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Project Reports

• Biogenic Gases From Anoxygenic Photosynthesis in Microbial Mats

  This lab and field project aims to measure biogenic gas fluxes in engineered and natural microbial mats composed of anoxygenic phototrophs and anaerobic chemotrophs, such as may have existed on the early Earth prior to the advent of oxygenic photosynthesis. The goal is to characterize the biogeochemical cycling of S, H, and C in an effort to constrain the sources and sinks of gaseous biosignatures that may be relevant to the detection of life in anoxic biospheres on habitable exoplanets.

  ROADMAP OBJECTIVES: 4.1 5.2 5.3 6.1 6.2 7.2

• Life Underground

  Our multi-disciplinary team from USC, Caltech, JPL, DRI, RPI, and now also Northwestern 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 3.3 4.1 5.1 5.2 5.3 6.1 6.2 7.2

• Astrobiology of Icy Worlds

  Our goal in the Astrobiology of the Icy Worlds Investigation is to advance our understanding of the role of ice in the broad context of astrobiology through a combined laboratory, numerical, analytical, and field investigations. Icy Worlds team pursues this goal through four major investigations namely, the habitability, survivability, and detectability of life of icy worlds coupled with “Path to Flight” Technology demonstrations. A search for life linked to the search for water should naturally “follow the ice”. Can life emerge and thrive in a cold, lightless world beneath hundreds of kilometers of ice? And if so, do the icy shells hold clues to life in the subsurface? These questions are the primary motivation of our science investigations

  ROADMAP OBJECTIVES: 1.1 2.1 2.2 3.1 3.2 4.1 5.1 5.2 5.3 6.2 7.1

• Project 1: Dynamics of Self-Programming Systems

  This project is a theoretical attempt to understand how evolution can arise from inanimate physical systems. The key idea is that matter can organize into structures that not only replicate and carry information, but are able to program and reprogram themselves functionally. We have already been able to construct simple computer programs that can increase their complexity in an open-ended way, but in this grant period we have been building a mathematical formulation of how this arises using recursive function theory. We have also been trying to develop cellular automata meta-programming pairs that can co-evolve complexity.

  ROADMAP OBJECTIVES: 3.2 4.1 4.2 5.3 6.2

• Biosignatures in Extraterrestrial Settings

  The Biosignatures in Extraterrestrial Environments group works on finding and characterizing exoplanets, in particular through very high resolution spectroscopy; and developing new techniques for finding exoplanets and characterizing their properties. It also works on understanding the evolution and dynamics of planetary systems, including the solar system, and the role of astrophysical processes in establishing and sustaining life in extraterrestrial environments.

  ROADMAP OBJECTIVES: 1.1 1.2 2.1 2.2 3.1 4.1 4.3 6.2 7.1 7.2

• Project 5: The Origins of Life’s Diversity

  The huge diversity of life poses a major challenge to ecological theory and a major source of optimism for astrobiology. Ecological theory argues that a single environmental niche should be colonized by a single species of organism, or perhaps a small community, and so the diversity of life should be essentially a measure of the number of niches present. The huge diversity of life does suggest, however, that the ability of life to explore, colonize and especially create environmental niches has been drastically underestimated. Accordingly, the likelihood of extraterrestrial life arising is also underestimated, or at least inadequately estimated, by our present understanding of biological evolution. This project attempts to solve this problem by developing a new theory for niche diversity.

  ROADMAP OBJECTIVES: 3.4 4.1 4.2 5.1 5.2 5.3 6.1 6.2

• Project 6. Mining Archaeal Genomes for Signatures of Early Life: Comparison of Metabolic Genes in Methanogens

  Methanogenic archaea derive energy from simple starting materials, producing methane and carbon dioxide in the process. The chemical simplicity of the growth substrates and versatility of the organisms in extreme environments provide for a possibility that they could exist on other planets. By characterizing the evolution of methanogens from the most simple to most complex organism as well as their growth characteristics under controlled environments, we hope to address the question as to whether they could exist on planets such as Mars, where bursts of methane have been seen, yet no source has yet been identified.

