2010 Annual Science Report

Arizona State University Reporting  |  SEP 2009 – AUG 2010

Executive Summary

Overview

In 2010, the Astrobiology Program at Arizona State University made solid progress on all 19 of the major research tasks described in our CAN5 proposal, exceptional progress on some, and initiated new efforts in several areas. These efforts resulted in ~ 70 publications that appeared in print, were submitted or reached an advanced state of preparation during the reporting period, as well as ~ 50 professional presentations. These included several publications in high-profile journals. Collectively, this initial research advanced our goal of integrating life science, geoscience, planetary science and astrophysics to understand how the distribution of chemical elements shapes the distribution of life in space and time, and to guide the search for life beyond Earth. These research advances are summarized below.

In addition to this research, a vibrant suite of EPO activities was undertaken, and some EPO flagship efforts were initiated. These activities reached a ... Continue reading.

Field Sites
39 Institutions
24 Project Reports
112 Publications
6 Field Sites

Project Reports

  • Habitability of Water-Rich Environments, Task 4: Evaluate the Habitability of Ancient Aqueous Solutions on Mars

    On Earth, hydrothermal systems teem with life and such systems could have been widespread in the solar system. The Mars habitability task has been focusing on understanding how to identify the fingerprints of hydrothermal processes in the ancient rock record, while assessing the potential of hydrothermal deposits to preserve signatures of life. The recent discovery of silica-rich hydrothermal deposits by the Mars Exploration Rover, Spirit, has provided renewed interest in hydrothermal deposits as targets for future in situ robotic missions and sample returns for Astrobiology.

    ROADMAP OBJECTIVES: 2.1
  • Habitability of Water Rich Environments – Task 6 – Waterworld Habitability

    We explored effects of initial compositions, 26Al content and major collisions on the composition and abundance of C-H-O-N volatiles during the formation of solid extrasolar planets.

    ROADMAP OBJECTIVES: 1.1
  • Habitability of Water-Rich Environments, Task 1: Improve and Test Codes to Model Water-Rock Interactions

    Two new models have been developed in order to calculate 1) phase transitions during concentrating/diluting and cooling/heating in salt-brine-ice systems (from -60°C to 250°C) and 2) the chemical composition of hydrothermal systems. The case of water-granite interaction vs. time has been simulated to test a model of aqueous alteration that combines thermodynamics and kinetics.

    ROADMAP OBJECTIVES: 2.1 2.2
  • Habitability of Water-Rich Environments, Task 2: Model the Dynamics of Icy Mantles

    Europa, one of Jupiter’s moons, is one of the few places in our solar system hypothesized
    to be habitable. Beneath a frozen, icy surface lies a liquid water ocean that could contain the chemical constituents required by life. Future missions to Europa will study its surface in detail in an effort to extrapolate the conditions below. So it is important to understand how mass can be transported from the deep ocean, through the ice, and to the surface of the moon. To understand this process, we are performing numerical fluid-dynamical calculations of 2-phase, thermochemical convection to investigate how chemistry from the deep ocean is transported to Europa’s surface. Furthermore, we are investigating how this material transport is expected to deform Europa’s surface, such that future missions will be able to infer deep, convective processes of the moon’s interior from surface observations.

    ROADMAP OBJECTIVES: 1.1 2.2
  • Stoichiometry of Life, Task 1a: Experimental Studies – Cellular Stoichiometry Under Nutrient Limitation in Chemostats

    In this project we are raising several species of “extremophile” microbes at different growth rates under different kinds of element limitation (N, P, and Fe) in order to determine how their “elemental recipes” (in terms of C, N, P, Fe, and other metals) change with environmental conditions. These data will help us understand similar data to be obtained from microbes in natural ecosystems.

    ROADMAP OBJECTIVES: 5.1 5.2 5.3 6.1 6.2 7.1
  • Astrophysical Controls on the Elements of Life, Task 1: High-Precision Isotopic Studies of Meteorites

    The evolution of habitable planets may be affected by the injection of short-lived radionuclides, produced by supernova explosions, early in solar system history. In this task we are finding evidence of such injection in some of the earliest Solar System materials (calcium-aluminum-rich inclusions) and constraining the timing of early Solar System events.

    ROADMAP OBJECTIVES: 1.1 3.1
  • Stoichiometry of Life – Task 1b – Experimental Studies – Microbial Production of Exopolymeric Subtances (EPS)

    One way that microscopic plankton affect the Earth system is by producing carbon compounds that can sink to the bottom of the ocean, thus burying C for extended periods. The production of “exopolymeric substances” (EPS), sticky molecules often made from sugars, is such a mechanism. This project seeks to determine some of the basic parameters that affect the production of EPS by marine phytoplankton.

    ROADMAP OBJECTIVES: 4.1 6.1
  • Stoichiometry of Life, Task 3a: Ancient Records – Geologic

    We are analyzing, at high resolution, Mid-Proterozoic drill core and outcrop samples in an effort to fingerprint the evolving redox state of the atmosphere and ocean at critical intervals in Earth history. This refined view of biospheric oxygenation provides the key backdrop for measuring and inferring abundances of diverse bioessential elements. Within this context we can better understand the distribution and evolution of early eukaryotic organisms at a variety of spatial and temporal scales.

