nai

Project Reports

• Mars Analog Studies: Reflectance Spectroscopy of Organics in Ancient Rocks and Meteorites

  Aside from laboratory analyses of meteorites and in situ measurements by mass spectrometers on rover and lander platforms, the search for extraterrestrial organic material on Mars, carbonaceous© chondrite parent bodies, and other planetary surfaces is primarily limited to remote sensing techniques. Our team has been exploring the use of visible and near-infrared reflectance spectros-copy for assessing the presence and abundance of organic materials preserved in ancient terrestrial rocks and C chondrite meteorites. We have continued a series of controlled laboratory experiments to analyze (1) a suite of isolated kerogens and ancient terrestrial sedimentary rocks from various depositional environments and (2) several suites of synthetic clay-organic mixtures. Our goal is to better characterize the potential of reflectance spectroscopy as a method for organic detection and quantification in planetary environments, with the benefits that this technique is rapid, non-destructive, and applicable at laboratory, rover and orbital scales. The spectral models we are de-veloping will provide a foundation for quantifying organics that may be observed in spectroscopic data returned by the Hayabusa2 and OSIRIS-REx missions, laboratory spectra of C chondrites, and future Mars missions equipped with imaging spectrometers.

  ROADMAP OBJECTIVES: 2.1 4.1 4.3 6.1

• 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, proto-planetary, and cometary ices and grains, and instrument development. This year, we continued our work analyzing the organic content of carbonaceous chondrites, including analyses of amino acids, aliphatic amines, aldehydes and ketones. We investigated model systems for potentially relevant prebiotic chemistry. We supported the Biomolecule Sequencer project for evaluating DNA-analysis in microgravity environments by flying a MinIon device on the International Space Station. We continued to support development of protocols for a liquid chromatograph-mass spectrometer aimed at in situ analyses of amino acids and chirality on airless bodies, including asteroids and outer-planet icy moons (e.g., Enceladus and Europa). We participated in numerous public outreach and education events. We continued our participation in the OSIRIS-REx asteroid sample return mission and provided support for the Sample Analysis at Mars instrument of NASA’s Mars rover Curiosity.

  ROADMAP OBJECTIVES: 2.1 3.1

• Jon Toner NAI NPP Postdoc Report

  Aqueous salt solutions are critical for understanding the potential for liquid water to form on icy worlds and the presence of liquid water in the past. Salty solutions can form potentially habitable environments by depressing the freezing point of water down to temperatures typical of Mars’ surface or the interiors of Europa or Enceladus. We are investigating such low-temperature aqueous environments by experimentally measuring the low temperature properties of salt solutions and developing thermodynamic models to predict salt precipitation sequences during either freezing or evaporation. These models, and the experimental data we are generating, are being applied to understand the conditions under which water can form, the properties of that water, and what crystalline salts indicate about environmental conditions such as pH, temperature, pressure, and salinity.

  ROADMAP OBJECTIVES: 2.1 5.2 5.3

• Life Underground

  Our multi-disciplinary team from the University of Southern California, California Institute of Technology, Jet Propulsion Lab, Desert Research Institute, Rensselaer Polytechnic Institute, and Northwestern University is developing and employing field, laboratory, and modeling approaches aimed at detecting and characterizing microbial life in the subsurface—the intraterrestrials. We posit that if life exists, or ever existed, on Mars or other planetary body in our solar system, evidence thereof would most likely be found in the subsurface. This study takes advantage of unique opportunities to explore the subsurface ecosystems on Earth through boreholes, mine shafts, sediment coring, marine vents and seeps, and deeply-sourced springs. Access to the subsurface—both continental and marine—and broad characterization of the rocks, fluids, and microbial inhabitants is central to this study. Our focused research themes require subsurface samples for laboratory and in situ experiments. Specifically, we are carrying out in situ life detection, culturing and isolation of heretofore unknown intraterrestrial archaea and bacteria using numerous novel and traditional techniques, and incorporating new and existing data into regional and global metabolic energy models.

  ROADMAP OBJECTIVES: 2.1 2.2 3.1 3.2 3.3 4.1 5.1 5.2 5.3 6.1 6.2 7.2

• Remote Sensing of Ancient Habitable Environments on Mars

  We are investigating variations in clay chemistry on Mars using CRISM, HiRISE and HRSC imagery. Initial work is focusing on the Mawrth Vallis region where aqueous outcrops are known to be varied and expansive. The mineralogy of these aqueous outcrops are under study in order to characterize and document changes in the environmental chemistry over time.