  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 7.2

• Titan as a Prebiotic Chemical System – Benner

  In 2007, NASA sponsored a committed of the National Academies of Science to explore whether life might exist in environments outside of the traditional habitable zone, defined as positions in a solar system where liquid surface water might be found. Alternative solvents which have analogous “habitable zones” farther away from their star include hydrocarbons, ammonia, and dinitrogen. The core question asked whether life having genetic biopolymers might exist in these solvents, which are in many cases (including methane) characterized by the need for “cold” (temperatures < 100K in the case of methane).

  These “weird” solvents would require “weird” genetic molecules, “weird” metabolic processes, and “weird” bio-structures. In pursuit of this “big picture” question, we turned to Titan, which has exotic solvents both on its surface (methane-hydrocarbon) and sub-surface (perhaps super-cooled ammonia-rich water). This work sought genetic molecules that might support Darwinian evolution in both environments, including non-ionic polyether molecules in the first and biopolymers linked by exotic oxyanions (such as phosphite, arsenate, arsenite, germanate) in the second.

  In the current year, we completed our studies that identified biopolymers that might work in hydrocarbon solvents. These studies have essentially ruled out biological processes in true cryosolvents. However, a series of hydrocarbons containing different numbers of carbon atoms (one, two, three, and four, for example, in methane, ethane, propane, and butane) cease to be cryosolvents as their chain lengths increase. These might be found on “warm Titans”. Further, they might exist deep in Titan’s hydrocarbon oceans, where heating from below would lead to warm hydrocarbon oceans.

  These studies showed that polyethers are insufficiently soluble in hydrocarbons at very low temperatures, such as the 90-100 K found on Titan’s surface where methane is a liquid at ambient pressures. However, we did show that “warm Titans” could exploit propane (and, of course, higher hydrocarbons) as a biosolvent for certain of these “weird” alternative genetic biopolymers; propane has a huge liquid range (far larger than water). Further, we integrated this work with mineralogy-based work that allows reduced molecules to appear as precursors for less “weird” genetic biomolecules, especially through interaction with various mineral species, including borates, molybdates, and sulfates.

  ROADMAP OBJECTIVES: 1.1 1.2 2.2 3.1 3.2 3.4 4.1 5.3 6.2 7.1 7.2

• Project 8 Culturing Microbial Communities in Controlled Stress Micro-Environments

  This project explores the adaptation and evolution of organisms under controlled environmental conditions, and compares the behavior across two Domains of Life in order to identify and quantify universal aspects of evolutionary response.

  ROADMAP OBJECTIVES: 6.1 6.2

• Project 10: Identifying Key Innovations in the Origin of the Cell

  Identifying essential functions of conserved hypothetical genes holds the key to understanding the origins of key innovations in the origin of the cell. Our goal is to take a comparative genomic approach to define the molecular machinery that differentiate the Bacterial from its sister lineage that later diverged to became the Archaea and Eukaryotes. One of the obstacles clouding our view of these early cells from a comparative approach is the large number of conserved hypothetical genes present in Archaeal and Eukaryote genomes whose cellular functions are unknown. Our approach is to identify which conserved hypothetical genes are essential to the function of the model crenarchaeon Sulfolobus islandicus. The Crenarchaea are one of the major lineages with in the Archaeal domain with close ties in function to the cellular biology of Eukaryotes. The essential gene profile has not been identified within any organism in this lineage and holds the key to understanding the origin of cellular features in central processing of genomic information through replication, recombination, repair and the shaping of the chromosome.

  ROADMAP OBJECTIVES: 3.4 4.2 5.1 6.1 6.2

• Stoichiometry of Life – Task 1 – Laboratory Studies in Biological Stoichiometry

  This project component involves a set of studies of microorganisms with which we are trying to better understand how living things use chemical elements (nitrogen, phosphorus, iron, etc.) and how they cope, in a physiological sense, with shortages of such elements. For example, how does the “elemental recipe of life” change when an organism is starved for phosphorus or nitrogen or iron? Is this change similar for different species of microorganisms? Are the changes the same if the organism is limited by a different key nutrient? Furthermore, how does an organism shift its patterns of gene expression when it is starved by various nutrients? This will help in interpreting studies of gene expression in natural environments.

