"Is it true that scientists at NASA are looking for life on the moons of Jupiter?"
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2009 DDF Selections
The NASA Astrobiology Institute is pleased to announce selections for research awards resulting from its 2009 Director’s Discretionary Fund competition. The selections embody a broad range of research topics, from the early habitability of Mars, to the evolution of microbial and more complex life, the origin and nature of meteoritic organics, ecosystem change and evolution, and the limits of life. Approximately $1.2M are allocated toward these awards.
Selections were based on external reviews, with selection priority given to proposals that
- integrate the research of and realize synergies among the current NAI teams;
- expand the scope of NAI research and the NAI community in innovative ways, accepting some risk in return for high pay-off potential;
- respond in a timely way to new scientific results or programmatic opportunities;
- develop connections between astrobiology research and other NASA science programs, particularly NASA’s Earth Science Program;
- directly support flight programs, particularly through instrument development; and/or
- use funding particularly effectively, for example through leveraging or building on past investments.
Selected Research Projects
Title: Water Inventory and Microbial Habitability of Early Mars During the Late Heavy Bombardment
Lead Investigator/Home Institution/NAI Team Affiliation: Oleg Abramov, U. Colorado (CUB)/U. Hawaii (UH) Team
Co-Investigators/Home Institutions: Steve Mojzsis, CUB; Karen Meech, Gal Sarid, Jeff Taylor, Norbert Schorghofer, Steve Freeland, UH.Summary:
We propose to apply existing models of impact-related thermal processes to evaluate the habitability of early Mars. In particular, we will investigate how impacts may have compromised (or enhanced?) the habitability of Mars’surface and crust in its Noachian Eon, or before ~3.8 Ga, particularly during the Late Heavy Bombardment at 3.9 Ga.
Title: The Evolution of Biological Metal Utilization: Integration of Genomic and Geologic Knowledge
Lead Investigator/Home Institution/NAI Team: Chris DuPont, J. Craig Venter Institute (JCVI), Arizona State Univ. (ASU) and Montana State Univ. (MSU) Teams
Co-Investigators/Home Institutions: Ariel Anbar, ASU; John Peters, Eric Boyd, MSU; John McCraw JCVI.Summary:
Metals are a fundamental part of the make-up of life. In particular, they are incorporated into very specific metal-binding sites within proteins where they serve vital structural and catalytic functions. With this in consideration, the dramatic, many-orders-of-magnitude shifts in environmental metal concentrations that are hypothesized to have occurred over Earth’s history are of particular significance. Essentially, the availability of trace metals likely place significant constraints on the evolution of both specific biochemical pathways and entire lineages of life. To examine this possibility, the distributions of specific metal-binding protein structures within fully sequenced genomes of organisms will be determined. In parallel, a phylogenomic reconstruction of protein evolution will provide relative ages for each of the different metal-binding protein structures. Together, these datasets will provide estimates of the age of modern proteomes and biochemical pathways.
Title: Minerals to Enzymes: The Path to CO Dehydrogenase/Acetyl – CoA synthase
Lead Investigator/Home Institution/NAI Team Affiliation: John Peters, MSU Team
Co-Investigators/Home Institutions: Greg Ferry, PSU; Joan Broderick, Robert Szilagyi, MSU; Mike Russell, JPL Icy Worlds Team; Martin Schoonen, SUNY Stony Brook/MSU Team.Summary:
Iron-sulfur-cluster-containing metalloenzymes catalyze key chemical transformations, their roles in overcoming barriers for early life in nitrogen, hydrogen, and energy metabolism being of paramount importance. Another representative of the complex iron-sulfur enzyme class that is related to hydrogenase and nitrogenase at the level of organometallic reactive sites is carbon monoxide dehydrogenase/acetyl CoA synthase. A nickel-iron-sulfur enzyme complex that catalyzes reversible carbon monoxide oxidation and carbon-carbon bond formation arguably was key to early carbon metabolism. We propose the creation of a strong distributed NAI team to tackle the reversible carbon monoxide oxidation / carbon-carbon bond formation problem in the context of the origin of life. The distributed team will examine the links between abiotic and biotic NiFeS motifs through the synthesis and characterization of the physical and catalytic properties of NiFeS clusters coordinated by short peptides.
