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2012 Annual Science Report

Astrobiology Roadmap Objective 2.2 Reports Reporting  |  SEP 2011 – AUG 2012

Project Reports

  • Astronomical Observations of Planetary Atmospheres and Exoplanets

    This task encompasses remote-sensing observations of Solar System and extrasolar planets made by the VPL team. These observations, while providing scientific exploration in its own right, also allow us to test our planetary models and help advance techniques to retrieve information from the astronomical data that we obtain. This can include improving our understanding of the accuracy of inputs into our models, such as spectral databases. This year we made and/or analyzed observations of Mars, Venus and Earth taken by ground-based and spaceborne observatories, to better understand how well we can determine planetary properties like atmospheric and surface temperature and pressure, when a terrestrial planet is observed only as a distant point of light.

    ROADMAP OBJECTIVES: 1.2 2.2 7.2
  • Cosmic Distribution of Chemical Complexity

    The three tasks of this project explore the connections between chemistry in space and the origin of life. We start by tracking the formation and evolution of chemical complexity in space, from simple carbon-rich molecules such as formaldehyde and acetylene to complex species including amino acids, nucleic acids and polycyclic aromatic hydrocarbons. The work focuses on carbon-rich species that are interesting from a biogenic perspective and on understanding their possible roles in the origin of life on habitable worlds. We do this by measuring the spectra and chemistry of analog materials in the laboratory, by remote sensing with small spacecraft, and by analysis of extraterrestrial samples returned by spacecraft or that fall to Earth as meteorites. We then use these results to interpret astronomical observations made with ground-based and orbiting telescopes.

    ROADMAP OBJECTIVES: 1.1 2.1 2.2 3.1 3.2 3.4 4.3 7.1 7.2
  • Habitability of Icy Worlds

    Habitability of Icy Worlds investigates the habitability of liquid water environments in icy worlds, with a focus on what processes may give rise to life, what processes may sustain life, and what processes may deliver that life to the surface. Habitability of Icy Worlds investigation has three major objectives. Objective 1, Seafloor Processes, explores conditions that might be conducive to originating and supporting life in icy world interiors. Objective 2, Ocean Processes, investigates the formation of prebiotic cell membranes under simulated deep-ocean conditions, and Objective 3, Ice Shell Processes, investigates astrobiological aspects of ice shell evolution.

    ROADMAP OBJECTIVES: 1.1 2.1 2.2 3.1 3.2 3.3 3.4 4.1 5.1 6.1 6.2 7.1 7.2
  • Task 1.1.1 Models of the Internal Dynamics: Formation of Liquids in the Subsurface and Relationships With Cryovolcanism

    The effort focused on establishing the geologically-determined conditions for organic evolution in the surface and interior. Using the standard prescription for modeling of satellite interiors, novel equations of state and thermal parameters were included that more realistically simulate Titan’s interior. The new value of the tidal love number for Titan was considered, along with inclusion of crustal clathrate. The likelihood of direct contact between an interior ocean and rock, as well as the cycling of hot water from rock to ocean, was demonstrated. The result raises the interest of Titan as an astrobiologically significant object in the solar system.

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

    This project integrates the work of Carnegie Institution Astronomers in the 1) the search for extrasolar planets, 2) understanding the flow of matter in protoplanetary disks around young stars, 3) understanding the origin of Near Earth Objects, in particular, their relationship with objects in the asteroid belt, and 4) understanding the composition of disks around young stars and the potential delivery of volatiles to terrestrial planets in other solar systems.

    ROADMAP OBJECTIVES: 1.1 1.2 2.2 3.1
  • Biosignatures in Extraterrestrial Settings

    Exploring the prospects for biosignatures in extraterrestrial settings is a multi

    ROADMAP OBJECTIVES: 1.1 1.2 2.1 2.2 3.1 4.1 4.3 6.2 7.1 7.2
  • Project 2: Origin and Evolution of Organic Matter in the Solar System

    Extraterrestrial organic matter as is found in comets and certain meteorites has the potential to tell us much about the origin of the solar system, the origin of planetary volatiles, and possible the origins of life. In this project, we bring a powerful array of analytical methods to bare on understanding extraterrestrial organic matter at the molecular level. Our work links astronomy, chemistry, physics, and planetary science.

