The First Billion Years: Habitability Producing Conditions Conducive to Life

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Program

September 8–11, 2019 Buck’s T-4 Lodge, Big Sky, Montana

Institutional Support

Lunar and Planetary Institute Universities Space Research Association NASA Topical Workshops, Symposia, and Conferences Program

Convener

Edgard G. Rivera-Valentín USRA/Lunar and Planetary Institute

Science Organizing Committee

Giada Arney Karen Olsson-Francis NASA Goddard Space Flight Center The Open University

Sherry Cady Cynthia Phillips Pacific Northwest National Laboratory Jet Propulsion Laboratory

Alfonso Davila Ramses Ramirez NASA Ames Research Center Earth-Life Science Institute, Tokyo Institute of Technology

Justin Filiberto Mitch Schulte USRA/Lunar and Planetary Institute NASA Headquarters

Nagissa Mahmoudi Susanne Schwenzer McGill University The Open University

Irena Mamajanov Steve Vance Earth-Life Science Institute, Tokyo Institute of Technology Jet Propulsion Laboratory

Abel Méndez Frances Westall Planetary Habitability Laboratory, CNRS-Centre de Biophysique Moléculaire University of Puerto Rico at Arecibo

Lunar and Planetary Institute 3600 Bay Area Boulevard Houston TX 77058-1113

Abstracts for this conference are available via the conference website at https://www.hou.usra.edu/meetings/habitability2019/ Abstracts can be cited as Author A. B. and Author C. D. (2019) Title of abstract. In The First Billion Years: Habitability, Abstract #XXXX. LPI Contribution No. 2134, Lunar and Planetary Institute, Houston. Guide to Sessions

Sunday, September 8, 2019 7:30 a.m. Yellowstone National Park Field Trip

Monday, September 9, 2019 8:00 a.m. Montana Room Entrance Registration 9:00 a.m. Montana Room Welcome and Introductions 9:15 a.m. Montana Room Keynote: Origins of Life 10:30 a.m. Montana Room Origins of Life: Physics and Physicochemistry 1:00 p.m. Montana Room Origins of Life: Chemistry, N-P-S 3:00 p.m. Montana Room Origins of Life: ...and All of the Above 4:30 p.m. Montana Room Lightning Posters: Origins of Life 5:00–6:30 p.m. Buck Ridge Room Poster Session: Origins and Signatures of the Living Posters

Tuesday, September 10, 2019 8:50 a.m. Montana Room Announcements 9:00 a.m. Montana Room Keynote: Habitability 10:10 a.m. Montana Room Habitability of Early Earth and Icy Worlds 1:00 p.m. Montana Room Habitability of Early Mars 3:00 p.m. Montana Room Habitability of Exoplanets 4:30 p.m. Montana Room Lightning Posters: Habitability 5:00–6:30 p.m. Buck Ridge Room Poster Session: Habitability of Posters

Wednesday, September 11, 2019 8:50 a.m. Montana Room Announcements 9:00 a.m. Montana Room Keynote: Biosignatures 10:10 a.m. Montana Room Biosignature Theory and Detecting Life on Earth 1:00 p.m. Montana Room Biosignatures on Mars 2:30 p.m. Montana Room Biosignatures of Exoplanets 3:45 p.m. Montana Room Wrap-Up Discussion

Program

Monday, September 9, 2019 KEYNOTE: ORIGINS OF LIFE 9:00 a.m. Montana Room

Chair: Ed Rivera-Valentín Times Authors (*Denotes Presenter) Abstract Title and Summary 9:00 a.m. Welcome and Introductions 9:15 a.m. Mamajanov I. * From Messy Chemistry to the Origins of Life [#1047] In the talk, I will outline the messy chemistry origins of life hypothesis, its advantages, and challenges. 10:15 a.m. Break

ORIGINS OF LIFE: PHYSICS AND PHYSICOCHEMISTRY 10:30 a.m. Montana Room

Chair: Matthew Pasek Times Authors (*Denotes Presenter) Abstract Title and Summary 10:30 a.m. Spitzer J. * Emergence of Life Energized by Cyclic Physicochemical Processes of Rotating Planets [#1003] A physicochemical ‘jigsaw puzzle’ of chemical reactions and colloidal phase separations at Hadean seashores is driven by the energies of cyclic solar radiation (day-and-night cycles) and concurrent hydration and dehydration by tidal seawater. 10:50 a.m. Kring D. A. * Updated Status of the Impact — Origin of Life Hypothesis [#1037] Two decades of research support the impact — origin of life hypothesis and illuminate interesting details about Hadean Earth conditions. 11:10 a.m. Hansma H. G. * Mechanical Energy and Mica Sheets at the Origins of Life [#1023] Mechanical energy is an endless energy source at the origins of life that may have powered prebiotic chemistry before reliable chemical energy sources such as ATP were available. Moving mica sheets may have provided this energy. 11:30 a.m. DISCUSSION 11:50 a.m. Lunch

Monday, September 9, 2019 ORIGINS OF LIFE: CHEMISTRY, N-P-S 1:00 p.m. Montana Room

Chair: Olaf Witkowski Times Authors (*Denotes Presenter) Abstract Title and Summary 1:00 p.m. Cleaves H. J. II * Laneuville M. A Systems Model of Earth’s Early Abiotic Nitrogen Cycle [#1045] Danielache S. We present results of a prebiological Earth-system model which takes into account atmospheric, atmosphere-ocean, ocean- sediment, and subduction processes and reservoirs to estimate Earth’s N-cycle before life began. 1:20 p.m. Ranjan S. * Todd Z. R. Rimmer P. B. Nitrogen Oxide Concentrations in Natural Waters on Sasselov D. D. Babbin A. R. Early Earth [#1042] Past work has concluded NOX- was high in the prebiotic oceans. We show that prebiotic NOX was likely low in the early oceans, but could have been high in prebiotic lakes. 1:40 p.m. Pasek M. A. * An Increase in Phosphorus Availability from Redox-Induced Changes by Water-Rock Interactions [#1027] The electrochemical reduction of phosphate via water-interactions to phosphite, followed by transport and oxidation of phosphite to polyphosphates are capable of providing energy for organophosphate synthesis, and may be active on ocean worlds. 2:00 p.m. Ranjan S. * Todd Z. R. Sutherland J. D. Sulfidic Anion Concentrations on Early Earth Relevant to Surficial Sasselov D. D. Prebiotic Chemistry [#1043] We show prebiotic lakes were probably sulfite rich but sulfide poor, and explore the implications for prebiotic chemistry. 2:20 p.m. DISCUSSION 2:40 p.m. Break

ORIGINS OF LIFE: ...AND ALL OF THE ABOVE 3:00 p.m. Montana Room

Chair: Penelope Boston Times Authors (*Denotes Presenter) Abstract Title and Summary 3:00 p.m. Sriaporn C. * Campbell K. A. Terrestrial Hot Spring Settings for the Origin of Life? The Role of Penrose L. K. Rowe M. C. Havig J. R. Mixing Zones in Enhancing Microbial Complexity [#1015] Hamilton T. L. Handley K. M. The study of the influences of mixing zones in terrestrial hot Van Kranendonk M. J. springs on microbial community composition and diversity — as analogs to early life development according to the terrestrial hot springs origin of life theory. 3:20 p.m. Clark B. C. * Kolb V. M. Environments Enabling the Origin of Life are Not Equal to Habitats for Extant Life [#1006] In addition to assessing habitability for living organisms, the suitability of extraterrestrial environments for prebiotic evolution for the origin of life must be considered. Many habitable environments are anti-thetical to the origin of life. 3:40 p.m. Witkowski O. * Delegating Control: From Information Flows Towards Intelligent Life [#1019] The transitions towards intelligent life can be understood as a reorganization of information flows within semi-autonomous entities. We combine artificial life models with information- theoretic measures to capture how living systems transfer control. 4:00 p.m. DISCUSSION 4:15 p.m. Break Monday, September 9, 2019 LIGHTNING POSTERS: ORIGINS OF LIFE 4:30 p.m. Montana Room

Chair: Allan Treiman Poster presenters are encouraged to give a 4-minute introduction that may include up to 6 slides.

POSTER SESSION: ORIGINS AND SIGNATURES OF THE LIVING POSTERS 5:00–6:30 p.m. Buck Ridge Room

Authors (*Denotes Presenter) Abstract Title and Summary Villafañe Barajas S. Role of Ions in the Sorption of Amino Acids onto Serpentinite: Essays of Colin Garcia M. Negrón- Prebiotic Chemistry [#1018] Mendoza A. Ortega F. Becerra A. The sorption of some amino acids onto serpentinite was performed considering a hydrothermal water model (HWM). The results suggest that dissolved ions, in particular divalent cations, can favor the sorption of these molecules even in basic medium. Cruz-Castañeda J. Negrón- Radiolysis and Thermolysis of Glycolaldehyde in Conditions Simulating the Vicinity of a Mendoza A. Ramos-Bernal S. Subaerial Hot Springs in the Primitive Earth [#1020] Heredia A. Our aim is to study the thermolysis and radiolysis of glycolaldehyde, in solid state, aqueous solution, and clays-suspensions, simulating the vicinity of a subaerial hot spring probable in the primitive Earth and its relevance in chemical evolution. Meléndez-López A. L. García- Gamma Irradiation of Mixtures of L-Aspartic Acid and Na-Montmorillonite: Relevance Hurtado M. F. Negrón- in Homochirality Studies and Origin of Life [#1021] Mendoza A. Ramos-Bernal S. Chirality is an important characteristic of life. Our aim is to study the stability of L- Heredia A. aspartic acid irradiated in solid-state mixtures of amino acid and Na-Montmorillonite at gamma irradiation to understand the role of clays in chiral processes. Carson J. H. Thermocycling Drives Evolution of RNA Granules [#1016] Thermocycling increases complexity, information content, stability, and selectivity in RNA granules. Thermocycling in hydrothermal vents may drive evolution of complexity, information content, stability, and selectivity in primordial RNA granules. Bahn P. R. Polyhedral Charts of the Commonly Occurring Amino Acids and Nucleic Acid Bases [#1004] The commonly occurring amino acids are shown on the faces of an icosahedron and the commonly occurring RNA and DNA bases are shown on the faces of tetrahedrons. The icosahedron and the tetrahedron are two of the five possible Platonic polyhedrons. Hotujec-Kantner C. A. Trace Element and Co Concentrations in 2.7 Ga Archean Metasedimentary Rocks of the Cherry Creek Suite, Gravelly Range, Montana, USA [#1040] Trace element and Co concentrations in Archean metasedimentary rocks from the Cherry Creek Metasedimentary Suite in the Gravelly Range, Montana provide information about redox conditions and bioavailability of Co during deposition 2.7 Ga. Crucilla S. J. Perl S. M. Preservation Features from Ice and Brines on Non-Radiation Tolerant Microbes in Lindensmith C. A. Nadeau J. Europa-Like Conditions [#1028] Sun H. Our objective is to determine the radiation sensitivity of non-radiation tolerant microbes within different ices, brines, mineral substrates as well as completely desiccated to determine survivability on Europa as well as other planets and moons. Dong C. F. Lingam M. Fang X. H. Role of Solar Energetic Particles in Prebiotic Chemistry and Origin of Life [#1046] Rimmer P. B. Wordsworth W. We carry out numerical simulations to assess the penetration and bombardment effects of Solar Energetic Particles (SEPs) on ancient and current Mars. SEPs may have been capable of facilitating the synthesis of a wide range of vital organic molecules.

Tuesday, September 10, 2019 KEYNOTE: HABITABILITY 8:50 a.m. Montana Room

Chair: Ed Rivera-Valentín Times Authors (*Denotes Presenter) Abstract Title and Summary 8:50 a.m. Announcements 9:00 a.m. Lyons T. W. * Rogers K. L. Our First Billion Years of Astrobiology: Life’s Earliest Relationships with the Environment [#1049] Understanding the origins of life requires a parallel understanding of the evolving environmental context. Future efforts will bridge those who think about the beginnings of life and cause-and-effect relationships with the surrounding environment. 10:00 a.m. Break

HABITABILITY OF EARLY EARTH AND ICY WORLDS 10:10 a.m. Montana Room

Chair: Justin Filiberto Times Authors (*Denotes Presenter) Abstract Title and Summary 10:10 a.m. Schulz T. * Viehmann S. Hezel D. C. Coupled Fe-Os Isotope Signatures in Banded Iron Formations — Koeberl C. Decoding Earth’s Oxygenation History and the Chemical Evolution of Precambrian Seawater [#1011] We report isotope data of banded iron formations, providing insights into the transformation of the Precambrian Earth from anoxic to progressively oxygenated conditions which set the stage for the evolution of the earliest microbial habitats. 10:30 a.m. Marchi S. * Black B. Drabon N. Understanding the Effects of Asteroid Collisions Across Earth’s Ebel D. Fu R. Johnson B. Schulz T. Great Oxidation 3.5-2 Ga [#1008] Wuennemann K. We will present a new model for 3.5-2 Ga terrestrial asteroid bombardment, and discuss the environmental consequences of these collisions, with emphasis on atmospheric redox state of the atmosphere and oceans. 10:50 a.m. Melwani Daswani M. * Vance S. D. Organic Molecule Concentration by Early Differentiation, and Dilution by Later Tidal Dissipation in Icy Ocean Worlds [#1044] The degree of heating that ocean worlds experience during their evolution determines the concentration and type of organic molecules and hydrocarbons that are flushed from the rocky interior into the ocean. 11:10 a.m. Castillo-Rogez J. C. * Raymond C. A. Early Habitability Potential of Dwarf Planet Ceres [#1025] De Sanctis M. C. Ermakov A. I. Ceres is the largest object in the asteroid belt and most water rich object after Earth in the inner solar system. We summarize the results from the Dawn mission that pertain to assessing Ceres’ early habitability potential. 11:30 a.m. DISCUSSION 11:50 a.m. Lunch

Tuesday, September 10, 2019 HABITABILITY OF EARLY MARS 1:00 p.m. Montana Room

Chair: Brandi Carrier Times Authors (*Denotes Presenter) Abstract Title and Summary 1:00 p.m. Ruff S. W. * Clues to the Habitability of Mars in Its First Billion Years from an Earth-Like Hydrothermal System in Gusev Crater [#1036] A volcanic hydrothermal system is now well documented on Mars, with clear implications for habitability and microbial preservation potential. Less clear is whether impact hydrothermal systems are equivalent targets in the search for past life. 1:20 p.m. Filiberto J. * Costello L. C. Habitability of the Early Martian Crust as Constrained by Crandall J. R. Potter-McIntyre S. L. Hydrothermal Alteration of a Mafic Dike [#1013] Schwenzer S. P. Hummer D. R. Olsson- As an analog for processes on the early martian crust, we have Francis K. Perl S. Miller M. A. investigated a mafic dike that was hydrothermally altered from Castle N. contact with ground water as it was emplaced. 1:40 p.m. Soto A. * Marchi S. Black B. A. Atmospheric Response to Impact-Generated Melt Outgassing on Mars [#1041] We investigate the atmospheric response to volatiles outgassed from impact-generated melt pools on early Mars. This outgassing would occur for 100s to millions of years after the initial impact and may produce a habitable environment on early Mars. 2:00 p.m. Steakley K. E. * Kahre M. A. Examining the Potential for Habitability in a Post-Impact Reducing Haberle R. M. Zahnle K. J. Greenhouse Climate on Early Mars [#1035] We simulate the early Mars climate response to an impact accounting for water, energy, and H2 injected into the atmosphere. We assess whether this environment induces surface conditions suitable for life with liquid water. 2:20 p.m. DISCUSSION 2:40 p.m. Break

HABITABILITY OF EXOPLANETS 3:00 p.m. Montana Room

Chair: Lisa Kaltenegger Times Authors (*Denotes Presenter) Abstract Title and Summary 3:00 p.m. Mendez A. * The Diversity and Distribution of Habitable Worlds [#1033] Planets larger than Earth and with denser atmospheres can be up to six times more habitable than Earth. Their biosignatures signals should be stronger, but their occurrence is very low. 3:20 p.m. Jusino M. * Mendez A. The Occurrence of Planets in the Abiogenesis Zone [#1026] So far, not a single Earth-sized planet has been discovered to be in both the Habitable Zone and the Abiogenesis Zone. 3:40 p.m. Ramirez R. * A Dynamic Habitable Zone and How to Find Potentially Habitable Planets [#1007] The habitable zone is a navigational tool and filter to find potentially habitable planets. However, it can be improved with a first principles approach that maximizes the chance that upcoming missions have of finding life elsewhere. I explain how. 4:00 p.m. DISCUSSION 4:15 p.m. Break

Tuesday, September 10, 2019 LIGHTNING POSTERS: HABITABILITY 4:30 p.m. Montana Room

Chair: Kennda Lynch Poster presenters are encouraged to give a 4-minute introduction that may include up to 6 slides.

POSTER SESSION: HABITABILITY OF POSTERS 5:00–6:30 p.m. Buck Ridge Room

Authors (*Denotes Presenter) Abstract Title and Summary Ortiz-Ceballos K. N. Mendez A. Arecibo REDS: The Stellar Activity of Stars with Potentially Habitable Planets [#1038] Zuluaga J. Heller R. Alexander D. Observing and characterizing stellar activity of M-dwarfs to study its impact on Pacini A. planetary atmospheres and habitability. Dobson M. J. Campbell K. A. Facies Mapping and Analysis of Diverse Hydrothermal Sediments and Siliceous Rowe M. Van Kranendonk M. Spicular Sinter at Tikitere Geothermal Field, Taup? Volcanic Zone, Drake B. Hamilton A. New Zealand [#1010] Mapping of spicular siliceous hot spring deposits (sinter) developing in spring outflow channels at Tikitere, Rotorua, New Zealand provided possible analogues for opaline silica deposits found at Columbia Hills, Gusev Crater, Mars. Perl S. M. Filiberto J. Olsson- Organic and Biomarker Detection Techniques for Hydrothermal Alterations in Francis K. Potter-McIntyre S. L. Sandstone Layers Within the Colorado Plateau [#1024] Schwenzer S. P. Crandall J. R. The purpose of this paper is to discuss the geobiology and habitability metrics of basaltic intrusions into sedimentary rocks where ancient fluids can lead to the modification of secondary minerals that can be used by life. Tasoff P. Perl S. M. Chin K. B. Survivability of Chemotrophic Microorganisms in Martian-Analogue Desai P. Cockell C. S. Water Activities [#1029] Life finds a unique way to adapt to changing and extreme environmental conditions; yet liquid water is required by all organisms on Earth. We seek to replicate martian analogue soil water activities and analyze metabolism in vitro of two chemotrophs. Torres N. Méndez A. Evolution of Terrestrial Habitability [#1030] In this study, we will use the mass and energy habitability model of Méndez et al., (2018) to trace the evolution of terrestrial habitability from early Earth to climate change. Filiberto J. Schwenzer S. P. Volatiles in the Martian Crust [#1009] Our recent book “Volatiles in the Martian Crust” focuses on constraining what is known about volatile reservoirs in the martian crust. Valluri S. R. Sangli V. T. Habitable Zones: A New Approach to Physical Factors [#1022] We have examined the present factors that affect habitability, and propose two more that can alter our perception on the issue: Obliquity and compartmentalized habitable zones (it is likely that only sections of a planet’s surface could be habitable).

Wednesday, September 11, 2019 KEYNOTE: BIOSIGNATURES 8:50 a.m. Montana Room

Chair: Ed Rivera-Valentín Times Authors (*Denotes Presenter) Abstract Title and Summary 8:50 a.m. Announcements 9:00 a.m. Mitch Schulte * The Search for Life Beyond Earth 10:00 a.m. Break

BIOSIGNATURE THEORY AND DETECTING LIFE ON EARTH 10:10 a.m. Montana Room

Chair: David Kring Times Authors (*Denotes Presenter) Abstract Title and Summary 10:10 a.m. Boston P. J. * Schubert K. E. The Conundrum of Structure and Pattern: We Need It...But We Northup D. E. Spilde M. N. Don’t Trust It! [#1031] Physical structures and spatial patterns were foundational to understand Earth’s ancient and modern life. Development of many non-visual techniques has resulted in distrust of morphology, but new refinements can still provide highly important clues. 10:30 a.m. Schopf J. W. * Paleobiological Evidence of the Immediate Aftermath of the Beginning Billion: Life Evolved Early, Far, and Fast [#1005] Cellularly preserved microscopic fossils of the ~3.43 Ga Strelley Pool Fm. and ~3.465 Ga Apex chert of Western Australia establish the anoxic nature of Earth’s early environment and show that Eoarchean life evolved early, far, and fast. 10:50 a.m. Perl S. M. * Baxter B. K. Celestian A. J. Photobiology and Biogenic Preservation Comparisons Between Cockell C. S. Sessions A. L. Tasoff P. Pleistocene Evaporite Beds and Buried Permian Brines [#1034] Crucilla S. J. Corsetti F. A. The purpose of this paper is to discuss the photobiological response from halophilic microorganisms in their preserved mineral settings from different solar flux environments. 11:10 a.m. Prufert-Bebout L. E. * Shih N. Characterization of Permeable Sediments as Habitable Refuges for Bebout B. Complex Microbial Ecosystems [#1039] Characteristics of sediments create suitable habitats for microbial life on Earth including: refuge from ultraviolet light, source of elements necessary for biological processes, and protection from erosion by water flow or wind processes. 11:30 a.m. DISCUSSION 11:50 a.m. Lunch

Wednesday, September 11, 2019 BIOSIGNATURES ON MARS 1:00 p.m. Montana Room

Chair: Kathryn Steakley Times Authors (*Denotes Presenter) Abstract Title and Summary 1:00 p.m. Lynch K. L. * The Pilot Valley Basin, Utah: Model System for Studying Subsurface Life on Early Earth, Mars, and Beyond [#1050] The Pilot Valley Basin, Utah is a potential modern laboratory for studying ancient subsurface environments on Mars, Earth, and beyond. 1:20 p.m. Carrier B. L. * Beaty D. W. Investigating and Constraining the Habitability of Early Mars iMOST Team Through Analysis of Returned Mars Samples [#1017] Analysis of returned samples from Mars would greatly increase our understanding of the evolution of the habitability of Mars and other terrestrial planets. 1:40 p.m. Treiman A. H. * Meteorite Allan Hills (ALH) 84001: Implications for Mars’ Inhabitation and Habitability [#1032] Meteorite ALH 84001, home to putative signs of ancient martian life, provides evidence on potentially habitable environments on early Mars. It is also a case study of what sorts of evidence might be acceptable as signs of extraterrestrial life. 2:00 p.m. DISCUSSION 2:15 p.m. Break

BIOSIGNATURES OF EXOPLANETS 2:30 p.m. Montana Room

Chair: Abel Mendez Times Authors (*Denotes Presenter) Abstract Title and Summary 2:30 p.m. Kaltenegger L. * O’Malley-James J. Lessons from Early Earth: UV Surface Environment of Earth-Like Rugheimer S. Planets: Comparing Close-by M-Star Planets to Earth Through Geological Evolution [#1048] We compare models of the UV surface radiation environments for Earth through geological time to both pre-biotic and post-biotic planets around the closest M stars. 2:50 p.m. Ceja A. Y. * Kane S. R. Developing an Astroecological Model for Characterizing Exoplanet Habitability [#1014] I develop an astroecology model to be used to identify potentially habitable worlds. Exoplanet surface climates are simulated using the climate model ROCKE-3D, which is then convolved with a biological layer responding to the thermal environment. 3:10 p.m. Leisawitz D. * The Origins Space Telescope and the Quest to Understand Habitability [#1001] The Origins Space Telescope will enable the community to learn how the conditions for habitability can arise during the process of planet formation, and to characterize exoplanets and search for biosignatures in their atmospheres. 3:30 p.m. DISCUSSION

Wednesday, September 11, 2019 WRAP-UP DISCUSSION 3:45 p.m. Montana Room

Panelists Objective Moderator: Edgard Rivera-Valentín Review of the material covered during the conference in order to plan a Panel Members: Irena Mamajanov journal special issue as well as discussion of the key open questions for Timothy Lyons development of a strategic plan. Mitch Schulte

CONTENTS

Polyhedral Charts of the Commonly Occurring Amino Acids and Nucleic Acid Bases P. R. Bahn ...... 1004

The Conundrum of Structure and Pattern: We Need It...But We Don’t Trust It! P. J. Boston, K. E. Schubert, D. E. Northup, and M. N. Spilde ...... 1031

Investigating and Constraining the Habitability of Early Mars Through Analysis of Returned Mars Samples B. L. Carrier, D. W. Beaty, and iMOST Team ...... 1017

Thermocycling Drives Evolution of RNA Granules J. H. Carson ...... 1016

Early Habitability Potential of Dwarf Planet Ceres J. C. Castillo-Rogez, C. A. Raymond, M. C. De Sanctis, and A. I. Ermakov ...... 1025

Developing an Astroecological Model for Characterizing Exoplanet Habitability A. Y. Ceja and S. R. Kane ...... 1014

Environments Enabling the Origin of Life are Not Equal to Habitats for Extant Life B. C. Clark and V. M. Kolb ...... 1006

A Systems Model of Earth’s Early Abiotic Nitrogen Cycle H. J. Cleaves, M. Laneuville, and S. Danielache ...... 1045

Preservation Features from Ice and Brines on Non-Radiation Tolerant Microbes in Europa-Like Conditions S. J. Crucilla, S. M. Perl, C. A. Lindensmith, J. Nadeau, and H. Sun ...... 1028

Radiolysis and Thermolysis of Glycolaldehyde in Conditions Simulating the Vicinity of a Subaerial Hot Springs in the Primitive Earth J. Cruz-Castañeda, A. Negrón-Mendoza, S. Ramos-Bernal, and A. Heredia ...... 1020

Facies Mapping and Analysis of Diverse Hydrothermal Sediments and Siliceous Spicular Sinter at Tikitere Geothermal Field, Taup? Volcanic Zone, New Zealand M. J. Dobson, K. A. Campbell, M. Rowe, M. Van Kranendonk, B. Drake, and A. Hamilton ...... 1010

Role of Solar Energetic Particles in Prebiotic Chemistry and Origin of Life C. F. Dong, M. Lingam, X. H. Fang, P. B. Rimmer, and W. Wordsworth ...... 1046

Volatiles in the Martian Crust J. Filiberto and S. P. Schwenzer ...... 1009

Habitability of the Early Martian Crust as Constrained by Hydrothermal Alteration of a Mafic Dike J. Filiberto, L. C. Costello, J. R. Crandall, S. L. Potter-McIntyre, S. P. Schwenzer, D. R. Hummer, K. Olsson-Francis, S. Perl, M. A. Miller, and N. Castle ...... 1013

Mechanical Energy and Mica Sheets at the Origins of Life H. G. Hansma ...... 1023

Trace Element and Co Concentrations in 2.7 Ga Archean Metasedimentary Rocks of the Cherry Creek Suite, Gravelly Range, Montana, USA C. A. Hotujec-Kantner ...... 1040

The Occurrence of Planets in the Abiogenesis Zone M. Jusino and A. Mendez ...... 1026

Lessons from Early Earth: UV Surface Environment of Earth-Like Planets: Comparing Close-by M-Star Planets to Earth Through Geological Evolution L. Kaltenegger, J. O’Malley-James, and S. Rugheimer ...... 1048

Updated Status of the Impact — Origin of Life Hypothesis D. A. Kring ...... 1037

The Origins Space Telescope and the Quest to Understand Habitability D. Leisawitz ...... 1001

The Pilot Valley Basin, Utah: Model System for Studying Subsurface Life on Early Earth, Mars, and Beyond K. L. Lynch ...... 1050

Our First Billion Years of Astrobiology: Life’s Earliest Relationships with the Environment T. W. Lyons and K. L. Rogers ...... 1049

From Messy Chemistry to the Origins of Life I. Mamajanov ...... 1047

Understanding the Effects of Asteroid Collisions Across Earth’s Great Oxidation 3.5-2 Ga S. Marchi, B. Black, N. Drabon, D. Ebel, R. Fu, B. Johnson, T. Schulz, and K. Wuennemann ...... 1008

Gamma Irradiation of Mixtures of L-Aspartic Acid and Na-Montmorillonite: Relevance in Homochirality Studies and Origin of Life A. L. Meléndez-López, M. F. García-Hurtado, A. Negrón-Mendoza, S. Ramos- Bernal, and A. Heredia...... 1021

Organic Molecule Concentration by Early Differentiation, and Dilution by Later Tidal Dissipation in Icy Ocean Worlds M. Melwani Daswani and S. D. Vance ...... 1044

The Diversity and Distribution of Habitable Worlds A. Mendez ...... 1033

Arecibo REDS: The Stellar Activity of Stars with Potentially Habitable Planets K. N. Ortiz-Ceballos, A. Mendez, J. Zuluaga, R. Heller, D. Alexander, and A. Pacini ...... 1038