    ROADMAP OBJECTIVES: 4.1 4.2
  • Stoichiometry of Life, Task 3b: Ancient Records – Genomic

    The goal of Task 3b is to advance understanding of elemental cycling in ancient ecosystems. Team members are developing experimental and computational approaches aimed at genomic analysis of modern ecosystems, and extending these approaches in novel ways to infer the function and composition of ancient communities.

    ROADMAP OBJECTIVES: 5.1 5.2 5.3
  • Stoichiometry of Life, Task 4: Biogeochemical Impacts on Planetary Atmospheres

    Oxygenation of Earth’s early atmosphere must have involved an efficient mode of carbon burial. In the modern ocean, carbon export of primary production is dominated by fecal pellets and aggregates produced by the animal grazer community. But during most of Earth history the oceans were dominated by unicellular, bacteria-like organisms (prokaryotes) causing a substantially altered biogeochemistry. The NASA Ocean Biogechemical Model (NOBM) is applied using cyanobacteria (blue-green algae) as the only photosynthetic group in the oceans. The analyses showed that the early Earth ocean had 19% less primary production and 35% more nitrate due to slower growth by the cyanobacteria, and reduced nutrient uptake efficiency relative to modern phytoplankton Additionally there was 8% more total carbon in the oceans as a result of higher atmospheric pCO2. We plan to optimize this early Proterozoic ocean model in combination with a 1 D model to account for changes in aggregate formation and sinking speed in response to varying nutrients.

    ROADMAP OBJECTIVES: 1.1 4.1 4.2 5.2 6.1 7.2
  • Stoichiometry of Life – Task 1f – Concept Studies – Nickel-Molybdenum Co-Limitation and Evolution of Mo-Nitrogenase

    The element molybdenum (Mo) is critical for key processes in the cycling of nitrogen (N); for example, it is essential for the enzyme nitrogenase which bacteria use to convert gaseous N to “fixed” N that can be used in biological processes. However, this process costs a lot of energy. In some microbes, this energy can be captured and used via enzymes that involve both Mo and nickel (Ni). This project investigates the role of these Ni-Fe enzymes in making nitrogenase-driven processes more energetically efficient and how these enzymes may have evolved in the deep past when Ni concentrations were lower.

    ROADMAP OBJECTIVES: 4.1 5.1 5.2 6.1
  • Stoichiometry of Life – Task 1d – Experimental Studies – the Role of Molybdenum in the Nitrogen Cycle, Past and Present

    The element molybdenum (Mo) is critical for key processes in the cycling of nitrogen (N); for example, it is essential for the enzyme nitrogenase which bacteria use to convert gaseous N to “fixed” N that can be used in biological processes. This project seeks to understand how Mo might limit N processing in modern ecosystems (lakes and oceans) and infer its potential role in the past.

    ROADMAP OBJECTIVES: 4.1 5.1 6.1
  • Stoichiometry of Life – Task 1c – Laboratory Studies – the Role of Arsenic in Microbial Physiology, Ecology, and Evolution

    It has previously been assumed that arsenic (or its more common form, arsenate) acts only as a poison for living things. However, As is very close to the nutrient element phosphorus (P; phosphate) in the Periodic Table suggesting that possibility that under some conditions organisms might use arsenate instead of phosphate in key molecules. This study examines microbes isolated from a high arsenate, low phosphate environment (Mono Lake, CA) to see whether or not they can grow on arsenate in the absence of phosphate and if As is incorporated into major molecules.

    ROADMAP OBJECTIVES: 3.2 5.1 5.3 6.1
  • Stoichiometry of Life, Task 2b: Field Studies – Cuatro Cienegas

    Cuatro Cienegas is a unique biological preserve in which there is striking microbial diversity, potentially related to extreme scarcity of phosphorus. We aim to understand this relationship via field sampling of biological and chemical characteristics and a series of enclosure and whole-pond fertilization experiments.

    ROADMAP OBJECTIVES: 5.1 5.2 5.3 6.1 6.2
  • Astrophysical Controls on the Elements of Life, Task 6: Determine Which Elemental or Isotopic Ratios Correlate With Key Elements

    Many of the elements important to life or to the development of potentially habitable solar systems are difficult or impossible to observe directly. We are working to understand where these elements are produced in stars and whether they correlate with elements that are more easily observed. This effort requires modeling of the dynamics and nuclear burning in supernova explosions to determine what elements are produced together and, equally important, how the ejected material is incorporated into the gas that forms stars and planets. We are also observing a region of star formation to detect the signature of enrichment of newly formed sunlike stars by the explosion of their nearby, more massive cousins.

