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2015 Annual Science Report

NASA Jet Propulsion Laboratory - Icy Worlds Reporting  |  JAN 2015 – DEC 2015

Executive Summary

In this interdisciplinary research we conduct a highly synergistic combination of experimental, theoretical, and field-based lines of inquiry focused on answering a single compelling question in astrobiology: How can geochemical disequilibria drive the emergence of metabolism and ultimately generate observable signatures on icy worlds?

Astrobiology at water-rock interfaces found on icy bodies (e.g., Europa, Enceladus and Ganymede) in our Solar System (and beyond) is the unifying theme for the proposed research. Several of the icy moons in our Solar System have subsurface oceans that, combined, contain many times the volume of liquid water on Earth. All of these icy worlds may host or may have once hosted water-rock interfaces generating free energy from geochemical gradients. Our transdisciplinary team of researchers are working together to examine bio-geochemical/-geophysical interactions taking place between rock/water/ice interfaces in these environments to better understand and constrain the ... Continue reading.

Field Sites
16 Institutions
4 Project Reports
15 Publications
6 Field Sites

Project Reports

  • Inv 1 – Geochemical Reactor: Energy Production at Water-Rock Interfaces

    INV 1 examines water-rock interactions in the lab and in the field, to characterize the geochemical gradients that could be present at water-rock interfaces on Earth and other worlds, taking into account different ocean and crustal chemistries. We have fully investigated serpentinization as the most likely of all possible environments for life’s emergence on Earth as well as other water-rich worlds – a key goal for astrobiology as stated in the NASA Astrobiology Roadmap 2008. (Russell, 2015). Serpentinization is now recognized as fundamental to delivering the appropriate chemical disequilibria at the emergence of life. And the fact that this process is likely inevitable on any icy, wet and rocky planet makes its study fundamental to emergence of life, habitability and habitancy. Nevertheless, notwithstanding the thermodynamic drives to CO2 reduction during the process, great uncertainty exists over just what kind of organic molecules (if any) are delivered to the submarine springs and consequential precipitate mounds. In attempts to clarify what these might be we have undertaken thermodynamic modelling and experimental investigations of the serpentinization process.

    ROADMAP OBJECTIVES: 2.2 3.1 3.2 3.3 3.4 4.1
  • Inv 2 – From Geochemistry to Biochemistry

    INV 2 focuses on experimentally simulating the geological disequilibrium in hydrothermal systems, and determining the role of minerals in harnessing these gradients toward the emergence of metabolism. Biology utilizes metals (to speed up reactions) and “engines” (such as electron bifurcators, to couple endergonic and exergonic reactions); these components in modern metabolism strongly resemble specific minerals found in hydrothermal environments. We focus on simulating these primordial geological components and processes that might have led to the beginning of metabolism in a seafloor system on a wet rocky planet.

    ROADMAP OBJECTIVES: 3.1 3.2 3.3 4.1 7.1
  • Inv 3 – Planetary Disequilibria: Characterizing Ocean Worlds and Implications for Habitability

    INV 3 looks at how, where, and for how long might
disequilibria exist in icy worlds, and what that may imply in terms of
habitability. A major interest for this work is how ocean composition affects habitability. We are investigating chemistry behaves under conditions of pressure, temperature, and composition not found on Earth. Our simulations of deep ocean world chemistry couple with models for ocean dynamics, ocean ice interaction, and tectonics within the ice. We are examining each of these, how they interact, and how they relate to what future missions may discover. Members of our team are involved in missions to Mars, Jupiter’s moon Europa, Saturn, and Pluto. We are also involved in studies of exoplanets, and are working to understand how ocean worlds like Ganymede and Europa might provide analogues for more distant watery super-earths.

    ROADMAP OBJECTIVES: 1.1 1.2 2.2 3.1 4.2 6.2 7.1 7.2
  • Inv 4 – Observable Chemical Signatures on Icy Worlds: A Window Into Habitability of Subsurface Oceans

    INV 4 aims to answer the Key Question: What can observable surface chemical signatures tell us about the habitability of subsurface oceans? We will shed light on the evolution of ocean materials expressed on the surface of airless icy bodies and exposed to relevant surface temperatures, vacuum, photolysis and radiolysis. To this end, we have initiated an experimental program designed to establish the extent to which chemical compositions of icy world surfaces are indicative of subsurface ocean chemistry. Our initial experiments have focused on freezing solutions of sodium, magnesium, sulfate and chloride – four commonly suggested major components of Europa’s Ocean.

    ROADMAP OBJECTIVES: 1.1 2.2 7.1