  ROADMAP OBJECTIVES: 2.1

• Characterizing Carbonate Outcrops on Mars

  Carbonate-rich rocks have been proposed for decades as a possible sink for a thicker CO₂-rich atmosphere on early Mars. We are mapping new detections of carbonates in ancient (Noachian) rocks in several regions of the martian southern highlands. These rocks represent enticing astrobiological targets for understanding paleo-environments, habitability and carbon cycling via in situ study with a future landed mission.

  ROADMAP OBJECTIVES: 2.1

• Mars Analog Studies: Mineral Assemblages in Terrestrial Settings

  It is now widely recognized that hydrated minerals, including clays, sulfates, chlorides and other salts, are important components of the martian crust. Such minerals and assemblages of minerals have the potential to record important information about past interactions between sediment, surface and groundwaters, and the atmosphere. The overarching theme of this project is to examine terrestrial analog sites to better understand how martian mineral assemblages may be used to infer these processes. Current sites include Rio Tinto, Spain and Lake Towuti, Indonesia. We have studied samples from the former and have determined that it may provide an appropriate mineralogical analog for enigmatic hydrous mineral-bearing terrains observed in Valles Marineris, Mars by orbiting spacecraft. Over the past year we have also begun to study mafic and ultramafic sediments in Lake Towuti to examine stratigraphic variations in Fe and Si-bearing mineral phases. Current results indicate these sediments and this lake system may be an appropriate mineralogical and/or chemical analog for ancient lacustrine sediments observed by the Curiosity rover in Gale Crater.

  ROADMAP OBJECTIVES: 2.1 4.1 4.3 6.1

• Analytical Protocols and Techniques for Detection and Quantitative Analysis of Complex Organics in Planetary Environments

  Robotic planetary missions enable critical in situ investigations into the character, diversity and distribution of organic compounds in their native environments. The next-generation mass spectrometers being developed for planetary exploration promise enhanced capabilities to elucidate the molecular structure of detected organic compounds via tandem mass spectrometry (MS/MS), and to disambiguate potential biosignatures via ultra high-resolution mass discrimination. The in situ detection and potential sequencing of individual organic polymers using synthetic trans-membrane nanopores is another example of an innovative technology geared towards the identification of key organic compounds. We are engaged in evaluating and extending such innovative technologies to address astrobiological initiatives on future NASA missions.

  ROADMAP OBJECTIVES: 2.1 2.2 7.1

• Project 1C: Analysis of Dissimilatory Iron-Reducing Microbial Communities in Chocolate Pots Hot Spring, Yellowstone National Park

  This study represents the first targeted exploration of the active microbial community at source vent of Chocolate Pots hot springs (CP), a warm, circumneutral pH hot spring in Yellowstone National Park. This work was motivated by previous in vitro dissimilatory iron reducing (DIR) incubations of the native microbial community present in the Fe(III) oxide deposits (hereafter referred to as “CP oxides”) near the vent. DIR has the potential to generate distinct signatures of microbial Fe redox metabolism, and identification of the microbial assemblages involved in this metabolism is important for making a concrete linkage between biological metabolism and the generation of geochemical and isotopic biosignatures in relation to redox gradients on Earth and other rocky planets. The central goal of this study was to obtain a phylogenetic and metagenomic characterization of the active acetate-oxidizing DIR community at CP using ¹³C stable isotope probing (SIP) techniques. CP oxide sediments and spring water were collected from the CP vent source and used to initiate in vitro SIP incubations using labeled (¹³C) and unlabeled acetate. Incubations targeted the active microbial community which is capable of coupling the oxidation of acetate to DIR. The SIP results allowed us to clearly separate the active acetate-metabolizing microbial community from the rest of the community and identify which organisms native to CP make up this population. The role of some members of this community can be inferred with reasonable confidence from the phylogeny of the OTUs from the amplicon libraries (e.g. Geobacter, Ignavibacteria), and the design of the incubations. The metabolic role of other dominant taxa is less well understood at this point and we are preparing to submit samples for shotgun metagenomic sequencing to address these questions.

  ROADMAP OBJECTIVES: 2.1 4.1 5.1 5.3

• Understanding Ancient Aqueous Environments on Mars

  Project 1: The goal of this project is to characterize ancient aqueous environments on Mars using Digital Terrain Model (DTM) analysis and mapping to understand the potential environments for past habitability. These include fluvial environments with morphological evidence for ponding, associated with hydrothermal systems and multiple episodes of surface and near surface flow in channelized systems. We will determine sediment and eroded volumes of fluvial landforms from DTM analysis and use transport equations and terrestrial analogs to understand likely discharges and flow durations.

