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2013 Annual Science Report

Astrobiology Roadmap Objective 1.1 Reports Reporting  |  SEP 2012 – AUG 2013

Project Reports

  • Astrophysical Controls on the Elements of Life, Task 1: High-Precision Isotopic Studies of Meteorites

    The initial Solar System abundances of the short-lived radionuclides (SLRs) 26Al (half life ~0.73 Ma) and 60Fe (half life ~2.6 Ma) are important to constrain since, if present in sufficient abundance, these SLRs served as heat sources for dehydration and differentiation processes on planetary bodies. The implications for this work include the astrophysical environment in which the Sun formed, and the abundance of water on the terrestrial planets.

    Research on this task was completed in Year 4.

  • Project 1: Looking Outward: Studies of the Physical and Chemical Evolution of Planetary Systems

    We continue to apply theory and observations to investigate the nature and distribution of extrasolar planets both through radial velocity and astrometric methods, the composition of circumstellar disks, early mixing and transport in young disks, and late mixing and planetary migration in the Solar System, and Solar System bodies.

    ROADMAP OBJECTIVES: 1.1 1.2 2.2 3.1
  • Task 1.1.1: Leaching of Radiogenic Potassium From Titan’s Core Into Its Ocean

    Working with graduate student Jason Hofgartner and NAI collaborator Christophe Sotin, we modeled the equilibrium chemistry of potassium at high pressure in the interior aqueous media in Saturn’s moon Titan to determine the extent of potassium leaching. This, in turn, allows us to test the hydrated silicate core model proposed by J. Castillo-Rogez and NAI Titan deputy PI Jonathan Lunine.

    ROADMAP OBJECTIVES: 1.1 2.1 2.2 3.2 7.1
  • Alteration of Asteroid Surfaces, Martian Meteorites and Terrestrial Rocks

    The inner solar system is relatively dry, but recent discoveries of water ice on the Moon, the subsurface of Mars, and potentially on a small class of asteroids known as main belt comets (MBCs), has forced us to re-evaluate our understanding of the inner solar system volatile distribution. Understanding the water content in asteroids and its evolution with time will be critical to constrain the origin and evolution of water in the asteroid belt.

    Interpreting the early aqueous history of the solar system requires an understanding of the processes that alter the original materials, including secondary alteration of minerals within parent bodies, and processes termed space weathering that influence surface layers. The nakhlite group of Martian meteorites is known to contain secondary alteration minerals that formed on Mars. We studied the fine-scale mineralogy and chemistry of these alteration minerals, and compared them to terrestrial alteration minerals formed in the Antarctic. The aim of these comparisons was to determine whether conditions such as water/rock ratio, pH and temperature were similar during the formation of alteration minerals in both planetary environments. Hence, the suitability of the Antarctic as a martian analogue site was tested.

    The distribution of MBCs and asteroids with hydrated minerals provide us with a tool to constrain the position of the snow line within the asteroid belt, which has important implications for the origin and distribution of volatiles for the terrestrial planets. However we need to understand the processes that alter the surface composition to be able to interpret the observations in the context of early solar system volatile distribution. Space weathering has been largely associated with “dry” S-type asteroids and is known to decrease the absorption depths and redden the spectral slopes of their surfaces. Only recently have studies indicated that C-type asteroids experience space weathering as well. Currently there are two contrasting views of how space weathering modifies the surfaces of these asteroids. One study found that the spectral slopes become redder with age, similar to S-type asteroids, but another study found that the spectral slopes become neutral with age. This discrepancy has been attributed to sampling effects and differences in mineralogy among C-type asteroids.

    ROADMAP OBJECTIVES: 1.1 2.1 3.1
  • Project 1: Interstellar Origins of Preplanetary Matter

    Interstellar space is rich in the raw materials required to build planets and life, including essential chemical elements (H, C, N, O, Mg, Si, Fe, etc.) and compounds (water, organic molecules, planet-building minerals). This research project seeks to characterize the composition and structure of these materials and the chemical pathways by which they form and evolve. The long-term goal is to determine the inventories of proto-planetary disks around young sun-like stars, leading to a clear understanding of the processes that led to our own origins and insight into the probability of life-supporting environments emerging around other stars.

  • Biosignatures in Ancient Rocks – Kasting Group

    The work by Ramirez concerned updating the absorption coefficients in our 1-D climate model. Harman’s work consisted of developing a 1-D code for modeling hydrodynamic escape of hydrogen from rocky planets.

    ROADMAP OBJECTIVES: 1.1 3.2 4.1 4.2 4.3 5.1 5.2 5.3 6.1 6.2 7.1 7.2
  • Climates and Evolution of Extrasolar Terrestrial Planets

    Planetary climate results from the interplay of a large number of different physical processes, including radiative heating and cooling, advection and dynamics, latent heating and cloud effects, atmosphere-interior interactions, and the presence of life. Atmospheres and climate then evolve through time due to interplay between these processes and longer-term effects, such as atmospheric escape, orbital evolution, and other dynamical interactions. Since planetary climate determines surface habitability, we can better understand how planets maintain habitability over long time periods by studying and modeling the large network of interactions that determine the atmospheric state of a planet and how it changes through time.

  • Habitability, Biosignatures, and Intelligence

    Understanding the nature and distribution of habitable environments in the Universe is one of the primary goals of astrobiology. Based on the only example of life we know, we have devel-oped various concepts to predict, detect, and investigate habitability, biosignatures and intelli-gence occurrence in the near-solar environment. In particular, we are searching for water vapor in atmospheres of extrasolar planets and protoplanets, developing techniques for remote detec-tion of photosynthetic organisms on other planets, have detected a possible bio-chemistry sig-nature in Martian clays contemporary with early life on Earth, developed a comprehensive methodology and an interactive website for calculating habitable zones in binary stellar systems, expanded on definitions of habitable zones in the Milky way Galaxy, and proposed a novel ap-proach for searching extraterrestrial intelligence.