An Increase in Phosphorus Availability from Redox-Induced Changes by Water-Rock Interactions M. A. Pasek ...... 1027

Photobiology and Biogenic Preservation Comparisons Between Pleistocene Evaporite Beds and Buried Permian Brines S. M. Perl, B. K. Baxter, A. J. Celestian, C. S. Cockell, A. L. Sessions, P. Tasoff, S. J. Crucilla, and F. A. Corsetti ...... 1034

Organic and Biomarker Detection Techniques for Hydrothermal Alterations in Sandstone Layers Within the Colorado Plateau S. M. Perl, J. Filiberto, K. Olsson-Francis, S. L. Potter-McIntyre, S. P. Schwenzer, and J. R. Crandall ...... 1024

Characterization of Permeable Sediments as Habitable Refuges for Complex Microbial Ecosystems L. E. Prufert-Bebout, N. Shih, and B. Bebout ...... 1039

A Dynamic Habitable Zone and How to Find Potentially Habitable Planets R. Ramirez...... 1007

Nitrogen Oxide Concentrations in Natural Waters on Early Earth S. Ranjan, Z. R. Todd, P. B. Rimmer, D. D. Sasselov, and A. R. Babbin ...... 1042

Sulfidic Anion Concentrations on Early Earth Relevant to Surficial Prebiotic Chemistry S. Ranjan, Z. R. Todd, J. D. Sutherland, and D. D. Sasselov ...... 1043

Clues to the Habitability of Mars in Its First Billion Years from an Earth-Like Hydrothermal System in Gusev Crater S. W. Ruff ...... 1036

Paleobiological Evidence of the Immediate Aftermath of the Beginning Billion: Life Evolved Early, Far, and Fast J. W. Schopf ...... 1005

Coupled Fe-Os Isotope Signatures in Banded Iron Formations — Decoding Earth’s Oxygenation History and the Chemical Evolution of Precambrian Seawater T. Schulz, S. Viehmann, D. C. Hezel, and C. Koeberl ...... 1011

Atmospheric Response to Impact-Generated Melt Outgassing on Mars A. Soto, S. Marchi, and B. A. Black ...... 1041

Emergence of Life Energized by Cyclic Physicochemical Processes of Rotating Planets J. Spitzer ...... 1003

Terrestrial Hot Spring Settings for the Origin of Life? The Role of Mixing Zones in Enhancing Microbial Complexity C. Sriaporn, K. A. Campbell, L. K. Penrose, M. C. Rowe, J. R. Havig, T. L. Hamilton, K. M. Handley, and M. J. Van Kranendonk ...... 1015

Examining the Potential for Habitability in a Post-Impact Reducing Greenhouse Climate on Early Mars K. E. Steakley, M. A. Kahre, R. M. Haberle, and K. J. Zahnle ...... 1035

Survivability of Chemotrophic Microorganisms in Martian-Analogue Water Activities P. Tasoff, S. M. Perl, K. B. Chin, P. Desai, and C. S. Cockell ...... 1029

Evolution of Terrestrial Habitability N. Torres and A. Méndez ...... 1030

Meteorite Allan Hills (ALH) 84001: Implications for Mars’ Inhabitation and Habitability A. H. Treiman ...... 1032 Habitable Zones: A New Approach to Physical Factors S.R. Valluri and V.T. Sangli ...... 1022

Role of Ions in the Sorption of Amino Acids onto Serpentinite: Essays of Prebiotic Chemistry S. Villafañe Barajas, M. Colin Garcia, A. Negrón-Mendoza, F. Ortega, and A. Becerra ...... 1018

Delegating Control: From Information Flows Towards Intelligent Life O. Witkowski ...... 1019

The First Billion Years: Habitability 2019 (LPI Contrib. No. 2134) 1004.pdf

ABSTRACT HABITABILITY The First Billion Years September 8-12, 2019 Laramie, Wyoming USA

POLYHEDRAL CHARTS OF THE COMMONLY OCCURRING AMINO ACIDS AND NUCLEIC ACID BASES

Peter R. Bahn Bahn Biotechnology Company, 10415 E. Boyd Rd., Mt. Vernon, IL 62864 USA E-Mail: [email protected]

The 20 commonly occurring amino acids are: Alanine, Arginine, Asparagine, Aspartic Acid, Cysteine, Glutamine, Glutamic Acid, Glycine, Histidine, Isoleucine, Leucine, Lysine, Methionine, Phenylalanine, Proline, Serine, Threonine, Tryptophan, Tyrosine, and Valine. The corresponding 3-letter symbols for the amino acids are: Ala, Arg, Asn, Asp, Cys, Gln, Glu, Gly, His, Ile, Leu, Lys, Met, Pro, Ser, Thr, Trp, Tyr, and Val. The corresponding 1-letter symbols for the amino acids are: A, R, N, D, C, Q, E, G, H, I, L, K, M, F, P, S, T, W, Y, and V. The 4 commonly occurring RNA (Ribo Nucleic Acid) and the 4 commonly occurring DNA (Deoxyribo Nucleic Acid) bases are: Adenine, Guanine, Cytosine, and Uracil in the case of RNA or Thymine in the case of DNA. The 1-letter symbol for Adenine is A, the 1-letter symbol for Guanine is G, the 1-letter symbol fro Cytosine is C, the 1-letter symbol for Uracil is U, and the 1-letter symbol for Thymine is T. Adenine and Guanine are purines. Cytosine and Uracil and Thymine are pyrimidines. In RNA and DNA, Adenine normally base pairs with Uracil and Thymine, respectively, and Guanine normally base pairs with Cytosine. A Platonic polyhedron is a polyhedron with congruent faces and the same number of faces meeting at each vertex. The 5 Platonic polyhedrons are: the Tetrahedron with 4 faces, the Cube with 6 faces, the Octahedron with 8 faces, the Dodecahedron with 12 faces, and the Icosahedron with 20 faces. Since there are 20 commonly occurring amino acids and there are 20 faces to an icosahedron, a useful heuristic device for learning the chemical structures, the names, the 3-letter symbols, and the 1-letter symbols for the amino acids can be constructed by placing the chemical structure, the 3-letter symbol, and the 1-letter symbol for each amino acid on a single face of an icosahedron. United States Design Patent Number US D721,005 S, by the author, shows such an icosahedron. Since there are 4 commonly occurring RNA bases and 4 commonly occurring DNA bases, useful heuristic devices for learning and remembering the chemical structures, the names, and the 1-letter symbols for each RNA and DNA base can be constructed by placing the chemical structure, the name, and the 1-letter symbol for each RNA and DNA base on a single face of an RNA or DNA tetrahedron. United States Design Patent Numbers US D755,287 S and US D759,753 S, by the author, show such tetrahedrons for RNA and DNA, respectively. Such polyhedral charts, when assembled, can be tossed like dice to generate random sequences of amino acids, RNA, and DNA. The First Billion Years: Habitability 2019 (LPI Contrib. No. 2134) 1031.pdf

THE CONUNDRUM OF STRUCTURE AND PATTERN: WE NEED IT…BUT WE DON’T TRUST IT! Penelope J. Boston1, K. Schubert2, D. E. Northup3, M. N. Spilde4, & J.J. Medley3. 1NASA Ames Research Center, Moffett Field, CA 94035 penelope.j.boston@nasa.gov, 2Dept. of Electrical & Computer Engineering, Baylor Univ., Waco, TX, 76798, 3Biology Dept. & 4Inst. Meteoritics, Univ. New Mexico, Albuquerque, NM 87131

Introduction: Physical structures and spatial documented them in a host of surface and other patterns have been the very foundation of subsurface examples and are attempting to distinguish understanding the rock record of life on Earth, catching them from other patterns in nature that are not the eye of ancient scholars like Aristotle, Pliny the produced by the same interactions of biological, Elder, and Avicenna who correctly interpreted them as physical and chemical processes. Little work has yet the remains of past life. With the rise of modern been done on strictly physico-chemical possible science, fossils comprised an important new field of production of such features, but clearly this is an area study as early as Leonardo da Vinci’s agreement with that must be interrogated. The plethora of measurable the fossil interpretations of Aristotle, observations by and comparable features within these patterns Robert Hooke and Georges Cuvier, and the linkage of (including physical and chemical properties) make modern life to ancient life by Darwin. However, with them a perfect trial case for testing machine learning the rise of the astounding array of chemical and other techniques. non-visual detection and characterization capabilities Micro-organisms that “masquerade as that we now possess, structure and pattern have not minerals”: The potential for preservation of only been greatly augmented by other lines of microbially produced or influenced textures in evidence, but in many cases are being dismissed sediments, minerals, and rocks is widely because the community does not trust morphology as a acknowledged, but the caveats are many e.g. [1, 3, 7, reliable type of evidence [1]. This is justifiable 8]. Interpretations can be quite controversial [9, 10]. because there are many physical and chemical But, the potential for using difficult and potentially phenomena that can superficially mimic structure and confusing types of data should not be abandoned just pattern that we know are produced by modern because dealing with them is challenging. Work of co- organisms [e.g. 2, 3]. authors Northup, Spilde, and Boston and other However, we argue that rather than stripping colleagues have repeatedly shown intimate links ourselves of a valuable set of tools for understanding between microbial, phylogenetic, geochemical and ancient (and perhaps recent or current extraterrestrial other lines of evidence e.g. [11, 8]. Recent work by life), that a more sophisticated approach to structural co-author Medley [12], pushes this multiple line of and biopattern understanding, combined with vigorous evidence connection further in a student thesis where and rigorous efforts to identify possible bioimposters, the author points out that, “Results showed a potential must be developed for us to fully use the clues with continuous relationship among the various parts of our which nature has gifted us. As with many arenas of continuum (moonmilk, bare rock, fingers, mineral science, the rise of machine learning, neural networks, crusts, coralloids, microbial mats, and ooze). NMDS and general advances in artificial intelligence may [SIC, “non-parametric multidimensional scaling”] allow us to greatly exceed the refinement of our showed some relationships among the data while interpretations of structure and pattern in a way that alpha-diversity revealed differences compared to prior eludes the unaided human eye and brain. We present studies. Biofilms were found on all samples, microbial two of several case studies within our own research mats showed fuzzy biological morphologies, and small experiences that can help to put structure and putative coccoid morphologies were found on fingers, biopattern into a new context. mineral crusts, coralloids, and ooze. This continuum Patterns as expression of ecological behavior: As could be used to help train scientists and Martian an example of a potentially universal biosignature rovers what to recognize as potential indicators of type, we are mathematically modeling distinctive life, past or present.” Such new, mathematically-based growth patterns of Earth organisms that we have analyses of the continua between biologically observed ranging in spatial scale from microscopic to produced and abiotic patterns and other characteristics landscape-scale, in an attempt to uncover the can provide new directions for understanding our first underlying mechanisms that govern the production of billion years on Earth and perhaps the early histories of such patterns. Using Cellular Automata (CA) future biospheres to be discovered. mathematical relationships, we can reproduce such Conclusions: The potential for extremely simple patterns and are attempting to uncover the underlying unicellular structure to be used as evidence of early life interactions that produce them [4,5,6]. Originally or extraterrestrial life detection is beset with many noticing such patterns on cave walls, we have now pitfalls. However, in our modern biosphere we see that The First Billion Years: Habitability 2019 (LPI Contrib. No. 2134) 1031.pdf

higher orders of complex behavior in microorganisms (not to mention multicellular forms) in response to environmental conditions can produce distinctive higher order patterns. Such patterns should not be ignored but mined for their ability to point us in the direction of where to employ chemical, biochemical, and multi-spectral methods to corroborate and validate the potential biogenicity of such occurrences. Questions to be tackled before we can confidently employ morphology include: How early in the history of life were higher order patterns produced? Are features such as stromatolites indicative of higher order patterning or abiotic sedimentation? and Can we tell the difference by training devices with vast numbers of examples so that they become more sensitive than we humans can become?

References: [1] Cady, S.L. and Noffke, N. (2009). GSA Today, 19(11), 4-10. [2] Grotzinger, J.P. and Knoll, A.H. (1999). Ann Rev Earth Planet Sci 27, 313- 358. [3] Cady, S.L. (2002). In, Signs of Life, Nat. Acad. Press, 149-155. [4] Strader, B. et al (2011). Adv. Exper. Med.& Biol. 696, 157-70. [5] Schubert, K.E. et al., (2010). In Proc. 2010 Internat. Conf. Bioinformatics & Computational Biol. Pp. 662-665. [6] Boston, P.J. et al. (2009) In, Proc. Third IEEE Internat. Conf. on Space Mission Challenges for Information Tech., Pp 221-226, EES Press. [7] Cady, S. L. et al. (2003). Astrobiology, 3(2), 351-368. [8] Boston, P. J. et al. (2001). Astrobiology, 1(1), 25-55. [9] Noffke, N. (2015), Astrobiol 15(2), 169-192. [10] Davies, N.S. et al., (2016), Earth-Sci Revs. 154, 210- 246. [11] Northup, D.E. et al. (2011), Astrobiology 11(7): DOI: 10.1089/ast.2010.0562 [12] Medley, J.J. (2019), Honors Thesis, “Microbes Masquerading as Minerals (M3): Subsurface Life Detection on Other Planets.” Biology Dept., Univ. New Mexico, Albuquerque, NM.

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INVESTIGATING AND CONSTRAINING THE HABITABILITY OF EARLY MARS THROUGH ANALYSIS OF RETURNED MARS SAMPLES. B. L. Carrier1, D. W Beaty1, and the iMOST Team, 1Jet Propul- sion Laboratory, California Institute of Technology ([email protected]).

Introduction: The current surface conditions on spacecraft or rover. The other major benefit would be Mars are relatively inhospitable to life as we know it the abaility to make discovery-driven choices in the due to factors including 1) the paucity of liquid water; investigation pathway. One shortcoming of in situ 2) low temperatures; 3) thin atmosphere lacking signif- measurements is the long lead time needed to follow up icant amounts of oxygen; 4) lack of magnetic field on interesting discoveries, not the mention the inability leading to high levels of radiolysis and; 5) oxidizing to return to the precise location of the initial discovery conditions. However, there are multiple lines of evi- to repeat the measurement or make a follow-on meas- dence that the martian surface was once much more urement. habitable, particularly during the Noachian and early There are several key areas of investigation, as out- Hesperian period. Observations from multiple orbital lined in the iMOST Report [2], which reflect open and rover missions show that Mars has changed drasti- questions in our understanding of Mars, and some of cally over time and once hosted a much thicker atmos- these are especially important for developing a more phere, warmer temperatures, large amounts of liquid complete understanding of the limits and progression water on the surface, and active volcanism [1] of Mars habitability from the pre-Noachian through the There may be environments on present day Mars early Hesperian and into today. that remain habitable, particularly in the subsurface, Geology: The geology and geomorphology of and life that potentially emerged during the Noachian Mars provided the initial evidence that water once could have evolved to move into those niches. The flowed across its surface. We now also see evidence in discovery of extant life on Mars would be absolutely the geochemical record that hydrous weathering was priceless for furthering our understanding of the limits once a dominant process, and the prescence of phyllo- of habitability and the evolution of habitable environ- silicates indicates that these weathering processes took ments over time. place under conditions conducive to the existence of The analysis of samples from Mars in terrestrial la- microbial life. By investigating returned samples we boraties would be a key strategy for developing a more would potentially be able to investigate different types complete understanding of the evolution of Mars’ hab- of habitable environments which could include (de- itable environments [2]. Lessons learned about Mars pending on availability at the Jezero landing site) an- can also be applied to understanding the evolution of cient hydrothermal systems, lacustrine deposits, subsur- terrestrial planets throughout the galaxy. Planning is face and subaerial environments. Understanding the currently underway by NASA and ESA to return sam- physical and chemical properties, extent, and duration ples via a potential Mars Sample Return campaign. The of these habitable environments will be important to Mars 2020 rover, which is scheduled to launch in 2020 constraining the habitable periods on Mars and what with a landing site in Jezero crater, is equipped with a the planet was like during its early history. sample caching system capable of collecting rock and Geochronology: A key piece of the puzzle lies in regolith samples from the surface (down to ~10 cm in better constraining the geochronology of Mars. This depth), sealing them into sample tubes, and caching can best be achieved through isotopic analysis of re- them on the martian surface for possible later return to turned igneous samples. The current dating system for Earth. The notional Mars Sample Return campaign Mars is heaviliy influenced by our knowledge of the includes a landed mission which would include a fetch lunar cratering record and has significant uncertainties. rover for collecting the samples and a rocket for deliv- A more definite method for age-dating the surface and ering the samples into Mars orbit. An orbiter would its craters, in concert with improved understanding of then collect the orbiting sample capsule in Mars orbit the evolution of habitable conditions on the planet, and return the samples to Earth. would allow for a clearer picture of the how long the The benefits of carefully selecting and returning habitable periods on Mars lasted and how they evolved samples from Mars and investigating them on Earth are through time. numerous. We would be able to bring to bear the full Biosignatures and prebiotic chemistry: Assum- breadth of state of the art instrumentation to make nu- ing that the surface of Mars was indeed habitable dur- merous measurements on single samples. There would ing the Noachian and early Hesperian, it would make be no need to miniaturize instruments or sacrifice sen- sense to look for biosignatures and evidence for prebi- sitivity or selectivity in order to fit the instrument on a otic chemistry in returned samples as well. There are The First Billion Years: Habitability 2019 (LPI Contrib. No. 2134) 1017.pdf

several proposed classes of potential biosignatures tion of the National Environmental Policy Act (NEPA) which could be targets of investigation in returned process. This document is being made available for samples including 1) organic molecules; 2) biotic min- information purposes only. erals; 3) morphological biosignatures such as structures and textures; 4) stable isotopic patterns; 5) other chemical evidence [2]. Mars Sample Return would allow us to look for all of these potential biosignatures, and if found, understand their geological and environmental context. This could substantially advance our understanding of the limits of habitability. If no biosignatures are found, this could also influence our future search strategies and constrain the limits of habitabilitiy on terrestrial planets, or at least on their potential for preservation. Conclusions: Although it is commonly believed that the martian surface once hosted habitable environments based on current evidence from orbital and in situ rover data, there is much that can be done to better understand the limits and evolution of the habitability of the red planet.

References: [1] Carr, M.H.; Head, J.W. (2010). "Geo- logic History of Mars". Earth Planet. Sci. Lett. 294: 185– 203.. [2] iMOST (International MSR Objectives and Samples Team: co-chairs: D. W. Beaty, M. M. Grady, H. Y. McSween, E. Sefton-Nash; documentarian: B. L. Carrier; team members: F. Altieri, Y. Amelin, E. Am- mannito, M. Anand, L. G. Benning, J. L. Bishop, L. E. Borg, D. Boucher, J. R. Brucato, H. Busemann, K. A. Campbell, A. D. Czaja, V. Debaille, D. J. Des Marais, M. Dixon, B. L. Ehlmann, J. D. Farmer, D. C. Fernan- dez-Remolar, J. Filiberto, J. Fogarty, D. P. Glavin, Y. S. Goreva, L. J. Hallis, A. D. Harrington, E. M. Haus- rath, C. D. K. Herd, B. Horgan, M. Humayun, T. Kleine, J. Kleinhenz, R. Mackelprang, N. Mangold, L. E. Mayhew, J. T. McCoy, F. M. McCubbin, S. M. McLennan, D. E. Moser, F. Moynier, J. F. Mustard, P. B. Niles, G. G. Ori, F. Raulin, P. Rettberg, M. A. Rucker, N. Schmitz, S. P. Schwenzer, M. A. Sephton, R. Shaheen, Z. D. Sharp, D. L. Shuster, S. Siljestrom, C. L. Smith, J. A. Spry, A. Steele, T. D. Swindle, I. L. ten Kate, N. J. Tosca, T. Usui, M. J. Van Kranendonk, M. Wadhwa, B. P. Weiss, S. C. Werner, F. Westall, R. M. Wheeler, J. Zipfel, and M. P. Zorzano) (2019), The Potential Science and Engineering Value of Samples Delivered to Earth by Mars Sample Return, Meteoritics & Planetary Science, vol. 54 (3), p. 667-671 (executive summary only), https://doi.org/10.1111/maps.13232; open access web link to full report (Meteoritics & Planetary Science, vol. 54, S3-S152): https://doi.org/10.1111/maps.13242.

Disclaimer: The decision to implement Mars Sam- ple Return will not be finalized until NASA’s comple- The First Billion Years: Habitability 2019 (LPI Contrib. No. 2134) 1016.pdf

THERMOCYCLING DRIVES EVOLUTION IN RNA GRANULES. John H. Carson1, 1University of Connecticut Health Center, 400 Farmington Ave, Farmington CT 06032.

Introduction: RNA granules represent a fundamental organizing principle of living cytoplasm. RNA granules are liquid droplets formed by phase separation of RNA and protein molecules. In modern cells mRNA molecules are localized and translated in RNA granules and their encoded protein molecules are associated with the same granules. We discovered that translation in individual RNA granules is cyclic, with periods of active translation interspersed with periods of inactive translation. Active translation generates heat energy resulting in thermocycling in individual granules. Thermocycling causes thermostatic switching between single stranded and double stranded RNA states, thermokinetic regulation of off rates for molecular binding and thermophoretic movement of protein and RNA molecules into and out of the granule. Priordial RNA granules may have formed by phase separation of oligoribonucleotides and oligo- peptides prior to the appearance of living cells. If primordial granules formed near hydrothermal vents, temperature fluctuations (thermocycling) in the vent may have caused thermostatic switching between translation and replication, thermokinetic selection for slower off rates and thermophoretic selection for longer RNA molecules in the granules. Thus, thermocycling near hydrothermal vents may have driven evolution of selectivity, stability, complexity and information content in primordial RNA granules. References: 1. Tatavarty V, Ifrim MF, Levin M, Korza G, Barbarese E, Yu J, Carson JH. 2012 Mol Biol Cell. 23(5):918-29.

The First Billion Years: Habitability 2019 (LPI Contrib. No. 2134) 1025.pdf

EARLY HABITABILITY POTENTIAL OF DWARF PLANET CERES. J. C. Castillo1, C. A. Raymond1, M. C. De Sanctis2, A. Ermakov1, 1Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA, Ju- [email protected], 2Istituto di Astrofisica and Planetologia Spaziali, INAF, Roma, Italy.

Introduction: Ceres, the largest object in the aster- discrepancy between the inferred pH2 and the theoreti- oid belt and most water rich object after Earth in the in- cal pressure that can be achieved in Ceres suggests it ner solar system, has been explored in detail by the was an open system early on, potentially due to an in- Dawn mission from 2015 to 2018. From the mineralog- tensive impact history. As the ocean frozen, it incorpo- ical, elemental, geological, and geophysical observa- rated an increasing amount of salts, in particular sodium tions returned by Dawn has emerged the picture of a carbonate, and organics. The latter are found in discrete body that hosted protracted activity for 100s My. We places across the Ernutet Crater region [8]. While their summarize the Dawn results and the constraints they origin inside Ceres is most likely [9], the mechanism for bring on Ceres’ early habitability potential. bringing them to the surface remains to be elucidated. Key Results: Combined geophysical and topogra- References: [1] Ermakov A. I., et al. (2017) JGR phy data indicate that Ceres is partially differentiated in 122, 2267–2293. [2] Fu R. R., et al. (2017) EPSL 476, a water-dominated crust and a hydrated and porous 153-164. [3] De Sanctis M. C., et al. (2015) Nature 528, mantle [1,2]. This, combined with a globally homoge- 241-244. [4] Castillo-Rogez J. C. and McCord T. B. neous surface composed of phyllosilicates, carbonates, (2010) Icarus 205, 443-459. [5] Travis B. J., et al. and a dark component [3] suggest the occurrence of a (2018) MAPS 53, 2008-2032. [6] Neveu M., et al. global ocean inside Ceres for some period of time. Mod- (2017) GCA 212, 324-371. [7] Castillo-Rogez J. C., et els indicate that volatile melting on a global scale real. (2018) MAPS 53, 1820-1843. [8] De Sanctis M. C., quired heat from aluminimum-26 [4], leading to the et al. (2017) Science 355, 719-722. [9] Bowling et al., presence of a deep ocean for <200 My [4]. However, in EPSL submitted. alternative thermal evolution models, the ocean may Acknowledgements: Part of this work was carried persist until present [5]. The surface mineralogy con- out at the Jet Propulsion Laboratory, California Insti- straints the conditions in the oceanic environment to be tute of Technology, under contract to NASA. Govern- o less than 50 C, pH=7-11, log pH2>-6 [6,7]. The ment sponsorship acknowledged.