  ROADMAP OBJECTIVES: 1.1 2.1 7.1

• Project 1D: Comparative Genomic Analysis of Chemolithotrophic Fe(II)-Oxidizing Bacteria

  A comparative genomic analysis was performed to identify candidate genes involved in extracellular electron transfer (EET) by Fe(II)-oxidizing bacteria (FeOB). The analysis included a variety of publically-available FeOB genomes, together with genomes from FeOB isolated from subsurface sediments, previously-isolated marine basalt-associated FeOB, and metagenomes from chemolithoautotrophic aerobic pyrite-oxidizing and nitrate-reducing Fe(II)-oxidizing enrichment cultures. We identified outer membrane multi-copper oxidase (MCO) genes homologous to proteins known to be involved in EET in several of the FeOB genomes, as well as homologs to the outer membrane c-type cytochrome (ctyc) Cyc2 known to be involved in bacterial Fe(II) oxidation by Acidithiobacillus ferrooxidans under acidic conditions. Further, we found gene clusters that may potentially encode novel “porin-cytochrome-c protein complex” (PCC) in the well-known neutral-pH FeOB S. lithotrophicus ES-1, and homologous operons were found in other recognized FeOB (Leptothrix cholodnii SP-6 and Leptothrix ochracea L12. Another gene cluster consisting of a porin and three periplasmic multiheme cytc was identified in Hyphomicrobium sp. genome retrieved from a pyrite-oxidizing enrichment culture, and its homologous gene clusters are also present in five marine Zetaproteobacterial FeOB genomes. Overall, this analysis, which is based on our current understanding of bacterial EET in Fe redox reactions, provides a list of candidate genes for further experimental and genomic studies.

  ROADMAP OBJECTIVES: 2.1 3.2 4.1 5.1 5.3

• Exploring the Evolution of the Water and Organic Reservoirs in the Solar System

  This project investigates the evolution and stability of water and organic reservoirs in our Solar System, with particular emphasis on the characterization of the current and ancient habitability of planet Mars. We employ extremely powerful observatories (e.g., ALMA, Keck, VLT, future JWST) to acquire high spatial and spectral resolution maps of the isotopic and organic signatures on several bodies in the Solar System. These maps allow us to investigate the stability and evolution of their atmospheres, while localized plumes can be used to identify regions of active release. In this reporting period, we emphasized three areas:

  1. We advanced our pioneering work on characterizing the evolution of water on Mars, by developing a new observational plan that combines the power of ALMA, of Keck and of MAVEN to obtain maps of the water D/H signatures on Mars.

  2. We identified previously unknown chemical processes affecting singlet-O₂ and odd-oxygen on Mars, which may be indicative of a much more active photochemical cycle (with the possible intervention of heterogeneous processes).

  3. We provided science leadership in the investigation of Mars with the James Webb Space Telescope (JWST), and established a variety of observing modes and scientific opportunities.

  ROADMAP OBJECTIVES: 1.1 2.1 3.1 3.2 4.1 7.1

• Mars Analogs: Habitability and Biosignatures in the Atacama Deser

  This project focuses on the study of habitability in the Atacama Desert of northern Chile, one of the driest regions on Earth. We want to understand how life adapts and survives in an environment where liquid water is exceedingly rare, and how biosignatures are preserved in that environment after microorganisms die. These studies can become a very useful guide for future robotic missions to Mars. This year we focused on microbial communities that inhabit the interior of salt nodules in evaporitic lake deposits. These are the only known active microbial comunities in the driest parts of the Atacama. We wanted to understand how these microbial communities survive in an environment that excludes every other form of life. We suspected that the salt communities use atmospheric water vapor as a source of water to run their metabolic processes. We showed that this is indeed the case with a combination of field and laboratory tools. Our results suggest that the salt substrate could be one of the last possible habitats for life in extremely dry environments.