    ROADMAP OBJECTIVES: 2.2 3.1 7.1
  • Survivability of Icy Worlds

    Survivability of 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: 2.2 3.2 5.1 5.3 7.1 7.2
  • Task Models of the Reaction Between Hydrocarbons and Water Ice (Part 1)

    Studying the morphology and composition of Titan’s northern lakes and seas allow refining the values of the carbon contained in different reservoirs (atmosphere, lakes, dune fields). From this a carbon cycle can be constructed that takes into account the interactions between the interior, surface, and atmosphere.

  • Detectability of Life

    Detectability of Life investigates the detectability of chemical and biological signatures 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.Detectability of life investigation has three major objectives: Detection of Life in the Laboratory, Detection of Life in the Field, and Detection of Life from Orbit.

    ROADMAP OBJECTIVES: 1.2 2.1 2.2 4.1 5.3 6.1 6.2 7.1 7.2
  • Task Models of the Reaction Between Hydrocarbons and Water Ice (Part 2)

    In the clathrate phase, there can be an exchange between primordial methane clathrates, which are believed to make at least part of Titan’s upper crust, and ethane, which is the primary product of Titan’s atmospheric chemistry and is one of the major constituents of the lakes. Including these exchanges in a geophysical model of Titan allows explaining Titan’s shape as measured by the Cassini mission. These exchanges also may have an influence on Titan’s hydrocarbon cycle.

  • Task 1.2 Interaction of Methane/ethane With Water Ice

    A Titan lake simulation system is under construction to provide a testbed for testing small instruments and components at Titan lake conditions in preparation for future in-situ missions.

  • Astrochemistry Theory and Observation Group NAI Report

    We have continued observational programs designed to explore the chemical composition of comets and establishing their potential for delivering pre-biotic organic materials and water to the young Earth and other planets. State of the art, international facilities are being employed to conduct multiwavelength, simultaneous, studies of comets in order to gain more accurate abundances, distributions, temperatures, and other physical parameters of various cometary species. Additionally, observational programs designed to test current theories of the origins of isotopically fractionated meteorite (and cometary) materials are currently underway. Recent chemical models have suggested that in the cold dense cores of star forming regions, significant isotope enrichment can occur for nitrogen and possibly vary between molecular species and trace an object’s chemical evolution. Observations are being conducted at millimeter and submillimeter wavelengths of HCN and HNC isotopologues for comparison to other nitrogen-bearing species to measure fractionation in cold star forming regions.

    ROADMAP OBJECTIVES: 2.2 3.1 3.2 7.1
  • Path to Flight

    The (Field Instrumentation and) Path to Flight investigation’s purpose is to enable in-situ measurements of organics and biological material with field instrumentation that have high potential for future flight instrumentation. The preceding three Investigations (Habitability, Survivability and Detectability) provide a variety of measurable goals that are used to modify or “tune” instrumentation that can be placed in the field. In addition the members involved with Investigation provide new measurement capabilities that have been developed with the specific goal of life-detection and organic detection using both non-contact/non-destructive means and ingestion based methods. The developments under this investigation (Inv 4) incorporate state-of-the-art laboratory instruments and next generation in-situ instrumentation that have been developed under programs that include NASA as well as NSF and DOD. These include mass-spectrometers, gas analyzers, and fluorescence/Raman spectrometry instruments.

    ROADMAP OBJECTIVES: 1.1 1.2 2.1 2.2 3.1 3.2 7.1 7.2
  • Task Master Atmospheric Chemistry Simulation

    A new approach to the condensation of molecules onto grains and sublimation back to the gas has been implemented to account for these processes in an approach that is numerically stable and relies on the extensive database of laboratory data on the saturation vapor pressures of molecules. This, combined with the new description of grain size distribution (implemented last year), will provide a great improvement in the description of the organic chemistry in Titan’s atmosphere.

  • Composition of Parent Volatiles in Comets

    During the period covered by this progress report we observed the Oort cloud comets C/2009 (Garradd) and C/2010 G2 (Hill). We completed our comprehensive study of prebiotic molecules in comet C/2007 N3 (Lulin). We continued our multi-comet surveys of spin temperatures and searches for deuterated species. We conducted spatially-resolved measurements of water rotational temperature, column abundance, and ortho-para ratio in the inner coma of comet 103P/Hartley 2 – the target of NASA the EPOXI fly-by mission. We studied the volatile composition of another Jupiter-family comets – 21P/Giacobini-Zinner. We studied the activity of comet Christensen beyond 3 AU from the Sun.