Figure 1. The Dawn mission at Ceres observed evidence of the ingredients for life: water, C-H-N-O-P-S elements, and energy. (a) Geophysical data confirm the presence of extensive water ice and the need for salts and/or clathrate hydrates to explain the observed topography and crustal density. (b) Various types of carbonates and ammonium chloride have been found in many sites across Ceres’ surface (e.g., salts exposed on the floor of Dantu crater). (c) Ernutet crater (~52 km) and its area present carbon species in three forms (reduced in CxHy form, oxidized in the form of carbonates and intermediate as graphitic compounds.) (d) Ceres shows extensive evidence for water ice in the form of ground ice and exposure via mass wasting and impacts (image: Juling crater, ~20 km.) (e) Recent expressions of volcanism point to the combined role of radiogenic heating and low-eutectic brines in preserving melt and driving activity (image: Ahuna Mons, ~4.5 km tall, ~20 km diameter.) (f) Impacts could create local chemical energy gradients in transient melt reservoirs throughout Ceres’ history (image: Cerealia Facula, ~14 km diameter.) The First Billion Years: Habitability 2019 (LPI Contrib. No. 2134) 1014.pdf

Developing an Astro-ecological Model for Characterizing Exoplanet Habitability

Alma Y. Ceja 1,*, Stephen R. Kane 1 1University of California, Riverside, CA, USA *[email protected]

Abstract: A primary objective of the field of termed the biokinetic spectrum for temperature (Corkrey astrobiology is to identify worlds outside of our own et al. 2016). The spectrum arises from a meta-analysis of which are capable of supporting life. Here, an cellular growth rate as a function of temperature. In this integrative approach is applied to characterize the agent-based model, the survivability of a biological habitability of selected exoplanets. We explore the organism is determined by its thermal response to relationship between alien environments and terrestrial simulated local and global exoplanet temperature life by developing a novel astro-ecology model which dynamics. This work produces a list of exoplanets with can be used as a tool to assess the habitable regions on the highest probability of having temperate surface exoplanet surfaces. In this model, simulated exoplanet conditions compatible with terrestrial-based environments are convolved with a real biological layer. thermophysiology, as well as surface maps highlighting Exoplanet thermal environments are simulated using the potentially thermally habitable regions. Life, however, is climate model, Resolving Orbital and Climate Keys of dependent upon multiple variables including the presence Earth and Exoplanet Environments (ROCKE-3D, Way of liquid water, nutrient content, and an energy source. et al. 2018). ROCKE-3D is a fully-coupled 3- Caveats of the methodology and application of our results dimensional oceanic-atmospheric general circulation are discussed with implications for extraterrestrial model (GCM) featuring interactive atmospheric evolution. chemistry, aerosols, the carbon cycle, vegetation, and References: other tracers, as well as the standard ocean, sea ice, and Corkrey, R., et al. (2016) PLOS One. land surface components. The GCM output is coupled https://doi.org/10.1371/journal.pone.0153343. in the astro-ecology model with empirically-derived Way M., et al. (2017) Astrophysical Journal, 231, 1, 12- thermal performance curves of 1,627 cell strains 34. representing extremophiles from all six Kingdoms,

The First Billion Years: Habitability 2019 (LPI Contrib. No. 2134) 1006.pdf

ENVIRONMENTS ENABLING THE ORIGIN OF LIFE ≠ HABITATS FOR EXTANT LIFE. Benton C. Clark1 and Vera M. Kolb2, 1Space Science Institute, 4750 Walnut St., Boulder, CO 80301, USA, [email protected], 2University of Wisconsin-Parkside, Kenosha, WI 53141, USA, [email protected]

Introduction: Although life forms, especially ty or a natural endowment of organic compounds could many archaea and some bacteria microorganisms, have have jump-started the origin of life. evolved to survive and thrive in an enormous diversity For planets such as early wet Mars and Venus, and of environmental niches, this would not have been the landmasses on Earth, the many fortuitous juxtaposi- case for the very earliest life. The settings for habita- tions of water and soil provide opportunities for the bility for extant life are not necessarily suitable for the perfect combination of essential conditions and con- origin of life. Many are antithetical. stituents for the origin of molecular life. An example Macrobiont -- the Incubator of Life: In consid- on a planetary surface of a proto-Macrobiont, the set- ering the various requirements for prebiotic synthesis ting in which molecular evolution to the RNA World, of the molecules leading to life, we analyze the one- or equivalent first spark of life, could occur is shown in site, heterogeneous, multi-component model of the Figure 2. Macrobiont (MB). This single setting intermingles numerous micro-environments into a single locale with semi-isolated access to sources of chemical ingredients in space and time. Ranging from organic precursors to essential major, minor, and trace elements, these ingredients provide not only the building blocks of molecular life but also chemical energy such as redox couples. Electromagnetic energy sources, in terms of IR, visible and ultraviolet light may also become available. Other energy sources range from electric discharge (lightning), volcanic energy, cosmic energetic charged particles, and hypervelocity meteorite impact with atmospheric gases to create ions. The Macrobiont is not an organism, but rather the Fig. 2. A proto-Macrobiont with Organics intimate consortium between its unique environmental setting and the primitive molecular organisms it hosts. This “little pond” scenario can be produced by any Laboratory Syntheses: Investigations into prebi- number of types of water infusion into natural depres- otic evolution toward life are saddled with the need to sions --- fed by rainfall; ephemeral streams; groundwa- explain plausible pathways for synthesis of numerous ter; lake overflow; snowmelt; etc. Small size is im- biochemically essential molecules, and at the same portant if the wet/dry cycling or freeze/thaw cycling time without producing higher yields of interfering or shown by several investigators [e.g., 1] to promote diluting organic residues. Traditionally, these require formation of bio-essential polymers (proteins from separate reaction systems and purification steps, intel- amino acids; RNA from nucleotides) is facilitated. ligently directed by highly experienced, knowledgea- This proceeds rather further than Darwin’s insightful ble, and innovative researchers. “warm little pond” concept (suggested at a time when biochemistry was in its infancy) to a “dirty little pond” with diverse and dynamic microenvironments to enable this single setting to actually provide multiple microenvironments and transient events to proceed along directions which the laboratory chemist achieves more efficiently with test tubes, pipettes, precipitations, solvent extractions, distillations, chromatographic separations, etc. Fig. 1. The Chemist’s Lab Hardiness and Habitability: On Earth, the reper- toire of microbes is astounding. Even though “all life Natural Settings for proto-Macrobiont: For on Earth is alike” due to DNA / protein / lipid com- ocean worlds, such as Europa, Enceladus, and possibly monalities, the metabolic diversity and tolerance of the early Earth, either sub-oceanic hydrothermal activi- environmental deviations has resulted in a plethora of The First Billion Years: Habitability 2019 (LPI Contrib. No. 2134) 1006.pdf

organism phenotypes, lifestyle behaviors, and energy pended load; or seeded exogenously by a comet [5] or sources. as if there are in effect millions of different carbonaceous meteorite [6]. types of life on our home planet. Many organisms in the current biosphere do not, The only true essential requirement for habitability however, need organic compounds. Photoautotrophs seems to be the occurrence of H2O in liquid form (or and chemolithoautotrophs are abundant and tolerate an close to it, such as near-saturation humidity; liquid enormous range of environmental settings. films on ice; or pressurization for temperatures above Trace elements Requirements: Trace elements in 100° C). The water does not even need to be continu- rocks and their weathering products play a strong role ously present for many life forms, which may store it in the metabolism of extant life. These include Fe, Zn, up or simply become temporarily dormant. Insects Mn, other transition metals and elements which geo- with anti-freeze constituents survive in deeply sub- chemically occur at trace levels, in soluble form. freezing environments when foraging for food. Modern organisms have special enzymes and regulato- Some organisms have the capability to grow in the ry functions for sensing and acquiring these essential chloride-rich brines on Earth or the sulfate-rich brines trace elements. Even the ultra-trace levels of Mo can such as those on Mars [2]. Other organisms are be obtained for nitrogenase. None of this was possible adapted to low pH, a condition which seems to be before life became highly advanced. counter to most pathways for prebiotic synthesis [3]. Recent prebiotic synthesis studies by investigators And other components of the “wet” environment have pinpointed the likely importance of other trace can be extreme. If water is available, whatever other elements, such as copper [7] and boron [8]. physicochemical properties there are of any given envi- With the goal of engineering the most primitive cell ronment, the probability that some organism has found possible, the Venter group finds that between 300 and a way to exist and prosper, or at least survive for better 400 genes are essential to the growth and reproduction times, seems to be very close to 1.0. of minimal cells, even when key nutrients are supplied Water Requirements for a Macrobiont: For externally [9]. Genes for managing trace elements prebiotic organic chemistry to proceed, it benefits from would add to this list. a solvent, although some solid state reactions or vapor These elements generally occur naturally at a too phase reactions may also occur [4]. Water is the logi- low level to be useful in the prebiotic and biotic evolu- cal solvent (availability, versatility) but can be inhibito- tion envisioned for the origin of life. Mineral weather- ry because the polymerization to form proteins, RNA ing and redox stratification can result in higher concen- and DNA from their monomer precursors are dihy- trations, but restricts the settings where pre-life pro- droxylation reactions. Once formed, hydrolysis reac- cesses could proceed. tions can destroy the polynucleotides. Conclusion: In addition to assessing Habitability Furthermore, too much H2O can also dilute compo- for living organisms, the suitability of extraterrestrial nents so much that reactions needed for increasing the environments for the prebiotic evolution necessary for levels of important prebiotic constituents may become the origin of life must be evaluated. The known bio- negligible. sphere contains innumerable examples of organisms In addition to C for organics, the macrobiont will which operate in diverse and adverse environments. need other key elements. These can be obtained from The origin of life requires, however, a much more con- soils in the forms of -ates/-ides of P, S, and N (phos- strained set of conditions (pH, Eh, W/R, μ, etc.) for the phates/phosphides, nitrates/-NH2, etc.) spark of life to have occurred in the first place. Not all Ocean water is highly diluted in several constitu- planets provide these circumstances equally. ents desired, both organic and inorganic, which has References: [1] Higgs, P.S. (2016) Life 6, 24. resulted in proposals that a possible role of large bod- [2] Fredsgaard, C. et al. (2017) Int’l J. Astrobiol. 16, ies of water might be instead for the tidal flats they can 156-162. [3] Knoll, A.H. et al. (2008), J. Geophys. produce, where the water/rock ratio (W/R) is suffi- Res. 113, E06516. [4] Kolb, V. (2019), Chap. 5.5, ciently low to avoid the dilutive effects and promote Hndbk Astrobiol., CRC, V. Kolb, Ed. [5] Clark, B. and wet/dry or freeze/thaw cycles. Kolb, V. (2018) Life 8, 12, 2-22. [6] Pearce, B. K. D. et MB Requirements for organics: On the primitive al. (2017) PNAS E.E., 1-6. [7] Sutherland, J.D. (2017) Earth and Mars, organics may have been intrinsically Nat. Rev. Chem. 1, 1–7. [8] Benner, S.A et al. (2012) rare. CO2 in a reductive atmosphere can provide a Acct. Chem. Res. 45, 2025–2034 [9] D. G. Gibson et feedstock for the formation of organics by Miller-Urey al. (2019), Chap. 2.3, Hndbk Astrobiol., CRC, V. Kolb, synthesis or other routes. Organics in the MB pond Ed. may have arrived through precipitation from the atmosphere; from transport by rivers and streams as sus- The First Billion Years: Habitability 2019 (LPI Contrib. No. 2134) 1045.pdf

A Systems Model of Earth’s Early Abiotic Nitrogen Cycle

Matthieu Laneuville 1 and H. James Cleaves II2 1 Earth-Life Science Institute (ELSI), Tokyo Institute of Technology, Tokyo, Japan ([email protected]) 2 Earth-Life Science Institute (ELSI), Tokyo Institute of Technology, Tokyo, Japan ([email protected]).

Introduction: The fluxes of various elements between dominated by biology, followed distantly by abiotic fixation by planetary reservoirs on the prebiotic Earth may have changed lightning. Biological N-cycling is tight, both fixing N from the considerably during the course of the planet’s evolution. While atmosphere more rapidly than abiotic mechanisms, and also much attention has been paid to the prebiotic C-cycle, returning it to the atmosphere efficiently [Galloway et al. (2004)]. especially due to its potential role in greenhouse warming, In the absence of efficient remineralization, all of the N in the relatively little has been paid to the prebiotic N-cycle. The present atmosphere, given current rates of abiotic fixation, could amount of N in various reservoirs could have been markedly be depleted in ~175 Ma. different in the past, and may have changed over time. Here we present results of a prebiological Earth-system Assuming chondritic values, the Earth’s total N inventory model which takes into account atmospheric, atmosphere-ocean, should be ~2e22 kg [Anders & Grevesse (1989)]. Presently, ocean-sediment, and subduction processes and reservoirs to ~4e21 kg are in the atmosphere, so either 90% of Earth’s N is estimate the nature of Earth’s N-cycle before life began. Our in deep reservoirs, large amounts of N have been lost over time, model may help place constraints on the early evolution of the or the Earth is largely non-chondritic [Campbell & O’Neill abiological N-cycle. (2012)]. Dissolving all atmospheric N or the entire chondritic inventory in oceans of the modern volume gives maximal References: oceanic (N) of 0.1 and 1 M, respectively, which would be quite Anders & Grevesse (1989) Geochim. Cosmochim. Acta 53:197- conducive to prebiotic synthesis. 214. The Earth system prior to ~3.5 Ga is poorly constrained but Campbell & O’Neill (2012) Nature 483:553-8. biology has undoubtedly significantly perturbed the Earth’s N- Galloway et al. (2004) Biogeochem. 70:153-226. cycle. Presently, the flux of N from the atmosphere is The First Billion Years: Habitability 2019 (LPI Contrib. No. 2134) 1028.pdf

PRESERVATION FEATURES FROM ICE AND BRINES ON NON-RADIATION TOLERANT MICROBES IN EUROPA-LIKE CONDITIONS Sarah J. Crucilla1,2, Scott M. Perl2,3, Chris A. Lindensmith2, Jay Nadeau4, Henry Sun5 1Division of Geological and Planetary Sciences, California Institute of Technology, 1200 E. California Blvd. Pasadena, CA 91125 ([email protected]) 2Jet Propulsion Laboratory, California Institute of Technology ([email protected]) 4800 Oak Grove Drive, Pasadena, CA 91109, 3Los Angeles Natural History Museum, Mineral Sciences, 900 W Exposition Blvd, Los Angeles, CA 90007, 4Microscopy and Materials Laboratory, Portland State University, PO Box 751 Portland, OR 97207-0751, 5Division of Earth and Ecosystem Sciences, 755 E. Flamingo Road, Las Vegas, NV 89119

Introduction & Motivation: The surfaces of most growth range of the bacteria to see whether or not those celestial bodies are exposed to ionizing radiation at levels factors correlate with survivability. Cell viability will be higher than most earthlike life can survive (e.g. [1, 2]) measured directly after exposure in the form of motility However, the depth under the surface as well as the and comparisons to pre-radiation growth curves. surface composition may mitigate the effects of radiation Exposures will all be the same duration. (e.g. [2]) creating a habitable environment in the subsurface. In addition, moons such as Europa [3, 4] and Applications to in-situ analyses: Europa, due it its ice Enceladus [5] have plumes which may bring up samples crust, world ocean, and hydrothermal vent activity, is a from the radiation-shielded ocean to the radiation-filled candidate for a system that can support extant life. Both surface. evidence from the Hubble Space Telescope [3] and Galileo The main objective of this experiment is to [1] indicate the presence of determine the radiation sensitivity of non-radiation vapor plumes on Europa, resistant terrestrial microbes within different ices, brines, which may deposit new mineral substrates as well as completely desiccated. layers of ice on its surface. Measuring the motile functions and metabolisms of these The molecules and particles microbes tell us how they are affected by radiation. within the vapor would Additionally, our measurements will test ability the therefore be detectable in digital holographic microscope (DHM) in distinguishing the uppermost portion of live and dead organisms, which has possible implications the ice, potentially in layers for future missions. in the case multiple particle deposition events take Methodology: The microbes used in our experiment place. The surface is also each have different metabolisms and growth ranges as exposed to ionizing they both may contribute to their ability remain viable radiation from Jupiter, after radiation exposure as well as represent a variety of which accumulates at conditions, from hot hydrothermal vents to ice, in which different levels depending microbes may be found. Barring our Deinococcus on the depth of ice ranging radiodurans control, all bacteria in this experiment are from around 1.00^107 rad in non-radiation resistant, which allows us to test the limits the uppermost layers to less of cell viability. Samples will be placed inside a liquid than 1.00 rad in layers nitrogen dewar. All samples will be cooled to 70 K using Fig. 1. Combined Digital below 100 cm (Reviewed in liquid nitrogen and maintained at those temperatures Holographic and [6]). Our hypotheses are throughout the initial stages of the experiment. The Fluorescence Microscope. that survival curves (cell samples will be exposed to increasing doses of radiation Our DHM setup allows for viability) after radiation fluid sample to be dyed and in a half-decade sequence (10, 30, 100, 300, 1000 krad). run through to measure cell exposure will be directly After irradiation, the frozen samples will be gradually motility and dye binding to related to the physical state warmed to determine the extent to which the substrate (or DNA and other organic of the medium (i.e. a mm- lack thereof) can protect against radiation. compounds within the cell scale ice layer may protect wall [7]. from radiation better than a Analyses and Motility Assessment: Directly after partially melted sample), experimentation, organisms will be placed under the the amount and distance from the radiation source, and the DHM and examined to determine whether they survived. duration of irradiation. Depending on our survivability The DHM is equipped with the ability to measure the curves, we can potentially determine a zone within the ice reflectivity of different sections of the sample, which of the moon where cellular life with certain properties may allows for it to tell between living microbes and minerals. likely survive, information useful for future lander Tracking software will also be used to determine whether missions. Through this experiment, we are also able to test microbes are viable. To confirm our analyses and see the the extent to which bacteria can survive in extreme extent to which organisms are alive, we will then use a conditions, which may give us an idea of how likely combination of LIVE/DEAD assay using STYO9 dye. mutations are to arise to allow for bacteria to survive in We will compare the results to both the metabolism and radiation conditions. The First Billion Years: Habitability 2019 (LPI Contrib. No. 2134) 1028.pdf

Applications to Mars. Mars is it with up to 325 cal/cm2 of radiation daily [8] and has no liquid water on References: [1] Rask et al. (n.d.). NASA. [2] Teodoro et its surface, making the surface an unlikely candidate for al. (2017). LPS XLVII. [3] Jia et al. (2018). Nature earthlike life. However, neither UV-B or UV-C were Astronomy, 2, 459-464 [4] Roth et al. (2014). Science, critical constraints on the formation of life on ancient 343(6167): 171-174. [5] Hansen et al. (2006). Science, Mars [9]. On Earth, subsurface communities use their 311 1422-1425. [6] National Research Council (2000). environment to create a barrier against extreme external Washington, DC: The National Academies Press. [7] conditions. At 1-2mm under the surface, DNA effective Bedrossian et al. (2017). Astrobiology 17, 913-925. [8] irradiance would be reduced to less than (~.01 W/m2) [9]. Kuhn et al. (1979). J. Mol. Evol., 14, 57-64. [9] Cockell The experiments with mineral substrates therefore can et al. (2000). Icarus, 146, 343-359. serve as an analogue for the recalcitrance of life living under the surface of Mars.

The First Billion Years: Habitability 2019 (LPI Contrib. No. 2134) 1020.pdf

RADIOLYSIS AND THERMOLYSIS OF GLYCOLALDEHYDE IN CONDITIONS SIMULATING THE VICINITY OF A SUBAERIAL HOT SPRINGS IN THE PRIMITIVE EARTH. J. Cruz-Castañeda1, A. Negrón-Mendoza1*, S. Ramos-Bernal1, and A. Heredia1. 1Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, UNAM. Cd. Universitaria, A. P. 70- 543, 04510 México, CDMX, México. *[email protected]

Introduction: Carbohydrates are organic mole- References: cules with minimal formula (CH2O)n. They are essential for the actual biological systems [1,2], since these [1] Gabius, H.-J. (2000) Naturwissenschaften, 87, molecules can serve as 1) energetic molecules, since 108–121 they are part of the molecules of ATP, GTP, etc. 2) [2]Joyce, G. F. (1989) Nature, 338, 217–224 [3] Jewell, J. M. H. and F. J. L. and P. R. (2000) structural molecules, as in nucleic acids, (e.g. ribose-5- Astrophys. J. Lett, 540, L107 phosphate in DNA and RNA), and 3) precursor for [4] Fournier, R. O. (1989) Annu. Rev. Earth Planet. more complex sugars. Some of them have been detect- Sci. 17, 13–53 ed in the Interstellar Medium (e.g. glycolaldehyde) [3], [5] Deamer, D. W. and Georgiou, C. D. (2015) that is of great relevance in the period of chemical evo- Astrobiology, 15, 1091–1095 lution on Earth

It has been proposed, that the sugars were the first

prebiotic auto-catalytic systems [1]. For all these reasons, the synthesis and stability of these compounds under primitive conditions is essential. Geological environments, where the scenery for chemical reactions that enriched the Earth with organic matter were developed. It has been proposed that in subaerial hydrothermal systems such as Yellowstone (common and widely distributed in primitive Earth) [4], nucleotide monomers could have been synthesized in the hydration- drying processes, and even these monomers could be polymerized through heterogeneous catalysis [5]. The objective of the present work is to study the thermolysis and gamma radiolysis of glycolaldehyde, in solid state, in aqueous solution, and suspensions with clays, simulating the vicinity of a subaerial hot spring probable in the primitive Earth. The results highlighted the reactivity of the sugars since they were determined to be labile to ionizing radiation and heat, even in the presence of mineral surfaces. Among the products obtained in the radiolysis processes of glycoladehyde, other sugar-type compounds were determined (e.g. eritriol). The chemical analysis was performed by ATR-FTIR, Liquid Chro- matography-UV Spectroscopy (UHPLC-UV) and HPLC Coupled to mass spectrometry (UHPLC-MS).

Acknowledgment: This work was supported by ICN-UNAM and PAPIIT project IN226817, We thank Chem. Claudia Camargo, M.Sc. Benjamin Leal, and Phys. Francisco Flores for their technical assistance.

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VOLATILES IN THE MARTIAN CRUST. J. Filiberto1 and S.P. Schwenzer2, 1Lunar and Planetary Institute, USRA, 3600 Bay Area Blvd, Houston, TX 77058 USA [email protected], 2School of Earth, Environment and Ecosystem Sciences, The Open University, Walton Hall, Milton Keynes, MK7 6AA, UK.

focusing on evidence for volatiles reservoirs from Martian meteorites and the second half of the book focuses on spacecraft (orbital, lander, and rover) investigations. All of this data is then synthesized in a conclusion that addresses habitability of Mars through geologic time. The results presented in the book demonstrate how much the view of Mars has changed since the initial images of a desolate planet. It is now clear that Mars is not a monotonous basaltic world, but instead has the rich geologic and hydrologic history of a complex planet. The diversity in Martian rocks is evident across all of our data sets, and we begin with a discussion of the volatile content and inventory of the Martian interior, with the Martian mantle being heterogeneous in terms of volatile elements and their isotopic signatures [4-7]. The crustal water reservoir is the most uncertain but the most important in terms of habitability of Mars [7-11]. The properties of this reservoir likely variy with location, depth in the crust, and geologic time [7-11]. As is demonstrated, the history of water, including different reservoirs, became and continues to become Figure 1. Cover of Volatiles in the Martian Crust [1] (top) more complex as more data is returned from meteorites, showing sulfate veins at Gale Crater from MSL Curiosity. orbiters, landers, and rovers. To fully understand Image: NASA. (middle) Crossed-polar image from the Martian habitability through time and between Lafayette meteorite (BM.1959,755). Image courtesy of the locations, more detailed investigations are required, Trustees of the Natural History Museum. Image: Virtual especially discerning mineral assemblages from out-of Microscope, The Open University. (bottom) Mounds on the equilibrium co-detections, and, of course, the lower slows of Mt Sharp in Gale Crater. Image: NASA. association of mineralogy with geomorphology must be understood. Introduction: Follow the water was the mantra for Beyond hydrogen and water, carbonates have been Martian exploration [2] for decades, because water found in both Martian meteorites and at every landing (along with nutrients, an energy source, and protection site [9-14]. Carbonates in Martian meteorites record from detrimental influences) is required for life as we evidence of low-temperature vein-type alteration, which know it [3]. However, water is just one volatile, and is attributed to impact-generated hydrothermal with many different metabolic pathways, utilizing processes and would have represented a habitable carbon, sulfur, nitrogen, amongst others, a wider range environment [12]. For sulfur, it has long been known of volatiles requires consideration. Our recent book that the Martian crust is rich in sulfur and one of the first “Volatiles in the Martian Crust” (Figure 1 [1]), focuses minerals analyzed at Meridiani Planum was jarosite, a on constraining what is known about volatile reservoirs potassium- and iron-bearing hydrous sulfate that forms in the Martian crust. With a set of expert chapter from acidic waters [11, 13-15]. The high sulfur content authors, we bring together constraints on volatiles of the crust could have provided both an energy source reservoirs in the Martian crust from vast data sets, with and nutrients for any potential microbes [15, 16]. substantially different footprints. The book is organized Based on our growing knowledge of Mars as a around these different datasets starting with the most system, the focus has moved from finding water and detailed discussions and building to a broader habitable environments, to the question if life ever understanding of volatiles in the crust with implications existed on Mars, when, where, and under what for habitability. The book is divided into two parts: first conditions would it have existed? Further, there has The First Billion Years: Habitability 2019 (LPI Contrib. No. 2134) 1009.pdf

been a shift from investigations around extremophiles that could have survived on the Martian surface based on the high sulfur content and the ‘acid-fog’ model of the crust [e.g., 17] to conditions that are more conducive for life, as we find evidence for more circumneutral pH fluids in Mars’ past [18]. In addition, the new findings and especially quantification of elements critical for life sparks new research into terrestrial metabolic pathways and their applicability for Mars, as exemplified for the case of nitrogen [22]. Using rover-based instrumentation on the surface of Mars (i.e., ExoMars and Mars 2020) and as the community builds towards future sample return [19-21], we will be able to address the question whether Mars was once habitable and possibly if Mars was ever inhabited.

References: [1] Filiberto J. and Schwenzer S.P. (2019) Volatiles in the Martian Crust. Elsevier, 426. [2] Hubbard G.S. et al. (2002) Acta Astronautica, 51, 337-350. [3] Conrad P.G. (2014) Science, 346, 1288-1289. [4] Filiberto J. and Schwenzer S.P. (2019) Chapter 1 - Volatiles in the Martian Crust, Elsevier, p. 1-12. [5] Filiberto et al. (2019) Chapter 2 - Volatiles in the Martian Crust, Elsevier, 13-33. [6] Ott U. et al. (2019) Chapter 3 - Volatiles in the Martian Crust, Elsevier, 35-70. [7] Usui T. (2019) Chapter 4 - Volatiles in the Martian Crust, Elsevier, 71-88. [8] Lasue J. et al. (2019) Chapter 7 - Volatiles in the Martian Crust, Elsevier, 185-246. [9] Mustard J.F. (2019) Chapter 8 - Volatiles in the Martian Crust, Elsevier, 247-263. [10] Kounaves S.P. and Oberlin E.A. (2019) Chapter 9 - Volatiles in the Martian Crust, Elsevier, 265-283. [11] Sutter B. et al. (2019) Chapter 12 - Volatiles in the Martian Crust, Elsevier, 369-392. [12] Bridges J.C. et al. (2019) Chapter 5 - Volatiles in the Martian Crust, Elsevier, 89-118. [13] Jolliff B.L. et al. (2019) Chapter 10 - Volatiles in the Martian Crust, Elsevier, 285-328. [14] Mittlefehldt D.W. et al (2019) Chapter 11 - Volatiles in the Martian Crust, Elsevier, 329-368. [15] Franz H.B. et al. (2019) Chapter 6 - Volatiles in the Martian Crust, Elsevier, 119-183. [16] Filiberto J. et al. (2019) Chapter 13 - Volatiles in the Martian Crust, Elsevier, 393-399. [17] Tosca N.J. et al. (2004) JGR: Planets, 109, 10.1029/2003JE002218. [18] Grotzinger J.P. et al. (2014) Science, 343, 10.1126/science.1242777. [19] Vago J. et al. (2015) Solar System Research, 49, 518-528. [20] iMOST team (2019) Meteoritics & Planetary Science, 54, S3- S152. [21] Mustard J. et al. (2013) Report of the Mars 2020 science definition team. [22] Price A. et al. (2019) Frontiers in Microbio. 9, 10.3389/fmicb.2018.00513.

The First Billion Years: Habitability 2019 (LPI Contrib. No. 2134) 1013.pdf

HABITABILITY OF THE EARLY MARTIAN CRUST AS CONSTRAINED BY HYDROTHERMAL ALTERATION OF A MAFIC DIKE. Justin Filiberto1, Lacey J. Costello2, Jake R. Crandall3, Sally L. Potter- McIntyre2, Susanne P. Schwenzer4, Daniel R. Hummer2, Karen Olsson-Francis4, Scott Perl5, Michael A. Miller6 and Nicholas Castle1. 1Lunar and Planetary Institute, USRA, 3600 Bay Area Blvd., Houston, TX 77058, USA. [email protected], 2Southern Illinois University, Department of Geology, 1259 Lincoln Drive, Carbondale, IL 62901, USA, 3Eastern Illinois University, Department of Geology & Geography, 600 Lincoln Ave., Charleston, IL 61920, USA, 4School of Environment, Earth, and Ecosystems Sciences, The Open University, Walton Hall, Milton Keynes MK7 6AA, UK, 5Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Dr, Pasadena, CA 91109, USA. 6Materials Engineering Department, Southwest Research Institute, 6220 Culebra Road, San Antonio, TX 78238-5166, USA.

Introduction: The Martian crust is largely basaltic Analytical Methods: Bulk composition was [1], with a wide range of alteration minerals observed measured by an IXRF Systems (Model 550i) energy in a wide diversity of settings (sedimentary, post- dispersive X-ray spectrometer attached to a Philips magmatic, volcanic-hydrothermal and impact (Model XL-40) scanning electron microscope at generated hydrothermal). Secondary minerals have Southwest Research Institute in San Antonio. been observed from orbit, by ground based missions, Mineralogy was determined by X-Ray Diffraction and and in Martian meteorites [2]. Therefore, the observed Visible-Near Infrared Spectroscopy. XRD was done alteration minerals would have formed from a mafic for bulk mineralogy, as well as the clay ( 2 m) protolith in a variety of conditions (P, T, and Xfluid). fraction. Higher temperature hydrothermal systems, caused by both volcanic activity and impact processes [3, 4], likely dominated the formation of alteration mineralogy on an early Martian basaltic crust. Any potential biological activity would have had to deal with these conditions but, assuming they could survive the high temperatures, could have used the energy and nutrients in a similar manner as organisms inhabiting hydrothermal systems on Earth [5]. As an analog for these processes on the Martian crust, we have investigated a mafic dike that was hydrothermally altered from contact with ground water as it was emplaced. Here we report the alteration conditions of the altered dike and mineralogical constraints on the hydrothermal fluid. This allows us to constrain the potential alteration mineralogy present in the Early Mars crust from high-temperature hydrothermal systems and the habitability potential of such systems. Field Site: Our field site is located in the Entrada formation on the Colorado Plateau. The investigation focuses on the 22 Ma Robbers Roost dike [6]. The dike intruded though the Jurassic Entrada Sandstone, an iron-cemented red silty-sandstone deposited in an eolian to tidal environment [7]. The dike can be separated into four visually distinct zones based on Figure 1. Field site showing each of the four visually differences in colors and textures correlated to distinct alteration zones of the dike. The alteration and different degrees of alteration. Samples of each zone oxidation of the dike changes from the ‘darkest’ zone (a), the were collected and analyzed (Figure 1). Further, ‘green’ zone (c), the ‘purple’ zone (b), and the ‘red’ zone (d). samples of the surrounding ‘baked contact zone’ of the Entrada sandstone (Figure 1), as well as bleached fractures distal to the dike (Figure 2) were collected to constrain the chemistry of the fluid. The First Billion Years: Habitability 2019 (LPI Contrib. No. 2134) 1013.pdf

contained key elements used by microbial life (C, S, and Fe), which could have been utilized as an energy source for chemolithotophic microorganisms [11]. Similar alteration mineralogy has been analyzed at multiple landing sites and from orbit: carbonates with olivine, sulfates, and kaolinite and/or other clay minerals [12-14]. Therefore, this site is an ideal analog location for informing about alteration of the Early Martian crust and it is paramount that future missions, such as Mars 2020 and ExoMars [15, 16], look at the interface of sediments with magmas or impact melts where microbial life, if present, could have taken advantage of a selection of favorable conditions. Figure 2. Bleached zone along a fracture - parallel, but References: [1] McSween H.Y. et al. (2003) JGR distal, to the dike in Figure 1. Planets 108, E12. [2] Filiberto J. and Schwenzer S.P.

