2014 Annual Science Report
NASA Goddard Space Flight Center Reporting | SEP 2013 – DEC 2014
Analysis of Prebiotic Organic Compounds in Astrobiologically Relevant Samples
The Astrobiology Analytical Laboratory (AAL) of the GCA is dedicated to the study of organic compounds derived from past and future sample return missions, meteorites, lab simulations of Mars, interstellar, protoplanetary, and cometary ices and grains, and instrument development. This year, we continued our work analyzing the organic content of carbonaceous chondrites, expanding beyond our previous amino acid and nucleobase analyses to determine distribution and abundances of pyridine carboxylic acids and aliphatic amines. We investigated the effects of cosmic ray irradiation on amino acids. We supported development of a liquid chromatographmass spectrometer aimed at in situ analyses of amino acids and chirality on airless bodies including asteroids and the outer planet’s icy moons Enceladus and Europa. We hosted an undergraduate and participated in numerous public outreach and education events. We continued our participation in the OSIRISREx asteroid sample return mission and provided support for the Sample Analysis at Mars instrument of NASA’s Mars rover Curiosity.
We analyzed the abundances, structural and enantiomeric distributions, and stable carbon isotopic ratios of amines in the Murchison meteorite. This resulted in the first published isotopic and enantiomeric measurements of meteoritic amines. This work allows the comparison of these compounds with other meteoritic organics such as amino acids, leading to a better understanding of prebiotic chemistry pathways.
We continued our research into the abundance and distributions of amino acids in a variety of meteorites, including the Sutter’s Mill CM2 carbonaceous chondrite and several CI carbonaceous chondrites. This ongoing work provides insights into the effects of parent body processing on meteoritic organic compounds. We have now characterized amino acids in all eight carbonaceous chondrite classes as well as certain other meteorites; see Figure 1 to see how amino acid abundances vary across different meteorite classes.
We collaborated with researchers from the IPTAI team (former NAI team) to examine the racemization rate of aspartic acid, helping to understand how the D/L ratio of aspartic acid in biological samples can be used as a tool to understand carbon turnover times.
We investigated the distribution and abundances of pyridine carboxylic acids in eight CM2 chondrites by means of liquid chromatographymass spectrometry. Nicotinic acid (pyridine-3-carboxylic acid) is a precursor to nicotinamide adenine dinucleotide, a likely ancient molecule used in cellular metabolism, and its common occurrence in CM2 chondrites may indicate that meteorites may have been a source of molecules for the emergence of more complex coenzymes on the early Earth. A NASA Goddard web feature was issued and this research received media attention.
We investigated the effect of cosmic rays on amino acids in meteorites, irradiating the Murchison meteorite to simulate the effects of cosmic ray exposure on the surface of an asteroid. We found that the amino acids in Murchison decompose at the same rate as pure amino acid standards and after 2 MGy (MegaGrays) of gamma ray exposure, approximately 30% of the original amino acids present were destroyed. We also found that there was no change to the amino acid chirality or carbon isotopic composition after gamma ray exposure. These results have important implications for interpreting the amino acid composition of near-surface samples returned from carbonrich asteroids by the Hayabusa 2 and OSIRIS-REx missions.
We supported the ASTID-funded development of a miniaturized LC-MS for in-situ analyses of amino acids and other soluble organics on icy planetary surfaces (ASTID PI Stephanie Getty). Our state-of-the-art laboratory equipment was used for component testing and method development.
Dworkin continued to serve as Project Scientist for the OSIRISREx New Frontiers-3 asteroid sample return mission, which addresses the Astrobiology Roadmap goal of determining chemical precursors of life in the solar system. Glavin is a Co-I, while Elsila and Callahan are Collaborators. The Astrobiology Analytical Lab is heavily involved in this mission, both in the Contamination Control and Contamination Knowledge areas, radiation experiments to understand the effect of space weathering on amino acids and other organics in meteorites, and in the eventual analysis of returned asteroidal material. The infrastructure, in part provided by NAI funding, continues to be used in OSIRISREx analysis in support of the development of an innovative contamination control approach to preserving chemistry important to astrobiology under a limited budget. This approach has been praised by independent science and engineering reviewers and is likely to be the template for contamination control for Mars sample return.
We hosted one undergraduate (Christina Nevin, Siena College) as part of the GCA summer program, Undergraduate Research Associates in Astrobiology (URAA).
Glavin was part of a radio podcast for NPR on research done in the Astrobiology Analytical Laboratory and what we hope to learn from the OSIRISREx sample return mission to asteroid Bennu.
PROJECT MEMBERS:Jason Dworkin
RELATED OBJECTIVES:Objective 2.1
Sources of prebiotic materials and catalysts