2009 Annual Science Report

Arizona State University Reporting  |  JUL 2008 – AUG 2009

Executive Summary

Overview

The year 2009 saw the revival of the Astrobiology Program at Arizona State University, building on the legacy of the CAN1 ASU NAI Team headed by co-I Jack Farmer (1999-2004). As summarized below, significant effort began on 18 of the 19 research tasks described in our CAN5 proposal. This effort resulted in ~ 50 publications that appeared in print, were submitted or reached an advanced state of preparation during the reporting period. Collectively, this initial research sets the stage for 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.

In addition to this research, a vibrant suite of EPO activities was undertaken. These activities reached a variety of constituencies, including K-12 children and educators, college students, and ... Continue reading.

Field Sites
25 Institutions
18 Project Reports
62 Publications
4 Field Sites

Project Reports

  • Stoichiometry of Life, Task 3b: Ancient Records – Genomic

    The genomic records of modern organisms carry clues to the evolution of the use of elements in biology. We are investigating these records in several ways, with a particular emphasis on the use of metals in enzyme active sites and nitrogen fixation.

    ROADMAP OBJECTIVES: 5.1 5.2 5.3
  • Astrophysical Controls on the Elements of Life, Task 5: Model the Variability of Elemental Ratios Within Clusters

    This task involves a comprehensive study of the chemical evolution of star forming regions arising from stellar processes, and its astrobiological implications. Our approach starts from the point of star formation and models 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 of over which molecular clouds – the primary units of star-forming gas – are converted into open clusters – the primary units of formed stars. We will then be able to determine the probability distribution of all elements that are important in the formation of terrestrial planets and life.

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

    Supernova-generated material can affect the evolution of a solar system when supernova ejecta enter protoplanetary disks. We are particularly interested in the injection of 26Al, a short-lived radioactive isotope that can affect the delivery of water to Earth-like planets when they are formed. In this task, we are conducting numerical calculations to model such injections in our Solar System, and to understand the consequences for oxygen isotope compositions that can be measured in meteorites.

    ROADMAP OBJECTIVES: 1.1 3.1
  • Stoichiometry of Life, Task 1: Laboratory Studies in Biological Stoichiometry

    Living things require a broad menu of chemical elements to function. This project aims to quantify the chemical elements required by prokaryotes – the class of terrestrial organisms thought most similar to those that might be present in extraterrestrial settings – through laboratory experiments. These experiments will also teach us the ways in which such organisms cope with scarcity of the bioessential elements nitrogen, phosphorus and iron. We are also conducting experiments to isolate micro-organisms that use the element arsenic in place of phosphorus, if they exist. In Year 1 we initiated the first stage of these experiments.

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

    Small bodies in the outer Solar System may harbor liquid water-ammonia oceans and many of the chemical ingredients of life. In this project, we are assessing how much liquid may be present in the Kuiper Belt and the geochemical evolution of Saturn’s volatile-rich moons Enceladus and Titan.

    ROADMAP OBJECTIVES: 2.2
  • Habitability of Water-Rich Environments, Task 4: Evaluate the Habitability of Ancient Aqueous Solutions on Mars

    We aim to reconstruct the compositions of ancient fluids on Mars by combining computational models with data on the mineralogy of Mars surface materials as they are preserved today. This effort requires that we better understand how well the types of data obtained today and in future missions reflects the mineralogy that exists today. In this task, we have begun to collect such data at Yellowstone National Park, an analog for possible hydrothermal sites on Mars, and have advanced the use of thermodynamic models to interpret observed mineralogical assemblages.

    ROADMAP OBJECTIVES: 2.1
  • Stoichiometry of Life, Task 4: Biogeochemical Impacts on Planetary Atmospheres

    The abundance of molecular oxygen in planetary atmospheres may be a useful way to look for evidence of life. The amount of photosynthetically produced oxygen that accumulates in an atmosphere depends in part on the export of photosynthetically produced organic carbon from the ocean surface to the seafloor, which in turn may depend on the availability of bioessential elements. We are using a computer model to determine how this carbon export processes might operate in an ocean dominated by prokaryotes rather than eukaryotes, as may have been common in Earth’s past and as an analog for hypothetical extrasolar planets.

    ROADMAP OBJECTIVES: 4.1 4.2 5.2 6.1 7.2
  • 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.