(2019) Volatiles in the Martian Crust, Elsevier, 426. Results: Samples contain calcite, hematite, and [3] Abramov O. and Kring D.A (2005) JGR, 110, kaolinite, with minor goethite, gypsum, and halite. The E12S09. [4] Carr M.H. and Head J.W. (2010) EPSL, alteration of the dike can be divided in four zones: a 294, 185-203. [5] Rothschild L.J. and Mancinelli R.L. dark, a green, a purple and a red zone (Fig. 1). The (2001) Nature, 409, 1092-1101. [6] Wannamaker P.E. mineralogy shows an increase in sulfate and iron-oxide et al. (2000) Journal of Volcanology and Geothermal minerals with increasing alteration. Interestingly, even Research, 96, 175-190. [7] Crabaugh M. and Kocurek the least altered sample contains alteration minerals. G. (1993) Geological Society, London, Special The bulk chemistry of these four zones is Publications, 72, 103-126. [8] Filiberto J. and consistent with fluid mobility removing Si and K but Schwenzer S.P. (2013) MaPS, 48, 1937-1957. [9] adding S, Fe, Ca, and possibly Mg as alteration Bridges J.C. et al. (2019) Chapter 5 - Volatiles in the progresses. Analyses of the contact and bleached zones Martian Crust, Elsevier, 89-118. [10] Conrad P.G. are ongoing and will be reported at the meeting. These (2014) Science, 2014, 346, 1288-1289. [11] Westall F. will track how the fluid cooled as it moved away from et al. (2015) Astrobiology, 15, 998-1029. [12] Ehlmann the dike and interacted with the sandstone. The B.L. and Edwards C.S. (2014) Annual Review of Earth presence or absence of specific minerals will allow us and Planetary Sciences, 42, 291-315. [13] Carter J. to put relative constraints on volumes of water that and Poulet F. (2012) Icarus, 219, 250-253. [14] were isolated within secondary alteration products. Salvatore M.R. et al. (2018) Icarus, 301, 76-96. [15] Conditions of Alteration of the Dike: Vago J., et al. (2015) Solar System Research, 2015, 49, Thermochemical models from [8] are used to constrain 518-528. [16] Mustard J. et al. (2013) Report of the the alteration conditions. Based on the dominance of Mars 2020 science definition team. JPL, California carbonates in the mineral assemblage, the fluid was Institute of Technology, Pasadena, CA, 2013. near-neutral in pH [9]. In order for Si to be mobile in a

near-neutral pH, high temperatures (>200 °C) would be required. As the system cooled (150 °C) carbonates, kaolinite, and hematite precipitated. Goethite would have been produced at lower temperatures. Finally, gypsum and halite would have precipitated from the fluid after formation of a more concentrated brine. Depending on their preserved locations and salinities, these minerals will show the longevity of fluid activity in the layered zones. Implications for Habitability and Application to Mars: If the requirements for life on Earth are reasonable constraints for potential life on Mars [10], the hydrothermal system that formed during interaction of the magma and ground water would have been a habitable environment once the system cooled below ~120 °C [5]. The fluid within the system would have The First Billion Years: Habitability 2019 (LPI Contrib. No. 2134) 1023.pdf

MECHANICAL ENERGY AND MICA SHEETS AT THE ORIGINS OF LIFE. H. G. Hansma, Department of Physics, University of California, Santa Barbara, CA 93106, [email protected].

Introduction: Mechanical energy provided an endless energy source at the origins of life. Mechanical energy and forces now operate in all living systems, at all size scales, from the molecular to the cellular and beyond. These forces are typically generated by the cells’ chemical energy, such as ATP. Perhaps mechanical energy in living cells is a remnant of mechanical energy that brought life into being, before chemical energy was readily available. There is a growing body of scientific literature about mechanochemical syntheses of biomolecules such as peptides, nucleosides, optically active products, Covalent bonds would form when molecules were oxidations, reductions, condensations, nucleophilic pushed into the attractive regime of the potential ener- reactions, and cascade reactions [1]. Therefore it is gy curve, as diagrammed here for a reaction between realistic to propose that mechanical energy was a prim- the amino-acid alanine and the dipeptide di-alanine, to itive energy source at life’s origins. form tri-alanine. Two prebiotic systems where mechanical energy might have been active are: (1) ponds or pools under- going wet/dry cycles [2], and (2) mica sheets [3-8]. Prebiotic chemistry has been tested successfully in wet/dry cycles [9]. This abstract discusses origins of life and ways of testing mechanochemistry in a ‘mica world’. Mica Sheets. The spaces between mica sheets have many advantages for the origins of life, including compartments before there were cells, potassium (K) ions bridging the sheets, and the mechanical energy of moving mica sheets. A ‘mica world’ has been imagined as follows: Testing Mechanochemistry between Mica Sheets. Make a ‘sandwich’ of split mica with a plausible prebiotic reaction mixture between the sheets. Cy- cle the ‘prebiotic’ sandwich through cycles of wet/dry, hot/cold, or pressure, in a suitable sample holder. The simplest procedure, suggested by David Deamer, is to use commercial fluorescent esterase substrates. Oth- erwise, the traces of reaction products would probably need to be analyzed by SIMS (Secondary Ion Mass Spectroscopy) or XPS (X-ray Photoelectron Spectros- Mechanical energy of moving mica sheets would occur copy). The image below shows a mica-water ‘sand- when water flows in and out and during heating and wich’ after several hours of drying. cooling in bubbles between mica sheets: The First Billion Years: Habitability 2019 (LPI Contrib. No. 2134) 1023.pdf

References: [1] Wang, G.-W. (2013) Chem. Soc. Rev., 42, 7668-7700. [2] Van Kranendonk, et al. (2017) Sci. Am., 317, 28-35. [3] Hansma, H.G. (2010) J. Theor. Biol., 266, 175-188. [4] Hansma, H.G. (2013) J. Biol. Struct. Dynamics, 31, 888-895. [5] Hansma, H. G. (2014) OLEB, 44, 307-311. [6] Hansma, H.G. (2017) Life, 7, 28. [7] Hansma, H. G. (2018) Biophys. J. 114, 440a. [8] Hansma, H. G. (2019) Sci, accepted for pub- lication. [9] Rajamani, S., et al. (2008) OLEB, 38, 57- 74. The First Billion Years: Habitability 2019 (LPI Contrib. No. 2134) 1040.pdf

Trace Element and Co Concentrations in 2.7 Ga Archean Metasedimentary Rocks of the Cherry Creek Suite, Gravelly Range, Montana, USA. C. A. Hotujec-Kantner1, 1University of Florida (Department of Geological Sci- ences, 241 Williamson Hall, P.O. Box 112120, Gainesville, FL 32611-2120 [email protected]),

Introduction: The evolution of the Co marine res- Discussion: ervoir is not completely understood, yet information Trace element concentrations measured are similar contributing to this timeline provides the ability to un- to contemporaneous Archean sediments. The observed derstand how Co availability influenced its role in bi- pattern suggests there was an elemental flux from an ology. Levels of Co were higher during the Archean early Earth landmass. Average Co concentrations are than in the modern ocean [1]. Modern cobalt budget similar to the reported values of 0.5 ±0.2 for the pre- sources include riverine flux, hydrothermal flux, oce- GOE Joffree Member of the Hammersly Group, Aus- anic reservoir mass and residence time and the sinks tralia [3]. Trace element and Co contributions from are determined by estimates of the mass accumulation both subaerial landmasses and hydrothermal sources rates for sediments deposited in oxic, anoxic, and eux- are indicated. inic conditions [2]. During the Archean the main The availability of Co and trace element concentra- source of Co was hydrothermal due to the lack of con- tions provide useful information regarding the prevail- tinental runoff and shelf detrital sediments [3] The ing surficial redox conditions and availability of Co for combination of longer Co residence time, abundant the evolution of marine microbes. hydrothermal fluids, ultramafic rocks, and predominantly anoxic conditions during the Archean suggests that there was a large dissolved marine Co reservoir References: [1] Condie K. C. (1993), Chemical whose bioavailability affected the development of ear- Geology 104: 1-37. [2] Swanner E. D. et. al (2014), ly life. Earth and Planetary Science Letters 390: 253-263. [3] Oxidative weathering of pyrite and other sulfide Thibon F. et. al (2019) Earth and Planetary Science minerals of the crust transports trace metals in marine Letters 506: 360-370. [4] Mueller P. A. and Nutman A. sediments to the ocean via rivers. Therefore, trace ele- P. (2017) The Geological Society of America Special ments trapped in sediments associated with early- Paper #523. condensed surface water provide evidence of the presence or absence of oxygen in the Earth’s atmosphere- hydrosphere. The rocks that form from these metallic sediments can provide information regarding the oxygen evolution of Earth’s surficial system as well, as long as their composition has not been subsequently altered [3]. Results: The trace element and Co concentrations in a set of Archean metasedimentary rocks from the Cherry Creek Metasedimentary Suite in the Gravelly Range, Montana that included banded iron formation and shale were examined for information about both the redox conditions of the atmosphere-hydrosphere and the bioavailability of Co during deposition 2.7 Ga.

The Co concentrations measured are 0.5 ±0.4. The First Billion Years: Habitability 2019 (LPI Contrib. No. 2134) 1026.pdf

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LESSONS FROM EARLY EARTH: UV SURFACE ENVIRONMENT OF EARTH-LIKE PLANETS: COMPARING CLOSE-BY M-STAR PLANETS TO EARTH THROUGH GEOLOGICAL EVOLUTION. Lisa Kaltenegger1, J O’Malley-James1,2, S. Rugheimer1,3, 1Carl Sagan Institute/Astronomy/Cornell 2Center for Planetary and Space Research, 1Oxford University, ([email protected], 302 Space Science Building, 14850 Ithaca, NY,USA).

Introduction: The closest potentially habitable Even for planet models with eroded and anoxic worlds outside our Solar System orbit a different kind atmospheres, surface UV radiation remains below of star than our Sun, smaller red dwarf stars. Such stars early Earth levels, even during flares. Given that the can flare frequently, bombarding their planets with early Earth was inhabited, we show that UV radiation biologically damaging high-energy UV radiation, should not be a limiting factor for the habitability of placing planetary atmospheres at risk of erosion and planets orbiting M stars. Our closest neighboring bringing the habitability of these worlds into question. worlds remain intriguing targets for the search for life However, the surface UV flux of these worlds is beyond our Solar System [11]. unknown. The stellar energy distribution of a host star affects the photochemistry in the atmosphere, and ultimately the surface UV environment for terrestrial planets and therefore the conditions for the origin and evolution of life. Depending on the intensity, UV radiation can be both useful and harmful to life as we know it. UV radiation can inhibit photosynthesis and cause damage to DNA and other macromolecule damage [1,2]. However, UV also drives several reactions thought necessary for the origin of life [3]. In this work, we compare models of the UV surface radiation environments for Earth through geological Fig. 1. Modeled UV surface fluxes for present-day time to both pre-biotic and post-biotic planets around Proxima-b, TRAPPIST-1e, Ross-128b and LHS-1140b the closest M stars. for oxygen-containing atmospheres at pressures of 1.0 Methods: We model the surface UV radiation bar, 0.5 bar and 0.1 bar, and a 1.0 bar anoxic environment for Earth-sized planets orbiting close-by atmosphere. Modern and Early Earth’s UV surface M stars and compare them to Earth through its flux is plotted for comparison. geological evolution. To model the planetary atmospheres, we use a coupled 1D radiative- References: convective atmosphere code developed for rocky [1] Kerwin B. A. and Remmel R.L. (2007) J. exoplanets [4,5,6] and a 1D photochemistry [7] to Pharmaceutical Sci, 96, 6. [2] Matsunaga et al. (1991) calculate the atmosphere transmission of UV fluxes to Photochem & Photobio, 54, 403. [3] Ritson D. and the ground of Earth-sized planets. Sutherland J. Nature Chemistry, 4, 895. [4] Kasting We explore four different types of atmospheres J.F. and Ackerman T.P. (1986) Science 234, 1383 [5] corresponding to an early Earth atmosphere at 3.9 Gyr Pavlov et al. (2000) J. Geophys. Res., 105, 11981 [6] ago and three atmospheres covering the rise of oxygen Haqq-Misra et al. (2008) Astrobiology, 8, 1127. [7] to present day levels at 2.0 Gyr ago, 0.8 Gyr ago and Segura et al. (2007) A&A, 472, 665. [8] Kaltenegger L. modern Earth [8][9][10]. et al. (2007) ApJ, 658, 598. [9] Rugheimer et al. (2018) Results: Astrobiology, 13, 251. [10] O’Malley-James & Here we show the first models of the surface UV Kaltenegger 2018 [11]. environment for the four closest potentially habitable exoplanets: Proxima-b, TRAPPIST-1e, Ross-128b and LHS-1140b assuming different atmospheric compositions, from Earth-analog to eroded and anoxic atmospheres (Fig 1) and compare them to Early Earth. The UV fluxes calculated here provide a grid of model UV environments during the evolution of an Earth-like planet. These models can be used as inputs into photo-biological experiments and for pre-biotic chemistry and early life evolution experiments [3]. The First Billion Years: Habitability 2019 (LPI Contrib. No. 2134) 1037.pdf

UPDATED STATUS OF THE IMPACT – ORIGIN OF LIFE HYPOTHESIS. David A. Kring, Lunar and Planetary Institute, USRA, 3600 Bay Area Blvd., Houston TX 77058 ([email protected]).

Introduction: In our initial studies of the Chicx- ulub impact crater (e.g., [1]), we found evidence of impact-generated hydrothermal activity. Soon thereaf- ter similar alteration was described by other investigators, notably Naumov [2-4], in other impact craters. Hydrothermal activity seemed to be a widespread consequence of impact heating of hydrous planetary crust. It was also understood from analyses of Apollo samples, that the Earth, at the dawn of life, was being pummeled by impacting asteroids and comets. Some of the largest of those impacts should have vaporized seas [5], making conditions untenable for life at the surface. Based on observations at Chicxulub [1], I Figure 1. Hydrothermally-altered impactite in the Yax- proposed [6-8] those same impact events were produc- copoil-1 core sample YAX-1_857.65m of the Chicxulub impact crater [46]. Field of view is 3.3 cm wide. ing vast subsurface hydrothermal systems that were perfect crucibles for pre-biotic chemistry and habitats the impact rate remains uncertain. Nonetheless, it is for the early evolution of life (the impact – origin of clear that the neighboring Hadean Earth was being re- life hypothesis). The end of the period of heavy bom- surfaced by an even larger quantity of impactors with bardment coincided with the earliest isotopic evidence larger sizes than the Moon (e.g., [21-24]). of life [9], although it was uncertain (and remains un- Earth on Moon? One wonders about the crust of certain) whether life truly emerged at that time or was the Hadean Earth being affected by impacts: was it of a type capable of surviving the bombardment ultramafic (e.g., reflective of komatiitic eruption tem- [10,11]. Analyses of ribosomal RNA made in the same peratures) or granitic (e.g., as inferred from Hadean decade indicated the earliest organisms on Earth were zircon chemistry). A fragment of a Hadean rock has thermophilic and hyperthermophilic [12-14]. It seemed tentatively been identified in an Apollo 14 sample [25] plausible life originated in an impact crater. that not only provides additional evidence of a granitic Two Decades of Investigation: There are two crustal component, but also is a product of the intense paths to take when testing that hypothesis. One is a bombardment occurring c. 4 Ga. biological path, exploring evolutionary roots. The idea Asteroids vs. Comets. Geological, mineralogical, of an community of thermophiles and hyperthermo- and geochemical fingerprints imply 80% of the im- philes is still favored by some, but challenged by oth- pactors were asteroids, not comets ([26] and references ers, often on grounds of horizontal gene transfer. It is therein). Impactors delivered significant quantities of still unsettled science. The other path is to examine the biogenic elements, but the bulk of Earth’s water was impact processes occurring during those first billion delivered during an earlier phase of accretion. years of Solar System history and their effects on envi- Extent of hydrothermal systems. We have had two ronmental conditions. That is the path explored here. opportunities to augment our initial investigations of Magnitude and duration of impact bombardment. the Chicxulub impact crater. In 2001-2002, we recov- Analyses of Apollo samples suggested the final third of ered hydrothermally-altered core from a second site lunar basins were produced c. 3.9-4.0 Ga [15,16]. (e.g., [27,28]) and in 2016 hydrothermally-altered core Analyses of additional Apollo samples and, important- from a third site (e.g., [29]), the latter of which probed ly, lunar meteorites representing a larger geographic the peak ring in a specific quest to test our model of region, support a large number of impacts at roughly impact-generated hydrothermal activity [30]. The re- that time (e.g., [17-19]), although we still debate pre- sults demonstrate hydrothermal activity affected a large cise ages (e.g., [20]). A tentative age for the oldest and volume of the crust, essentially the entire diameter of largest basin on the Moon, the South Pole-Aitken ba- the crater. Hydrothermal alteration at other impact sin, is c. 4.35 Ga [21]. If accurate, then an intense sites continued to accumulate, too (e.g., [31-33]). bombardment affected the Moon for ~400 Myr. The Lifetime of a hydrothermal system. Models indi- flux was probably not constant. Indeed, SPA may have cate the systems are long-lived [30,34], allowing for been produced from a different population of impactors, so the magnitude and duration of any spike in The First Billion Years: Habitability 2019 (LPI Contrib. No. 2134) 1037.pdf

evolutionary processes to occur within a crater and Events and Mass Extinctions: Impacts and Beyond, migration of biologic material to adjacent impact sites. 106–107. [8] Kring D. A. (2003) Astrobiology, 3, 133– Nature of the crust, mineral assemblages, and 152. [9] Mojzsis S. J. and Harrison T. M. (2000) GSA chemical reactions providing energy. Because the bulk Today, 10(4), 1-4. [10] Maher K. A. and Stevenson D. Earth was hotter in the Hadean, the crust may have J. (1988) Nature, 331, 612–614. [11] Chyba C. F. been dominated by ultramafic to mafic lithologies. In (1993) Geochim. Cosmochim. Acta, 57, 3351–3358. that case, impact-generated hydrothermal activity [12] Woese C. R. et al. (1990) Proc. Natl. Acad. Sci. would produce serpentinization reactions, which are a USA, 87, 4576–4579. [13] Pace N. R. (1991) Cell, 65, notable energy source for organisms (e.g., [35]). How- 531–533. [14] Pace, N. R. (1997) Science, 276, 734– ever, evidence of granitic crustal components has been 740. [15] Turner G. et al. (1973) in Proceedings of the growing. The energy source for organisms in that case 4th Lunar Sci. Conf., 1889–1914. [16] Tera F. et al. is less clear. (1974) EPSL, 22, 1–21. [17] Cohen B. A. et al. (2000) Application to Mars and elsewhere. It became evi- Science, 290, 1754–1756. [18] Norman M. D. et al. dent (e.g., [36-38]) that the lunar impact cataclysm was (2006) Geochim. Cosmochim. Acta, 70, 6032–6049. an inner Solar System event that affected all terrestrial [19] Niihara et al. (2019) Meteoritics Planet. Sci., 54, planetary surfaces. Because impact-generated hydro- 675–698. [20] Bottke W. F. and Norman M. D. (2017) thermal systems are possible in any hydrous planetary Ann. Rev. Earth Planet. Sci., 45, 619–647. [21] Mor- crust, models for systems on Mars have been devel- bidelli A. et al. (2012) EPSL, 355-356, 144–151. [22] oped (e.g., [39-44]). Those are obvious targets for Marchi S. et al. (2012) EPSL, 325-326, 27–38. [23] astrobiological investigation. Abramov O. et al. (2013) Chemie der Erde, 73, 227– 248. [24] Marchi S. et al. (2014) Nature, 511, 578– Conclusions: Several features of the impact – 582. [25] Bellucci J. J. et al. (2019) EPSL, 510, 173– origin of life hypothesis have been investigated since it 185. [26] Kring D. A. (2018) Bombardment: Shaping was first proposed. A period of bombardment is con- Planetary Surfaces and Their Environments, Abstract firmed; impactors are dominated by asteroids; the im- #2013. [27] Hecht L. et al. (2004) Meteoritics Planet. pacts resurfaced the Earth and generated geographical- Sci., 39, 1169–1186. [28] Zürcher L. and Kring D. A. ly broad and long-lived hydrothermal systems. More (2004) Meteoritics Planet. Sci., 39, 879–897. [29] remains to be done. Chicxulub core samples should be Kring D. A. et al. (2017) LPS XLVIII, Abstract #1212. probed to extract additional clues about the thermal [30] Abramov O. and Kring D. A. (2007) Meteoritics and chemical evolution of large hydrothermal systems. Planet. Sci., 42, 93–112. [31] McCarville P. and Theoretical or experimental studies of potential energy Crossey L. J. (1996) in The Manson Impact Structure, sources for organisms in granitic crust during the Ha- Iowa: Anatomy of an Impact Crater, 347–376. [32] dean are needed. Samples from specific basins on the Osinski G. R. (2001) Meteoritics Planet. Sci., 36, 731– Moon, such as the Schrödinger, South Pole-Aitken, and 745. [33] Ames D. E. et al. (2006) in Biological Pro- Orientale basins, are needed to clarify impact chronol- cesses Associated with Impact Events, 55–100. [34] ogy. Finally, surveys of lunar regolith samples for Abramov O. and Kring D. A. (2004) JGR, 109, 16p. fragments of Hadean Earth should continue. If sedi- [35] Cockell C. S. (2006) Phil. Trans. R. Soc. B, 361, mentary and fossiliferous samples can be located, they 1845–1856. [36] Bogard D. A. (1995) Meteoritics, 30, would provide a direct record of the early evolution of 244–268. [37] Kring D. A. and Cohen B. A. (2002) life on Earth. JGR, 107, 4p. [38] Swindle T. D. and Kring D. A. Acknowledgements: Much of the work summa- (2018) Bombardment: Shaping Planetary Surfaces and rized here is the product of students and postdocs who Their Environments, Abstract #2026. [39] Rathbun J. worked in my group. I thank them. For a list of those A. and Squyres S. W. (2002) Icarus, 157, 362–372. contributions, see [45]. [40] Abramov O. and Kring D. A. (2005) JGR, 110, References: [1] Kring D. A. and Boynton W. V. 19p. [41] Schwenzer S. P. and Kring D. A. (2009) Ge- (1992) Nature, 358, 141–144. [2] Naumov M. V. ology, 37, 1091–1094. [42] Schwenzer S. P. et al. (1993) (in Russian) Zapiski Vsesoyuznogo Mineralog- (2012) EPSL, 335-336, 9–17. [43] Schwenzer S. P. and icheskogo Obshchestva, 122/4, 1–12. [3] Naumov M. Kring D. A. (2013) Icarus, 226, 487–496. [44] Osinski V. (1996) Solar System Research, 30, 21–27. [4] G. R. et al. (2013) Icarus, 224, 347–363. [45] An an- Naumov M. V. (1999) (in Russian) in Deep Drilling in notated bibliography tracking our work was moved the Puchezh-KatunkiImpact Structure, 276–286. [5] from the University of Arizona to the LPI Zahnle K. J. and Sleep N. H. (1997) in Comets and the [https://www.lpi.usra.edu/science/kring/Kring_Cataclys Origin and Evolution of Life, 175–208. [6] Kring D. A. m_ConceptDevelopment.pdf]. [46] Kring D. A. et al. (2000a) GSA Today, 10(8), 1–7. [7] Kring D.A. (2004) Meteoritics Planet. Sci., 39, 879–897. (2000b) in LPI Contribution 1053: Catastrophic The First Billion Years: Habitability 2019 (LPI Contrib. No. 2134) 1001.pdf

THE ORIGINS SPACE TELESCOPE AND THE QUEST TO UNDERSTAND HABITABILITY. D. Leisawitz1 and the Origins Space Telescope Mission Concept Study Team, 1Sciences and Exploration Directorate, NASA Goddard Space Flight Center, Code 605, 8800 Greenbelt Rd., Greenbelt, MD 20771, [email protected].

Abstract: The Origins Space Telescope will trace the history Table 1. Features of the Originsg Mission Concept of our origins from the time dust and heavy elements permanently altered the cosmic landscape to present- day life. How did the universe evolve in response to its changing ingredients? How do habitable conditions arise during the process of planet formation? How common are life-bearing planets? To enable the community to answer these and other important questions, Origins will operate at mid and far-infrared wavelengths and of- fer sensitivity and spectroscopic capabilities vastly ex- ceeding those found in any previous far-IR observatory. During the past two years, the Origins mission concept study team prioritized scientific objectives, explored many facets of the mission concept solution space, evaluated two alternative mission architectures, developed designs for and assessed the performance of four science instruments, and took steps to reduce cost and risk while retaining the measurement capabilities needed to answer definitively the driving science questions. The Origins study culminated in the recommen- dation of a scientifically compelling, low-risk, and exe- cutable mission concept to the National Academies’ 2020 Decadal Survey in Astrophysics. Figure 1 is an artist’s concept of the Origins Space Telescope. Table 1 and Figure 2 summarize key features of the design. The science case for Origins is strongly aligned with the focus of the Habitability conference on the development of conditions conducive to life. This presentation will summarize the mission concept and describe the habitability-related science program envisaged for Ori- gins.

Figure 2. The Origins Space Telescope has the light-collecting area of JWST and an architecture similar to that of the Spitzer Space Telescope. The community will use Origins to learn how the conditions for habitability can arise during the process of planet formation, and to characterize exoplanets and search for biosignatures in their atmospheres.

Figure 1. Artist’s concept of the Origins Space Tel- escope. The First Billion Years: Habitability 2019 (LPI Contrib. No. 2134) 1050.pdf

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0.<9, 036;%(33,@(:05$;(/&! ) #+ ' )( ** *#*+)#,+ +#- )"#- ' + ) )+" *(,) * * )-+#('' # ' '+ )#(,.%%* (,+"$(+ 036;%(33,@0:(3:6),05.:;<+0,+(:(/()0;()030;@ (5(36.-69)6;/(5*0,5;(5+46+,95(9;0(5/()0;()3, The First Billion Years: Habitability 2019 (LPI Contrib. No. 2134) 1049.pdf

OUR FIRST BILLION YEARS OF ASTROBIOLOGY: LIFE’S EARLIEST RELATIONSHIPS WITH THE ENRIVONMENT. T.W. Lyons1,3 and K.L. Rogers2,3; 1Department of Earth and Planetary Sciences and Alterative Earths Astrobiology Center, University of California, Riverside, CA 92521, USA ([email protected]); 2Departments of Earth and Environmental Sciences and Biological Sciences, Rensselaer Polytechnic Institute, Troy, NY 12180, USA ([email protected]); 3NASA Prebiotic Chemistry and Early Earth Environments Consortium.