    ROADMAP OBJECTIVES: 1.1 1.2 2.2 3.1 3.2 4.1 4.2 6.2 7.1 7.2
  • Astrophysical Controls on the Elements of Life, Task 2: Model the Chemical and Dynamical Evolution of Massive Stars

    Stars create the chemical elements heavier than hydrogen and helium, with the majority arising from the lives and violent deaths of massive stars in supernova explosions. The starting chemical composition of stars also affects their evolution and that of their associated planets. We have performed computational simulations for a large range of stellar masses to provide predictions for important stellar characteristics (i.e. brightness, temperature, stellar winds, composition) over the stars’ lifetimes and made the data available to the public. We have also simulated the explosions of massive stars to predict the chemical abundances of material ejected from the dying stars and how that material is distributed in the surrounding universe. As a complement, we are modeling how the habitable zones and planets of stars with different abundances evolve.

  • Project 2: Processing of Precometary Ices in the Early Solar System

    The discovery of numerous planetary systems still in the process of formation provides a unique opportunity to see how our own solar system may have formed 4.6 billion years ago. Our research group studies physical processes that determine thermal environments in and around young planetary systems in order to constrain the prebiotic chemistry which can occur there. In one study we have built a unique code which simulates the heating of dense molecular gas in chemically active outflows (CAOs) associated with protostars. Our code will be used to model the wealth of molecular observations of CAOs which will be obtained by SOFIA and other observatories. In another study we have discovered a new mechanism whereby asteroids in the solar nebula are heated by magnetohydrodynamical processes. The goal of the second study is to determine whether asteroids can be warm enough to support prebiotic chemistry in protoplanetary systems that were not innoculated by short-lived radionuclides such as aluminum-26.

    ROADMAP OBJECTIVES: 1.1 3.1 3.2
  • Disks and the Origins of Planetary Systems

    This task is concerned with the evolution of complex habitable environments. The planet formation process begins with fragmentation of large molecular clouds into flattened disks. This disk is in many ways an astrochemical “primeval soup” in which cosmically abundant elements are assembled into increasingly complex hydrocarbons and mixed in the dust and gas within the disk. Gravitational attraction among the myriad small bodies leads to planet formation. If the newly formed planet is a suitable distance from its star to support liquid water at the surface, it is in the so-called “habitable zone.” The formation process and identification of such life-supporting bodies is the goal of this project.

    ROADMAP OBJECTIVES: 1.1 1.2 2.2 3.1 4.1 4.3
  • Investigation 2: Survivability on Icy Worlds

    Investigation 2 focuses on survivability. As part of our survivability investigation, we examine the similarities and differences between the abiotic chemistry of planetary ices irradiated with ultraviolet photons (UV), electrons, and ions, and the chemistry of biomolecules exposed to similar conditions. Can the chemical products resulting from these two scenarios be distinguished? Can viable microbes persist after exposure to such conditions? These are motivating questions for our investigation.

    ROADMAP OBJECTIVES: 1.1 2.2 3.2 5.1 5.3 6.1 6.2
  • 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 see if material ejected from a star that has exploded as a supernova can make its way into the gas as it is forming new solar systems. It has been expected that this material, because it is moving so fast (> 2000 km/s) when it hits the cold, dense molecular cloud in which stars are forming, would shock, heat up, and then “bounce” off of the cloud boundary.

  • Investigation 3: Detectability of Icy Worlds

    Detectability of Icy Worlds investigates the detectability of life and biological materials on the surface of icy worlds, with a focus on spectroscopic techniques, and on spectral bands that are not in some way connected to photosynthesis.The primary component of Investigation 3 is the field campaign in Barrow, AK to characterize and quantify methane release from the Alaskan North Slope region and to understand the origin and fate of the methane.

    ROADMAP OBJECTIVES: 1.1 2.2 5.3 6.1 6.2
  • Project 3: The Origin, Evolution, and Volatile Inventories of Terrestrial Planets

    We study the origin and evolution of the terrestrial planets with a special emphasis on CHON volatiles, their delivery and retention in the deep interiors of terrestrial planets. We will experimentally investigate how CHON volatiles may be retained even during magma ocean phases of terrestrial evolution. We investigate the early Earth’s recycling processes studying the isotopic composition of diamonds, diamond inclusions, and associated lithologies. We continue to integrate new information from the NASA Messenger Mission to Mercury into the broader context of understanding the inner Solar System planets.

    ROADMAP OBJECTIVES: 1.1 3.1 4.1
  • Project 4: Survival of Sugars in Ice/Mineral Mixtures on High Velocity Impact

    Understanding the delivery and preservation of organic molecules in meteoritic material is important to understanding the origin of life on Earth. Though we know that organic molecules are abundant in meteorites, comets, and interplanetary dust particles, few studies have examined how impact processes affect their chemistry and survivability under extreme temperatures and pressures. We are investigating how impact events may change the structure of simple sugars, both alone and when combined with ice mixtures. The experiments will allow us to understand how sugar chemistry is affected by high pressure events and to contrast the survival probabilities of sugars in meteorite and comet impacts. This will lead to a better understanding of how organic molecules are affected during their delivery to Earth. This project leverages expertise in two different NAI nodes, increasing collaborative interaction among NAI investigators.