Title: Thermodynamic Efficiency of Electron-transfer Reactions in Purified Photosystem I and II Complexes in the Chlorophyll d-containing Cyanobacterium, Acaryochloris marina
Lead Investigator/Home Institution/NAI Team Affiliation: Nancy Kiang, NASA Goddard Institute for Space Studies (GISS)/VPL @ U. Washington Team
Co-Investigators/Home Institutions: David Mauzerall, Rockefeller Univ.; Steven Mielke, GISS; Robert Blankenship, Washington U.Summary:
To support NASA’s goal to discover and characterize life on extrasolar planets, the investigators have been conducting research to constrain the range of plausible biosignatures that could be produced by photosynthesis that is adapted to other star types than the Earth’s Sun, in particular the spectral absorbance signature of photosynthetic pigments. Our driving question is to find out if there is an upper bound on the useful photon wavelength to drive oxygenic photosynthesis, and thereby determine predictive rules for main wavelength(s) for this process should it arise on a planet with a different kind of parent star from the Earth’s Sun. Until recently, chlorophyll a (Chl a) was the only known photopigment involved in oxygenic photosynthesis, utilizing photon energy in the red, but a cyanobacterium, Acaryochloris marina, was discovered to have Chl a substituted with Chl d, utilizing photons in the far-red/near-infrared, yet is still able to perform oxygenic photosynthesis. A. marina is adapted to an environment depleted in visible light and enriched in the far-red/near-infrared, with implications that oxygenic photosynthesis with different photosystem absorbance spectra in alternative spectral radiation environments is entirely plausible. To quantify the difference, if any, in thermodynamic efficiency in the photon energy use in A. marina compared to Chl a-utilizing photosystems, and hence to bound the possible long wavelength limit for oxygenic photosynthesis, we have been performing photoacoustic measurements on intact photosynthetic bacteria cells, under a funding from the 2008 NAI DDF. This funding request is to extend this work by performing these measurements on purified photosystem complexes from A. marina, to partition the energy losses along different components of the electron transfer pathway. Partitioning these components will allow us to narrow down the key adjustments that have occurred in A. marina in comparison to what is known in the Chl a-utilizing photosystems.
Title: Fostering Synergetic Interactions Among NAI Teams Reconstructing Early Life on Earth, and Attaching a Time Scale to the Genomic Record of Life
Lead Investigator/Home Institution/NAI Team Affiliation: Jim Lake, UCLA/Georgia Inst. Tech. Team
Summary:
Phylogenomics can determine when new biological functions arose, such as oxygenproducing photosynthesis or methanogenesis, by mapping the first appearance of novel genes. By correlating the appearance of these new genes with the timing of specific geological, paleontological, astronomical, and climatological events, we can attach a time scale to the evolution of life on Earth.
Today there is a nearly universal consensus that a tree cannot describe the early evolution of life. Recent work in press in Nature (Lake 2009), however, provides evidence that the double membrane, Gram negative, prokaryotes originated as the result of an endosymbiosis between prokaryotes. Hence the evolutionary path of the double membrane group is represented by a specific ring, rather than by a tree. This group, which includes the Cyanobacteria and other intriguing prokaryotes, has profoundly altered life on Earth by producing 20% of the Earth’s atmosphere. Knowledge of the specific ring topology that accounts for the emergence of the double membrane group allows us to determine when the ring formed and to attach a reliable time scale to this part of the “tree of life”, thereby reducing the large errors introduced by the use of inadequate tree models.
Here, we propose to determine more accurately the time of important innovations on Earth, including the appearance of oxygenic photosynthesis. Funds are requested to organize and run a Strategic Planning-based Winter meeting for NAI team members from diverse Earth-related sciences broadly related to this proposal and for a graduate student to perform these studies.
Title: Following the Biogenic Elements in the CR Chondrites: An NAI Consortium Study
Lead Investigator/Home Institution/NAI Team Affiliation: Dante Lauretta, U. Arizona (UA)/ASU Team
Co-Investigators/Home Institutions: Sandra Pizzarello, ASU; Devin Schrader, UA; Gary Huss, UH; Tom Zega, NRLSummary:
The Renazzo-like carbonaceous chondrites (CR) are among the most primitive material in the Solar System. Like the thoroughly studied CI and CM chondrites, the CR chondrites have experienced extensive aqueous alteration. The CR chondrites thus represent only the third highly aqueously altered asteroid sampled in the meteorite collection.