The First Steps: In the 1920s Oparin and Haldane magnetic field [8] allow us to speculate on shielding of independently argued that Earth’s earliest atmosphere harmful UV radiation and early protection of our at- was reducing, in contrast to the oxygen-rich conditions mosphere from the scouring effects of solar winds. we now know started during the Great Oxidation Event Given the far less hellish conditions now envisaged (GOE) around 2.3 to 2.4 billion years ago (Ga). Those for our first half a billion years, it comes as no surprise earlier anoxic conditions could have yielded the organ- that rock-bound archives of early life followed soon ic building blocks of life’s beginnings when energy after. That those records are mostly isotopic, rather derived from lightning or the sun was added to the than fossil or molecular, should be a lesson to anyone mix. A few decades later, Miller and Urey famously looking for life elsewhere in the solar system. Possible simulated the early ‘prebiotic soup’ of Oparin and evidence for the earliest carbon fixation—autotrophy Haldane in the lab and produced multiple amino ac- by early microbes—appears tentatively in carbon iso- ids—launching the modern era of origins-of-life stud- tope data from 4.1 Ga [9] and more convincingly by ies. An incomplete, and ever-evolving understanding about 3.7 Ga. By 3.5 Ga, the rock record reveals the of the early atmosphere limited this initial progress, first putative microfossils [10], although their bi- and while modern estimates favor dominance by CO2 ogencity has been challenged [11]. From the same rock [1] many of the same gaps in understanding persist sequences, however, we see convincing evidence for today, particularly the relative amounts of ammonia microbial mats (stromatolites). In this same general (NH3), hydrogen (H2), methane (CH4), and other or- time window, combined isotopic and genomic perspec- ganic compounds. More recently, hydrothermal vents tives place early microbial sulfur cycling back at least on the seafloor have become popular as the early to 3.5 Ga [12], nitrogen cycling at 3.2 Ga or greater sources of energy and reduced compounds. The one [13], and photosynthetic oxygen production back to 3.2 universal point of agreement in these discussions is the to 3.0 Ga or more [14,15]. importance of the surrounding world—that is, the pri- Biological production of O2 almost certainly pre- mordial conditions that were the backdrop for the ear- dated the GOE by hundreds of millions years, suggest- liest reactions that paved a pathway to life. ing that accumulation in the atmosphere was delayed Recent Progress: Those Hadean settings (4.54 to through reaction with reduced materials at Earth’s sur- 4.0 Ga), in addition to being potentially reducing, were face [16] and/or gases emerging from our interior [re- long portrayed as ‘hellish’—hot and broadly inhospi- viewed in 17]. Against this backdrop of profound re- table—with magma oceans and frequent and large im- dox change in our outer shell, Earth maintained its pacts. But all that changed in the early 2000s. Isotopic liquid oceans and thus habitability through a combina- data from zircon grains dating back to roughly 4.4 Ga tion mostly of carbon dioxide (CO2), the related sili- pointed to relatively cool surface conditions, likely cate weathering feedback, and redox-dependent CH4— oceans [2,3], and a solid crust [4], although it might all of which were required to heat our surface stably in not have been subaerial. Impact of one massive object the face of a still faint sun. Biological production of within our first 108 years that gave us our moon and methane was certainly among the most ancient of mi- started the clock for a habitable world also helped de- crobial metabolisms, and how those fluxes balanced in fine the tilt of our axis and thus the seasons that pulse combination with abiotic sourcing by important reac- life on our planet. What is more, interactions between tions such as serpentinization remains a critical ques- the Earth and moon help explain why we are not likely tion. Among the key unknowns is the cycling of me- to tidally lock with the sun anytime soon, and that thane during the Hadean and related production of or- same large impact may have delivered many of the ganic compounds formed in the atmosphere. These light elements, such as carbon, that would soon domi- photochemical products delivered to the surface may nate Earth’s biology [5]. A resurgence of large and have seeded life’s earliest progress. frequent impacts, the so-called ‘Late Heavy Bom- The predictably dim beginnings of our early sun bardment’ posited for 4.1 to 3.8 Ga based on the and its steady brightening are perhaps at the center of moon’s crater history, may not have been as dramatic our history of sustained habitability and inhabitation. in its magnitude and as deleterious to life as once im- Yet how and when land/continents first appeared, in- aged [6]. In fact, early impacts could have stimulated teracted, and emerged from the oceans must also be the hydrothermal activity that instead triggered or at better understood [18]. Deep disagreements about the- least supported early life [7]. Recent hints at an early se details remain, but the early zircon records have The First Billion Years: Habitability 2019 (LPI Contrib. No. 2134) 1049.pdf

given us windows to the first half billion years not pre- Planavsky N.J. et al. (2014) Nat. Geo., 7, 283-286. [15] viously imagined. Satkoski A.M. et al. (2015) EPSL, 430, 43-53. [16] New Frontiers: Going forward, we can build a Lee, C.T. et al. (2016) Nat. Geo., 9, 417-424. [17] Ly- roadmap to search for life beyond Earth and outside ons T.W. et al. (2014) Nature, 506, 307-315. [18] Bada our solar system using lessons from our own history. J.L. and Korenaga J. (2018), Life, 8, 55-63. [19] Olson We might even make confident predictions about con- S.L. et al. (2018) Handbook of Exoplanets, 1-37. tingencies such as very large impacts—like the one that helped set our planet on the right path to life. As- trobiology of Earth’s first billion years thus stands poised for a new beginning—one in which hypotheses for life’s emergence are informed more rigorously by independent models, data, and experiments focused on the beginnings of our oceans, continents, and evolving stellar neighbor. Similar rigor will be aimed at better understanding our atmosphere and its photochemical evolution and delivery of essential ingredients from our atmosphere and space. Particularly fruitful areas of related research will simultaneously explore the first billion years of Venus, Earth, and Mars when the three may have looked much more alike than the do today. One common trait then may have been vast surface reservoirs of liquid water—a precondition for habita- bly that soon disappeared for all but Earth. Encourag- ingly, NASA’s commitment to these frontiers has nev- er been stronger, including desires for better understanding of the Hadean. This time slice, our earliest alternative Earth, will also help guide the search for life on exoplanets in much the same way we use Earth’s later chapters [19]. A measure of this strong buy-in by NASA is the recently launched PCE3 (Prebiotic Chemistry and Early Earth Environments) Consortium. The goal of this Re- search Coordination Network (RCN) is to facilitate cooperative, interdisciplinary investigations of the delivery, synthesis, and fate of small molecules under the conditions of the early Earth and the subsequent formation of proto-biological molecules and pathways that lead to systems harboring the potential for life. This effort, perhaps with unprecedented communica- tion and coordination, will bridge communities that will think collaboratively about the beginnings of life and the cause-and-effect relationships with the surrounding environment. References: [1] Zahnle K. et al. (2007) Space Sci. Rev., 129, 35-78. [2] Mojzsis S.J. et al. (2001) Nature, 409, 178-181. [3] Wilde S.A. et al. (2001) Nature, 409, 175-178. [4] Harrison T.M. et al. (2008) EPSL, 268, 476-486. [5] Grewal D.S. et al. (2019) Sci. Adv., 5, eaau3669. [6] Fassett C.I. and Minton D.A. (2013) Nat. Geo., 6, 520-524. [7] Simone Marchi (pers. comm.). [8] Tarduno J.A. et al. (2015) Science, 349, 521-524. [9] Bell E.A. et al. (2015) PNAS, 112, 14518- 14521. [10] Schopf J.W. (1993) Science, 260, 640-646. [11] Brasier M.D. et al. (2002) Nature, 416, 76-81. [12] Shen Y. et al. (2001) Nature, 410, 77-81. [13] Stüeken E.E. et al. (2015) Nature, 520, 666-669. [14] The First Billion Years: Habitability 2019 (LPI Contrib. No. 2134) 1047.pdf

FROM MESSY CHEMISTRY TO THE ORIGIN OF LIFE. I. Mamajanov1, 1Earth-Life Science Institute, Tokyo Institute of Technology, Meguro, Tokyo 152-8550, Japan, [email protected]

Introduction: In the last 65 years, prebiotic cally bind, and encapsulate substrates while creating a chemistry has been explored in many plausible Early microenvironment suited for reaction progression. Earth conditions. Biological building blocks have When considering enzyme-like prebiotic catalysts, been discovered in the Miller-Urey experiment [1] certain small molecules, mineral and metal cofactors and at high pressure and temperature in geothermal are prebiotically plausible unlike high functional pro- vent conditions [2]. Some biomolecules have been teins and RNA molecules. Could simple polymers generated by HCN chemistry [3] and in Fischer- substitute RNA or protein scaffold at the early stages Tropsch-type reactions [4]. Additionally, interesting of chemical evolution? Such an approach is well es- “life-like properties” such as functioning autocatalysis tablished within synthetic biomimetics, where enzyme and self-assembling nucleoside analogs have been analogs are commonly synthesized by inserting model discovered in formose reaction [5] and cyanuric acid- catalytic sites within polymeric structures. One of the triaminopyrimidine coupling [6], respectively. Many most well-known structures used for enzyme mimics of these prebiotic systems share a common feature – are dendrimers, regular tree-like macromolecules with they are messy. The systems produce vast multi- an embedded distinct reactive core [9]. Similar to component mixtures of compounds through an abun- dendrimers, the branched structure of irregular den- dance of reaction pathways. When messy prebiotic dritic or hyperbranched polymers (HBPs) results in a systems reach steady state or equilibrium, they pro- multitude of end groups that can bind catalysts and duce heterogeneous intractable polymeric structures, substrates, as well as control the polarity of the intra- dubbed “tar” or “asphalt”. molecular microenvironment. In contrast to den- On the contrary, the enzyme-controlled world of drimers, HBPs do not contain a distinct core; have biochemistry is characterized by complex yet defined less defined intramolecular cargo space and broad chemical net-works with clearly delineated reaction distribution of molecular structures and sizes. Alt- mechanisms and product diversity. Messy chemistry hough less controlled functionally, the advantage of hypothesis conceptualizes the transition between the HBPs over dendrimers is their straightforward, often uncontrolled prebiotic chemistry and biochemistry one-pot synthesis, whereas dendrimers require multi- through the grasp of methods of organization in chem- step procedures. As proof-of-principle I will describe istry. The open-ended objective of messy chemistry is the capability tertiary amine-bearing HPBs form hy- building a purely chemical system capable of chemi- drophobic pockets as a reaction-promoting medium cal evolution. In the talk, I will discuss several princi- for the Kemp elimination reaction [10] and the ability ples of messy chemistry as exemplified by the follow- of HBPs to support metal-sulfide nanoparticles that ing experimental and biological models. catalyze redox reactions. Messy Polyesters: Ester bonds are common in Selectivity in Messy Systems: Gelation is a prop- modern biochemistry predominantly in the form of erty of branched polymer related to tar formation. triesters of glycerol and fatty acids in lipids. Ester Gelation occurs when a polymer forms large intercon- formation has a slightly negative bond energy (~1 nected polymer molecules through cross-linking [11]. kcal/mol under physiological conditions) making this We have explored the gel formation in hyperbranched functional group’s synthesis facile. Polyesters have polyester systems under continuous drying and wet- been hypothesized to have preceded peptides due to dry cycling associated with environmental conditions, their ease of formation, and this notion is perhaps such as dew formation or tidal activities. The results supported by the demonstrated ability of the ribosome reveal that periodic wetting during which partial hy- to catalyze alpha-hydroxy acid coupling [7]. We have drolysis of the polyester occurs helps to control the explored the polyesterification of alpha-hydroxy ac- chain growth and delays the gel transition. Moreover, ids, which are plausibly abundant prebiotic mono- the NMR and mass spec analyses indicate that contin- mers, can be oligomerized to generate vast, likely uously dried samples contain higher quantities of sequence-complete libraries [8]. cross-linked and macrocyclic products, whereas cy- Biomimetic Prebiotic Systems: Enzymes are cled systems are enriched in branched structures. Os- composed of organic, mineral or metal cofactors, tensibly, environmental conditions can exert a rudi- agents that actively participate in the reaction mecha- mentary pressure to selectively enrich the polyesteri- nism, and folded globular protein or RNA scaffold. fication products in polymers of different structures The function of the biopolymer scaffold is to specifi- and properties. At the early stages of chemical evolu- The First Billion Years: Habitability 2019 (LPI Contrib. No. 2134) 1047.pdf

tion, in the absence of biological machinery, this example of environmental control could have been for selectivity in chemical systems. As expected in mar- ginally controlled systems, the identification of each component of the heterogeneous system has proved challenging, but it is not crucial for concluding [12]. Autocatalysis in Messy Systems: How could complex biocatalysts first have arisen on planet Earth? Previous studies have suggested autocatalytic cycles as a partial answer to this question since such reactions exhibit the life-like property of exponential growth while being composed of relatively simple molecules. However, a question remains as to the likelihood of an autocatalytic cycle forming spontaneously in the absence of highly specific catalysts. We have explored an artificial chemistry model in which such cycles form readily even though the initial conditions of the system involve no direct catalytic processes. Catalytic effects nevertheless emerge as properties of the reaction network. This suggests that the conditions for the formation of such cycles are not challenging to achieve. The resulting cycles solve the problem of specificity not by being small and simple but by being large and complicated, suggesting that early prebiotic metabolisms could have been extremely complex [13]. Heredity in Messy Chemistry: Molecular im- printing technology concerns the formation of particular sites in a polymer matrix with the memory of a template. While the principle is usually applied in the chemical synthetic system, it might apply to prebiotic systems, such as peptide synthesis [14]. Such a process would be simpler, and therefore more prebiotically plausible than nucleic acids systems. Conclusions: Through above examples and model systems I will outline the messy chemistry origins of life hypothesis, its advantages and challenges. References: [1] Miller S.L. (1953) Science, 117, 528–529. [2] Wächtershäuser G. (2000) Science, 289, 1307–1308. [3] Moser R. et al. (1968) Tetrahedron Letters, 9, 1605–1608. [4] McCollom T. M. et al. (1999) OLEB, 29, 153–166. [5] Breslow R. (1959) Tetrahedron Letters, 1, 22–26. [6] Chen M. C. (2013) JACS, 136, 5640-5646. [7] Fahnestock S. et. al. (1970) Biochemistry, 9, 2477–2483. [8] Chandru K. et al. (2018) Comm Chem, 1, 30. [9] Liu L. and Breslow R. (2003) JACS, 125, 12110–12111. [10] Mamajanov I. and Cody G.D. (2017) Philos. Trans. R. Soc. Math. Phys. Eng. Sci., 357, 20160357. [11] Flory P. J. (1941). JACS, 63, 3083. [12] Mamajanov I. (2019) Life, 9, 56. [13] Virgo N. and Ikegami T. (2016) Alife, 22, 138–152. [14] Drexler, K.E. (2018) arXiv, 1807.07065v1

The First Billion Years: Habitability 2019 (LPI Contrib. No. 2134) 1008.pdf

UNDERSTANDING THE EFFECTS OF ASTEROID COLLISIONS ACROSS EARTH’S GREAT OXIDATION 3.5-2 Ga. Simone Marchi1,B.Black 2,N.Drabon 3,D.Ebel 4,R.Fu 5, B. Johnson6, T. Schulz7,8,K. Wuennemann9, 1Southwest Research Institute, Boulder, CO ([email protected]), 2City University of New York, New York, NY; 3Stanford University, Stanford, CA; 4American Museum of Natural History, New York, NY; 5Harvard University, Cambridge, MA; 6Brown University, Providence, RI; 7University of Vienna, Vienna, Austria; 8University of Cologne, Germany; 9Natural History Museum, Berlin, Germany.

Introduction: Advances have recently been made Subsequent late Archean and Paleoproterozoic in understanding the nature and rate of collisions bombardment (~3.5-2.0 Ga), however, has been poorly between the Earth and planetesimals left over from investigated due to the paucity of observational planet formation (e.g., [1-3]). This work suggests that constraints. For instance, the oldest known terrestrial while life was emerging and evolving, the Earth was crater is the 300-km Vredefort structure, ~2 Ga; while subject to cosmic collisions that may have there are no available lunar absolute calibration sites in fundamentally modulated the ensuing geochemical the time frame ~0.8-3.1 Ga. The Archean is an interval evolution of the biosphere. Of particular interest is the in Earth history where massive collisions (> 100 km in evolution of the biosphere during the Archean and diameter) likely gave way to smaller but still sizable Paleoproterozoic (~3.5-2 Ga), which was punctuated impactors (~10-100 km). The stochastic nature of the by drastic environmental changes, such as the rise of bombardment associated with a declining flux may atmospheric oxygen at ~2.4 Ga (e.g., [4]). Although have resulted in a few massive collisions (~100 km). early Earth collisional models are uncertain, the geological record retains strong evidence for the occurrence of large collisions during this time, as witnessed by the numerous impact spherule layers 3.4-2.4 Ga. As a reference, the estimated individual energy of these collisions ranges from a few times to ~500 times that of the Chicxulub impact. The causal connection of the Chicxulub impact with the Cretaceous-Paleogene (K-Pg) mass extinction at ~66 Ma is the best known example of the effects of collisions on the biosphere. The energy range of the impacts recorded in the spherule layers underlines their potential repercussions on early environments. Large collisions are associated with localized environmental havoc. Global scale environmental Figure 1. Schematic view of impact meting (red) and changes, however, are less understood (e.g., [5-6]). For vaporization (blue) with consequences on atmospheric example, impact melting and vaporization of target and redox, and hydrothermal migration of key redox projectile materials can lead to outgassing with poorly elements and nutrients to the environment understood consequences for the redox state of the (schematically indicated by blue and red arrows). atmosphere and oceans. Collisions also deliver and mobilize key nutrients in the crust (e.g., Ni, P, Fe). Crucial constraints can be obtained from direct Through such processes, collisions may have shaped records of collisions, such as impact spherule layers. the short and long term evolution of the Earth’s The spherule layers probably represent an incomplete biosphere (Fig. 1). In this light, it is important to record of impacts during this time interval (e.g., [9]); consider whether and how collisions altered however, they do provide a useful lower limit for the habitability of the Archean and Paleoproterozoic Earth. bombardment flux. Revising the terrestrial asteroid impact flux There are currently 16 known impact spherule 3.5-2 Ga: In recent years, the intensity of layers identified in outcrops in the 3.5-2.0 Ga time bombardment in the Earth-Moon system during the range, some of which have only very recently been Hadean-Eoarchean (>3.5 Ga) has been subject to discovered (Fig. 2). Additional spherule layers have intense debate. A combination of geophysical been found in drill cores, however, it remains unclear observations, geochemical data, and dynamical models whether they represent new, independent impacts or have been used to constrain the combined Earth-Moon are duplicates of known spherule layers [10-12]. collisions history (e.g., [1,3,7,8]). We will present an updated list of spherule layers and corresponding impactor sizes, based on the The First Billion Years: Habitability 2019 (LPI Contrib. No. 2134) 1008.pdf

methods proposed by [13]. This method relies solely projectile is vaporized [19], we expect ~3×1017 kg of on aggregate spherule layer thickness, and it has been gas (for an impactor density of 2600 kg/m3, shown to provide realistic results for the K-Pg layers representative of ordinary chondrite-like asteroids). and Chicxulub impact [13]. As an example, a spherule For context, the modern atmosphere has a mass of layer aggregate thickness of 10 cm yields projectile ~5×1018 kg. Global natural methane emissions total diameters from ~29 to ~46 km, and the projectile ~1.5-3.0×1011 kg/year (e.g., [20]). Based on diameters from Archean and Paleoproterozoic spherule calculations for equilibrium with a chondritic projectile layers range from 10 to 80 km. [18], 25% vaporization of a 100 km CI chondrite 16 In addition, the impactor sizes corresponding to the bearing ~3 wt% C [21] translates to ~10 kg of CH4 spherule layers will be used to calibrate available delivered nearly instantaneously. Given the fluxes of collisional models (e.g., [1,3]). The resulting calibrated vapor involved, and assuming a similar atmospheric impact flux for the Archean and Paleoproterozoic will density in the Archean, a 10-100 km projectile can provide the basis for subsequent investigations of the dramatically perturb atmospheric composition. environmental consequences of these collisions. In addition, hydrothermal alteration of impact melts may produce significant fluxes to surface environments of Fe, P, and trace elements such as Cr, Mo, Ni. Shifts in availability of key nutrients including Ni have been invoked to explain the structure of Archean redox evolution (e.g., [22]). Fluctuations in the concentrations of redox-sensitive trace elements, such as Cr and Mo, in marine sediments have been applied as tracers of Earth’s oxygenation history. To correctly understand and interpret potential nutrient sources in Earth’s Archean and Paleoproterozoic oceans and to assess the implications of impact melt emplacement for interpretation of seawater trace element records, improved constraints are needed on potential fluxes of both nutrients and trace elements from hydrothermal alteration of impact melt. Discussion: In this contribution, we will aim to Figure 2. Main impact spherule layers discovered in present a revised terrestrial impact flux 3.5-2 Ga. This outcrops in the Barberton Belt, South Africa. The constitutes the prerequisite for further investigations newly discovered layers are indicated with S4-S8. attempting to study the environmental effects of Main stratigraphic units and their ages are also Archean and Paleoproterozoic collisions. shown. The figure is adapted from [14]. References: [1] Marchi S. etal. Nature 511, 578, Environmental effects of asteroid collisions: The 2014; [2] Marchi S. etal. Nature Geo. 11, 77, 2018; [3] Earth experienced several major shifts in its surface Morbidelli A. etal. Icarus 305, 262, 2018;[4] Lyons T. environments from 3.5-2 Ga, including possible whiffs W. etal. Nature 506, 307, 2014; [5] Kring D.A. GSA of oxygenation in the runup to the Great Oxidation 10, 2000; [6] Kring D.A. Astrobiology 3, 2003; [7] Event at ~2.4 Ga (GOE [4]). The oldest preserved Bottke W.F. etal. Nature 485, 78, 2012; [8] Marchi S. evaporates date to ~2 Ga, documenting the etal. EPSL 325, 27, 2012; [9] Glass B. & Simonson B. establishment of a significant reservoir of surface 10.1007/978-3-540-88262-6, 2013; [10] Drabon N. oxidant in the form of sulfates by that time [15]. The etal. Geology 45, 803, 2017; [11] Schulz T. etal. GCA role of volcanism and the shifting redox of volcanic 211, 322, 2017; [12] Ozdemir S. etal. MPS doi: gases (e.g., [16,17]) in regulating the oxygenation of 10.1111/-maps.13234, 2019; [13] Johnson B.C. & surface environments has been discussed. However, Melosh H.J. Icarus 217, 416, 2012; [14] Lowe D.R. the contribution of declining fluxes of strongly reduced etal. Geology 42, 747–750, 2014; [15] Blattler C. etal. impact vapors (e.g., [18]) remains to be assessed. Science 360, 320, 2018; [16] Holland H.D. GCA 66, In this contribution we will outline and discuss the 381, 2002; [17] Gaillard F. etal. Nature 478, 229, overall effects of impact vaporization of both target 2011; [18] Schaefer L. & Fegley Jr.B. Icarus 186, 462, and projectile materials on atmospheric chemistry. 2007; [19] Pierazzo E. & Melosh H.J. Icarus 145, 252, Consider the following examples. In an impact with a 2000; [20] Saunois M. etal. ESSD 8, 697, 2016; [21] 100-km projectile, and assuming that 25% of the Kring D.A. etal. EPSL 140, 201, 1996; [22] Konhauser K.O. et al. Nature 458, 750, 2009. The First Billion Years: Habitability 2019 (LPI Contrib. No. 2134) 1021.pdf

GAMMA IRRADIATION OF MIXTURES OF L-ASPARTIC ACID AND Na-MONTMORILLONITE: RELEVANCE IN HOMOCHIRALITY STUDIES AND ORIGIN OF LIFE. A.L. Meléndez-López1, M.F. García-Hurtado2, A. Negrón-Mendoza1*, S. Ramos-Bernal1 and A. Heredia1 1Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México,. Cd. Universitaria, A. P. 70-543, 04510 México, CDMX, México 2Facultad de Ciencias, Universidad Nacional Autónoma de México, Av. Universidad 3000, Circuito Exterior S/N Delegación Coyoacán, C.P. 04510. Ciudad Universitaria, CDMX, México *[email protected]

Introduction: Amino acids are the principal com- [3] Chyba, C. F. et al. (1990). Sci., 249, 366. ponents of proteins, which are fundamental pieces for [4] Negrón-Mendoza A. et al. (1992) Adv Space live organisms. Beside the presence of biomolecules, Res., 12, 4, 63-66. life needs homochiral molecules to work together in a [5] Bernal J. (1949) JPS Conf. Proc.,62, 537. complex system called “metabolism”. The use of only [6] López-Esquivel K. et al. (2010). Nucl. Instr. L-amino acids has long been known to be an important Meth. Phys. Res. B., A61, 51–54. characteristic of life [1]. [7] Guzmán A. et al. (2002). Int Rev Cell Mol Biol., Homochiral molecules may have been from extra- 48, 525. terrestrial origin and delivered to the surface of the Earth by comets and meteorites during the heavy bombardment phase [2][3]. The stability of these molecules against external sources of high doses of radiation are important [4]. Several works have demonstrated that clays might protect organic molecules from high-energy radiation [5][6][7]. The present study aims to investigate the stability of L-aspartic acid irradiated in solid-state mixed with Na-Montmorillonite at kGy doses (at a Gamma beam 651 PT facility at Instituto de Ciencias Nucleares, UNAM). This amino acid is considered to be primitive amino acid and it is a component of actual proteins. We irradiated L-enantiomer and the racemic mix (D and L) in the presence of Na-montmorillonite to compare both systems. The stability of L-aspartic acid was studied and analyzed with UV spectroscopy and chromatography techniques (HPLC-ESI-MS) identifying the gamma irradiation products and investigating its behavior under gamma irradiation. The solid superficies were analyzed with IR spectroscopy. The results showed that the decomposition of aspartic acid considerably decreased in the presence of clay, independently of the chiral activity, which would be advantageous in primitive conditions.

Acknowledgment: The authors thank to Chem. C. Camargo, B. Leal and J. Flores for their technical assistance. This work was supported by ICN-UNAM and PAPIIT project IN226817.

References: [1] Lehninger, A. L., et al. (2000). Principles of Bi- ochemistry. New York: Worth Publishers. [2] Bada, J. L. et al. (1983). Nature, 301, 494-496. The First Billion Years: Habitability 2019 (LPI Contrib. No. 2134) 1044.pdf

ORGANIC MOLECULE CONCENTRATION BY EARLY DIFFERENTIATION, AND DILUTION BY LATER TIDAL DISSIPATION IN ICY OCEAN WORLDS. Mohit Melwani Daswani1 and Steve D. Vance1, 1Jet Propulsion Laboratory, California Institute of Technology ([email protected]).

Introduction: Aqueous environments in chemical amino acids, carboxylic acids and alcohols (glutarate, disequilibrium are candidate locations for the emer- lactate, glycolate, ethanol, methanol and formic acid) gence and existence of life. Icy ocean worlds could be (Fig. 1). such locations in the solar system, but questions remain about the persistence of chemical disequilibria within the oceans through geologic time. High pressures at the seafloor and relatively low temperatures in the interior [e.g. 1] may seriously restrict the hydrothermal venting and water-rock interaction [2] required for element fluxes and redox disequilibria favorable for life [e.g. 3]. We have been investigating whether the tidal and thermal evolution of icy ocean worlds enhances or restricts the availability of hydrocarbons and redox- sensitive molecules pumped into the ocean in time. Here we focus on Titan as an example of an icy ocean world of astrobiological interest. Methods: We modeled the evolution of icy worlds’

interior structure (the distribution of their spherical Figure 1. Major composition of the fluids produced shell components, including the silicate and ocean lay- and extracted from the interior of Titan during ers, as in Vance et al. [1]) as a consequence of their heating of the interior by differentiation and tidal accretion history in the jovian or saturnian systems. dissipation. In this model, 100 % of the fluid pro- Bulk compositions of the bodies were determined by duced is extracted and removed into the ocean res- simple accretion models based on the parameterization ervoir, and does not interact with the silicate interi- by Squyres et al. [4], using chondritic and cometary or afterwards. building blocks consistent with the distribution of these With continued heating of the interior, in the early solar system [5]. phyllosilicates become dehydroxylated and release Constraining Planetary Scale Geochemical Reser- water. Further heating destabilizes amphiboles and voirs and Fluxes. The accretion-structure-composition sulfides originating from the initial chondritic accreted simulations determine the composition and starting matierial, releasing more water, and SO2. Finally, thermal state of the icy ocean worlds immediately after carbonates and reduced carbon (as graphite) is accretion. We subject the bodies to the plausible ther- destabilized with further heating, and produces CO2 mal excursions resulting from radionuclide decay, (Fig. 1). gravitational settling and tidal dissipation, and resolve Thus, the earliest heating on Titan produces the the distribution of heat/energy, and petrologi- most organic-rich fluids, and later fluids produced by cal/geochemical changes in the interior using a Gibbs further heating (as by later radionuclide decay and tidal energy minimization code integrating the Deep Earth dissipation occurring in the silicate interior) dilute the Water model and electrolytic fluid speciation [6, 7, 8, early hydrocarbon-rich fluid with water, SO2 and CO2. 9]. The changing thermal state of the bodies determines Acknowledgements: A part of the research was what chemical species are mobilized and where to carried out at the Jet Propulsion Laboratory, California (ocean, silicate, or core). Institute of Technology, under a contract with the Na- Results and Discussion: tional Aeronautics and Space Administration. Copy- Early Differentiation Dewatering on Titan. In early right 2019. All rights reserved. heating stages, we computed the dehydration of the References: [1] Vance S. D. et al. (2018) JGR interior of Titan as water migrates to the outer shells, Planets, 123, 180 – 205. [2] Byrne P. K. et al. (2018) forming early oceans. The fluid composition changes Ocean Worlds, LPI contrib. 2085, Abstract #6030. markedly as temperature rises. For Titan, fluids re- [3] McCollom T. M. (1999) JGR Planets 104, 30729 – leased from the silicate interior are initially water and 30742. [4] Squyres S. W. et al. (1988) JGR Solid Earth hydrocarbon rich, with methane >> ethane > propane > The First Billion Years: Habitability 2019 (LPI Contrib. No. 2134) 1044.pdf

93, 8779 – 9794. [5] Desch S. J. et al. (2018), ApJSS 238, 11. [6] Connolly J. A. D. (2005), EPSL 236, 524 – 541. [7] Connolly J. A. D. (2009), G3 10, Q10014. [8] Mayne M. J. et al. (2016) J. Metamorph. Geol. 34, 663 – 682. [9] Connolly J. A. D. and Galvez M. E. (2018) EPSL 501, 90 – 102. [10] Anderson J. D. et al. (1998), Science 281, 2019 – 2022.