    ROADMAP OBJECTIVES: 1.1 3.1 4.1 4.3
  • Biosignatures in Extraterrestrial Settings

    We are working on finding potentially habitable extrasolar planets, using a variety of search techniques, and developing some of the technology necessary to find and characterize low mass extrasolar planets. We also work on modeling and numerical techniques relevant to the problem of identifying extrasolar sites for life, and on some aspects of the prospects for life in the Solar System outside the Earth. The ultimate goal is to find signatures of life on nearby extrasolar planets.

    ROADMAP OBJECTIVES: 1.1 1.2 2.1 2.2 3.1 4.1 4.3 6.2 7.1 7.2
  • Astrophysical Controls on the Elements of Life, Task 4: Model the Injection of Supernova Material Into Protoplanetary Disks

    The goal of this project has been to determine whether supernova material could be injected into a proto-planetary disk, the disk of gas and dust from which planets form. A secondary issue is whether these materials would be mixed within the disk efficiently, and whether such an injection into our own proto-planetary disk can explain the isotopic evidence from meteorites that the solar system contained short-lived radionuclides like 26Al.

  • Origin of Earth’s Water

    Understanding the sources and delivery mechanisms of water to the Earth and the other terrestrial planets allows for the validation of planetary accretion models. This information can help us establish at what time the Earth contained sufficient water for the development of life. A key parameter in determining the source(s) of terrestrial planetary water is the hydrogen isotope composition of this water. However, hydrogen fractionation during surface and atmospheric processes on terrestrial planets such as Earth and Mars may have significantly changed the Deuterium/Hydrogen (D/H) ratio in the various water reservoirs. Therefore, to determine the primordial D/H ratio of these planets water we must find reservoirs that has been unaffected by surface processes. Plate tectonics is known to drag surface water down into the crust and the upper mantle, but the transition zone and lower mantle are thought to be uncontaminated by surface water. Therefore, we aimed to sample terrestrial hydrous minerals and melt inclusions sourced from these uncontaminated regions, such as deep mantle plume samples from Iceland and Baffin Island, along with possible deep mantle diamond inclusions. As plate tectonics never developed on Mars, the primary igneous hydrous minerals in martian meteroites were assumed to be isolated from martian surface processes. We analyzed the D/H ratio of these samples using the Cameca ims 1280 ionmicroprobe at the University of Hawaii to produce a dataset that establishes the primordial D/H ratio of Earth and Mars.

    To gain insights into the amount of water present in terrestrial planetary mantle material we synthesized samples of high-pressure mineral phases that are likely hosts for H, and thus water, in planetary interiors. We measured the physical properties of these minerals, including crystal structure, density, elasticity, and electrical conductivity, to investigate the degree to which water may be incorporated into these minerals in the Earth’s mantle.

    Models of terrestrial planet formation have been successful in producing terrestrial-class planets with sizes in the range of Venus and Earth. However, these models have generally failed to produce Mars-sized objects. The body that is usually formed around Mars’ semimajor axis is, in general, much more massive than Mars. We have developed new model for the formation of Mars in which a local depletion in the density of the protosolar nebula results in a non-uniform formation of embryos and ultimately the formation of Mars-sized planets.

  • Evolution of Protoplanetary Disks and Preparations for Future Observations of Habitable Worlds

    The evolution of protoplanetary disks tells the story of the birth of planets and the formation of habitable environments. Microscopic interstellar materials are built up into larger and larger bodies, eventually forming planetesimals that are the building blocks of terrestrial planets and their atmospheres. With the advent of ALMA, we are poised to break open the study of young exoplanetesimals, probing their organic content with detailed observations comparable to those obtained for Solar System bodies. Furthermore, studies of planetesimal debris around nearby mature stars are paving the way for future NASA missions to directly observe potentially habitable exoplanets.

    ROADMAP OBJECTIVES: 1.1 1.2 3.1 4.3 7.2
  • Astrophysical Controls on the Elements of Life, Task 5: Model the Variability of Elemental Ratios Within Clusters

    We carried out studies of self-enrichment of the earliest star clusters, building on the turbulence simulations in Pan & Scannapieco (2010) and Pan et al. (2011), and developing a method to track the formation of metal free stars.

  • Project 5: Vistas of Early Mars: In Preparation for Sample Return

    To understand the history of life in the solar system requires knowledge of how hydrous minerals form on planetary surfaces, and the role minerals may play in the development of potential life forms. The minerals hematite and jarosite have been identified on Mars and presented as in situ evidence for aqueous activity. This project seeks to understand (i) the conditions required for jarosite and hematite formation and preservation on planetary surfaces, and (ii) the conditions under which their “radiometric clocks” can be reset (e.g., during changes in environmental conditions such as temperature). By investigating the kinetics of noble gases in minerals, known to occur on Mars and Earth, we will be prepared to analyze and properly interpret ages measured on samples from future Mars sample return missions.

