2003 Annual Science Report

NASA Johnson Space Center Reporting  |  JUL 2002 – JUN 2003

Organic Biosignatures

Project Summary
4 Institutions
3 Teams
0 Publications
0 Field Sites
Field Sites

Project Progress

We have divided our MASSE Development Project and our organic analysis of Martian meteorites projects and combined the sciences into 2 categories: Organic Biosignatures and New Technique Development and Applications.

The acronym for MASSE comes from Microarray Assay for Solar System Exploration. The NASA Fundamental Biology Program has supported early development, but the project has transitioned over to an Astrobiology Institute project. Other acronyms used by us for the same general concept include MIDI (Mars Immunoassay Detection Instrument), PASO, Protein Array Sensor for Organics, and one or two others. We work extensively with Carnegie and Montana State to develop reliable and robust biosignatures. The goal for MASSE research is to develop a flight worthy instrument. Much of the instrumentation aspects will be the focus of the New Techniques project report. We have now proven the instrument concept and have been busy working on the background science to test the MASSE instrument prototypes.

Antibody selection is critical to the success of MASSE instrument. Jake Maule from Carnegie conducts the study of the antibody to hopane at NASA JSC. Hopane is an organic molecule only found in bacterial walls and is extremely stable over geologic time. Hopane antibody development and testing has progressed to rock samples and low gravity experiments. Hopane antibodies reacted with 3-hydroxyhopane, hopane and sediments from the Enspel formation, Germany – known to contain high levels of hopane. (Jan Toporski, personal communication). Little cross-reactivity was observed between hopane antibodies and BAP-13 (BAP-13 is a commercially available anti-polycyclic aromatic hydrocarbon (PAH) antibody).

We will use many other different techniques to analyze samples and use a variety of common materials the astrobiology community uses in biosignature research. The types of test samples are interplanetary dust particles (IDPs), lunar samples, meteorites such as Murchison and Tagish Lake and Martian meteorites, and terrestrial samples such as rock varnish and Archean samples from the Pilbara in Western Australia. The goal of this wide range in samples is to better understand terrestrial organics versus indigenous organic material inherent in every rock and provide a more clear understanding of what constitutes an organic biosignature.

Work by Dr. Flynn, Dr. Clemett and Dr. Keller have used infrared spectroscopy as a well-established technique for the identification of organic functional groups. We examine ALH84001 samples (as well as other meteorites and IDPs) using much more sensitive Fourier Transform InfraRed (FTIR) instruments, consisting of conventional Spectra-Tech IRms and Nicollet Continuum FTIR microscopes coupled to a synchrotron-generated infrared beam that achieves ~1,000 times the intensity of a conventional global infrared source. We have also employed the STXM to search for organic matter in an ultramicrotome section of an ALH84001 carbonate globule consisting of three different types of carbonate: an inner core of Fe-rich carbonate and an outer rim of Mg-rich carbonate separated by a band of porous carbonate. We also performed C-XANES spectroscopy on each of the three regions, and found two large pre-edge absorptions, one at ~285 eV, characteristic of the C-ring functional group, and a second at ~288.5 eV, characteristic of carbonyl (C=O). The presence of carbonyl demonstrates that this carbon is organic, while the C-ring is consistent with the detection of PAHs associated with the carbonate globules. We found that carbon was approximately uniformly distributed throughout the carbonate, although the C-ring and C=O to total carbon (which is mainly in carbonate) is highest in the rim carbonate (Flynn et al., 1988; Flynn et al., 1989).

Other organic analysis work from Dr. Flynn includes the preservation of organic matter in fossils. The presence of organic carbon in the likely position of cell walls in a population of spheres having a small range of radii might well serve as a biosignature. Although the traditional view is that organic carbon is easily destroyed in the fossilization process, we have recently demonstrated that carbon is still present in detectable concentrations in the walls of certain Eocene and early-Devonian fossils that they examined using the STXM, and that C-XANES spectra of that carbon demonstrate indicate that it is organic. The C-XANES spectra of organic matter in the cell walls of terrestrial bacteria are quite distinct from the spectrum of the abiotic organic matter in interplanetary dust particles and meteorites. We expect that bacterial protein will degrade with time. The focus of this effort is to determine how long after the onset of fossilization the C-XANES spectrum remains distinct from abiotic organic matter. Initially we will examine samples of recent desert varnish, Bahamian stromatolite, and the Warawoona formation (~3.5 Ga old) to determine if any carbon remains. If so, we will measure its C-XANES spectrum, and determine how long it takes for the signature of proteins to disappear.