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AN INCREASE IN PHOSPHORUS AVAILABILITY FROM REDOX-INDUCED CHANGES BY WATER- ROCK INTERACTIONS. M. A. Pasek, University of South Florida, 4202 E. Fowler Ave, NES 204, Tampa FL 33620. [email protected]

The element phosphorus is a key nutrient in modern ecosystems, and given its prevalence in informa- tional biomolecules (RNA and DNA), metabolism (ATP and other coenzymes), and cell structure (phos- pholipids), it has presumably been an important con- stituent since the onset of life. However, the liberation of phosphorus from rocks is confounded by the poor solubility of calcium phosphate minerals that are pre- sumed to be the original phosphate source on a developing world. In addition, the poor reactivity of phosphate towards organic substrates suggests either unu- sual environmental conditions or reactive phosphorus

phases were necessary to promote organophosphate formation for the prebiotic to biotic transition. Fig. 1. 31P NMR spectrum of phosphorus extracted Here I argue an alternative route to making phos- from a serpentinite from Josephine county, OR, USA. phorus available for the development of life that may The singlet at 3 ppm (bottom) splits into a wide dou- have resulted from the natural geochemical cycle of blet (top) with a J-coupling constant of about 580 Hz. phosphorus, if redox changes to phosphorus are con- The concentration of P measured using this method sidered (as opposed to immutable phosphate). First, was about ~10-5 M at this signal to noise for these the chemistry of phosphorus during water-rock interac- scans. tions such as serpentinization (Fig. 1) is shown to change from phosphate to phosphite (P5+ to P3+) due to the concomitant oxidation of iron (Fe2+ to Fe3+). Sec- ond, due to the heightened solubility of P3+, this phosphite can be extracted from rock as water flows through it, resulting in enrichment of total P. Third, the phosphite itself is stable to oxidation in the absence of free radicals, such as those formed by UV photoly- sis of water, or promoted by iron-catalyzed Fenton reactions. The result of this oxidation are high energy polyphosphates, which I then show to be capable phosphorylating organic substrates, able to make nucleotides from nucleosides, and possibly even nucleotide dimers through the excess energy stored from the oxidation of phosphite. Altogether, this pathway may have been active on the early earth, and on water worlds where redox occurs at water-rock interfaces. The result is a potential solution to the problem of the low solubility and poor reactivity of phosphate. By considering the potential for redox changes of phosphorus, both issues may be addressed and provide a lead to the origin of phos- phorylated biomolecules.

The First Billion Years: Habitability 2019 (LPI Contrib. No. 2134) 1034.pdf

PHOTOBIOLOGY AND BIOGENIC PRESERVATION COMPARISONS BETWEEN PLEISTOCENE EVAPORITE BEDS AND BURIED PERMIAN BRINES. Scott M. Perl1-3 Bonnie K. Baxter4, Aaron J. Celes- tian2, Charles S. Cockell5, Alex L.Sessions6, Preston Tasoff1, Sarah J. Crucilla1, Frank A. Corsetti7

1NASA Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109, United States ([email protected]) 2Mineral Sciences, Los Angeles Natural History Museum, 900 Exposition Blvd, Los Angeles, CA 90007, United States 3Blue Marble Space Institute of Science, 1001 4th Ave, Suite 3201, Seattle, Washington 98154 4Westminster College, Great Salt Lake Institute, 1840 South 1300 East, Salt Lake City, UT 84105, United States 5School of Physics and Astronomy, University of Edinburgh, United Kingdom. 6Division of Geological and Planetary Sciences, California Institute of Technology, 1200 E. California Blvd., Pasadena, CA 91125, USA 7Department of Earth Sciences, University of Southern California, 3651 Trousdale Pkwy, Los Angeles, CA 90089, United States

Introduction: Evaporite mineralogy can precipi- motic challenges. These poly-extremophile microor- tate on Earth and other planets following the evapora- ganisms may be excellent life forms to study when con- tion of hypersaline lakebeds. These mineral types are a sidering a search for potential current or extant life in a record of former aqueous histories and a more robust Martian evaporite formation. Considering that the and diagnostic feature showing the timing and potential timescales of geological changes are magnitudes longer chemistries of the ancient lake systems. Evaporites are than the adaptation of halophilic and other extreme life, key features in studying fluid systems and preserved survivability of biological evidence in ever-changing geobiological markers from those aqueous systems, hypersaline settings can be both physical and chemical. both modern and ancient, and minerals halite and gyp- [1]. To live in salt-saturated brine, halophiles must sum have been observed in sites where cellular life has balance osmotically such that their cells do not shrivel lived inside the water columns of active and former Fig. 1. Sterile closed basin lake systems. These evaporite minerals are extracted NaCl diagnostic of aqueous activity and potential regions for mineralogy biogenic entombment of organic matter sourced from from Permian microorganisms [1]. evaporite beds. The purpose of this paper is to discuss the photobi- Extracted salts ological response from halophilic microorganisms in and evaporitic their preserved mineral settings from different solar material show versions of pig- flux environments. ments observed Methodology & Field Sites: The chosen field sites in the modern are an evaporating closed-section of the Great Salt but significantly Lake, Utah, USA [2], a dried Pleistocene evaporite lacking in opaci- lakebed of Mojave Desert, CA, USA [1], and the Per- ty (as compared mian Boulby salt mine formed from the Zechstein Sea to Fig. 2). Fluids leading to the Zechstein Formation suite of evaporites are still present in these salts and [3], (Fig 1). These evaporitic settings serve as my Mars show distribu- analogue sites due to the high saline waters and similar tion differences evaporite minerals to those found on Mars [4]. This between the site gives the proper Martian analogue settings since Permian NaCl, they have similar geochemical and fluvial settings as KCl, and poly- the ancient sites that Opportunity and Curiosity have halite sets [3]. explored [5,6]. While the benefit of having active terrestrial (modern) study sites is being able to investigate up due to water loss. This is accomplished in part by mineral precipitation reactions in real time, these mod- the intracellular accumulation of osmotic reflection ern records also provide a proper initial “stopwatch” coefficients, which balance against the salt on the out- for the monitoring of preserved biological processes side of the cell membrane [7]. Halophiles are shown to and mineral modification solely due to the added pres- accumulate potassium ions and organic compatible ence of microbial life. solutes [8,9], which explains their success in salty envi- Geobiology of Preserved Extant Life: Halophilic ronments. These extremophiles also have modifications microorganisms can survive high doses of ultraviolet (UV) light, desiccation of their environment, and os- The First Billion Years: Habitability 2019 (LPI Contrib. No. 2134) 1034.pdf

in their proteins that help them function at high salt DNA has been lost to time. These same detection strat- [10]. egies can be critical for future astrobiology and plane- Applications to Recurring Slope Lineae (RSL): tary landed campaigns to determine not only the sur- Recent evidence of potentially seasonally flowing brine vivability of organics, which can be found with no rela- fluids have been observed by CRISM in the form of the tionship to biological processes, but to future life (as Recurring Slope Lineae (RSL) [11] These dark slope we don’t know it) mission concepts that since the Vi- streaks seem to become elongated over several Martian king missions, we have not done yet. years on crater walls of steep angles of repose leading into the possibility of these streaks being sourced by a References: [1] Perl, S.M. (submitted) [2] Baxter & highly viscous brine that is extends during the warmer Zalar (2019) Model Ecosystems in Extreme Environ- Martian seasons and remains at its previous length dur- ments [3] Cockell, Wilhelm, Perl, Wadsworth, Payler, ing the colder months. The survivability and somewhat Palin, McMahon (2019, in-prep) [4] Viviano‐Beck et stable nature of potential surface brines bodes well for al. (2014) JGR-Planets 119, 1403–1431 [5] Squyres et subsurface fluidic flow where more recent evaporite al. (2004) Science, 306(5702):709-1714. [6] McLen- mineralogy may be precipitated on modern Mars. In a nan et al. (2005) EPSL 240:95–121 [7] Brown (1976) saturated brine water molecules that interact with ions Microbial Water Stress. Bacteriological Reviews are less available to support life (as we know it) and 40:803-846. [8] Larsen (1967) Biochemical aspects of some have theorized that life cannot tolerate the satu- extreme halophilism. Advances in Microbial Physiolo- rated acidic Martian brines [12] however there is ample gy 1:97-132. [9] Oren (1999) Bioenergetic aspects of evidence from several hypersaline environments where halophilism. Microbiology and Molecular Biology halophilic organisms that are able to maintain homeo- Reviews 63(2):334-348. [10] Litchfield (1998) Mete- stasis and thrive just as non-extreme microorganisms oritics and Planetary Science 33(4):813-819. [11] Ojha et al. (2015) Nature Geoscience 8(11):829-832. can despite the lower aw and acidic saline lakes [13, 18] [12] Tosca et al. (2008). Science, 320 (5880), 1204- Using Modern Evaporites for Relative Microbi- 1207. [13] Benison et al. (2008) Astrobiology al Preservation Timing: The modern Great Salt Lake 8(4):807-821. [14] Lindsay et al. (2017) Geobiology. is highly productive despite the reduced solubility of (1) 131-145 [15] Boyd et al. (2017) Science of the To- oxygen of hypersaline waters. Phototrophs power the tal Environment 581–582:495–506 [16] Baxter et al. system [14] anaerobic activities are prevalent [15], and (2005) Life in Extreme Habitats and Astrobiology, vol 9 p9-25. [17] Ward & Brock (1978). Hydrocarbon methanogenesis has been detected [16]. The metabo- biodegradation in hypersaline environments. Applied lism of these microbial communities, living at salt satu- Environmental Microbiology, 35:353-359. [18] Tasoff ration, is complex, but such reactions occur more slow- et al. (this conference). ly than at lower salinity levels [17] These pigments underlie important strategies for overcoming the challenges of an extreme environment and also give us clues to potential biosignatures (Fig. 2, [1]) even after

Fig. 2. (Left) Modern evaporite NaCl with traces of embedded gypsum and larger microbial material (Right) Highly pigmented NaCl showing modification of the evaporite matrix due to photobiological processes . (Left) Recent preservation of organic and biological material intact due to the inactivity of younger fluids in the region post- precipitation. (Right) Originally surface evaporites from a dried lakebed retaining pigments from the initial preservation and later burial. The First Billion Years: Habitability 2019 (LPI Contrib. No. 2134) 1024.pdf

ORGANIC AND BIOMARKER DETECTION TECHNIQUES FOR HYDROTHERMAL ALTERATIONS IN SANDSTONE LAYERS WITHIN THE COLORADO PLATEAU. Scott M. Perl1-3, Justin Filiberto4, Karen Olsson-Francis5, Sally L. Potter-McIntyre6, Susanne P. Schwenzer5, Jake R. Crandall6. 1NASA Jet Propulsion La- boratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109, USA ([email protected]). 2Mineral Sciences, Los Angeles Natural History Museum, 900 W Exposition Blvd, Los Angeles, CA 90007, USA. 3Blue Marble Space Institute of Science, 1001 4th Ave, Suite 3201, Seattle, Washington 98154, USA. 4Lunar and Planetary Institute, USRA, 3600 Bay Area Blvd., Houston, TX 77058, USA. 5School of Environment, Earth, and Ecosystems Sciences, The Open University, Walton Hall, Milton Keynes MK7 6AA, UK 6Eastern Illinois University, Department of Geology & Geography, 600 Lincoln Ave., Charleston, IL 61920, USA

Introduction: Measuring the habitability of a re- tions under these conditions produce reactions that can gion is directly related to the presence and longevity of lead to clay formation, carbonate precipitation, and a solvent, usually liquid water, interacting and modify- others [5] that can provide biosignature preservation ing parent minerals or precipitating primary mineralogy environments away from harmful Martian UV-C [6]. as a function of fluid volume and salinity. The stability of evaporites can rely on the continued volume of liquid water (post-precipitation) and the proximity of non- soluble mineralogy or rock boundaries. On Mars, rocks from the Burns Formation show evidence of groundwater upwelling and the dissolution of Fe and Mg sulfate salts. The overall alteration of the rock from acidic groundwaters also provided mm-scale habitable settings within pore spaces [1] due to multiple redox fronts from water-rock interaction where life could have utilized these small pockets of fluid [2]. The purpose of this paper is to two-fold. Primarily we will discuss the geobiology and habitability metrics of basaltic intrusions into sedimentary rocks where ancient fluids can lead to the modification of secondary Fig. 1. (Left) Entrada Formation field site (Right) Repre- minerals that can be used by life. Secondly, we will sentative gypsum evaporites with dike material from the highlight in-situ and laboratory techniques that can be Carmel Formation. (Left) Altered dike in contact with the utilized for assessing biosignature validation and sandstone showing evidence for hydrothermal fluids (also reviewed in [8]). (Right) Carmel Formation sample contains preservation. gypsum vein material [9]. Field Site & Planetary Analogue: Mafic dikes were deposited within Jurassic sedimentary rocks in the Laboratory Capabilities: After sterile sample vicinity of the Colorado Plateau in southern Utah. One manipulation to expose interiors of the gypsum, we will of these exposed dikes – the 22 Myr Robbers Roost generate directed Raman point analyses and concentra- dike intruded through the Entrada Sandstone within the tion maps to show the distribution and preservation of San Rafael Group. This red silty sandstone contains organic material. Moreover we will measure intrusion Fe-cements and it an ideal Martian analogue due to the features alongside unaltered material to determine the water-rock ratio and interaction between the basaltic extant of alteration into the parent rock. Evaporite fea- rock and the nearby subsurface rock (Fig. 1). Minerals ture that show signs of fluid preservation will be inves- on both Earth and Mars that have formed from in-situ tigated further using biogenic validation techniques [7] alteration of mafic dike material (and groundwater) can and if possible specific organic compounds using local provide relative timing of both ancient fluid flow and soils as a biological control (DNA + compounds). constraints on the potential chemistry that chemo- lithotrophic biology can utilize as nutrient sources as References: [1] Perl & McLennan (2008) 8th Mars Conf. well as the generation of biomarker features (e.g., mi- [2] Cockell et al. (2016) Astrobiology, v16 p89-117. [3] crobial mats, unique organic distributions) within par- Crabaugh & Kocurek (1993) Geo Soc. v72, 1, 103-126. ent minerals and dike material. [4] Costello et al. (submitted). [5] Stroncik & Schmincke In-Situ Mineralogy: The basaltic crust of Mars (2002) Int. J. Earth. Sci. v. 91, 4, 680-697. [6] Muñoz contains altered mineralogy formed from a mafic unal- Caro et al. (2006) Sensors 6(6): 688–696. [7] Perl et al. tered parent rock under changing temperature, and if (submitted). [8] Filiberto et al. (this conference). [9] buried, pressure conditions [3,4]. Water-rock interac- Crandall et al. (2018) LPSC Abstract #2083. The First Billion Years: Habitability 2019 (LPI Contrib. No. 2134) 1039.pdf

CHARACTERIZATION OF PERMEABLE SEDIMENTS AS HABITABLE REFUGES FOR COMPLEX MICROBIAL ECOSYSTEMS . L. E. Prufert-Bebout1, N. Shih2, and B. Bebout3, 1NASA Ames Research Center, Mailstop 239-4, Moffett Field, CA. [email protected], 2University of Washington, Seattle, WA [email protected], 3NASA Ames Research Center, Mailstop 239-4, Moffett Field, CA. [email protected].

Introduction: Permeable sediments created by macromorphology under full solar, defined shade and weathering of parent igneous or metamorphic rock directional irradiance regimes. types into smaller grain sizes (sand, silt) on Earth are Prior Investigations: Initial studies have shown often colonized by a complex assemblage of microbes, that introducing new deposits (mimicking a burial living within the pore spaces between mineral grains event) onto the surfaces of microbial mats can produce and resulting in coherent laminated structures known as rapid colonization and binding of the introduced sedi- microbial mats [1]. The enormous variety of types of ments. Changing the mean grain size of introduced microbes and sediments varying in mineralogy and siliciclastic sand deposits, resulted in observable dif- particle size in different environments results in a di- ferences in the distributions of the primary cyanobacte- verse array of microbially influenced sedimentary rial populations, and also produced differences in sed- structures (MISS) [2]. Characteristics of sediments iment binding, coherence and other observable mor provide many features that create suitable habitats for phological features (Fig 1). life on Earth and potentially other planets, including: refuge from ultraviolet light, while still permitting access to visible irradiance for photosynthesis, source of elements necessary for biological processes, and protection from erosion by water flow or wind processes. Closer examination of how these properties influence microbial colonization may provide valuable clues to inform our understanding of the complex relationships between microbes and their sedimentary habitats and how those interactions influenced evolution of life on early Earth. These considerations will also be critical Figure 1. Left most column, Elkhorn Slough microbial mat in assessing potential habitable niches on other worlds. covered with top to bottom, sorted: fine (.075-.15 mm), me- To contribute to our understanding in these fields, dium (0.15-0.5mm) and coarse (0.5-2mm) grain size sand we are taking a reductive approach, exposing natural fractions. Next 4 columns progressively show images of microbial ecosystems and a large library of cyanobac- surface colonization at weeks 1 through 4. Last column terial cultures derived from diverse, hypersaline, fresh, shows newly developed vertical cross section at week 4. marine and arid high altitude ecosystems, to defined Trials conducted under natural solar irradiance conditions in conditions of sedimentary type, irradiance and flow, greenhouse housed flumes. collecting data on resulting colonization patterns, sed- Future Work: Additional trials with defined sedi- iment coherence, creation of oxidizing-reducing gradi- ment types, grain sizes, irradiance and flow conditions ents, and morphological biosignatures in response to are planned, Surface images and additional characteri- imposed conditions. zations of live and post-mortem mat-mineral assem- Spectral characteristics: Prior radiative transfer blages, will be archived in the Astrobiology Habitable modeling has calculated substantial decrease in light Environments Database (AHED) [5] contributing to a penetration with decreasing grain size in packed sand public access database of potential mineral, morpho- bed substrates [3]. Changing ratios of translucent logical and organic biosignatures formed by defined (quartz) to opaque minerals, or alterations in incident microbial – mineral assemblages. spectral intensity or quality also result in different mi- References: [1] Lassen C. et al (1994). In: L. J. crobial colonization patterns. Stal and P. Caumette (eds.), Microbial Mats: Structure, Physical Structure and flow dynamics: Variance Development and Environmental Significance. Spring- in flow rates have been shown to change the morpho- er, Berlin, pp. 305-311. [2] Noffke N., Geobiology: logical structures of microbial mats [4]. Our approach Microbial Mats in Sandy Deposits from the Archean will be to expose natural and grown microbial mats to Era to Today (2010). [3] Murphy T. E. et al. (2016) stagnant, low and high flow regimes, examining chang- NASA Space Science and Astrobiology Jamboree, [4] es in photosynthetic efficiency, layer formation and Petroff, A. P. et al., Biophysical basis for the geometry of conical stromatolites (2010) PNAS 107(22) 9956 - The First Billion Years: Habitability 2019 (LPI Contrib. No. 2134) 1039.pdf

9961 [5] Detweiler A.M. et al (2019) AbSciCon, Ab- stract # 481514.

Acknowledgements: Nathan Shih was supported by the NASA Community College Aerospace Scholars (NCAS) program. Contributions to this work were provided from the NPP-ORAU (T. Murphy), Ames SIF (S. Pilorz and L. Bebout), and NASA OSSI (Natalie Jones) programs. Support for this research was also provided by NASA’s Planetary Science Division As- trobiology Research Program. The First Billion Years: Habitability 2019 (LPI Contrib. No. 2134) 1007.pdf

A Dynamic Habitable Zone and how to find Potentially Habitable Planets Ramses Ramirez1 1Earth-Life Science Institute (ELSI), Tokyo Institute of Technology, email: [email protected]

Introduction: The habitable zone (HZ) is the circular Is the carbonate-silicate cycle really universal? region around a star(s) where standing bodies of water could exist on the surface of a rocky planet (Fig- Several Earth-centric assumptions define the stand- ure 1) [1,2]. Space missions employ the HZ to select ard habitable zone. This “classical HZ” is traditionally promising targets for follow-up habitability assessment. characterized by H2O-dominated planets near the inner The classical HZ definition assumes that the most im- edge and CO2-dominated planets at the outer edge [1]. portant greenhouse gases for habitable planets orbiting This variation in atmospheric composition with dis- main-sequence stars are CO2 and H2O [1]. Although tance is assumed to be dictated by the carbonate- the classical HZ is a useful navigational tool, recent HZ silicate cycle, which is thought to regulate CO2 levels formulations suggest that the concept must evolve to over million-year timescales on our planet[1]. Howev- better capture the diversity of habitable exoplanets. er, there is still no direct evidence that this cycle exists With that goal in mind, I will be discussing on Earth, and even if it does, the details are poorly un- the temporal, spatial, planetary, and stellar processes derstood. Plus, its universality elsewhere is completely that are key to inferring planetary habitability. Supple- untested [2,4]. This is why we should test the existence menting the classical HZ with additional considerations of a universal carbonate-silicate cycle with upcoming improves our capability to filter out worlds that are missions that will measure atmospheric CO2 levels in unlikely to host life. Such improved HZ tools will be planets orbiting many stars. Even should such a cycle necessary for current and upcoming missions aiming to prove common throughout the cosmos, this would not detect, rank, and characterize potentially habitable ex- necessarily preclude the existence of other planets, oplanets. including ocean worlds, which might be habitable even In addition, as we consider next generation in the absence of such a cycle [5]. Such ocean words missions in the search for extraterrestrial life (e.g would have lower interior densities and be easily dis- HabEX, LUVOIR, and OST), I also discuss the im- tinguished from other terrestrial planets [5]. portance of improved observations, and what needs to

be done to advance future models of the HZ from a The untested universality of habitable planets with first principles approach in the burgeoning field of CO -H O atmospheres “dynamic habitability [2,3].” 2 2

The notion that CO2 and H2O are the only greenhouse gases of importance in potentially habitable planets, is another questionable (but testable) assumption of the classical HZ [1]. For instance, CO2 levels of planets near the outer edge of the classical habitable zone are so high that they would be poisonous to Earth- like life anyway [1], raising questions about whether so-called “Earth-like” life can be expected in such planetary environments. However, the atmospheric CO2 levels fostering habitable surface conditions can reduce dramatically if the additional warming from Figure 1: Extended classical habitable zone for stellar secondary greenhouse gases is considered. For in- temperatures from 2,600 to 10,00 K. Reproduced from stance, hydrogen outgassing from volcanoes, together ref [2] with CO2 and H2O, can increase HZ width by ~50% [6] ͘ (Figure 2). The solar system HZ can extend outward to Rethinking the Classical Habitable Zone near Saturn’s orbit if habitable planets can acquire pri- The HZ is still the best metric out there for finding mordial H2 envelopes [7]. Moreover, hydrogen is a life on other planets, but it needs a modern update. known food source for life, which makes these planets Here are a few example of topics I will be discussing in potentially attractive observational targets. Such plan- more detail in my talk. ets are also considerably easier to observe via transmission spectroscopy than are CO2-rich planets [6,8]. Other gases which are produced by life, like CH4, may be a major greenhouse gas for worlds orbiting hotter The First Billion Years: Habitability 2019 (LPI Contrib. No. 2134) 1007.pdf

stars [9] (Figure 2). In contrast, around M-stars, CH4 traditional hydrogen-rich or methane rich atmospheres, actually acts as a cooling gas that may not be so good planets orbiting binary stars, worlds around white for life’s prospects [9]. Therefore, I argue that stellar dwarfs, habitats orbiting red giants, environments type (in part) determines what biosignatures gases we around very young and luminous stars, and even ocean should be observing around different stars. worlds (summarized in ref 2). All will be discussed. The main concepts in my recent review paper provide many suggestions that current and upcoming mission concepts (e.g HabEX, LUVOIR, and OST) can employ in their search. An example of how a more “dynamic HZ” can be applied is shown in Figure 3. I will also discuss several ways an improved HZ can be used to find potentially habitable planets and rank them using metrics such as in ref.[10]. My review talk aims to incite new interdisciplinary discussion about the various possibilities, leading to new research into the prospects for life elsewhere.

Figure 2: The classical HZ (blue) with CO2-CH4 (green) and CO2-H2 (red) extension for stars of temperatures between 2,600 and 10,000 K. Classical HZ shown as in Fig. 1. Reproduced from ref [2]

Dynamic Habitability: A First Principles Approach

Motivated by arguments such as these and others, improving our understanding of planetary habitability (and, ultimately, life) outside of our solar system will require employing first principles that focus on assessing the individual planetary system’s unique traits rather than assuming that certain Earth characteristics must a priori apply elsewhere. Indeed, this very senti- ment has led to the growing field of “dynamic habitability”, which suggests that planetary habitability and its environment must be considered over both spatial Figure 3: Sample flow chart using the classical HZ, and temporal scales [3]. I will be stressing the im- along with CO2-H2, CO2-CH4, and pre-main-sequence portance of this first principles dynamic habitability HZ extensions to assess the potential habitability of approach and how it will be necessary to maximize our planets. End states are in yellow. Reproduced from ref chances of finding life elsewhere. [2]

A more comprehensive habitable zone for finding References: life on other planets [1] Kasting, J.F. et al. (1993) Icarus 101, 1, 108 – 128. [2] Ramirez, R.M (2018) Geosciences 8, 8, 280 Ramirez [2] recently published the first review pa- [3] National Academies of Sciences, Engineering, and per (to the author’s knowledge) of dynamic habitabil- Medicine (2018) Washington D.C. The National Acad- ity, showing how the HZ concept, which is often con- emies Press. http://doi.org/10.17226/25252 [4] Bean, sidered to be very Earth-centric, can really become J.L. et al. (2017) ApJL 841, 2, L24 [5] Ramirez, R.M. much more versatile than what has been credited in the and Levi, A. (2018) MNRAS 477, 4, 4627 – 4640. [6] past. Although the HZ can continue to be used to find Ramirez, R.M. and Kaltenegger, L. (2017) ApJL 837, potentially habitable planets that are similar to our own 1, L4. [7] Pierrehumbert, R. and Gaidos, E. (2017) ApJ planet, it is also versatile enough to be used to search 734, 1, L13. [8] Seager et al. (2013) ApJ 777, 2,95 [9] for those that may exhibit conditions somewhat differ- Ramirez, R.M. and Kaltenegger, L. (2018) ApJ 858 2, ent from those on our planet. 72 [10]Mendez A. et al. (2018) LPSC 49, 2083 A few examples of such planets with the potential for life as we-do-not-know-it include: worlds with non- The First Billion Years: Habitability 2019 (LPI Contrib. No. 2134) 1042.pdf

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CLUES TO THE HABITABILITY OF MARS IN ITS FIRST BILLION YEARS FROM AN EARTH-LIKE HYDROTHERMAL SYSTEM IN GUSEV CRATER. S. W. Ruff1, 1School of Earth and Space Exploration, Arizona State University, Tempe, AZ, [email protected].