    ROADMAP OBJECTIVES: 1.1 2.1 7.1
  • Solar System Volatile Distributions – Icy Bodies

    One of the forefront areas of science related to the early solar system, and highlighted in the Plane-tary Decadal Survey, is the need to understand the source of volatiles for planets in the habitable zone and the role that primitive bodies played in creating habitable worlds. Comets, which have escaped the high-temperature melting and differentiation that asteroids experience, are “astrobio-logical time capsules” that have preserved a valuable record of the complex chemical and physical environment in the early solar Nebula. In the early 1970’s we were at the threshold of a new era of asteroid physical studies. After four decades the asteroid population is yielding information about compositional gradients in the nebula, aqueous alteration processes in the protoplanetary disk and the early dynamic environment as the giant planets formed. Similarly, large surveys of Kuiper belt objects have lead to a new understanding of the dynamic solar system architecture and of the outer solar system composition and collisional environment. Surveys are beginning to yield information on comet physical properties, including spectroscopic measurement of volatile comet outgassing at optical and IR wavelengths, nucleus sizes and activity from space and from the ground. As these surveys obtain small solar system body data, they enable a new science that involves studies of clas-ses, secular evolution of physical characteristics and processes. Our team is undertaking several studies to directly observe the volatiles in small bodies and the mechanisms of their activity, to dis-cover and characterize objects that may represent previously unstudied reservoirs of volatiles and to discover the interrelationships between various classes of small bodies in the context of the new dynamical solar system models.

    ROADMAP OBJECTIVES: 1.1 2.2 3.1
  • Exploring the Chemical Composition of Hot Exoplanets With the Hubble Space Telescope

    We have used the new Wide Field Camera 3 (WFC3) instrument on the Hubble Space Telescope (HST) to observe exoplanet transit and eclipse measurements for a number of highly irradiated, Jupiter-mass planets, with a focus on confirming which planets exhibit water absorption in transit and/or eclipse and measuring the characteristic brightness temperature at these wavelengths. Measurements of molecular absorption in the atmospheres of these planets offer the chance to explore several outstanding questions regarding the atmospheric structure and composition of hot Jupiters, including the possibility of bulk compositional variations between planets and the presence or absence of a stratospheric temperature inversion.

    ROADMAP OBJECTIVES: 1.1 1.2 7.2
  • Project 6: The Environment of the Early Earth

    This project involves the development of capabilities that will allow scientists to obtain information about the conditions on early Earth (3.0 to 4.5 billion years ago) by conducting chemical analyzes of crystals (minerals) that have survived since that time. Minerals incorporate trace concentrations of ions and gaseous molecules from the local environment. We are conducting experiments to calibrate the uptake of these “impurities” that we expect to serve as indicators of temperature, moisture, oxidation state and atmosphere composition. Our focus has been mainly on zircon, quartz, and apatite.

    ROADMAP OBJECTIVES: 1.1 4.1 4.3
  • Astrophysical Controls on the Elements of Life, Task 6: Determine Which Elemental or Isotopic Ratios Correlate With Key Elements

    Abundances of both common and trace elements can have substantial effects on the habitability of stellar systems. We study the formation and composition of structures in supernova explosions that deliver isotopes that influence habitability to material that will form new stars and planets. We examine ratios of elements that have substantial effects of the mineralogy and interiors of planets. The relative abundances of common elements vary substantially among nearby stars, and we find that the impact of this on a star’s evolution can change the amount of time its planets are habitable by large factors.

  • Star Formation and the Variable Young Stellar Objects Survey

    Planets form in circumstellar disks around young stars in the early stage of star formation and the physical, chemical, and kinematic properties of young stellar objects set the initial conditions of planet formation and affect subsequent evolution of protostars and planets. In this project we perform optical and submillimeter observations to study young stellar objects. In the optical wave-lengths, the Variable Young Stellar Objects Survey (VYSOS) aims at surveying all the major star forming regions visible from Hawaii for variable young stars. A small survey telescope provides shallow observations over a large area of the sky, and a larger telescope allows deeper more detailed observations of smaller regions. VYSOS observations are done robotically. In the submillimeter wave-lengths, high resolution interferometric observations combined with radiative transfer modeling reveal structures of protostellar envelopes and resolve the embedded disks. We also study the spatial distributions of a deuterated molecule relative to its hydrogenbearing counterpart in the envelopes and compare to chemical models. Lastly, brown dwarf triple systems are studied via numerical simulations, and the results show that when such triple systems break up during the protostellar phase, a common result is the formation of a brown dwarf binary.

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

    Abundances of both common and trace elements can have substantial effects on the habitability of stellar systems. Elemental ratios can change the stellar evolution and mineralogy, geophysics, and surface processes of planets. We study the abundances of large samples of nearby stars and individual systems and the extent of their variation. We examine ratios of elements that have substantial effects on the mineralogy and interiors of planets. The relative abundances of common elements vary substantially among nearby stars. Extremely non-solar abundance ratios at the level that can produce substantial changes in planetary and stellar properties are present in interesting numbers.

  • Fingerprinting Late Additions to the Earth and Moon via the Study of Highly Siderophile Elements in Lunar Impact Melt Rocks

    We have completed analysis of highly siderophile element (HSE) abundances and Os isotopes in seven Apollo 17 impact melt breccias. The project represents a portion of UMd Ph.D. student Miriam Sharp’s dissertation, and the results of three years of GCA summer internships of Lorne Loudin and Iva Gerasimenko. The resulting large database for impact melt rocks from this site is consistent with a dominant signature imparted to rocks from this site by a single major impactor, most likely the impactor that created the Serenitatis basin. The composition of this impactor was broadly chondritic with respect to HSE, but characteristically enriched in Re, Ru and Pd relative to most chondrites that have been analyzed for these elements. The characteristics of the dominant impactor are most similar to chondritic meteorites that are relatively poor in organics and volatiles. These results suggest that the Serenitatis impactor originated in the inner portion of the present asteroid belt. The formation of this basin was likely not a process that delivered substantial water and/or organics to the lunar crust.