  ROADMAP OBJECTIVES: 2.1 5.1 5.3 6.1 6.2 7.1 7.2

• Project 1F: Study of Modern Fe-Mn Nodules in Green Bay Sediments as Analog to the Fe-Nodules and Fe-Oxyhydroxide Minerals on Mars

  Fe-oxide nodules and concretions are common in terrestrial sedimentary rocks and also occur in Martial sediments. The precursors of the hematite are nano-phases of Fe-oxyhydroxides. Modern Fe-Mn nodules from Green Bay sediments were investigated by in-situ XRD, scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), Z-contrast imaging, and ab-initio calculations using the density functional theory (DFT) method. Nano-phase minerals for hosting trace elements of As, P, Ba, Co, Ni, and Zn have been identified. Structural sites of the trace elements and their incorporation mechanisms are also proposed. The Fe-Mn nodules can be used as analog for understanding the Fe-nodules and Fe-oxyhydroxide minerals on Mars.

  ROADMAP OBJECTIVES: 2.1 7.1

• Biosignature Capture and Preservation in Sulfate Evaporite Deposits

  Sulfate minerals are regarded as key exploration targets for Mars sample return. These minerals form in liquid water over a broad range of environmental conditions, thus providing sensitive measures of past habitability. We are studying the preservation potential of fossil kerogen in Miocene sulfate deposits of the Camp Verde Formation, central AZ. The primary tools used in the study were selected to emulate capabilities of the Mars 2020 payload. Our results suggest ways to enhance in situ kerogen detection in sulfates, as well as operational synergies that may improve mission operations.

  ROADMAP OBJECTIVES: 2.1 7.1

• Detection of Biosignatures

  The project is developing methods of interpreting data, detecting novelty, and identifying biosignatures in data at multiple scales (Figure 1). Investigation will improve detection and decrease diagnostic uncertainty in selecting high-probability regions and high-priority samples. In year one, objectives are to develop algorithms for orbital data analysis and feature extraction and to develop algorithms for novelty detection.

  ROADMAP OBJECTIVES: 2.1 2.2 7.1 7.2

• Project 7: Mining Archaeal Genomes for Signatures of Early Life: Comparison of Metabolic Genes in Methanogens

  Methanogens represent the largest diversity among the archaea and have the unique ability to generate methane from simple compounds such as carbon dioxide, acetate and methylamines which were common in the anaerobic environments of early Earth and perhaps Mars. Methane biosynthesis also requires the presence/uptake of important ions such as sulfates, sulfides, carbonates, phosphates, and various light metal ions. In this project, we are attempting to analyze the evolution of the methanogens’ central cellular functions of translation, transcription, replication, and metabolism. To accomplish this, we are constructing the metabolic and regulatory networks of Methanosarcina acetivorans, the most complex methanogen known, and using these models to establish a framework for studying the evolution of methanogens. Results will be tested through microfluidic studies using varying carbon and ion sources.

  ROADMAP OBJECTIVES: 1.1 2.1 3.1 3.2 3.3 3.4 4.1 4.2 5.1 5.2 5.3 6.1 6.2 7.1

• Subglacial Environments as Water‐Rock Hosted Microbial Ecosystems

  Glaciers, ice sheets and ice caps cover ~11% of the earth’s surface, and likely covered up to 100% during Neoproterozoic glaciations. The beds of these ice masses can have significant sectors at the pressure melting point. The resulting water lubricates ice sliding and accelerates erosion, provides habitat for subglacial microbial ecosystems, and may have acted as refugia during past global glaciations on Earth. Such environments may also act as habitats for life on other planetary bodies.

  Grinding of bedrock by glaciers exposes fresh mineral surfaces capable of sustaining microbial metabolism. The foci of RPL investigations on subglacial environments are categorized into two key areas of relevance to habitability studies: i) determine the extent to which minerals support chemotrophic metabolism and the production of biosignatures (e.g., weathering products), and ii) quantifying the influence of water-rock interactions in supplying substrates to support energy metabolism. Through these interdisciplinary and collaborative studies, we aim to characterize the active microbial processes in subglacial environments and to define the sources of energy that sustains this microbial life.

  ROADMAP OBJECTIVES: 2.1 5.1 5.2 5.3 6.1 6.2 7.2

• Laboratory Investigations Into Chemical Evolution in Icy Solids: Mars, Carbonaceous Meteorites, and ISM

  The goal of this project is to investigate chemical and physical changes and properties of molecules in low-temperature environments, such as found in interstellar space and the outer regions of the Solar System. Some of the molecules studied have been detected in meteorites and samples returned from NASA missions.