Introduction: The recognition of the habitability tem [6], as commonly expressed in hydrothermal sys- and microbial preservation potential of hot springs in tems on Earth including at Yellowstone. volcanic hydrothermal systems on Earth sparked inter- The opaline silica deposits occur as monomineralic, est in such settings in the search for life on Mars stratiform, nodular outcrops displaying a sharp contact [e.g.,1]. This interest was motivated in part by the with an underlying altered ash deposit [5; 10], features identification of microbially mediated stromatolites most consistent with hot spring/geyser silica sinter [6]. among the hot springs of Yellowstone National Park, Some of the silica nodules display mm-scale digitate which also provided insights into the nature of stro- structures resembling biomediated hot spring stromato- matolites in the Archean [2]. More recently, evidence lites that are widely recognized on Earth [7]. Nodular for hot spring deposits and associated biomediated hot spring silica is common on Earth, including at Yel- textures and structures have been recognized in rocks lowstone (Fig. 1), and in some cases is biomediated from the Pilbara Craton of Western Australia dating [e.g., 11], so conceivably also the case on Mars. back ~3.5 Ga [3]. Such observations reinforce the importance of hot springs both in origin of life investigations [e.g., 4] and in the search for life beyond Earth. In this context, the discovery of a volcanic hydrothermal system by the Spirit Rover in the Columbia Hills of Gusev crater, Mars [5] merits additional scru- tiny, as highlighted herein. A suite of observations support the identification of a volcanic hydrothermal system active at >3.5 Ga, with multiple manifestations including both fumaroles and hot springs that produced features recognizable in active hydrothermal systems on Earth today [6], including potential biosignatures [7]. The wealth of evidence for the habitability and preservation potential of volcanic hydrothermal systems across time and space contrasts with the more limited evidence for these aspects in impact-generated hydrothermal systems on Earth. As discussed herein, the features that distinguish these two hydrothermal systems probably affect the available metabolic strategies and perhaps the preservation potential of any microbial inhabitants. Columbia Hills Hydrothermal System: The Spirit rover encountered sulfur-rich soils and deposits of opaline silica (amorphous SiO2nH2O) in the vicinity of an ~80 m diameter volcanic landform dubbed Home Plate that predates the emplacement of Gusev plains basaltic lava flows, which have been dated to 3.65 Ga [8]. Multiple lines of evidence clearly indicate that volcanic hydrothermal activity is responsible for these materials [e.g., 5]. The S-rich soils likely represent alteration of basaltic materials by fumarolic acid- sulfate leaching [e.g., 9] and the silica deposits likely are chemical sedimentary rocks (sinter) produced from hot springs and/or geysers [10]. Both are readily inter- Figure 1. Nodular, digitate opaline silica outcrops on preted as manifestations of a single hydrothermal sys- Earth and Mars. (A) Porcelain Basin, Yellowstone. (B) Columbia Hills, Mars. Both scenes span ~60 cm. The First Billion Years: Habitability 2019 (LPI Contrib. No. 2134) 1036.pdf

Adding to the evidence of hot spring activity in the Conclusions: Hydrothermal systems are desirable Columbia Hills are new observations related to a fea- exploration targets in the search for life on ancient ture known as Pioneer Mound adjacent to Home Plate. Earth and planets beyond, by virtue of their known Previously, the rocks on this small (~12 m diameter) habitability and preservation potential. Manifestations mound were recognized as candidate opaline silica of a volcanic hydrothermal system including fumaroles deposits based on their color and distribution [10]. and hot springs and/or geysers are clearly recognizable Now infrared spectra from Spirit’s Miniature Thermal on Mars from its first billion years, with tantalizing Emission Spectrometer support this hypothesis, lead- evidence for potential biosignatures. This expands by ing to the interpretation that this landform is an extinct one the number of planets confirmed to host such set- hot spring vent mound [6](Fig. 2). tings. It remains to be determined whether impact- generated hydrothermal systems represent an equiva- lently desirable exploration target. References: [1] Walter, M. R., and D. J. Des Marais (1993), Icarus, 101, 129-143. [2] Walter, M. R., et al. (1972), Science, 178, 4059, 402-405. [3] Djokic, T., et al. (2017), Nat. Commun., 8, 15263. [4] Deamer, D. W., and C. D. Georgiou (2015), Astrobiology, 15, 12, 1091-1095. [5] Squyres, S. W., et al. (2008), Science, 320, 1063- 1067. [6] Ruff, S. W., et al. (in revision), Astrobiology. [7] Ruff, S. W., and J. D. Farmer (2016), Nat. Commun., 7, 13554. [8] Greeley, R., et al. (2005), J. Geophys. Res. Planets, 110, E05008. [9] Yen, A. S., et al. (2008), J. Geophys. Res. Planets, 113, E06S10. [10] Ruff, S. W., et al. (2011), J. Geophys. Res. Figure 2. (A) Opaline-silica-bearing Pioneer Mound Planets, 116, E00F23. adjacent to Home Plate resembles (B) an extinct opal- [11] Jones, B., and R. W. Renaut (1997), ine silica hot spring vent mound in Chile. Sedimentology, 44, 287-304. Volcanic vs. Impact Hydrothermal Systems: [12] Newsom, H. E. (1980), Icarus, 44, 207-216. The likelihood of impact-generated hydrothermal sys- [13] Cockell, C. S., et al. (2012), Icarus, 217, 1, 184- tems (IHS) on Earth and Mars has been recognized and 193. investigated for decades [e.g.,12], with many studies [14] Abramov, O., and D. A. Kring (2005), J. noting the habitability potential of these systems Geophys. Res. Planets, 110, E12. [e.g.,13; 14]. Less clear is whether such systems are [15] Shock, E. L., et al. (2010), Geochim. Cosmochim. equivalent to volcanic hydrothermal systems (VHS) Acta, 74, 14, 4005-4043. with regard to habitability and preservation potential. For example, volcanic inputs to VHS contribute to a rich variety of metabolic strategies like those involving S and S-compounds [e.g., 15]. The potential for comparable inputs to IHS and resulting microbial diversity need to be explored. Hot spring/geyser silica sinter deposits are a hall- mark of VHS, recognizable throughout the geologic record on Earth and found on Mars, but apparently yet to be observed in IHS. This raises the question of whether the known microbial preservation potential of VHS attributed to rapid entombment by silica has an equivalent potential in IHS.

The First Billion Years: Habitability 2019 (LPI Contrib. No. 2134) 1005.pdf

PALEOBIOLOGICAL EVIDENCE OF THE IMMEDIATE AFTERMATH OF THE BEGINNING BILLION: LIFE EVOLVED EARLY, FAR AND FAST James William Schopf1 1Department of Earth, Planetary and Space Sciences, University of California, Los Angeles (595 Charles E. Young Drive East, Los Angeles, CA 90095; [email protected])

Introduction: Though relevant geological data are What, then, is firmly known about life’s earliest scanty, during Earth’s first 600 years million years – history? The convincing answer comes, as it must, the Hadean (4.6-4.0 Ga), the planet’s so-called “hell- from the preserved paleobiologic record of Earth’s ish” formative stage – the planet is thought to have earliest fossils. But we here reach a conundrum. The evolved from having an initial short-lived surficial fossil record can be known only from rocks that have magma ocean (produced by the frictional energy of survived to the present and – because of the geological accreting planetesimals and resulting core formation) cycle of deposition, erosion, and recycling of once- to the mafic-sialic separation that resulted in develop- formed rocks to ever-younger geological units – ment of the mantle and overriding sialic, presumably Earth’s earliest geology has been wiped from history, scattered islands. The Sun also evolved, like all young the more-or-less continuous rock record dating only Main Sequence Stars, gradually becoming more lumi- back to about 3.5 billion years ago near the onset of nous and emitting a gradually less intense UV-flux. the Paleoarchean (3.6-3.2 Ga). And Earth’s atmosphere and surface temperature Fossil Evidence of the Immediate Aftermath of evolved as well as the initially high atmospheric CO2- the Beginning Billion: Fortunately, however, the content (cf. present-day Venus) declined, with data preserved fossil record reveals early stages in the his- from early-formed zircons indicating by 4.3 Ga surface tory of life – not the beginnings of life, which because temperature had decreased sufficiently to permit ac- of the fragility of the formative molecular components cumulation of liquid water [1, 2]. can now and perhaps forever only be modeled in labo- Over time, the attainment of a liquid water ocean ratory experiments but, instead, life’s status at the beset the stage for the emergence of life, a watery milieu ginning of the continuous rock record – in essence, being paramount for the protection of the ephemeral evidence of the immediate aftermath of the Beginning products of prebiotic organic syntheses from the still- Billion. Although as early as 1983 carbon isotopic data high destructive UV flux. It matters little whether these from bulk (kg-sized) rock samples traced the record of abiotics were produced in the atmosphere by Miller- photosynthesis to ~3.5 Ga [7] and diverse stromatolites Urey syntheses, at submarine fumaroles by Fischer- (microbially produced distinctively laminated Tropsch-type reactions, or elsewhere by some other megascopic structures) are now well-known from mechanism. In all cases the products were small, la- similarly aged deposits [8, 9], the present discussion bile, water-soluble organics that the overlying waters focuses on two ancient rock units from Earth’s earliest protected from UV-induced photodissociation. preserved geological record, ~3.43 and ~3.465 Ga in When, then, did life emerge? The current, if unsat- age, that contain cellular microscopic fossils for which isfying answer: No one knows. There are of course the biological affinities and physiology can be dis- “hints” of life in the Hadean and immediately follow- cerned. Taken together, these and comparably ancient ing 4.0-3.6 Ga Eoarchean, among the best known be- fossiliferous units reveal the nature of Earth’s early ing the “biologic-like” 13C-depleted carbonaceous in- habitable environment and the evolutionary status of clusions in redeposited ancient zircons as old as 4.1 Ga early life. [3]; microscopic mineralic tubes in >3.77 Ga Eoar- ~3.43 Ga Strelley Pool microbial consortium. chean volcanics of northeastern Canada [4] – possibly Both of the featured units are from the Pilbara Craton biologic but perhaps more likely gas evasion channels; of northwestern Western Australia. The younger of the and the occurrence of “stromatolite-like” rock layers in preserved microbial assemblages, that of the ~3.43 Ga evidently a single specimen at a single locality of a Strelley Pool Formation at the “Anchor Ridge” locality ~3.7 Ga deposit of Greenland [5] – the claimed bio- [10], is a shallow-water evidently mudflat-inhabiting genicity of which has been subject to debate [6]. Un- biota fossilized in a sulfate-depositing evaporitic set- fortunately, none of these hints is fully convincing – ting and composed of intimately intermeshed flat-lying the examples are too few, the evidence too conten- anaerobic anoxygenic photosynthetic bacteria and tious, and none is backed by the co-occurrence of cel- similarly anaerobic globular assemblages of sulfur- lular, carbonaceous, microscopic fossils. cycling microbes (sulfuretums). Together these microbes constitute a mutualistic microbial consortium – The First Billion Years: Habitability 2019 (LPI Contrib. No. 2134) 1005.pdf

a “consortium” because of the interactive close coop- cally comparable both to living and fossil filamentous eration of the two distinctly differing biotic lineages microbes. Moreover, the most recent such study of five and “mutualistic” because of the shared beneficial re- species and 11 individual specimens of the Apex as- sults of their symbiosis, the light-dependent photosyn- semblage [12] show it to include photosynthetic bacte- thesizers using the H2S produced by the sulfuretums to ria, methane-producers and methane-consumers, mi- power production of their life-sustaining photosyn- crobes like those of the sulfur-cycling ~3.43 Strelley thetic products and the H2S-producers benefiting from Pool consortium that are obligately anaerobic and the removal of this potentially lethal effluent from their among the earliest branches of the rRNA Tree of Life immediate environs. Thus, the photosynthesizers re- [10, 12, 13]. quired the sulfur-cyclers for sustenance and the H2S- Conclusion: The evidence is firm, the conclusion producers were dependent on the removal of this nox- clear: Life on Earth evolved early, far and fast! ious gas to maintain viability. References: [1] Wilde, S. A. et al. (2001) Nature Perhaps even more importantly, this consortium, 409, 175-178. [2] Mojzsis, S. J. et al.(2001) Nature one of only three such interactive multi-component 409, 178-181. [3] Bell E. A. et al. (2015) PNAS, 112, microbial assemblages yet documented in the geologi- 14518-14521. [4] Dodd M. S. et al. (2017) Nature, cal record (a rather surprising finding given the >90% 543, 60-64. [5] Nutman A. P. et al. (2016) Nature, prevalence of similar consortia in the modern biota) 537, 535-538. [6] Allwood, A. C. et al. (2018) Nature, evidences both the nature of Earth’s early habitable 563, 241-244. [7]. Schidlowski M. et al. (1983) in: environment and the genomic evolution that had al- Schopf, J. W. [Ed.], Earth’s Earliest Biosphere, Its ready resulted in life’s capability to not only survive Origin and Evolution, pp. 149-186 (Princeton). [8] but thrive in an environment that by current standards Hofmann H. J. et al. (1999) G.S.A. Bull., 111, 1256– could only be regarded as exceptionally hostile. The 1262. [9] Allwood A. C. et al. (2006) Nature, 441, occurrence of this ancient anaerobic microbial consor- 714-718. [10] Schopf J. W. (2017) Precam. Res., 299, tium in a shallow-water, evaporitic, mudflat-like sur- 309-318. [11] Schopf J. W. (1993) Science, 260, 640- face-exposed environment evidences that Earth’s over- 646. [12] Schopf J. W. (2018) PNAS, 115, 53-58. [13] lying Eoarchean atmosphere was anoxic – essentially Schopf J. W. (2019) Life in Deep Time: Darwin's devoid of oxygen and markedly unlike Earth’s later "Missing" Fossil Record, A Personal Account of Pa- surficial environment – and that the numerous intracel- radigm-Changing Science, 229 pp. (CRC). lular mechanisms required for repair of UV-induced damage to intracellular components and adaptation to this harsh environment had already evolved [10]. For geologists, geochemists, “origin-of-lifers” and all others concerned about the nature of the life-generating early environment, for the first time this consortium documents the long-held assumption that Earth’s early atmosphere was in fact essentially devoid of oxygen. ~3.465 Ga Apex chert oldest known diverse micro- biota. The other unit here considered, the slightly older ~3.465 Ga Apex chert, is arguably even more significant, hosting the oldest diverse multi-component microbial assemblage now known in the geological record. First reported in 1993 [11], study of the Apex assemblage continued to 2018 [12], a recently summarized [13] decades-long series of investigations. The cascade of evidence there summarized establishes that the fossils are indigenous to and syngenetic with the microcrystalline chert in which they occur; that like members of modern and other fossil microbiotas they are abundant and diverse, including hundreds of specimens and some 11 defined species; and that the putative fossils are not organic-coated opaque minerals or some other non-biologic artifact but, instead, are demonstrably composed of biologic organics and are cylindrical, carbonaceous, cellular and morphologi- The First Billion Years: Habitability 2019 (LPI Contrib. No. 2134) 1011.pdf

COUPLED Fe-Os ISOTOPE SIGNATURES IN BANDED IRON FORMATIONS - DECODING EARTH’S OXYGENATION HISTORY AND THE CHEMICAL EVOLUTION OF PRECAMBRIAN SEAWATER Toni Schulz1,2, Sebastian Viehmann3, Dominik C. Hezel2, Christian Koeberl1,4. 1Department of Lithospheric Re- search, University of Vienna, Austria ([email protected]). 2Institute for Geology and Mineralogy, University of Cologne, Germany. 3Department of Geodynamics and Sedimentology, University of Vienna, Austria. 4Natural History Museum Vienna, Austria

Introduction: Seawater archives, in the form of impacts [e.g., 15-17], causing severe environmental marine chemical sediments and their geochemical changes. proxies, provide excellent opportunities to better un- Thus, BIFs constitute an invaluable geochemical derstand the physico-chemical evolution of the ancient archive which remains to be fully exploited. hydro- and atmosphere through Earth’s history. How- Approach: In this contribution we aim to present ever, pure seawater precipitates, devoid of syn- or post- preliminary results of a comprehensive study of cou- depositional alterations, are scarce in the geological pled Fe-Os isotope analyses of a series of BIFs cover- rock record, but essential to understand the interplay of ing the time-span from the Eoarchean to the Neopro- the geodynamic evolution of the Earth and its marine terozoic. This allows us to study secular variations of habitats. the physico-chemical evolution of ancient environ- Banded iron formations (BIFs) are non-actualistic ments prior to, during, and in the wake of the GOE at rocks which provide the most robust archives for an- around 2.4 Ga [e.g., 18]. cient seawater. They consist of alternating silica-rich Iron isotopic fractionations in BIFs allow tracing and iron-rich layers of often large lateral extent (>50 biological processes that dictated oxidation mecha- km). They precipitated on the seafloor almost exclu- nisms and pathways [e.g., 19]. Further, the residence sively during the first two billion years of Earth’s his- time of Os in the oceans of ~10 kyr [20], allows to tory and reflect variations in the ancient seawater detect periodic fluctuations in the global 187Os seawa- chemistry. ter composition [e.g., 21-23]. Although Os seawater The formation of BIFs required the transport of residence times during the Precambrian might differ, dissolved Fe(II), as Fe(III) is nearly insoluble in the this provides the potential to discriminate between presence of even trace amounts of oxygen [e.g., 1]. source contributions during BIF deposition (e.g., con- Models for the genesis of BIFs, therefore, require an tinental, hydrothermal and, probably, meteoritic). The assessment of the sources for elemental supplies (e.g., sensitivity of the Os isotope approach relies on varying iron among other chemical elements and potential nu- time-integrated radiogenic accumulations of 187Os (due trients for the earliest life on Earth) to the ancient sea- to the decay of 187Re) between different source reser- water, as well as the oxidation mechanisms which led voirs, which are accompanied by concentration gradi- to their precipitation. Such models are often highly ents of the highly siderophile elements (HSE). controversial and encompass continental [e.g., 2,3] Samples and Methods: Our preliminary data en- and/or hydrothermal [e.g., 4-6] elemental sources, ex- compass HSE concentrations and coupled plaining oceanic Fe removal by either inorganic [e.g., δ56/54Fe-187/188Os isotope analyses of the 2.7 Ga old 7,8] or biologically promoted [e.g., 2,9] Fe(II) oxida- Temagami Iron Formation from the Abitibi Greenstone tion, or a combination of these processes [e.g., 10]. Belt, Ontario, Canada. The Temagami BIF represents a It is not known if and to what extent oxidation pro- well-preserved Algoma-type BIF that has only been cesses changed through time [e.g., 11,12]. However, subjected to lower greenschist facies metamorphism the Great Oxidation Event (GOE) likely provided a [24] and contains no or only minute amounts of alumi- major turning point, after which direct oxidation, due nosiliciclastic detritus [25,26]. to significant amounts of free oxygen in the at- Between 1 and 2 g of homogeneous sample pow- mosphere, likely dominated a declining BIF deposition ders were obtained from individual, detritus-free BIF in progressively iron-depleted and oxidized oceans. layers, spiked with a mixed HSE tracer and digested in The formation of BIFs is occasionally related to inverse aqua-regia in an Anton-Paar high pressure ash- major tectono-magmatic events that accompanied the er. After digestion, Os was separated from the other early evolution of the Earth’s hydrosphere-atmosphere HSE using a solvent extraction procedure described in system, which then allow to assess the fate of the earli- [27], and further purified using a microdistillation est exposed landmasses. The tectono-magmatic events technique [28]. The remaining HSE were separated are characterized by massive magmatic outpourings from the aqua-regia fraction using anion exchange [e.g., 13,14] in part likely triggered by large asteroid columns [e.g., 29]. The First Billion Years: Habitability 2019 (LPI Contrib. No. 2134) 1011.pdf

Highly siderophile element concentrations were However, the interpretation of stable Fe isotope determined using a Thermo Element XR-SF-ICP-MS signatures remains highly controversial in the scientific in single collector mode at the Steinmann Institute at community and additional δ56Fe data on BIFs of vari- the University of Bonn, Germany. The 187Os/188Os ra- ous ages are required to confirm or disprove any such tios and the Os concentrations were determined at the trends. Department of Lithospheric Research at the University Our HSE and Os isotope data for the Temagami of Vienna (Austria), using a ThermoFinnigan Triton BIF presented in this study confirm the lack of exten- Thermal Ionization Mass Spectrometer operating in sive post-depositional metamorphism. Rather, the negative mode. enormous HSE and 187Os/188Os heterogeneities on a Iron isotope measurements were performed on ~50 hand-specimen scale may record changes of the vari- mg of the bulk powders at the University of Cologne ous sources contributing to the Temagami seawater using chromatographic separation techniques follow- chemistry during BIF deposition. Hence, this provides ing published methods [30] and a Thermo Finnigan evidence for riverine transport of radiogenic crustal Os Neptune ICP-MS for mass spectrometric analysis. to the seawater under oxidizing conditions and Os in- Results: Samples from individual BIF layers ex- put from hydrothermal (and probably also extraterres- hibit ubiquitous enrichments in the heavy Fe isotopes, trial) sources. In contrast to δ56Fe values, which are correlating with alternating magnetite and chert layers. systematically lower in magnetite than in chert, 187Os/ δ56Fe values range from +0.65 to +0.95‰ for mag- 188Os ratios and HSE concentrations are similarly ho- netite-layers and are relatively constant around mogeneous among different layers. Areas of low HSE +1.05‰ in chert layers. concentrations (low ppt range) and radiogenic Os iso- Our preliminary HSE abundance data reveal signif- topes (187Os/188Os ~1-4) extend over four intercalating icant heterogeneities of HSE concentrations and 187Os magnetite and chert layers and alternate with areas of signatures on a cm-scale. Notably, these hetero- near-chondritic 187Os/188Os ratios corresponding to geneities show no correlation with the alternating Si- HSE concentrations of 30 to 100 ppt. Our preliminary and Fe-rich BIF layers. Osmium and Ir concentrations HSE-187Os dataset may, thus, provide a new geochemi- vary from ~1 to ~100 ppt, correlating with 187Os/188Os cal proxy that may help to decipher elemental sources ratios, which vary from near-chondritic ratios in „high from hydrothermal, extraterrestrial and emerged conti- HSE“ layers to values up to ~4 in „low-HSE“ layers. nental sources that affected ancient seawater chemistry Discussion: The presence of Fe isotope hetero- in the earliest marine habitats on Earth. geneities on a hand-specimen scale in conjunction with References: [1] Bekker A. et al. (2014) Treatise on Geo- δ56Fe interlayer correlations are interpreted to reflect chemistry, eds Holland HD, Turekian KK (Elsevier, Oxford), 2nd Ed, Vol 9, pp 561–628. [2] Cloud P. (1973) Econ. Geol. 68 (7): 1135- primary or low-temperature signatures despite subse- 1143. [3] Lepp H. and Goldich S.S. (1964) Econ. Geol. 59 (6): 1025- quent metamorphism. 1060. [4] Klein C. and Beukes N.J. (1989) Econ. Geol. 84, A comparison of magnetite Fe isotope data between 1733-1774. [5] Bau M. and Möller B (1993) Geochim. Cosmochim. Acta 57, 2239-2249. [6] Alexander B.W. et al. (2008) Geochim. Archean and Proterozoic BIFs led [31] to conclude that Cosmochim. Acta 72, 378-394. [7] Cairns-Smith A.G. (1978) Nature there was a fundamental difference between the Fe 276, 807–808. [8] Thibon F. et al. Earth Planet. Sci. Lett. 506, cycles that produced the BIFs during these time peri- 360-370. [9] Konhauser K.O. et al. (2005) Geobiology 3, 167–177. [10] Li W. (2015) Proc. Natl. Acad. Sci. 112(27), 8193–8198. [11] ods, reflecting different extents of oxidation, as well as Konhauser K.O. et al. (2002) J. Geol. 30, 1079-1082. [12] Klein C. microbial diagenesis. Magnetite from Archean Isua (2005) Am. Mineral. 90, 1473- 1499. [13] Isley A.E. and Abbott BIFs exhibit a narrow range of positive δ56Fe values, D.H. (1999) J. Geophys. Res. 104, B7. [14] Viehmann S. et al. (2015) Precambrian Geol. 270, 165-180. [15] Simonson B.M. whereas magnetite in the Proterozoic Hamersley and (1992) Geol. Soc. Am. Bull. 104, 829–839. [16] Slack J.F. and Can- Transvaal BIFs exhibit a wider range of slightly nega- non W.F. (2009) Geology 37, 1011-1014. [17] Glikson A.Y. (2014) J. tive δ56Fe values. This dichotomy was correlated with Earth Sci. 61, 689-701. [18] Lyons T.W. et al. (2014) Nature 506, 307-315. [19] Johnson C.M. et al. (2008) Geochim. Cosmochim. low ambient O2 contents and small extents of oxidation Acta 72, 151–169. [20] Oxburgh R. (2001) Geochem. Geophys. 2(6). in the Archean and inheritance of δ56Fe values of mag- [21] Vivier A. (2014) Earth Planet. Sci. Lett. 389, 23-33. [22] netite that was produced by complete oxidation of Peucker-Ehrenbrink B. et al. (1995) Earth Planet. Sci. Lett. 130, 155-167. [23] Ravizza G.E. and Peucker-Ehrenbrinck F. (2003) Fe(II)aq in Proterozoic BIFs [31]. Notably, our data for Earth Planet. Sci. Lett. 210, 151-165. [24] Fyon J.A. and Cole S. the magnetite layer in the Temagami BIF show (1989) in Summary of Field Work and Other Activities 1989, On- markedly positive δ56Fe values and, thus, mirror typi- tario Geological Survey, Misc. Paper 146, p.108-115. [25] Bau M. 56 and Alexander B.W. (2009) Precambrian Res. 174, 337-346. [26] cal δ Fe values of the Eoarchean Isua BIF. This is best Viehmann et al. (2014) Geology 42, 115-118. [27] Cohen A. S. and explained by anoxygenic photosynthesis or low atmos- Waters F. G. (1996) Anal. Chim. Acta 332, 269–275. [28] Birck J. L. pheric O2 levels during the deposition of Temagami et al. (1997) Geostandard Newslett. 20, 19–27. [29] Coggon J. et al. (2015) Geochim. Cosmochim. Acta 167, 205–240. [30] Dauphas N. BIFs, and opposes the advocated Proterozoic trend et al. (2004) Science 306, 2077-2080. [31] Czaja A.D. et al. (2013) [31]. Earth Planet. Sci. Lett. 363, 192-203. The First Billion Years: Habitability 2019 (LPI Contrib. No. 2134) 1041.pdf

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EMERGENCE OF LIFE ENERGIZED BY CYCLIC PHYSICOCHEMICAL PROCESSES OF ROTATING PLANETS. J. Spitzer, MCP Inc. (retired), Charlotte NC

Introduction: Many views about life’s origins (chemical engineering) simulators of young Earth to have been promulgated since the seminal work of demonstrate chemical evolution of multicomponent Oparin, Haldane, Schrödinger and Stanley Miller. But colloidal patterns at the gaseous(vapor)-liquid-solid they have remained controversial and mutually isolat- boundaries of Hadean seashores [12]. The top-down ed. They do not add up to a convincing scenario of proto-microbiology can be designed as cyclic ‘resur- life’s emergence for two reasons: (i) The proposed rection’ processes that re-assemble and evolve living scenarios have not taken advantage of constraints of- prokaryotes from their dead biomolecules and biom- fered by physical chemistry [1-3]. (ii) Many proposals acromolecules [13]. (Today’s PCR protocols echo the of ‘clean’ chemical reactions neglect Stanley Miller’s cyclic evolution of nucleic acids during the Hadean experimental fact that they create mixtures of organic eon.) The top-down and bottom-up approaches meet at tarry molecules [4]. Thus, the current ‘complexifica- the crowding transition, a key requirement for life to tion’ paradigm—prebiotic syntheses of life’s building emerge. The crowding transition signifies the cyclic blocks and their polymerizations and assembly into evolution of interacting proto-macromolecular surfac- proto-cells—lacks clear foundational principles. es at about 1 nm separations. This estimate reflects the The origins problem is currently viewed as refrac- range of commensurate interactions of the excluded tory to scientific inquiry, and its assumptions are be- volume effect (biomacromolecular crowding), hydro- ing re-assessed [e.g., 5-8]. How to proceed? One pos- gen bonding and screened electrostatic forces.1 sibility is to construct a physicochemical jigsaw puzzle Conclusion: Single-cell microbial life, the cyclic of prebiotic processes to serve as a firm framework for transmission of genetic information, emerged on the further research [1-3]. The suggested jigsaw puzzle fly from cyclic prebiotic tidal chemistry. Life did not satisfies the diagnostic criteria of prebiotic plausibil- spontaneously ‘self-assemble’ from a pool of prebiotic ity: planetary ubiquity, evolutionary continuity, and molecules—a physicochemical impossibility. physicochemical robustness [9]. References: [1] Spitzer J. et al. (2015) Biol. Di- The jigsaw puzzle of life’s emergence: The jig- rect. doi: 101186/s13062-015-0060-y. [2] Spitzer J. saw puzzle pieces described in Fig. 1 are underpinned (2017) J Mol Evol. doi 10.1007/s00239-016-9775-3. by cyclic (evolutionary) chemical reactions and phase [3] Spitzer J. (2019) Chapter 6.6. In “Handbook of separations that are concurrently and continuously Astrobiology”, CRC Press. [4] Shapiro R. (1986) stoked by two planetary energies: (i) solar radiation Origins, Schuster & Simon. [5] Sutherland J. D. impinging on the surfaces of rotating planets, and (ii) (2017). Nat Rev Chem. doi: 10.1038/s41570-016- the concurrent hydration and dehydration cycles of 0012. [6] Walker S. I. et al. (2017) Philos Trans A tidal seawater [10]. Without a regular, periodic supply Math Phys Eng Sci. doi: 10.1098/rsta.2016.0337. [7] of energy, first cellular organisms could not have Szostak J. W. (2017) Angew Chem Int Ed. doi: spontaneously self-assembled from prebiotic mole- 10.1002/anie.201704048. [8] Luisi P. L. (2014) Orig cules. The stoking of the ‘soup of chemicals’ in prebi- Life Evol Biosph. doi: 10.1007/s11084-014-9386-1. otic tidal environments created evolving patterns of [9] Deamer D. W. and Fleischaker G. R. (1994) Ori- chemical reactions and phase-separations, inevitably gins of life. Jones and Bartlett Publishers. [10] By- accompanied by purifications (compositional chemical water R. P. and Conde-Frieboes K. (2005) Astrobiolo- simplifications) on colloidal nano- and micro- scales. gy 5, 568–574. [11] Pauling L. and Delbrück M. The jigsaw puzzle is based on the Pau- (1940) Science 92, 77–79. [12] Spitzer J. (2013) As- ling-Delbrück premise of 1940 [11], specifying that trobiology 13, 404–413. [13] Spitzer J. (2014) Res current physicochemical laws (chiefly quantum me- Microbiol 165, 457–461. chanics and chemical thermodynamics) are sufficient to understand life. This premise contradicts Schrö- 1 The same non-covalent forces (the Pauling Delbrück prem- dinger’s 1944 call to look for new physical laws that ise) also suggest a model of bacterial cytoplasm based on could explain life. The jigsaw puzzle pieces—the evo- sol-gel transitions controlled by epigenetic biochemical reactions that attach ‘tags’ to biomacromolecules, e.g. phos- lutionary questions—identify research areas which phate or methyl groups. The transient gels are vectorially can be tackled through new kinds of experiments with wired by aqueous electrolytic channels that distribute power multicomponent compositions, using both ‘bottom-up’ and metabolites to molecular machines immobilized in the and ‘top-down’ approaches. The bottom-up prebiotic gels, while the disordered sol enables fast diffusion. Spitzer chemistry can be investigated by means of large J. (2011) Microbiol Mol Biol R 75, 491–506. Spitzer J. and Poolman B. (2013) FEBS Letts 587, 2094–2098. The First Billion Years: Habitability 2019 (LPI Contrib. No. 2134) 1003.pdf

Fig. 1. Pieces of the jigsaw puzzle of the emergence of first single-cell organisms.