    ROADMAP OBJECTIVES: 5.1 5.2 5.3 6.1 6.2
  • Stoichiometry of Life, Task 3a: Ancient Records – Geologic

    The primary goal of this effort is to understand the evolving redox state of the atmosphere and ocean at critical intervals in Earth history, its effect on the availability of bioessential elements, and the consequences for evolution. In support of this goal, a major effort is underway to analyze, at high resolution, ~2.5- to 1.5-billion-year-old drill core samples so that we can better understand the distribution and evolution of early eukaryotic organisms at a variety of spatial and temporal scales. Additional efforts focus on characterizing life and environment leading in to the Cambrian explosion of metazoan life.

    ROADMAP OBJECTIVES: 4.1 4.2
  • Astrophysical Controls on the Elements of Life, Task 2: Model the Chemical and Dynamical Evolution of Massive Stars

    In order to understand the distribution of elements both on the scale of the Galaxy and individual solar systems we must understand the production of elements in stars and the dispersal of newly synthesized elements in supernova explosions. We are especially interested in the production and distribution of the radioactive isotope 26Al because the amount of this element present in the early Solar System may have affected the heating of planetesimals and hence their ability to retain water and deliver it to early planets. This task uses computational models of stellar evolution and supernovae with the most accurate treatments of physics available to predict the production elements by individual stars and by populations of stars over time.

    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 influence of supernova-generated material on the evolution of a solar system depends on the effectiveness with which supernova ejecta can enter the molecular clouds from which solar systems are formed. In this task, we are using computational codes to model the injection of supernova-generated material.

    ROADMAP OBJECTIVES: 1.1 3.1
  • Astrophysical Controls on the Elements of Life, Task 6: Determine Which Elemental or Isotopic Ratios Correlate With Key Elements

    In our “follow the elements” strategy we work to refine searches for planetary systems likely to host life by identifying systems with favorable elemental compositions. Because some relevant elements or isotopes (for example 26Al) are difficult or impossible to observe due to low abundances or short lifetimes, we wish to find easily observable indicators of their presence. In most cases this involves identifying elements or isotopes that are either produced primarily by the same process as the isotope of interest or produced in unique ratios to other isotopes by that process. This requires simulating the synthesis of isotopes in stars and supernovae and their ejection into space and incorporation into forming planetary systems.

    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 making 3D maps of the elements in stars within 1000 light-years of the Sun. When completed, these maps will be useful for discovering whether there are neighborhoods or streams of stars more favorable to Earth-like planets and life as we know it.

    ROADMAP OBJECTIVES: 1.1 7.2
  • Habitability of Water-Rich Environments, Task 1: Improve and Test Codes to Model Water-Rock Interactions

    Many potentially habitable water-rich environments are not directly observable. These include ancient fluids on Mars, the subsurface oceans on Europa and other icy bodies, and the oceans of postulated extrasolar planets. Computer models are required to simulate the chemical compositions of these environments. In this task we are improving the computer codes used to model water-rock interactions.

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

    A major aim of future missions to Jupiter’s moon Europa will be to determine whether or not a subsurface ocean exists beneath the icy surface, and assess its habitability. Such investigations require that we understand how features visible at the surface are related to the ocean that may lie below. A major process governing this interaction is convection within ice. To this end, we are developing a new model of Europa ice convection.

    ROADMAP OBJECTIVES: 1.1 2.2
  • Habitability of Water-Rich Environments, Task 3: Evaluate the Habitability of Europa’s Subsurface Ocean

    We are assessing the habitability of Europa’s ocean by integrating geologic mapping of the Europa surface with geodynamic models of ice convection and geochemical models of ocean and ice composition.

    ROADMAP OBJECTIVES: 1.1 2.2
  • Stoichiometry of Life, Task 2a: Field Studies – Yellowstone National Park

    We are investigating how the element requirements of microbes are affected by element availability in their environment in Yellowstone National Park, where there are extreme variations in the abundances of bioessential elements in addition to extremes of temperature and pH. In Year 1 we organized a multi-disciplinary field expedition to collect samples and conduct experiments. Analyses of these samples is now underway.

    ROADMAP OBJECTIVES: 5.1 5.2 5.3 6.1 6.2 7.2