  ROADMAP OBJECTIVES: 2.1 2.2 3.1

• Characterization of Habitability and Biosignature Preservation in Cold Springs

  In an increasingly colder Mars where permafrost was thickening, mineralizing cold springs could have provided extant subsurface habitats and a means to transport evidence of subsurface life to the surface. Depending on conditions and geochemistry, these precipitates could have encapsulated a record of past life, and the residual remnants of such spring mounds could still be exposed at the martian surface. On Earth, high latitude spring systems are rare due to the relatively impermeable permafrost. However, several groups of perennial springs are located at Axel Heiberg Island in the Canadian High Arctic (~80°N). With mean annual air temperatures of -17°C and permafrost depths ≥ 600 meters, these springs flow throughout the year despite minimum air temperatures reaching <-50°C during winter. Thick residual icing pastes form as a result of evaporation, sublimation and freeze fractionation, the mineralogy being dominated by halite, hydrohalite, calcite, gypsum, elemental sulfur, thenardite, and mirabilite. These springs provide an environment where prokaryotes thrive despite extreme conditions and their presence suggests that such systems could have been present throughout Mars history, and activated during cyclical climate changes.The primary goal of this investigation is to evaluate the potential of spring deposits in regions with thick, continuous permafrost and define their taphonomic window and biogeological context. Samples of icing pastes, travertine and other mineral precipitates have been sampled to understand the relationships between geochemistry, environment, presence of biosignatures and their potential preservation.

  ROADMAP OBJECTIVES: 2.1 4.1 7.1

• Lake Sediment Habitats; Lake Habitability and Sediment Biosignatures

  Regions where lakes and ponds existed once existed on Mars martian are among the highest priority environments for exploration. The physicochemical and biological characteristics of the unique of perennially ice-covered lake ecosystems found on earth in Antarctica, the High Arctic, and in high altitude environments (Altiplano and High Andes) serve as important analogs of earily Mars. Active and abundant microbial communities live in these extreme environments, suggesting the presence of habitable conditions on early on Mars. Unlike temperate lakes, these ecosystems are largely dominated and constrained by their physical environment (e.g., mean annual temperatures near or well below 0°C, with arid or hyper-arid conditions year-round). In these environments, lake sediments accumulate organic biosignatures due to relatively low metabolic rates and cold water. Less understood is their preservation potential once the water evaporates, and sediments are exposed to extreme cold and hyper-arid conditions. Perennially ice-covered lakes are rare on Earth. Their dry, paleo-counterparts are even more exotic, and biosignature preservation in such lake deposits remains largely unstudied. Lake Untersee, one of the largest perennially ice-covered surface lakes in East Antarctica hosts a robust microbial ecosystem including the presence of photosynthetic microbial mats that colonize the lake bottom to depths greater than 100m. These mats are primarily composed of filamentous cyanophytes and form two distinct macroscopic structures – cm-scale cuspate pinnacles dominated by Leptolyngbya spp. and laminated, large conical stromatolites that rise up to 0.5 m above the lake floor, dominated by Phormidium spp. (Andersen et al. 2011). Adjacent to Lake Untersee is the Aurkjosen Cirque, a basin that was once inundated by a large lake which has since evaporated. Desiccated, buried microbial mats have been recovered from this paleo- lacustrine site, and they provide material for the identification of biosignatures and their preservation in and extremely cold setting. Our investigations include the studies of the physical and biogeochemical characteristics of the two lakes, deposition and preservation of biomarkers, and in situ analytical techniques (IR reflectance, Raman, XRD/XRF) to identify organic signatures within a mineralogical context while developing synergistic operational concepts for in situ analyses in paleolake analogs.

  ROADMAP OBJECTIVES: 2.1 4.1 7.1

• Mars Analog Studies: Ice Covered Lakes on Earth and Mars

  Ice-covered lakes in Antarctica provide models for sedimentary processes on ancient Mars and microbial ecosystems for early Earth. Ice affects sedimentation because sand grains can be blown onto the ice, where they can eventually go through the ice into the lake below. Understanding the details of these processes and resulting sediments will allow us to better reconstruct details of lake environments and their implications for climate on early Mars. Early Earth ecosystems, and those on early Mars if life ever existed there, consist exclusively of microorganisms, which is also true for many Antarctic lakes. Thus, these lakes provide the opportunities to investigate ecological principles for early ecosystems. Data from the microbial mats in these lakes are providing insights into the growth of stromatolite, the geochemical impacts of oxygen-producing photosynthesis, and environments that may have promoted the early diversification of animals.