  • Project 2A: Magnesium Isotope Fractionation Between Brucite [Mg(OH)2] and Mg Aqueous Species

    Recognition of clay minerals on Noachian martian terranes provides important information on the habitability of early Mars. Magnesium isotopic studies can aid in constraining the paleoenvironmental conditions of these clay deposits. Our goal is to conduct Mg isotope exchange experiments between clay minerals and aqueous Mg solutions to better understand how the formation of clay minerals can produce Mg isotope variability. In Mg-bearing phyllosilicates, octahedrally coordinated Mg2+ cations occur in a sheeted structure that is the same as brucite. Determination of Mg isotope fractionation between brucite and aqueous solution, therefore, may provide insight into the origin of Mg isotope variations during weathering and alteration of silicate rocks. Our results document the distinct Mg isotope signals produced by weathering in the presence of organic ligands, raising the possibility that abiotic weathering may be distinguished from biologically-catalyzed weathering using stable Mg isotopes.

    ROADMAP OBJECTIVES: 1.1 2.1 7.1 7.2
  • Habitable Planet Formation and Orbital Dynamical Effects on Planetary Habitability

    The VPL explores how variations in orbital properties affects the growth, evolution and habitability of planets. The formation process must deliver the appropriate ingredients for life to a planet in order for it to become habitable. After planets form, interactions between a habitable planet at its host star and/or other planets in the system can change planetary properties, possibly rendering the planet uninhabitable. The VPL models these processes through computer models in order to understand how the Earth became and remains habitable, as well as examining and predicting habitability on planets outside the Solar System.

    ROADMAP OBJECTIVES: 1.1 1.2 3.1 4.3
  • Task 3.2: Longer Wavelength Photochemistry of Condensates and Aerosols in Titan’s Lower Atmosphere and on the Surface.

    This study focuses on the condensed phase photochemistry on Titan. In particular, we focus on understanding longer wavelength photochemistry of solid hydrocarbons to simulate photochemistry that could occur based on the UV penetration through the atmosphere and on the evolution of complex organic species in astrobiologically significant regions on Titan’s surface. Here we investigate the oxygenation chemistry involving the condensed Titan’s organic aerosols with water-ice on Titan’s surface – induced by high energy photons simulating the cosmic ray induced chemistry on Titan’s surface.

    ROADMAP OBJECTIVES: 1.1 2.2 3.1 3.2 3.3
  • The Nature and Timing of Aqueous Alteration in Ordinary and Carbonaceous Chondrites

    Water plays a key role in the search for life and habitable planets outside of our Solar System. However, a fundamental question remains unanswered: what is the origin of water on Earth and the terrestrial planets? Our research addresses this question by looking towards chondrites, the building blocks of the Solar System. Chondritic meteorites were assembled within a few million years after the birth of the Sun, and preserve a record of the earliest Solar System processes. We are working to constrain the origin of water in chondritic asteroids, to understand the timescales and conditions of aqueous alteration on chondritic parent bodies, and the effects of aqueous alteration on synthesis and modification of organic matter in chondrites, and to explore how water affected the geologic evolution of primitive material. This work has important implications for the amount of water accreted or delivered to the inner Solar System planets, and the synthesis and delivery of organic matter necessary for life on Earth.

  • Fischer-Tropsch-Type Reactions in the Solar Nebula

    We are studying Fischer-Tropsch-Type reactions in order to investigate the formation of complex hydrocarbons by surface-mediated reactions using simple gases (CO, N2, and H2) found in the early Solar Nebula. Although several theories exist as to how hydrocarbons are formed in the early Solar System, the compelling nature of this type of reaction is that it is passive and generates a wide variety of complex hydrocarbons using commonly available components (gases/grains) without invoking a complex set of conditions for formation. This method for generating hydrocarbons is important because it provides insight or potential as to how comets, meteorites, and the early Earth may have obtained their first hydrocarbon inventory. From this study, we have expanded the FTT experiments into several related areas of interest, of which the formation of amino acids and the trapping of noble gases are two examples.

    ROADMAP OBJECTIVES: 1.1 2.2 3.1 3.2
  • Planetary Surface and Interior Models and SuperEarths

    We use computer models to simulate the evolution of the interior and the surface of real and hypothetical planets around other stars. Our goal is to work out what sorts of initial characteristics are most likely to contribute to making a planet habitable in the long run. Observations in our own Solar System show us that water and other essential materials are continuously consumed via weathering (and other processes: e.g., subduction, sediment burial) and must be replenished from the planet’s interior via volcanic activity to maintain a biosphere. The surface models we are developing will be used to predict how gases and other materials will be trapped through weathering and biological processes over time. Our interior models are designed to predict tidal effects, heat flow, and how much and what sort of materials will come to a planet’s surface through resurfacing and volcanic activity throughout its history.

    ROADMAP OBJECTIVES: 1.1 1.2 4.1 5.2 6.1
  • Task 3.3.1: Solubility of Organics in Simulated Titan Lake Solutions

    Widespread lakes of liquid methane and ethane were discovered on Titan by the Cassini mission in 2006, which naturally motivates questions about the solubility of surface materials in the liquid. Our goal is to measure the solubilities of Titan surface and atmospheric species in cryogenic liquid hydrocarbons, in order to constrain the composition of the hydrocarbon lakes, and provide an understanding into the nature of erosion and sedimentation on Titan. To date, we have measured the solubilities of argon and krypton in liquid methane and ethane, and the solubilities of benzene, naphthalene, and biphenyl in liquid ethane. Relatively high organic solubilities suggest that liquid hydrocarbon based weathering and sorting of surface organics should be occurring on Titan.