  • Task Titan Aerosol Chemistry

    The observed vertical profiles of Titan organic aerosols have been analyzed and the possible chemistry forming these aerosols studied. The elementary reaction of the ethynyl radical with diacetylene represents an efficient pathway to produce triacetylene in Titan’s atmosphere in those regions where density profiles of photolytically-generated ethynyl radicals and diacetylene overlap. The model of Titan’s atmosphere indicates that successive reactions of the triacetylene molecule can yield even more complex polyynes. These polyynes are thought to be the basis out of which the organic aerosols are formed.

  • Discovery of a Periodicity in X-Ray Emission From an Erupting Young Star and Diffuse Emission in the Carina Star Forming Region

    High-energy photons in the young stellar environment are known to be important in stimulating chemical reactions of molecules and producing pre-biotic materials. In this reporting period, we approached this problem from two directions: systematic study of X-ray light curves of a young star that experienced an episodic outburst and spectral characteristics of diffuse X-ray emission from the Carina massive star-forming region. We discovered a periodicity of a day in the highly elevated X-ray emission from a protostar for the first time. This result was press-released from NASA/GSFC, ESA and NAI. We also found a strong X-ray emission line in a diffuse spectrum around Eta Carinae, which may require a non-thermal process such as charge exchange.

  • Task Atmospheric State and Dynamics

    To support the master atmospheric model, realistic Titan atmospheric profiles [winds, temperatures and densities] from the surface to ~1200km, for a variety of seasons and solar cycles, is needed.

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

    The new computer codes could be used to calculate changes in phase composition during freezing or melting in cold icy environments on Mars, large water-bearing asteroids, icy moons of giant planets, comets, and other trans-neptunian objects. Another model will allow us to calculate composition of liquid hydrocarbons on the surface of Titan.

  • Task Atmospheric Observations

    Airglow emission from the atmosphere was discovered while Titan was deep in Saturn’s shadow. This suggests an important role for charged particles in producing this airglow.

  • 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.

  • Task 2.2.1 Characterization of Aerosol Nucleation and Growth

    One goal has been to elucidate the mechanisms and develop a quantitative understanding of particle formation and growth in the Titan atmosphere. Work has focused on elucidating the role of molecular interactions in growth of Titan aerosol particles using numerical simulations.

  • The Subglacial Biosphere – Insights Into Life-Sustaining Strategies in an Extraterrestrial Analog Environment

    Sub-ice environments are prevalent on Earth today and are likely to have been more prevalent the Earth’s past during episodes of significant glacial advances (e.g., snow-ball Earth). Numerous metabolic strategies have been hypothesized to sustain life in sub-ice environments. Common among these hypotheses is that they are all independent of photosynthesis, and instead rely on chemical energy. Recently, we demonstrated the presence of an active assemblage of methanogens in the subglacial environment of an Alpine glacier (Boyd et al., 2010). The distribution of methanogens is narrowly constrained, due in part to the energetics of the reactions which support this functional class of organism (namely carbon dioxide reduction with hydrogen and acetate fermentation). Methanogens utilize a number of metalloenzymes that have active site clusters comprised of a unique array of metals. During the course of this study, we identified other features that were suggestive of other active and potentially relevant metabolic strategies in the subglacial environment, such as nitrogen cycling. The goals of this project are 1) identifying a suite of biomarkers indicative of biological CH4 production 2). quantifying the flux of CH4 from sub-ice systems and 3). developing an understanding how life thrives at the thermodynamic limits of life. This project represents a unique extension of the ABRC and bridges the research goals of several nodes, namely the JPL-Icy Worlds team and the ASU-Follow the Elements team.

    ROADMAP OBJECTIVES: 2.1 2.2 5.1 5.2 5.3 6.1 6.2 7.1 7.2
  • Ice Chemistry of the Solar System

    We are currently in the process of establishing a research program at the University of Hawai’i at Manoa to investigate the evolution of Solar System and interstellar ices; these grains are chemically processed continuously by radiation from either our Sun, or galactic cosmic radiation (GCR). The nature of the chemistry that occurs here is an important component of understanding the origin of complex biomolecules that could have seeded the primordial Earth, helping to kick-start the origin of life. We have constructed one of the leading laboratory facilities in the world capable of carrying out this research, and we focus on establishing the underlying chemical pathways.