  ROADMAP OBJECTIVES: 2.1 4.1 4.2 5.1 5.2 6.1

• The MER Mission to Mars

  NAI team member Andrew Knoll continued to work as part of the science team for the MER mission to Mars. Exploration continues along the clay-rich lip of Endeavor crater. Publications in 2015 include a synthesis of recent research in the Endeavour region and a analysis of Mn-bearing surface features exposed along Murray Ridge.

  ROADMAP OBJECTIVES: 1.1 2.1

• Environmental and Biological Signatures in Yellowstone National Park Silica Precipitating Hot Springs

  Radiation from the Sun potentially affects solids, liquids, and gases found on the surfaces of planets. Radiation exposure could change the chemical and mineralogical make-up of the surface materials. Sample-return missions aim to collect samples, cache them for a period of time, and then return them to Earth for additional analysis. We have performed field experiments to document environmental radiation levels and exposures and their impact on recently formed materials and associated organic matter.

  ROADMAP OBJECTIVES: 1.1 2.1 6.1 7.1 7.2

• Rock Sample Biosignature Library and Automated Identification of Biosignatures

  The goals of this project are to: 1) build a Raman spectra and imaging library of rock samples containing biosignatures as no publically available online sample library currently exists; and to: 2) use this library as testing and training sets to develop automated classifiers for identifying biosignatures in rock spectra. Building a sample library and developing automated classifiers would enable field scientists or robotic explorers on the surface of Mars or elsewhere to automatically identify biosignatures in rock samples from Raman spectra out in the field.

  ROADMAP OBJECTIVES: 1.1 2.1 7.1

• The MSL Mission to Mars

  The overall scientific goal of the Mars Science Laboratory (MSL) mission is to explore and quantitatively assess a local region on Mars’ surface as a potential habitat for life, past or present. The MSL rover carries ten scientific instruments and a sample acquisition, processing, and distribution system. The various payload elements work together to detect and study potential sampling targets with remote and in situ measurements; acquires samples of rock, soil, and atmosphere and analyze them in onboard analytical instruments; and to observe the environment around the rover. MSL has been investigating a site that shows clear evidence for ancient aqueous processes based on orbital and ground-based data and has been undertaking a search for past and present habitable environments.

  ROADMAP OBJECTIVES: 2.1

• Modeling Habitable Environments Generated by Water/rock Reactions

  This project within the RPL NAI seeks to develop a framework for predicting biological potential (for example, volumetric biomass abundance) as a function of enviromental variables such as rock and fluid composition, water-to-rock ratio, and temperature. Building on the prediction that energy availability will be a key limitation in subsurface systems, we evaluating how variabliity in these environmental factors changes the potential to generate energy through particular metabolisms, and how that potential compares to the corresponding energetic demands of life within a particular set of physicochemcial conditions. We inform and ground truth this approach by comparing the landscape of energy availability in natural systems, such as the CROMO system, to the distribution of microorganisms observed there.

  ROADMAP OBJECTIVES: 2.1 2.2

• Undergraduate Research Associates in Astrobiology (URAA)

  2015 saw the twelfth session of our summer program for talented science students (Under-graduate Research Associates in Astrobiology), a ten-week residential research program tenured at Goddard Space Flight Center and the University of Maryland, College Park (http://astrobiology.gsfc.nasa.gov/education.html). Competition was again very keen, with an over-subscription ratio of 4.7. Students applied from over 19 Colleges and Universities in the United States, and 4 Interns from 4 institutions were selected. Each Intern carried out a defined research project working directly with a GCA scientist at Goddard Space Flight Center or the University of Maryland. As a group, the Associates met with a different GCA scientist each week, learning about his/her respective area of research, visiting diverse laboratories and gaining a broader view of astrobiology as a whole. At summer’s end, each Associate reported his/her research in a power point presentation projected nation-wide to member Teams in NASA’s Astrobiology Institute, as part of the NAI Forum for Astrobiology Research (FAR) Series.

  ROADMAP OBJECTIVES: 1.1 1.2 2.1 2.2 3.1 6.2 7.1

• Taphonomy of Microbial Ecosystems

  We perform experiments to understand shapes, molecules and isotopic signals of microbial processes in modern and old sediments. Experimental studies of microbial interactions with sediments, ions in the solution and the flow help us elucidate mechanisms that may have shaped sandy surfaces and preserved fossils on these surfaces at the dawn of animal life. Culture-based studies of isotopic fractionations produced by microbial processes and microbial membrane lipids help us interpret corresponding signals in the rock record and modern environments.

  ROADMAP OBJECTIVES: 2.1 4.1 4.2 5.1 5.2 6.1 7.1 7.2