    ROADMAP OBJECTIVES: 1.1 2.2 3.1 3.2
  • Habitability of Water-Rich Environments, Task 2: Model the Dynamics of Icy Mantles

    One of Jupiter’s moons, Europa, is one of the few places in the solar system in which the physical and chemical conditions may be suitable for sustaining life. Europa is composed on an outer H2O layer, comprised of rigid ice overlying a liquid water ocean. It is this liquid water ocean which has been hypothesized as having the ingredients necessary for life, but it is shielded from our observation by the thick ice layer. However, under certain conditions, the ice layer is expected to undergo convection, possibly transporting chemicals from the liquid ocean to the surface, where we may be able to detect them. We perform computer modeling of ice/ocean convection to investigate how ocean material is carried up through the ice layer and whether it is expected to reach Europa’s surface. This work provides guidance for future missions which may probe the chemistry of the ice surface.

  • Stellar Effects on Planetary Habitability and the Limits of the Habitable Zone

    In this task VPL Team members explore the interactions between a planet and its parent star and how these interactions affect whether or not the planet can support life. These interactions can be radiative, with light from the star affecting the planet’s climate, or UV from stellar flares affecting the radiation environment at the planet’s surface. Or they interactions can be gravitational, with the star periodically deforming planets on elliptical orbits and thereby transferring energy into the planet. Both radiative and gravitational effects can input too much heat into a planet’s environment and cause it to lose the ability to maintain liquid water at the surface. Research this year included looking at the limits of the habitable zone with new calculations, exploring how gravitational tidal energy could cause a planet to lose its ocean, and understanding the effects that tidal deformation and incoming stellar radiation would have on the habitability of exomoons.

    ROADMAP OBJECTIVES: 1.1 1.2 4.1
  • Water and Habitability of Mars and the Moon and Antarctica

    Water plays an important role in shaping the crusts of the Earth and Mars, and now we know it is present inside the Moon and on its surface. We are assessing the water budgets and total inventories on the Moon and Mars by analyzing samples from these bodies.

    We also study local concentrations of water ice on the Moon, Mars, and at terrestrial analogue sites such as Antarctica and Mauna Kea, Hawaii. We are particularly interested in how local phenomena or microclimates enable ice to form and persist in areas that are otherwise free of ice, such as cold traps on the Moon, tropical craters with permafrost, and ice caves in tropical latitudes. We approach these problems with field studies, modeling, and data analysis. We also develop new instruments and exploration methods to characterize these sites. Several of the terrestrial field sites have only recently become available for scientific exploration.

    HI-SEAS (Hawaii Space Exploration Analog and Simulation, is a small habitat at a Mars analog site in the saddle area of the Island of Hawaii. It is a venue for conducting research relevant to long-duration human space exploration. We have just completed our first four-month long mission, and are preparing for three more, of four, eight and twelve months in length. The habitat is a 36’ geodesic dome, with about 1000 square feet of floor space over two stories. It is a low-impact temporary structure that can accommodate six crewmembers, and has a kitchen, a laboratory, and a flexible workspace. Although it is not airtight, the habitat does have simulated airlock, and crew-members don mockup EVA suits before going outside. The site is a disused quarry on the side of a cinder/splatter cone, surrounded by young lava fields. There is almost no human activity or plant life visible from the habitat, making it ideal for ICE (isolated/confined/extreme) research.

    ROADMAP OBJECTIVES: 1.1 2.1 3.1 5.3 6.1 6.2 7.1
  • Habitability of Water-Rich Environments, Task 3: Evaluate the Habitability of Europa’s Subsurface Ocean

    Mikhail Zolotov, Co-Investigator (Co-I) has provided arguments and performed numerical modeling to explain the presence of sulfates on Europa’s ocean and carbonaceous asteroids (chondrites), which could have been the building block of Galilean satellites. Sulfates could have formed through sulfide oxidation by O2 and H2O2 accreted with ices irradiated in the solar nebula.

  • Task 3.3.2: Trapping of Methane and Ethane in Titan Surface Materials

    We demonstrate that solid benzene can trap significant amounts of ethane and methane within its crystal structure at Titan surface temperatures. Experiments also suggest that liquid ethane can diffuse into solid benzene, resulting in the formation of a co-crystalline structure. This implies that lake edges and evaporite basins on Titan may hold important quantities of ethane. These results can help explain the release of methane observed at the Huygens landing site, and point toward a large possible reservoir of methane and ethane hidden within Titan’s surface organics.

    ROADMAP OBJECTIVES: 1.1 2.2 3.1 3.2
  • Infrared Detections of Hypervolatiles in Distant Comets – Implications for Chemical Taxonomy

    Most IR taxonomic databases of comets concentrate on objects at heliocentric distances within 2 AU, where water (the main volatile species in comets) is active. In 2012, we found that we could quantify hypervolatiles (such as carbon monoxide and methane) using infrared facilities in comets at distances even beyond Jupiter, where water ice cannot sublime efficiently. This project has focused on a new approach to understand the activity of distant comets using infrared facilities, as well as on the role of hypervolatiles in the onset of activity and the implications for current taxonomic databases of primary volatiles.

    ROADMAP OBJECTIVES: 1.1 3.1 3.2 7.1
  • The Nature and Detectability of Astronomical Biosignatures

    In this project VPL team members explore the nature and detectability of biosignatures, global signs of life in the atmosphere or on the surface of a planet. This year we completed comprehensive modeling work that explores the potential for non-biological generation of oxygen and ozone in early Earth-like atmospheres, which could result in a “false positives” for photosynthetic life. We also explored the detectability of molecular dimers, especially O2-O2 as potentially easier to detect biosignature gases for transit transmission observations.