Preliminary work shows that the amino acids, amines and aldehydes in CR chondrites differ significantly from those of CM chondrites in both overall abundances and molecular distribution (Pizzarello and Holmes, 2009). We propose a comprehensive consortium study of the CR chondrites, using expertise across four institutions: ASU, UA, UH, and CIW. Consortium PI Dante Lauretta oversees the effort and supervises graduate student Devin Schrader, who performs comprehensive characterization of the mineralogy, petrology, and geochemistry of the CR chondrites using optical microscopy, electron microprobe analysis, and ICP-MS. Sandra Pizzarello uses GC-MS to measure the abundances, distribution, isotopic compositions, and chirality of organic molecules. Gary Huss leads the analysis of O-isotopic ratios in key mineral phases representing both the anhydrous and aqueously altered population. Tom Zega performs FIB-TEM studies of the crystallography and atomic scale microstructure of representative phases. Ultimately, this work provides insight into the origin of the hydrated phase and associated organics in the CR chondrites.
Title: Remote Sensing of Microbial and Plant Abundance and Diversity in SF Bay Salt Ponds: Principles Shaping the Future of Life on Earth and Beyond
Lead Investigator/Home Institution/NAI Team Affiliation: Rocco Mancinelli, SETI Institute/MSU Team
Co-Investigators/Home Institutions: Lee Johnson, Monterey Bay Aquarium Research Institute; Stephen Dunagan, NASA Ames Research Center (ARC), Dana Rogoff, SETI InstituteSummary:
Monitoring restoration of San Francisco Bay’s hypersaline ponds provides opportunity to observe habitat change and ecosystem evolution on a relatively short time scale. We propose a remote sensing aerial platform to track habitat changes over this large region. Equipment upon the local airship, Zeppelin NT, and high-resolution images will be compared to ground-truth measurements and satellite imagery for confirmation. Habitat maps created will be distributed through the SETI Institute website.
Our Objectives are: 1) Correlate salinity levels in aquatic habitats with microbial populations and diversity; 2) Determine the habitat type cover in terrestrial regions surrounding the South Bay’s former salt ponds; 3) Develop an aerial platform for use in other local applications; 4) Develop strategies for searching other solar system bodies for potential habitats for life; and 5) Determine the function of microbial activity in ecosystem health, cycling and evolution through the use of remote sensing.
Title: Selectivity of Small Molecule Adsorption, Conformation, Kinetics: Selection, Preservation, and Delivery of Pre-Biotic Organics and Potential Biosignatures
Lead Investigator/Home Institution/NAI Team Affiliation: Nita Sahai, U. Wisconsin Team
Co-Investigators/Home Institutions: H. James Cleaves, Carnegie Institution of Washington; Jason Dworkin, NASA Goddard Space Flight CenterSummary:
The role of mineral surfaces in extraterrestrial organic synthesis, pre-biotic chemistry, and the early evolution of life remains an open question. Mineral surfaces could promote synthesis, preservation, or degradation of chiral excesses of organic small molecules, polymers, and cells. Different minerals, crystal faces of a mineral, or defects on a face may selectively interact with specific organics, providing an enormous range of chemical possibilities. We focus here on amino-acid isomer adsorption, conformation, and racemization on minerals representing primitive and altered peridotite found in chondrites and on planetary bodies. The study is inspired by the discovery of an excess of L-isovaline, a non-biologic amino acid, in a few carbonaceous meteorites (Glavin and Dworkin, 2009). The results could have implications for understanding the origin of chirality in biology, selective preservation of certain organics in the geological record, and pre-biotic self-organization for chemical evolution. A major contribution is the introduction of high-throughput screening methods to the field of mineral-organic interactions.
Title: The Effect of Variable CO2 Atmosphere on Modern Day Microbialites: Simulations using the NAI Variable Atmosphere Laboratory (VAL) as a Window into Earth’s Past
Lead Investigator/Home Institution/NAI Team Affiliation: Janet Siefert, Rice Univ./VPL@U. Washington Team
Co-Investigators/Home Institutions: Peter Ward, U. Washington; Jim Elser, ASUSummary:
The proposed research will assess the adaptive response of an extant freshwater microbialite system at Cuatro Cienegas, Mexico, to simulated early Cambrian atmospheric CO2 values, using the NAI Variable Atmosphere Laboratory (VAL) at the University of Washington. Two specific metrics will be measured during the 4-week exposure experiment; i) the change in growth rate and overall community structure and ii) the actual transcription level changes that occur during the 4-week course of the adaptation. The data, analyses, and results will be cross-linked with data that are being generated on several research fronts within the NAI, especially in connection with ASU’s efforts to ‘Follow the Elements’ and U. of Washington’s biosignature models for the VPL. More broadly, the results will provide indications of the role global warming is playing and may have played in Earth’s past.
