Rettberg P, Robert F, Sephton M.  2008.  Urey: Mars Organic and Oxidant Detector. Space Science Reviews. 135:269-279.   10.1007/s11214-007-9213-3   AbstractWebsite

One of the fundamental challenges facing the scientific community as we enter this new century of Mars research is to understand, in a rigorous manner, the biotic potential both past and present of this outermost terrestrial-like planet in our solar system. Urey: Mars Organic and Oxidant Detector has been selected for the Pasteur payload of the European Space Agency's (ESA's) ExoMars rover mission and is considered a fundamental instrument to achieve the mission's scientific objectives. The instrument is named Urey in recognition of Harold Clayton Urey's seminal contributions to cosmochemistry, geochemistry, and the study of the origin of life. The overall goal of Urey is to search for organic compounds directly in the regolith of Mars and to assess their origin. Urey will perform a groundbreaking investigation of the Martian environment that will involve searching for organic compounds indicative of life and prebiotic chemistry at a sensitivity many orders of magnitude greater than Viking or other in situ organic detection systems. Urey will perform the first in situ search for key classes of organic molecules using state-of-the-art analytical methods that provide part-per-trillion sensitivity. It will ascertain whether any of these molecules are abiotic or biotic in origin and will evaluate the survival potential of organic compounds in the environment using state-of-the-art chemoresistor oxidant sensors.

Aubrey, AD, Chalmers JH, Bada JL, Grunthaner FJ, Amashukeli X, Willis P, Skelley AM, Mathies RA, Quinn RC, Zent AP, Ehrenfreund P, Amundson R, Glavin DP, Botta O, Barron L, Blaney DL, Clark BC, Coleman M, Hofmann BA, Josset JL, Rettberg P, Ride S, Robert F, Sephton MA, Yen A.  2008.  The Urey instrument: An advanced in situ organic and oxidant detector for Mars exploration. Astrobiology. 8:583-595.   10.1089/ast.2007.0169   AbstractWebsite

The Urey organic and oxidant detector consists of a suite of instruments designed to search for several classes of organic molecules in the martian regolith and ascertain whether these compounds were produced by biotic or abiotic processes using chirality measurements. These experiments will also determine the chemical stability of organic molecules within the host regolith based on the presence and chemical reactivity of surface and atmospheric oxidants. Urey has been selected for the Pasteur payload on the European Space Agency's (ESA's) upcoming 2013 ExoMars rover mission. The diverse and effective capabilities of Urey make it an integral part of the payload and will help to achieve a large portion of the mission's primary scientific objective: "to search for signs of past and present life on Mars." This instrument is named in honor of Harold Urey for his seminal contributions to the fields of cosmochemistry and the origin of life.

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Orgel, L, A'Hearn M, Bada J, Baross J, Chapman C, Drake M, Kerridge J, Race M, Sogin M, Squyres S.  2000.  Sample return from small solar system bodies. Advances in Space Research. 25:239-48.   10.1016/s0273-1177(99)00954-0   AbstractWebsite

With plans for multiple sample return missions in the next decade, NASA requested guidance from the National Research Council's Space Studies Board on how to treat samples returned from solar system bodies such as planetary satellites, asteroids and comets. A special task group assessed the potential for a living entity to be included in return samples from various bodies as well as the potential for large scale effects if such an entity were inadvertently introduced into the Earth's biosphere. The group also assessed differences among solar system bodies, identified investigations that could reduce uncertainty about the bodies, and considered risks of returned samples compared to the natural influx of material to the Earth in the form of interplanetary dust particles, meteorites and other small impactors. The final report (NRC, 1998) provides a decision making framework for future missions and makes recommendations on how to handle samples from different planetary satellites and primitive solar system bodies

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Grutters, M, van Raaphorst W, Epping E, Helder W, de Leeuw JW, Glavin DP, Bada J.  2002.  Preservation of amino acids from in situ-produced bacterial cell wall peptidoglycans in northeastern Atlantic continental margin sediments. Limnology and Oceanography. 47:1521-1524. AbstractWebsite

In this study we present the results of total hydrolysable amino acids (THAA) and amino acid D/L-enantiomers in northeastern Atlantic continental margin sediments. There is increasing evidence that intrinsically labile amino acids are present in old marine sediments as part of a refractory network of peptide-like material. We used amino acid enantiomers to identify the contribution of amino acids from bacterial cell walls to THAA in organic matter ranging from relatively young to 18,000 yr old. The ratio of D/L-amino acids increased with depth in the sediment mixed layer. Application of a transport-racemization-degradation model excludes a significant production of D-amino acids by racemization and implies in situ bacterial production as the main source. Amino acids associated with a refractory pool of bacterial cell walls could account for approximately one third of the THAA deeper in the sediments. We propose that in situ bacterial production and the primary flux of labile organic matter from the water column result in a small but highly reactive pool of amino acids in the surface mixed sediment only, whereas amino acids associated with refractory cell walls persist in marine sediments.