    We also calculated maximum methane fluxes from the geological process of serpentinization, as a potential false positive for life, and looked at the nature and detectability of non-photosynthetic pigments as potential biosignatures for life on exoplanets. We also started work to develop new, more generalized biosignatures via measurement of thermodyamic and kinetic anomalies in planetary atmospheric compositions that are associated with life. We complemented this theoretical work with field work in caves dominated by sulfur-bacteria, to understand isotopic processing of sulfur by life, as a potential biosignature for life on Mars, or for planets with sulfur-domianted biospheres.

    ROADMAP OBJECTIVES: 1.1 1.2 4.1 7.2
  • Understanding Past Earth Environments

    For much of the history Earth, life on the planet existed in an environment very different than that of modern-day Earth. Thus, the ancient Earth represents a planet with a biosphere that is both dramatically different than the one in which we live, but that is also accessible to detailed study. As such, it serves as a model for what types of biospheres we may find on other planets. A particular focus of our work was on the “Early Earth” (formation through to about 500 million years ago), a timeframe poorly represented in the geological and fossil records but comprises the majority of Earth’s history. We have studied the composition, pressure and climate of the ancient atmosphere; the delivery of biologically available phosphorus; studied the sulfur, oxygen and nitrogen cycles; and explored atmospheric formation of molecules that were likely important to the origins of life on Earth.

    ROADMAP OBJECTIVES: 1.1 1.2 4.1 4.2 5.1 5.2 6.1
  • NNX09AH63A Origin and Evolution of Organics in Planetary Systems

    The Blake group has been carrying out joint observational and laboratory program with NAI node scientists on the water and simple organic chemistry in the protoplanetary disk analogs of the solar nebula and in comets. Observationally, we continue to build on our extensive (>100 disks) Spitzer IRS survey of the infrared molecular emission from the terrestrial planet forming region of disks with follow-up work using the high spectral resolution ground-based observations of such emission (via the Keck and the Very Large Telescopes, the Herschel Space Observatory, and ALMA) along with that from comets. This year, we emphasized the disk systems in which we have probed the outer disk’s water emission with the Herschel HIFI instrument. With Herschel PACS we have measured the ground state emission from HD for the first time, yielding much more accurate mass estimates, that we have used in turn to carry out the first detailed examination of the radial water abundance structure in the planet-forming environments represented by the so-called transitional disk class. In the laboratory, we have developed a novel approach to broad-band chirped pulse microwave spectroscopy that promises to drop the size, mass and cost of such instruments by one to two orders of magnitude. We are using the new instrument to measure the rotational spectra of prebiotic compounds, and our existing THz Time Domain Spectrometer to characterize their large amplitude vibrations. Looking forward, these techniques have the potential to make site-specific stable isotope measurements, a capability we will explore with GSFC Node scientists.

    ROADMAP OBJECTIVES: 1.1 1.2 3.1
  • Project 3B: Carbon Isotope Analysis of Archean Microfossils

    We have completed a study of petrography, Raman microspectroscopy, and in situ analyses of carbon isotope and H/C ratios using secondary ion mass spectrometry (SIMS) of diverse organic microstructures, including possible microfossils. This work has focussed on two localities of the 3.4-billion-year-old Strelley Pool Formation (Western Australia). For the first time, we show that the wide range of carbon isotope ratios recorded at the micrometer scale correlates with specific types of texture for organic matter (OM), arguing against abiotic processes to produce the textural and isotopic relations. These results support the biogenicity of OM in the Strelley Pool Formation.

    ROADMAP OBJECTIVES: 1.1 2.1 4.1 4.2 5.2 6.2 7.2
  • Understanding the Early Mars Environment

    There is no liquid water on modern Mars, although there is plenty of solid ice. Observations from orbiting satellites and rovers on the ground suggest that liquid water may have flowed over the Martian surface in the distant past. VPL researchers are studying the geologic record of Mars for clues of past water, and investigating climate and chemical conditions under which water would be stable. Team members examined different climate feedbacks and geochemical processes that could have warmed the early Mars. Some members are also active members of the MSL science team.

    This year, team members used climate and interior models to demonstrated that broadening of carbon dioxide and water absorption by volcanically-released hydrogen in Mars early atmosphere may have been enough to raise the mean surface temperature of early Mars above the freezing point of water. We also looked for mechanisms that might have produced the abundant perchlorate molecule found on the Martian surface today.

  • Task 3.5.1: Titan as a Prebiotic Chemical System

    Six years ago, NASA sponsored a National Academies report that asked whether life might exist in environments outside of the traditional habitable zone, where “weird” genetic molecules, metabolic processes, and bio‐structures might avoid the water‐based biochemistry that is found across the terran biosphere. 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. Further, we asked about the possibility that Titan might inform our understanding of prebiotic chemical processes, including those on “warm Titans”. Our experimental activities found few possibilities for non‐phosphate-based genetics in subsurface aqueous environments, even if they are rich in ammonia at very low temperatures. Further, we showed that polyethers are insufficiently soluble in hydrocarbons at very low temperatures, such as the 90‐100 K found on Titan’s surface. However, we did show that “warm Titans” could exploit propane 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 other work that allows reduced molecules to appear as precursors for more standard genetic biomolecules, especially through interaction with various mineral species.

    ROADMAP OBJECTIVES: 1.1 1.2 2.2 3.1 3.2 4.1 4.2 5.3 6.2 7.1 7.2
  • Neoproterozoic Aerobic Transition

    The Proterozoic carbon isotopic record contains evidence of a series of large perturbations to the global carbon cycle, some or all of which may be associated with changes in atmospheric O2. Our team is formulating a theoretical model to explain not only these disruptions but also the permanent increase in O2 levels that occurred by the end of the Proterozoic.