    ROADMAP OBJECTIVES: 1.1 2.2 3.1 3.2 3.3 4.1 7.1 7.2
  • Habitability of Water-Rich Environments, Task 3: Evaluate the Habitability of Europa’s Subsurface Ocean

    Europa is of keen interest to astrobiology and planetary geology due to its indications of a sub-surface ocean. Understanding of Europa’s oceanic composition and pH is important to evaluate habitability of the icy moon. Knowledge of the global distribution and timing of Europan geologic units is a key step for understanding the history of the satellite and for identifying areas of recent activity. We are evaluating the habitability of a subsurface ocean of Europa through evaluation of chemical composition and salinity of oceanic water. We use numerical approaches to model interaction of possible rocks on Europa with water formed through melting of ices. In addition, we use chemical and mineralogical signs of water-rock interactions in carbonaceous chondrites as a proxy for aqueous processes on Europa.

  • Task 2.2.2 Ultraviolet/infrared Spectroscopy and Photoprocessing of Ice Films

    Investigations of the condensed phase chemistry of Titan’s atmospheric aerosols has continued. The focus this year has been on the photochemistry of acetylene imbedded in C4N2 ice—to simulate atmospheric aerosol photochemistry involving most abundant unsaturated molecule (acetylene) in Titan’s atmosphere.

  • Task Reactions of Organic Ices With Electrons (Part 1)

    Ices exposed to low-energy electrons can be the cradle to further chemical reactions.

  • Task Reactions of Organic Ices With Electrons (Part 2)

    Secondary electrons can stimulate the polymerization of HCN. These electrons are present at low altitudes and in the near surface regions of Titan and not only lead to polymerization, but also negative charging of the haze particles.

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

    The goal of this project is to determine the internal structure of small icy bodies, especially the objects like Pluto and its moon Charon, which are Kuiper Belt Objects (KBOs). The possibility exists that these icy bodies may contain liquid water at great depths, despite their frigid surface temperatures and small sizes, because radioactivities heat them and their ices might contain antifreezes like ammonia. We are also evaluating the chemical composition of aqueous solutions which could have formed shortly after formation of asteroids and moons of giant planets. Another of our tasks is to estimate chemical composition of methane-rich liquids that are present at the surface of Titan at extremely low temperatures.

  • Main Belt Comets and Water in the Outer Asteroid Belt

    The ongoing discovery of potential members of a new class of objects, known as Main Belt Comets (MBCs), raises a number of questions regarding their structure, composition, and origin. These may indicate that the entire outer asteroid belt contains significant volatile material, and this has impli-cations for its delivery to the terrestrial planets. Whatever the origin is, they have spent most of their lifetimes in the asteroid main belt, which has been considered too hot for ice to survive for any length of time. The low conductivity of porous cometary material suggests, however, that ice may be retained in the interior of main belt bodies, despite continual solar heating. Indeed, analytical estimates, as well as numerical computations, indicate that this is possible. We investigate the ice survival question by means of detailed numerical modeling of long-term evolution for a range of ini-tial parameters. As another step in this study, we try to characterize the impact-triggering mecha-nism that supports the observed activity, however diffuse and weak it may be. This is achieved by means of statistical estimates of how a population of very small colliding bodies will ablate the sur-face and affect the way heat is conducted into any deeper buried water ice pockets. The main ques-tions that we address are: (a) To what extent and under what conditions (related to structure and composition) may water ice be preserved in MBCs for the age of the Solar System; (b) How deep below the surface is the ice expected to be found? (c) What is the rate at which small impacts ex-pose fresh water ice pockets and cause it to sublimate?

  • Task Reactions of Organics With Ices and Mineral Grains

    One focus is on understanding reactions occurring on Titan’s surface with an emphasis on determining whether mineral deposits from meteoritic infall can catalyze the formation of more complex molecules of prebiotic relevance such as amines, polyamines or simple amino acids.

  • Measuring Interdisciplinarity Within Astrobiology Research

    To integrate the work of the diverse scientists working on astrobiology, we have harvested and analyzed thousands of astrobiology documents to reveal areas of potential connection. This framework allows us to identify crossover documents that guide scientists quickly across vast interdisciplinary libraries, suggest productive interdisciplinary collaborations, and provide a metric of interdisciplinary science.

    ROADMAP OBJECTIVES: 1.1 1.2 2.1 2.2 3.1 3.2 3.3 3.4 4.1 4.2 4.3 5.1 5.2 5.3 6.1 6.2 7.1 7.2
  • Task 3.1.2 Chemistry Active in Titan Dunes

    The goal of this project is to demonstrate that chemical reactions can occur between atmospheric organics and water ice, even at the low temperature (ca. 100 K) of Titan’s surface, leading to the incorporation of oxygen to form molecules of astrobiological significance. Studies using a low temperature fluidized bed reactor demonstrate that amino acids, glycine specifically, are produced by tribochemical reactions driven by Aeolian processes in Titan’s dunes.