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.

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Becker, L, Popp B, Rust T, Bada JL.  1999.  The origin of organic matter in the Martian meteorite ALH84001. Earth and Planetary Science Letters. 167:71-79.   10.1016/s0012-821x(99)00014-x   AbstractWebsite

Stable carbon isotope measurements of the organic matter associated with the carbonate globules and the bulk matrix material in the ALH84001 Martian meteorite indicate that two distinct sources are present in the sample. The delta(13)C values for the organic matter associated with the carbonate globules averaged -26 parts per thousand and is attributed to terrestrial contamination, In contrast, the delta(13)C values for the organic matter associated with the bulk matrix material yielded a value of -15 parts per thousand. The only common sources of carbon on the Earth that yield similar delta(13)C values, other then some diagenetically altered marine carbonates, are C(4) plants. A delta(13)C value of -15 parts per thousand, on the other hand, is consistent with a kerogen-like component, the most ubiquitous form of organic matter found in carbonaceous chondrites such as the Murchison meteorite. Examination of the carbonate globules and bulk matrix material using laser desorption mass spectrometry (LDMS) indicates the presence of a high molecular weight organic component which appears to be extraterrestrial in origin, possibly derived from the exogenous delivery of meteoritic or cometary debris to the surface of Mars. (C) 1999 Published by Elsevier Science B.V. All rights reserved.

Becker, L, Popp B, Rust T, Bada JL.  1999.  The origin of organic matter in the Martian meteorite ALH84001. Life Sciences: New Insights into Complex Organics in Space. 24( Ehrenfreund P, Robert F, Eds.).:477-488., Oxford: Pergamon Press Ltd   10.1016/s0273-1177(99)00090-3   Abstract

Stable carbon isotope measurements of the organic matter associated with the carbonate globules and the bulk matrix material in the ALH84001 Martian meteorite indicate that two distinct sources are present in the sample. The delta(13) C values for the organic matter associated with the carbonate globules averaged -26 parts per thousand and is attributed to terrestrial contamination. In contrast, the delta(13)C values for the organic matter associated with the bulk matrix material yielded a value of -15 parts per thousand. The only common carbon sources on the Earth that yield similar delta(13) values, other then some diagenetically altered marine carbonates, are C(4) plants. A delta(13)C value of -15 parts per thousand, on the other hand, is consistent with a kerogen-like component, the most ubiquitous form of organic matter found in carbonaceous chondrites such as the Murchison meteorite. Examination of the carbonate globules and bull; matrix material using laser desorption mass spectrometry (LDMS) indicates the presence of a high molecular weight organic component which appears to be extraterrestrial in origin, possibly derived from the exogenous delivery of meteoritic or cometary debris to the surface of Mars. (C) 1999 COSPAR. Published by Elsevier Science Ltd.

Raggi, L, Bada JL, Lazcano A.  2016.  On the lack of evolutionary continuity between prebiotic peptides and extant enzymes. Physical Chemistry Chemical Physics. 18:20028-20032.   10.1039/c6cp00793g   AbstractWebsite

The significance of experiments that claim to simulate the properties of prebiotic small peptides and polypeptides as models of the polymers that may have preceded proteins is critically addressed. As discussed here, most of these experiments are based only on a small number of a larger set of amino acids that may have been present in the prebiotic environment, supported by both experimental simulations and the repertoire of organic compounds reported in carbonaceous chondrites. Model experiments with small peptides may offer some insights into the processes that contributed to generate the chemical environment leading to the emergence of informational oligomers, but not to the origin of proteins. The large body of circumstantial evidence indicating that catalytic RNA played a key role in the origin of protein synthesis during the early stages of cellular evolution implies that the emergence of the genetic code and of protein biosynthesis are no longer synonymous with the origin of life. Hence, reports on the abiotic synthesis of small catalytic peptides under potential prebiotic conditions do not provide information on the origin of triplet encoded protein biosynthesis, but in some cases may serve as models to understand the properties of the earliest proteins.