  ROADMAP OBJECTIVES: 5.2 5.3 6.1 6.2

• The Long Wavelength Limit of Oxygenic Photosynthesis

  Oxygenic photosynthesis (OP) produces the strongest biosignatures at the planetary scale on Earth: atmospheric oxygen and the spectral reflectance of vegetation. Both are controlled by the properties of chlorophyll a (Chl a), its ability to perform the water-splitting to produce oxygen, and its spectral absorbance that is limited to red and shorter wavelength photons. We seek to answer what is the long wavelength limit at which OP might remain viable, and how. This would clarify whether and how to look for OP adapted to the light from stars redder than our Sun.

  Previously under this project, with other co-investigators we spectrally quantified the thermodynamic efficiency of photon energy use in the chlorophyll d utilizing cyanobacterium, Acaryochloris marina str. MBIC11017, determining that it is more efficient than a Chl a cyanobacterium. The current focus of the project is aimed at understanding the adaptations of far-red/near-infrared (NIR) oxygenic photosynthetic organisms in general: what is their ecological niche where they are competitive against chlorophyll a organisms in nature, and what energetic shifts have been made in their photosynthetic reactions centers to enable their use of far-red/NIR photons. Field sampling and measurements are being conducted to isolate new strains of far-red utilizing oxygenic photosynthetic organisms, to quantify the spectral and temporal light regime in which they and previously discovered strains live in nature, and use these light measurements to drive kinetic models of photon energy use to ascertain light thresholds of survival.

  ROADMAP OBJECTIVES: 3.2 4.2 5.1 5.3 6.2 7.2

• Stoichiometry of Life, Task 2a: Field Studies – Yellowstone National Park

  Yellowstone National Park harbors an array of hydrothermal ecosystems with widely varying geochemical characteristics and microbial communities. Our research aimed to understand how the geochemistry of these hot springs shapes their constituent microbial communities including their composition and function. To accomplish this aim, we measured (1) physical and geochemical properties of hot spring fluids and sediments, (2) the rates of biogeochemical processes (i.e., methane oxidation, nitrogen fixation, microbial Fe cycling, photosynthesis, de-nitrification, etc.), and (3) markers for microbial community diversity (i.e., SSU rRNA, metabolic genes, lipids, proteins).

  ROADMAP OBJECTIVES: 5.1 5.2 5.3 6.1 6.2 7.2

• Stoichiometry of Life – Task 2b – Field Studies in Cuatro Cienegas

  We performed two studies to evaluate ecological impacts of nitrogen and/or phosphorus fertilization in a P-deficient and hyperdiverse shallow pond in the valley of Cuatro Cienegas, Mexico.

  ROADMAP OBJECTIVES: 5.1 5.2 5.3 6.1 6.2

• Education and Public Outreach

  Our ongoing Education and Public Outreach activities include: (1) a Massively Open Online Course (MOOC) in which over 36,000 students have participated worldwide; (2) workshops for middle school and high school teachers; (3) formal in person and online for-credit courses at the University of Illinois Urbana-Champaign in which 240 students have participated; informal courses in Yellowstone in collaboration with the Yellowstone Association Institute; and (4) ongoing development and writing of a new book.

  ROADMAP OBJECTIVES: 6.1 6.2

• Undergraduate Research Associates in Astrobiology (URAA)

  In 2014, the Goddard Center for Astrobiology (GCA) hosted the tenth session of our summer program for talented science students (Undergraduate 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 very keen, with an oversubscription ratio of 3.0. Students applied from over 15 Colleges and Universities in the United States, and 2 Interns from 2 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 3.1 6.2

• Project 3F — Apatitic Latest Precambrian and Early Cambrian Fossils Provide Direct Evidence of Concentrations of Environmental Oxygen

  Means are not currently available to asses either quantitatively or semi-quantitatively the concentration of oxygen in Earth’s atmosphere over geological time. Despite this, the environmental availability of O₂ has been repeatedly postulated to be a cause of major changes in Earth’s biota, most particularly at the Precambrian-Cambrian boundary-defining “Cambrian Explosion of Life,” a time in Earth history when large deposits of phosphate-rich apatite were deposited in shallow basins worldwide. This study shows that substitution of Sm⁺³ in the Ca I and Ca II sites of fossil-permineralizing, -infilling, and -encrusting apatite can differentiate between oxic, dysoxic, an anoxic settings of apatite formation. Further studies are to be undertaken to establish such REE-substitution as a quantitative O₂ paleobarometer.

  ROADMAP OBJECTIVES: 4.1 4.2 6.1 6.2 7.2