The project is receiving support from the Department of Energy’s Joint Genome Institute Community Sequencing Program for metagenomic and metatranscriptomic sequencing of successive layers of the Cuatro Cienegas microbialites. Although microbialites are minor contributors to overall aquatic carbon sequestration, a more detailed understanding of the mechanisms of microbialite carbon mineralization could aid in developing methods for engineered carbon sequestration that could be deployed on a large scale. This research will also provide NASA a better understanding of possible microbial communities on extra-terrestrial planets.
Title: Alternative Chirality Amino Acid Utilization Research in Support of Mars
Astrobiology Mission DevelopmentLead Investigator/Home Institution/NAI Team Affiliation: Henry Sun, Desert Research Institution/ASU Team
Co-Investigators/Home Institutions: Ariel Anbar, ASU, Chris McKay, NASA ARCSummary:
Laboratory experiments will test a new concept for Martian life detection. Chiral preference in organic consumption may distinguish between biological and chemical reactions. Offered D- and L-form of a chiral organic compound, living organisms should select only one for utilization, whereas abiotic redox processes are indiscriminate and would destroy both. Proposed experiments with archaea, fungi, and bacteria will define a list of amino acids that are suitable for a chiral experiment on Mars, because not all amino acid species appear to be stereo specific. Necessary analytical capability and a culture collection of extremophiles already exist from an ongoing Exobiology project. This proposal complements existing themes of the ASU team. In particular, it ties to the search for life as we don’t know it on Earth or the “shadow biosphere”. Could it be that some of the microorganisms are unculturable on normal nutrient media because they prefer alternative chirality substrates?
Title: Using the NAI Variable Atmosphere Laboratory (VAL) to Test the Kump et al. (2005) (H2S poisoning) Hypothesis
Lead Investigator/Home Institution/NAI Team Affiliation: Peter Ward, U. Washington/ VPL@U. Washington Team
Summary:
The proposed research is a hypothesis-driven study of the effects (if any) of increased H2S, CO2, and increased or decreased O2 on various groups of organisms in order to determine lethal limits or other effects of various gas combinations either in air or water. The values of gas used will be best estimates of global atmospheric compositions at the end of the Permian and Triassic Periods (low O2, , high CO2, possible high H2S, and in the middle of the Carboniferous Period (high O2,, low CO2. The objectives are to discover kill-mechanisms and growth rates of various groups at different times in Earth History. The benefits are potentially large: this kind of work has already revolutionized the medical and biological disciplines by showing that H2S can cause suspended animation in certain animal groups. Here we will also test to see if the long delay in the evolution of animal life was perhaps due in part, or entirely, to the presence of toxic levels of H2S dissolved in seawater during the Archean and Proterozoic. The benefits to NASA will be a better understanding of mass extinction events, and better estimates of the number of habitable Earths in the Cosmos.
Title: Arsenic and Old Life: Novel Geo‐biochemistry of Arsenic in Biological Systems
Lead Investigator/Home Institution/NAI Team Affiliation: Felisa Wolfe-Simon, Harvard U./ASU and MIT Teams
Co-Investigators/Home Institutions: Ron Oremland, USGS; Paul Davies, Ariel Anbar, ASU; Ann Pearson, Harvard; Roger Summons, MITSummary:
This proposal begins to search for new and novel uses of arsenic by biology on Earth. There are two main experiments unified in this direction. Briefly, all known life requires phosphorus (P) in the form of inorganic phosphate (PO4 ‐ or Pi) and phosphate‐containing organic molecules. Pi serves as the backbone of the nucleic acids that constitute genetic material and as the major repository of chemical energy for metabolism in polyphosphate bonds. Arsenic (As) lies directly below P on the periodic table and so the two elements share many chemical properties, although their chemistries are sufficiently dissimilar that As cannot directly replace P in modern biochemistry. Arsenic is toxic because As and P are similar enough that organisms attempt this substitution. We hypothesize that As‐using biochemical systems analogous to but distinct from P‐based metabolism may exist today in As‐rich environments. As‐based metabolism could be ancestral to known biochemistry, finding refuge in such settings, or could arise as a later adaptation in such settings. This proposal seeks to cultivate organisms utilizing such "weird life" biochemical pathways to determine if they are still present on Earth in As‐rich environments.
We also seek to isolate, confirm and characterize a unique form of As‐utilizing photosynthesis in cyanobacteria. Arsenite can be used by purple anoxygenic photosynthetic bacteria as an electron source in As‐rich environments. Therefore, there is the strong possibility that cyanobacteria in these environments can execute this type of metabolism as well. To execute this project, we have formed a multi‐NAI team with involvement as well from those new to the NAI. Our contributions to NASA may well range from a better understanding of the possible biology on Earth to greater insight as to what to look for out in the Universe.