    ROADMAP OBJECTIVES: 1.1 3.1
  • Astrophysical Controls on the Elements of Life, Task 4: Model the Injection of Supernova Material Into Protoplanetary Disks

    The goal of this task is to determine how much supernova material can make its way into a forming solar system, after the star has formed and is surrounded by a protoplanetary disk. This supernova material may contain radioactive isotopes like 26Al, which is the primary mechanism by which asteroids melted and which may control delivery of water and other elements to terrestrial planets. This supernova material may also change the abundance ratios of bioessential elements.

    ROADMAP OBJECTIVES: 1.1 3.1
  • Astrophysical Controls on the Elements of Life, Task 2: Model the Chemical and Dynamical Evolution of Massive Stars

    Massive stars are the primary source for the elements heavier than hydrogen and helium on the periodic table. We are simulating the evolution of these stars and their eventual deaths in supernova explosions with state of the art physics in order to generate the most accurate estimates possible of the yields of chemical elements from both individual stars and stellar populations. We are also observing the variations of elemental abundances in nearby planet host candidates in order to determine the range of variation in bioessential elements and the effects of non-sunlike compositions on the evolution of the host stars.

    ROADMAP OBJECTIVES: 1.1 3.1
  • Astrophysical Controls on the Elements of Life, Task 3: Model the Injection of Supernova Material Into Star-Forming Molecular Clouds

    The goal of this task is to determine how much supernova material can make its way into a forming solar system during its initial stages, when the gas that will form the star and the planets are collapsing from a molecular cloud. This supernova material may contain radioactive isotopes like 26Al, which is the primary mechanism by which asteroids melted and which may control delivery of water and other elements to terrestrial planets. This supernova material may also change the abundance ratios of bioessential elements.

    ROADMAP OBJECTIVES: 1.1 3.1
  • Astrophysical Controls on the Elements of Life, Task 7: Update Catalog of Elemental Ratios in Nearby Stars

    We are creating the first 3D maps of the elements for stars within 1000 light-years of the Sun, building upon the Habitable Star Catalog produced by Maggie Turnbull and Jill Tarter in 2003. We currently have abundance levels of bioessential elements for about 800 of the 17,000 stars listed in the Habitable Star Catalog. This project employs 2 graduate students (resulting in 1 PhD and 1 masters degree) and 1 undergraduate student. When this project is completed, our publicly available 3D maps will enable discovery of directions, or regions, in space where stars have abundance patterns more favorable to producing habitable worlds.

    ROADMAP OBJECTIVES: 1.1 7.2
  • Astrophysical Controls on the Elements of Life, Task 5: Model the Variability of Elemental Ratios Within Clusters

    This involves a comprehensive chemodynamic study of the self-enrichment of star forming regions and its astrobiological implications. Our approach will start from the point of star formation and diligently model the subsequent production, dissemination, and accretion of 92 chemical elements, with a special focus on bioessential elements and short-lived radionucides. Our goal is to capture the full evolution over which a molecular cloud, the primary units of star-forming gas, is converted into an open cluster, the primary units of formed stars — determining the probability distribution of all elements that are important in the formation of terrestrial planets and life.

    ROADMAP OBJECTIVES: 1.1 3.1
  • Habitability of Water-Rich Environments, Task 3: Evaluate the Habitability of Europa’s Subsurface Ocean

    We completed several reviews that summarize current knowledge about the geological and chemical evolution of Europa’s icy shell and its putative ocean.

    ROADMAP OBJECTIVES: 1.1 2.2
  • Habitability of Water-Rich Environments, Task 5: Evaluate the Habitability of Small Icy Satellites and Minor Planets

    A better understanding of the physical and chemical properties of putative aquatic systems on icy satellites is needed to assess their potential for life. We developed new models to assess the origins of carbon and nitrogen species on Titan, the composition and salinity of an ocean on Enceladus, the chemical energy available for metabolism on Enceladus, and the formation of crystalline ice on the surfaces of icy moon.

    ROADMAP OBJECTIVES: 2.2
  • Stoichiometry of Life – Task 1e- Experimental Studies – Diatom Growth on Iron Nanoparticles

    In some environments (such as ocean regions fed by icebergs), the critical element iron (Fe) is supplied in the form of very small (“nano”) particles that are suspended rather than dissolved in water. However, it’s not known if this nanoparticle Fe is available to microscopic phytoplankton. This project involves experiments testing whether diatoms (a key oceanic phytoplankton group) can access nanoparticle Fe.

    ROADMAP OBJECTIVES: 6.1
  • Stoichiometry of Life, Task 2a: Field Studies – Yellowstone National Park

    Field work and subsequent laboratory analysis is an integral part of following the elements. One of our field areas is the hot spring ecosystems of Yellowstone, which are dominated by microbes, and where reactions between water and rock generate diverse chemical compositions.
    These natural laboratories provide numerous opportunities to test our ideas about how microbes respond to different geochemical supplies of elements. Summer field work and lab work the rest of the year includes characterizing the natural systems, and controlled experiments on the effects of changing nutrient and metal concentrations (done so as to not impact the natural features!).

    ROADMAP OBJECTIVES: 5.1 5.2 5.3 6.1 6.2 7.2