    ROADMAP OBJECTIVES: 1.1 4.1 4.2 5.2 6.1
  • Remote Sensing of Organic Volatiles on Mars and Modeling of Cometary Atmospheres

    Using our newly developed analytical routines, Villanueva reported the most comprehensive search for trace species on Mars (Villanueva et al. 2013b, Icarus) and described in detail the chemical taxonomy of comets C/2001 Q4 and C/2002 T7 (de Val-Borro et al. 2013). He expanded our already comprehensive high-resolution spectroscopic database to include billions of spectral lines of ammonia (NH3, Villanueva et al. 2013a), hydrogen cyanide (HCN, Villanueva et al. 2013a, Lippi et al. 2013), hydrogen isocyanide (HNC, Villanueva et al. 2013a), cyanoacetylene (HC3N, Villanueva et al. 2013a), monodeuterated methane (CH3D, Gibb et al. 2013), and methanol (CH3OH, DiSanti et al. 2013). For each species, he developed improved or new fluorescence models using the new spectral models. These permit unprecedented improvement in models of absorption spectra in planetary atmospheres (Earth, Mars), and in computing fluorescence cascades for emission spectra of cometary gases pumped by solar radiation. Villanueva utilized these new models in analyzing spectra of comets that enabled record observations of CO in comet 29P/Schwassmann-Wachmann-1 (see report by Paganini), revealed the unusual organic composition of comet 2P/Encke (see report by Mumma), developed new fluorescence models for the ν2 band of methanol and for the ν3 band of CH3D in comets (see reports by DiSanti and by Bonev), and discovered two modes of water release in comet 103P/Hartley-2 (see report by Bonev).

    ROADMAP OBJECTIVES: 1.1 2.1 3.1 3.2 4.1 7.1
  • SMACK: A New Algorithm for Modeling Collisions and Dynamics of Planetesimals in Debris Disks

    Finding habitable planets and understanding the delivery of volatiles to their surfaces requires understanding the disks of rocky and icy debris that these planets orbit within. But modeling the physics of these disks is complicated because of the challenge of tracking collisions among trillions of trillions of colliding bodies. We developed a new technique and a new code for modeling the collisions and dynamics of debris disks, called “SMACK” which will help us interpret images of planetary systems to better understand how planetesimals transport material within young planetary systems.

    ROADMAP OBJECTIVES: 1.1 1.2 3.1
  • Project 4A: Better, Faster, Smaller Fe Isotope Analysis on Iron Oxides and Sulfides by Femtosecond Laser Ablation: Aerosol Characterization and the Influence of Ablation Cells

    New methods are being developed for in situ stable isotope analysis that increase the precision and/or decrease the volume sampled during the analysis. These improvements allow one to identify isotopic anomalies with increasing spatial resolution. We have focused on improving the ablation cell and mass spectrometer electronics to increase the spatial resolution of Fe isotope studies on iron oxides and sulfides whilst maintaining an external precision of +0.2 ‰ in 56Fe/54Fe using femtosecond Laser Ablation (fs-LA) with isotopic analysis by MC-ICP-MS (Micromass “IsoProbe”). These improvements have allowed us to decrease the volume needed for an Fe isotope analysis to ~600μm3 with an external precision of 0.2 ‰ in 56Fe/54Fe (for a typical analysis the laser beam is rastered over an area of 20 by 15 μm). Compared to previous LA Fe isotope studies the volume used for an analysis in an order of magnitude smaller and is similar to Fe isotope studies that have been done by ion microprobe.

    ROADMAP OBJECTIVES: 1.1 2.1 7.1 7.2
  • Undergraduate Research Associates in Astrobiology (URAA)

    2013 featured the Tenth URAA offering (Undergraduate Research Associates in Astrobiology), a ten-week residential research program at the Goddard Center for Astrobiology (GCA) ( Competition was very keen, with an oversubscription ratio of 3.0. Students applied from over 19 colleges and universities in the United States, and 6 Associates from 6 institutions were selected. Each Associate 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 2.1 3.1 6.2 7.1
  • The Astrobiology Walk

    The Goddard Center for Astrobiology (GCA) has completed the development and installation of a permanent outdoor exhibit at the Goddard Space Flight Center (GSFC) Visitor Center as a major public outreach effort. The “Astrobiology Walk” is designed to showcase the latest scientific discoveries from the GCA research theme “Search for the Origin and Evolution of Organics” in the context of a timeline for the evolution of the Universe and the Solar System. The exhibit consists of ten outdoor stations situated on the circular pathway around the Visi-tor Center’s “Rocket Garden”, each with a memorable iconic 3D object to convey the main scientific message. QR codes link each placard to web sites relevant to that topic.

    ROADMAP OBJECTIVES: 1.1 1.2 2.1 2.2 3.1 3.2 4.1 4.3 7.1 7.2
  • Undergraduate Research Associates in Astrobiology (URAA)

    2013 featured the Tenth URAA offering (Undergraduate Research Associates in Astrobiolo-gy), a ten-week residential research program at the Goddard Center for Astrobiology (GCA) ( Competition was very keen, with an oversubscription ratio of 3.0. Students applied from over 19 colleges and universities in the United States, and 6 Associates from 6 institutions were selected. Each Associate 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 la-boratories and gaining a broader view of astrobiology as a whole. At summer’s end, each As-sociate 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 2.1 3.1 6.2 7.1