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Bada, JL, Sephton MA, Ehrenfreund P, Mathies RA, Skelley AM, Grunthaner FJ, Zent AP, Quinn RC, Josset JL, Robert F, Botta O, Glavin DP.  2005.  New strategies to detect life on Mars. Astronomy & Geophysics. 46:26-27. AbstractWebsite

The quest to determine whether life existed, or still exists, on Mars continues with several missions planned for the red planet by both the European Space Agency (ESA) and the National Aeronautics and Space Administration (NASA) in the next few decades. One instrument designed for these missions is the Mars Organic Detector (MOD), which uses a new approach to achieve exceptionally high detection sensitivities and analysis capabilities for key bio-organic compounds. MOD is scheduled to fly in the ESA ExoMars mission early next decade and will attempt to answer the question of whether we are alone in the solar system. Here the MOD team explains why we have reason to be optimistic about uncovering the organic secrets of Mars.

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Rivas, M, Becerra A, Pereto J, Bada JL, Lazcano A.  2011.  Metalloproteins and the Pyrite-based Origin of Life: A Critical Assessment. Origins of Life and Evolution of Biospheres. 41:347-356.   10.1007/s11084-011-9238-1   AbstractWebsite

We critically examine the proposal by W chtersh user (Prokaryotes 1: 275-283, 2006a, Philos Trans R Soc Lond B Biol Sci 361: 787-1808, 2006b) that putative transition metal binding sites in protein components of the translation machinery of hyper-thermophiles provide evidence of a direct relationship with the FeS clusters of pyrite and thus indicate an autotrophic origin of life in volcanic environments. Analysis of completely sequenced cellular genomes of Bacteria, Archaea and Eucarya does not support the suggestion by W chtersh user (Prokaryotes 1: 275-283, 2006a, Philos Trans R Soc Lond B Biol Sci 361: 787-1808, 2006b) that aminoacyl-tRNA synthetases and ribosomal proteins bear sequence signatures typical of strong covalent metal bonding whose absence in mesophilic species reveals a process of adaptation towards less extreme environments.

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Bada, JL, Zhao MX, Steinberg S, Ruth E.  1986.  Isoleucine Stereoisomers on the Earth. Nature. 319:314-316.   10.1038/319314a0   Website
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Msters, PM, Bada J, Hoopes E, Darling D.  1979.  The Dating of Fossil Bones Using Amimo Acid Racemization. Radiocarbon and other dating methods. ( and Rainer B, Ed.).:757-773., Berkley: UC Press
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Msters, PM, Bada J.  1979.  Amimo Acid Racemization dating of fossil shells from Southern California. Radiocarbon and other dating methods. ( and Rainer B, Ed.)., Berkley: UC Press
Rosa, C, Zeh J, George JC, Botta O, Zauscher M, Bada J, O'Hara TM.  2013.  Age estimates based on aspartic acid racemization for bowhead whales (Balaena mysticetus) harvested in 1998-2000 and the relationship between racemization rate and body temperature. Marine Mammal Science. 29:424-445.   10.1111/j.1748-7692.2012.00593.x   AbstractWebsite

Fifty-two eyes were collected and analyzed to estimate ages of 42 bowhead whales using the aspartic acid racemization aging technique. Between-eye and within-eye variance components for the ratio of the D and L optical isomers (D/L ratio) were estimated via analysis of variance using multiple measurements from nine whales with both eyes sampled and analyzed. For whales with more than one (D/L)(act) value, an inverse variance weighted average of the values was used as (D/L)(act) for the whale. Racemization rate (k(Asp)) and D/L ratio at birth (D/L)(0) were estimated using (D/L)(act) from 27 bowhead whales with age estimates based on baleen or ovarian corpora data and two term fetuses. The estimates were k(Asp) = 0.977x10(-3)/yr and (D/L)(0) = 0.0250. The nonlinear least squares analysis that produced these estimates also estimated female age at sexual maturity as ASM=25.86yr. SE(age) was estimated via a bootstrap that took into account the SE of (D/L)(act) and the variances and covariance of k(Asp) and (D/L)(0). One male exceeded 100yr of age; the oldest female was 88. A strong linear relationship between k(Asp) and body temperature was estimated by combining bowhead data with independent data from studies of humans and fin whales. Using this relationship, we estimated k(Asp) and ASM for North Atlantic minke whales.

Robertson, KJ, Williams PM, Bada JL.  1987.  Acid-Hydrolysis of Dissolved Combined Amino-Acids in Seawater - a Precautionary Note. Limnology and Oceanography. 32:996-997.Website