  • Remote Sensing of Organic Volatiles in Planetary and Cometary Atmospheres

    In the last year, we have greatly advanced our capabilities to model spectra of cometary and planetary atmospheres (Villanueva et al. 2012a, 2012b). Using these newly developed analytical methods, we derived the most comprehensive search for biomarkers on Mars (Villanueva et al. 2012, submitted) from our extensive database of high-quality Mars spectra. Furthermore, we retrieved molecular abundances of several comets (Villanueva et al. 2012c, Gibb et al. 2012, Paganini et al. 2012a/b), and of several young circumstellar disks (Mandell et al. 2012). These great advancements have allowed us to understand the infrared spectrum of planetary bodies and their composition with unprecedented precision.

    ROADMAP OBJECTIVES: 1.1 1.2 2.1 2.2 3.1 3.2 7.1 7.2
  • Task 3.2 Cosmic-Ray Induced Surface Ice Chemistry

    Oxygenation chemistry involving the condensed Titan’s organic aerosols with water-ice on Titan’s surface may be induced by high energy photons simulating the cosmic ray induced chemistry on Titan’s surface.

  • The Chemical Composition of Comets

    Understanding the origin and the distribution of organic matter and volatile material in the early Solar System is of central importance to astrobiology. Comets, which have escaped the high-temperature melting and differentiation that asteroids experience, are “astrobiological time cap-sules” that have preserved a valuable record of the complex chemical and physical environment in the early solar nebula. Studying the primordial chemistry and evolution of cometary nuclei will pro-vide important clues about the birthplace of comets and in turn place strong constraints on the cur-rent Solar System formation models. In late 2011 and 2012, two bright comets, C/2011 L4 (Pan-STARRS) and C/2009 P1 (Garradd), visited the inner Solar System for the first time. In March 2012, C/2011 L4 (PanSTARRS) is expected to appear even brighter than the comet Hale-Bopp, the bright-est since 1996. We have recently studied C/2011 L4 and C/2009 P1 in the sub-millimeter and infra-red wavelength regimes using the James Clerk Maxwell Telescope (JCMT), Caltech Submillimeter Observatory (CSO), Gemini-North and the Keck Telescopes on Mauna Kea, Hawaii. We investigated the chemical compositions of these comets and compared them with those of other comets. Our unique observations of these two bright comets over a wide range of heliocentric distances allow monitoring of the abundances of several native molecules that are key to understanding comet formation.

    We are also conducting a systematic survey of comet brightness around their orbits in order to model their volatile composition. Using space-based data from the Akari Satellite, the WISE Satel-lite, and the EPOXI mission we are showing that these models can provide information on gas spe-cies normally not detectable through Earth’s atmosphere. This gives us the opportunity to investi-gate the wide spread distribution of key cometary volatiles (water, carbon monoxide and carbon dioxide) and their relation to protoplanetary disk chemistry.

    ROADMAP OBJECTIVES: 1.1 2.2 3.1
  • Task 3.3.1 Solubility of Gases and Organics in Liquid Methane and Ethane

    A 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.

  • Task 3.3.2 Precipitation of Organics in Titan Lakes

    Laboratory experiments simulating processes on the beaches of Titan lakes have been pursued. Work to date suggests that, at 94 K and 1 bar pressure, the precipitation of dissolved acetylene and benzene results in the formation of both solids on the beaches.

  • Task 3.4.1 Tholin Chemical Analysis Using Nuclear Magnetic Resonance

    One effort is to develop techniques for analyzing the structural features of Titan organic aerosol analogues (tholins) and HCN polymers.

  • Task 3.4.2 Tholin Analysis Based on Selective Detection of Functional Groups

    The goal of this project has been to develop methods to identify and determine the structure of complex organic compounds formed in the Titan environment. These methods also may be useful for in situ chemical analyses in future robotic explorations of Titan’s complex atmospheric and surface chemical environment.

  • Task 3.5.1 Titan Genetics

    This project seeks to determine what chemical structures might support the genetic component of Darwinian evolution in Titan environments.

    ROADMAP OBJECTIVES: 2.2 3.2 4.2 6.2
  • Task 3.5.2 Energetics of Titan Life

    Infall to the Titan system of both interplanetary and circum-Saturnian dust and ice particles can provide exogenic fluxes of several elements, such as germanium and oxygen, which may be important in facilitating potential Titan metabolisms.