After the formation of the Moon, Earth’s rotation slowed down and the Moon migrated away from Earth (black dotted arrow). Earth began to cool and the condensation of water initiated chemical evolution toward living states of matter [A]. Red arrows represent Earth’s daily chemical evolution; black arrows represent Earth’s chemical and microbiological evolution during the Hadean and Archaean eons (for one to two billion years).

[1] Earth cooled until water condensed and created the first seas. [2] Formation of colloidal compartments in tidal zones. [3] Persisting compartments begin to evolve, retaining chemical memory from previous cycles, a pre-condition for a potential evolution toward life [B]. [4] The principle of triple-coevolution of proto-proteins, proto-nucleic acids and proto-cell-envelopes through cyclic self-purifying processes toward phosphorus dominated carbon chemistry. [5] The crowding transition directs cyclic chemical evolution toward proto- microbiology and cellular life [C]. [6] Progenotes becoming alive through environmental cyclic energies [7] Progenotes becoming proto-cells with better enclosures and fast-evolving initial heredity. [8] Proto-cells become homeostatic, less dependent on cyclic environmental energies, with longer-term heredity, giving rise to LUCAs and Darwinian evolution [D].

LUCAs lived in the deep phylogenetic roots of the Tree of Life, from which three domains of life emerged: Bacteria, Archaea and Eukaryota [Sapp J. (2009) The New Foundations of Evolution. On the Tree of Life. Ox- ford University Press]. The First Billion Years: Habitability 2019 (LPI Contrib. No. 2134) 1015.pdf

Terrestrial Hot Spring Settings for the Origin of Life? The Role of Mixing Zones in Enhancing Microbial Complexity. Chanenath Sriaporn1, Kathleen A. Campbell2, Laura K. Penrose2, Michael Rowe2, Jeff Havig3, Trinity Hamilton4, Kim M. Handley1 and Martin Van Kranendonk5, 1School of Biological Sciences, University of Auckland, Auckland, New Zea- land, 2School of Environment, University of Auckland, Auckland, New Zealand, 3Department of Earth Sciences, University of Minnesota, Minnesota, USA, 4College of Biological Sciences, University of Minnesota, Minnesota, USA, 5School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney, Australia, (Corresponding Email: [email protected])

The terrestrial hot spring hypothesis of a warm little pond, first proposed by Charles Darwin in 1871, has been recently evaluated in depth and found to have many important attributes that may have contributed to life’s first beginnings on land rather than in the sea [1- 4]. This hypothesis comprises seven fundamental steps (Fig. 1). This includes synthesis and accumulation of organic molecules, in which their earlier forms were prevalent and could have been derived from space during terraforming. The compounds then concentrated in a warm little pond, i.e. early terrestrial hot springs. There they underwent many wetting and drying cycles and developed into progenotes and finally the last universal common ancestor (LUCA) evolved [4-5]. Ter- restrial hot spring environments can also exchange energy and materials by wind, splashing, flowing, or underground plumbing systems, allowing the distribution of progenotes from one hot pool to another. These Fig.1 The terrestrial hot spring origin of life hypothesis ancient forms of life, then, adapted specifically to such (Credit: Bruce Damer) pools, and finally started colonizing other habitats like coastal areas, and eventually the sea. References: Active hot springs systems can contain up to hun- [1] Deamer, D. W. (2011). First Life. University of dreds of pools, each with different pH, temperature, California Press chemistry, and activity level [6]. Variations and inter- [2] Deamer, D. W., & Georgiou, C. D. (2015). actions between pools allows an exchange of materials Hydrothermal conditions and the origin of cellular life. and energies. Here we studied mixing zones in modern Astrobiology, 15(12), 1091-1095. hot springs in New Zealand to gain a better understand- [3] Damer, B. (2016). A field trip to the Archaean ing of the influence of fluid mixing and variable ener- in search of Darwin’s warm little pond. Life, 6(2), 21. getics on microbial communities. [4] Van Kranendonk, M. J., Deamer, D. W., & Sampling sites were selected based on the presence Djokic, T. (2017). Life springs. Scientific American, of mixing zones between source pools or channels and 317(2), 28-35. mixing areas. Sediment samples were collected from [5] Di Giulio, M. (2011). The last universal com- four geothermal areas in the Taupo Volcanic Zone (Ti- mon ancestor (LUCA) and the ancestors of archaea and kitere, Rotokawa, Parariki Stream, and Wai-O-Tapu). bacteria were progenotes. Journal of molecular evolu- DNA extraction, PCR amplification and Next- tion, 72(1), 119-126. Generation Sequencing were conducted. DNA se- [6] Jones, B., & Renaut, R. W. (2011). Hot springs quencing results will be used to characterize the com- and geysers. Encyclopedia of geobiology, 447-451. positional change in microbial communities between source pools and mixing zones, and impacts on community diversity.

The First Billion Years: Habitability 2019 (LPI Contrib. No. 2134) 1035.pdf

EXAMINING THE POTENTIAL FOR HABITABILITY IN A POST-IMPACT REDUCING GREENHOUSE CLIMATE ON EARLY MARS. K. E. Steakley1, M. A. Kahre1, R. M. Haberle1, K. J. Zahnle1, 1NASA Ames Research Center, MS 245-3, Moffett Field, CA 94035, [email protected].

Introduction: Surface geologic evidence implies al. [10], now accounting for H2 delivered by these that liquid water altered Mars’s surface in various ways impacts to test whether this extends the duration of during the Late Noachian and Early Hesperian eras warm and wet conditions. We examine reducing (roughly 3.6 - 3.8 Gya) [1]. There is debate within the greenhouse post-impact climate conditions including community regarding what mechanism(s) may have global distributions of rainfall and warm surface induced warmer, wetter periods during the first billion temperatures and their evolution over time and assess years of Mars’s history and the timescales over which metrics of fractional habitability in these climates. they were active. Initial Conditions: In the early, extremely hot stage Collision induced absorption (CIA) between CO2 of a post-impact environment, reduced iron from an molecules and reducing greenhouse gases such as H2 impactor and water (from both an impactor and water and CH4 are one potential mechanism for inducing at that is excavated from the planet subsurface during least a temporary warm and wet climate on early Mars crater formation) can react to produce FeO and H2. Here [2, 3, 4]. However, it remains to be shown what could we estimate the amount of H2 that could be produced have produced reducing greenhouse gases in the from Fe and H2O given a few simple assumptions. We quantities required to raise surface temperatures above assume the impactor is an iron rich H-type ordinary freezing (molar mixing ratios of a few to 10% of a CO2 chondrite that is 30% iron by mass [14] and has a atmosphere depending on surface pressure; [3, 4]). density of 3.4 g/cm3. Assuming all the iron is used to Haberle et al. [5, 6] propose that asteroids could have make H2 (Fe + H2O → FeO + H2), we estimate that the been capable of delivering reducing greenhouse gases to atmospheric molar concentration of H2 produced by an early Mars via impact degassing. It has been suggested impact. Other compounds (e.g., CH4) could be that impact degassing could have maintained a reducing generated during this process, however, for this study atmosphere for the early Earth rich in CH4, H2, H2O, N2, we focus exclusively on the maximum amount of H2 and NH3 [7, 8, 9]. Haberle et al. [5, 6] calculate the that could be produced. Given these assumptions, quantities of H2 that could be delivered to early Mars by minimum impact diameters of roughly 83 km and 101 impacts and show that for large impactors (>100 km), km in 2- and 1- bar atmospheres respectively could they exceed quantities required to support above- produce molar concentrations (of 0.03 in a 2-bar freezing mean annual surface temperatures in a 1-bar atmosphere and 0.1 in a 1 bar atmosphere) high enough atmosphere according to Wordsworth et al. [3]. They to maintain surface temperatures > 270K [3]. It is estimate that the cumulative durations of above-freezing therefore feasible that impactors of the larger sizes surface temperatures due to impact degassing of H2 explored in Segura et al. [11, 12] and Steakley et al. [10] during the mid to late Noachian were of the order of 105 could have delivered planetwide warming quantities of – 106 years [6]. The impact hypothesis has the advantage hydrogen if they impacted atmospheres with large over other mechanisms in that there is ample evidence enough surface pressures. of crater formation during the Noachian, but is Here, we simulate a 2-bar CO2 atmosphere problematic for explaining some geologic observations following an impact by a 100-km diameter object in because the largest craters pre-date the end of valley which only the water and energy injected into the network activity and the formation of alluvial fans [10]. atmosphere by that impact are considered (Case A), and Previous assessments of potential post-impact a simulation in which Fe delivered by a 100-km impact greenhouse warming for early Mars focused only on the reacts with the H2O injected into the atmosphere to form water and energy delivered by impacts and show that – H2 (Case B). Following the post-impact initial although capable of inducing periods of above-freezing conditions described in Segura et al. [12], the temperatures and high rainfall rates – these effects are simulations are initialized with a vertical atmospheric short lived, on the order of a few years at most following temperature profile following the moist adiabatic lapse an individual impact [10, 11, 12, 13]. The introduction rate with a near-surface temperature of 700K. Initially, of H2 to an already warm and wet environment there is a hot (1500K) subsurface layer that is 2.23 m following an impact is an ideal way to prolong warm deep to represent a global debris layer formed from the and wet climate conditions on early Mars. Here, we use impact. Case A is initialized with a well-mixed a 3-D global climate model (GCM) to simulate post- atmospheric water vapor content equivalent to a 1.75-m impact scenarios similar to those explored in Steakley et thick layer of water if it were evenly distributed on the The First Billion Years: Habitability 2019 (LPI Contrib. No. 2134) 1035.pdf

surface. For case B, we initialize the simulation with a warm conditions above 273 K (as also shown in [3, 4]). well-mixed water vapor content equivalent to a global A clear potential issue for habitability in these layer 0.5566 m thick and a fixed molecular environments is the extremely high temperatures from concentration of hydrogen of 0.054 to account for the the impact itself. If these initial conditions could be quantities of H2O lost and H2 produced following a 100- survived, the resulting long-term conditions may be km diameter impactor that is 30% iron by mass. On the suitable for life. We will examine simulation results for timescales over which we run our simulation (15 Mars their potential to produce habitable environments, years), the escape rates of hydrogen from the including annual surface temperature variations, annual atmosphere (on the order of 1011 molecules cm-1 s-1 [3, rainfall patterns, and fractional habitability metrics with 6]) are negligible. respect to time and planet surface area as in Spiegel et Early Mars Global Climate Model: We utilize the al. [17]. NASA Ames Legacy early Mars Global Climate Model References: [1] Kite et al. (2019) Space Sci. Rev., (eMGCM), which is supported by the Agency’s Mars 25, 10. [2] Ramirez R. M., et al. (2014) Nat. Geosci., 7, Climate Modeling Center. This version of the model 59. [3] Wordsworth R., et al. (2017) Geophys. Res. Lett., uses an Arakawa C-grid dynamical core: ARIES version 44, 665. [4] Ramirez R. M., (2017) Icarus, 297, 71. [5] 2 [10]. A 2-stream radiative transfer scheme with Haberle R. M., et al. (2017) LPI Contrib. 2014, 3022. correlated-k’s accounts for gaseous CO2 and H2O [6] Haberle R. M., et al. (2018) LPSC vol. 49. pp. 1682. absorption. We incorporate the Wordsworth et al. [3] [7] Hashimoto G. L., et al. (2007) J. Geophys. Res., 112, coefficients for CO2-H2 CIA (adjusted by a factor of 1.6 E05010. [8] Schaefer L. and Fegley B. (2007), Icarus, as per Turbet et al. [15]) into the eMGCM radiation 186, 462–483. [9] Schaefer L. and Fegley B. (2010), treatment in addition to existing coefficients for CO2- Icarus, 208, 438–448. [10] Steakley et al. (2019), CO2 CIA. The radiative effects of liquid and ice H2O Icarus, 330, 169. [11] Segura T. L. et al. (2002) Science cloud particles are also accounted for [10]. Physical 298, 1977. [12] Segura T. L. et al. (2008) J. Geophys. treatments of water cloud microphysics in the eMGCM Res. (Planets) 113, E11007. [13] Turbet et al. (2019) include bulk H2O cloud condensation and sublimation arXiv e-prints, arXiv:1902.07666v1. [14] Kallemeyn G. when the atmosphere is supersaturated or sub-saturated W. et al. (1989) Geochimica et Cosmochimica Acta, 53, (with condensed cloud mass distributed equally 2747. [15] Turbet M., et al. (2019) Icarus, 321, 189. [16] between a constant number of spherical particles; 105 Gough D. O., (1981) Sol. Phys. 74, 21. [17] Spiegel D. condensation nuclei per kg of CO2), precipitation when S. et al. (2008) ApJ, 681, 1609. cloud mass mixing ratios exceed 0.001 kg of H2O per kg of CO2, gravitational sedimentation, and moist convection [10]. In these simulations, the CO2 cycle is excluded such that CO2 does not condense onto the surface nor condense to form clouds. Dust exists as condensation nuclei for H2O clouds but is not radiatively active, is not lifted from the surface, nor advected through the atmosphere. To represent the faint young Sun approximately 3.8 Gya, solar flux is decreased to 75% of its present day value [16]. Constant values are used for surface thermal inertia (250 J m-2 s- 1/2 K-1 ) and surface albedo (0.2 for regolith, 0.5 if surface ice is present, 0.07 if liquid surface water is present). Mars’ present day topography is used. Preliminary Results: We will present preliminary 3-D eMGCM simulation results examining post-impact environments which account for H2 impact degassing and those in which it is absent and will evaluate the potential habitability of these climates. We will specifically examine annual rainfall and surface temperature distributions in this assessment. Our preliminary eMGCM simulation results suggest that in the aftermath of a 100-km diameter impact in a 2-bar CO2 atmosphere with impact-degassed H2, surface temperatures initially cool rapidly but can equilibrate to The First Billion Years: Habitability 2019 (LPI Contrib. No. 2134) 1029.pdf

SURVIVABILITY OF CHEMOTROPHIC MICROORGANISMS IN MARTIAN-ANALOGUE WATER ACTIVITIES. Preston Tasoff 1,2 , Scott M. Perl1,3, Keith B. Chin1, Prarthana Desai4, Charles S. Cockell4

1NASA Jet Propulsion Laboratory, California Institute of Technology, Origins and Habitability Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 ([email protected]),2Department of Biology, Washington University in St. Louis, 1 Brookings Dr, St. Louis, MO 63130,3Mineral Sciences, Los Angeles Natural History Museum, 900 W Exposition Blvd, Los Angeles, CA 90007, 4University of Edinburgh, Old College, South Bridge, Edinburgh, UK, EH8 9YL.

Introduction: Life finds a unique way to adapt to Crater [14]. Furthermore, groundwater downwelling into changing and extreme environmental conditions; yet potential closed basin systems in the Martian subsurface liquid water is required by all organisms on earth as both may have provided low, but adequate aw to sustain a solvent and reactant to preform essential biological drought tolerant life as we know of on Earth. Our goals processes. Water activity (aw), the measure of are to quantify the aw needed to sustain microbial chemically unbound water in a substance, determines metabolism. cellular osmosis via gradients established from higher Methods: Experiments were conducted in our EIS extracellular water activities. In low aw environments instrument (Figure 1), capable of in-situ electrochemical such as arid or high saline, osmotic stress forces cells to impedance spectroscopy, variable humidity controls, shut off their processes and go dormant or even die [1]. temperature (-70° to 190°), N2 purging, and 2 to 4 From extensive research in the food safety industry, we electrode configurations based on sample type [15]. We know that most of life thrives over a range of aw from used chemotrophic Bacillus subtilis (ATCC 6051) and 1.0 (pure water) to .7 for more robust halophiles [2], Deinococcus radiodurans (ATCC BAA-816D-5) even .62 in extreme cases [3]. bacteria because of their ability to survive in anoxic, low Most of Earth’s crust lies between aw of .98 and 1.0 solar flux environments using Martian occurring organics [4], seawater at .98, and closed basin systems such as and inorganics as an energy source. Neither of these the Great Salt Lake ~.75 due to increasing salinities organisms are xerophilic in nature, B. subtilis preferring which decrease aw values (3.5% salt in seawater vs. 23- aw around .90 [16], while D. radiodurans is hardier to 27% for Great Salt Lake) [2,5]. However little research desiccation [17]. Therefore, the microbes ability to adapt is available on the necessary water activities in to or endure low water activity could be studied. sedimentary settings needed to sustain life in terrestrial Prior to microbial introduction and growth, we settings and planetary analogues. Our goals for this adjusted EIS chamber humidity to establish our research investigation is to fill in these gaps for both experimental water activities as a function of electrical baseline aw and usage of these values for Martian current in our control (Martian soil analogue MMS-2 [18] sedimentary material comparisons. and Media: Figure 2A). We then tested B. subtilis in and Motivation: It is estimated that evaporation of D. radiodurans in TGY media, each in two cups at 30°C Meridiani groundwater in the late Noachian/early for 3 hours and 9 hours respectively at aw’s of 1.0, .92, Hesperian led to a sustained aw of 0.78 to 0.86 [4]. These .89, .86, and .83 (Figure 2B). estimates are based on sedimentary analysis of We used a three diode EIS system to monitor redox groundwater diagenesis in the Burns Formation at currents produced by chemolithotrophs in real time Meridiani Planum [6,7], layering at Gale crater, and showing instantaneous water activity effects on global hydrated mineralogy as observed by metabolism. Raman spectroscopy on the inorganic broth MRO/CRISM and the OMEGA instrument on Mars before and after experiment determined how much Express [8-11]. If life evolved on Mars to the point of substrate had been oxidized by the bacteria. utilizing chemical molecules as an energy source (chemotrophy), the adaptation of those organisms to low aw would be necessary for survival. We seek to replicate Martian analogue water activities in vitro with chemotrophs to determine if life can indeed find a way to survive and carry out metabolic processes in low solar flux and xerophilic conditions that occurred globally on Mars well into the Amazonian period. Ongoing work [12] showed that hydrated mineral evaporites, including modern gypsum clays and halite salts from Great Salt Lake, can preserve and maintain μm-scale habitats and DNA. Preservation was six-fold higher in gypsum clays which naturally precipitate at higher aw (determined by Usiglio in 1884 [13]), suggesting a correlation between Figure 1: EIS chamber and sample cup with diode high aw and the ability to preserve and/or harbor life. configuration capable of measuring current. These evaporites occur globally on Mars in areas of past surface and groundwater movement such as Jezero The First Billion Years: Habitability 2019 (LPI Contrib. No. 2134) 1029.pdf

low aw may be a proxy for Martian life because of their flexibility in adapting to available ions [12], changing solar conditions, and water burial. Our experiment shows using EIS technology we can study metabolisms in real time for microbes in Martian environmental conditions. After baseline EIS measurements for water activity we will use the MUFFINS water activity sensor [20] for additional instrument comparisons. Future experiments in EIS can include UV conditions and eventually pressure conditions to create a near complete analogue for closed basin aquifers in the Martian subsurface.

References: [1] Ho S. N. (2005) J. Cell. Phys, 206,1,15-19. [2] Shultz, 2016, J. Med. Thera,1,1. [3] Leong et al. (2011) Int. J. Food Microbio, 31,145(1),57- 63. [4] Tosca et al (2008) Sci,320,1204-7. [5] Baxter, B Figure 2: (A) Control setup to establish water activity in (2018) Int. Microbio., 21:79–95 [6] Andrews-Hanna et al. the absence of microbes (B) Microbes added and brought (2010) JGPR, 115,E06002. [7] McLennan et al. (2005) to established humidity for water activity. EPSL, 240,95-121. [8] Murchie et al. (2008) JGPR, 114,E00D05. [9] Ehlmann et al. (2011) AREPS, Discussion: Low water activity presents habitability 42,1,291-315. [10] Seelos et al. (2014) challenges for both ancient and modern mars. Ancient doi:10.1002/2014GL060310. [11] Arvidson et al. (2004) closed-basin, subsurface aquifers may have supported AGU abstract. [12] Perl et al. (2019, submitted) Astrobio. life that could adapt to the changing conditions; the >@%ąEHO06FKUHLEHU%& 5HI in ESES, mystery of RSL’s could support the presence of a liquid 9,483-560. [14] Ehlmann, B. L. and Edwards, C. S. groundwater system even today [19]. In either case, (2014) AREPS, 42,291-315. [15] Chin, K.B. (2019) Mars contains a plethora of inorganics used by AbSciCon 2019, abstract. [16] Sperber, W.H. (1983) J. chemolithotrophs on Earth such as iron-sulfide reducing Food Protection, 46,2,142-150. [17] Bauermeister, A. or perchlorate-nitrate reducing microbes. If the highest (2011) Microb. Ecol., 61,715–722. [18] Peters et al. level of aw available occurred in the subsurface, (2008) Icarus,197,470-479. [19] Ohja et al. (2015) Nat. chemotrophy would be the only sustainable form of Geosci. 8,829–832 . [20] Desai, P. (2019) AbSciCon metabolism. Therefore, chemotrophs that can survive 2019, abstract.

The First Billion Years: Habitability 2019 (LPI Contrib. No. 2134) 1030.pdf

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METEORITE ALLAN HILLS (ALH) 84001: IMPLICATIONS FOR MARS’ INHABITATION AND HABITABILITY. Allan H. Treiman. Lunar and Planetary Institute, 3600 Bay Area Blvd., Houston TX 77058

Introduction: Meteorite ALH 84001, home to ed. The bacteria-shaped objects are, most likely, arte- putative signs of ancient martian life, is the most in- facts produced by gold-coating (for SEM analysis) of tensely studied martian sample. As such, it provided ridges on a weathered mineral surface [15]. evidence (albeit a single point) on potentially habita- Magnetite Grains. The carbonate globules in ALH ble conditions on early Mars, and a case study in what 84001 contain a variety of submicron grains of mag- sorts of evidence might be acceptable as signs of ex- netite, which are concentrated in clearly defined lay- traterrestrial life. ers. A quarter of these magnetites were suggested as ALH 84001 & Mars Life: The meteorite ALH biosignatures, based on their size distribution, shapes 84001 is an orthopyroxenite – composed primarily of [16] and compositions [17], all seen as distinctive of that mineral with lesser chromite, augite, glass of pla- grains from magnetotactic bacteria However, these gioclase- and silica-rich compositions, olivine, and magnetite grains are not of the distinctive magneto- apatite; it was first classified as an diogenite (asteroi- tactic shape [18], their size distribution is consistent dal), and was later recognized as Martian [1]. It in- with inorganic processes [19], and their compositions cludes disc-shaped and hemispherical globules of are consistent with abiotic formation [20]. (primarily) Fe-Mg carbonate minerals [2] that contain Summary. Although some people remain con- sub-micron magnetite grains [3] and organic matter vinced that ALH 84001 contains proof of ancient mar- [h4]. The meteorite has experienced several intense tian life [21] the preponderance of evidence is that all shock events [5,6]. the putative biosignatures reported in ALH 84001 are McKay et al. [4] proposed that ALH 84001 con- either natural inorganic products or analytical arte- tained signs of ancient Martian life – that the combi- facts. nation of chemically zoned carbonate globules, bacte- Habitability on Mars: ria-shaped objects, polycyclic aromatic hydrocarbons, Early Aqueous Environment. From the chemical and magnetite grains that resembled those from mag- zoning and isotope thermometry, it is clear that the netotactic bacteria constituted a strong biosignature. ALH 84001 carbonate globules formed at low tem- Anders [7] argued that these characteristics could (and perature [2,10], and thus from aqueous fluids. The do) arise from simple inorganic processes, and that [4] changes in the carbonate compositions (from CaCO3- was inherently biased towards biogenic origins. rich cores to (Fe,Mg)CO3 mantles to MgCO3 rims) Carbonate Globules. Chemically zoned Fe-Mg bespeaks regular and oscillating changes in fluid carbonates occur in carbonaceous chondrite meteor- compositions [22,23] ites [7], where they are certainly abiotic. Similar The aqueous history was, however, more complex. globules also occur in volcanics on Earth [k8], and The rock must have contained open (fluid-filled) seem to be a common alteration product. The car- spaces, into which the carbonate hemispheres could bonate globules formed at low temperatures, as im- have grown unimpeded [5,8]. These open spaces were plied by their strong chemical zoning [2,9], and prov- crushed closed in the later impact shocks that pro- en by clumped oxygen isotopes [10]. duced the rock’s plagioclase-composition glasses. Organic Matter. The organic matter in ALH composition glass, interpreted as shock melts [5,6]. 84001 includes complex polycyclic aromatic hydro- But how could these void spaces form? ALH carbons (PAHs) [l11,12], which are known to form 84001 was (at that point) a shocked plutonic rock, and abiotically in Fischer-Tropsch-like reactions [7]. unlikely to have had primary void space. It was noted Much of the organic matter is indigenous (i.e., Mar- that carbonate hemispheres were spatially associated tian) [13], although the rock has been invaded by ter- with olivine [24], which led to the suggestion that the restrial biota [14]. No martian PAHs of convincing void spaces formed by the dissolution of olivine [25], biogenic heritage have been reported. as described in terrestrial analogs [8]. “Nanobacteria”. McKay et al. [h4] figured sever- There is evidence (albeit thin) of aqueous activity al sub-micron cylindrical objects on broken surfaces after formation of the carbonate globules, but before of ALH84001, and inferred that they were mineral- the shock event that crushed the rock’s porosity. Phyl- ized Martian bacteria. These observation have been losilicates are reported in the carbonate globules [26- replicated, i.e. the objects in [4] have not been re- 28], with textures suggesting formation after the car- imaged, and additional objects have not been report- bonates [27,28]. The aqueous history of ALH 84001 The First Billion Years: Habitability 2019 (LPI Contrib. No. 2134) 1032.pdf

then includes: (1) dissolution of igneous olivine; (2) vides another data point on the range of possible hab- deposition of carbonate minerals, dominantly Fe-Mg; itable environments on early Mars. and (3) alteration of the carbonates to form phyllosilicates. Acknowledgments: Work excerpted here was This sequence of aqueous alteration nearly identi- supported by NASA Cosmochemistry and SSW cal to that in the nakhlite meteorites [29,30], although grants, and the MSL mission. to different extents. Most nakhlites contain little carbonate remaining, it having been replaced by phyllo- References: [1] Mittlefehldt D.W. (1994) Meteoritics silicate; and the nakhlites contain late-stage amor- 29, 214-221. [2] Valley J.W. et al. (1997) Science phous silicate ‘gel,’ which has not been noted in ALH 275, 1633-1638. [3] Bradley J.P. et al. (1996) GCA 84001. Thus, it is possible that aqueous alterations in 60, 5149-5155. [4] McKay D.S. et al. (1996) Science both the ALH 84001 and the nakhlites represented the 273, 924–930. [5] Treiman A.H. (1995) Meteoritics same sort of process on Mars (e.g., impact induced 30, 294-302. [6] Treiman A.H. (1998) MaPS 33, 753- hydrothermal systems [31]), albeit separated by sever- 764. [7] Anders E. (1996) Science 274, 2119-2120. al thousand million years. [8] Treiman A.H. et al. (2002) EPSL 204, 323-332. For ALH 84001, its aqueous alteration history ap- [9] Kent A.J.R. et al. (2001) GCA 65, 311-321. [10] pears to represent a series of potentially habitable Halevy I. et al. (2011) PNAS 108, 16895-16899. [11] Stephan T. et al. (2003) MaPS 38, 109-116. [12] environments (although not, with available data, in- Steele A. et al. (2007) MaPS 42, 1549-1566. [13] habited [32]). The waters were carbonate-rich and Clemett S. et al. (1998) Faraday Discussions 109, neutral-to-alkaline (presence of carbonates and ab- 417-436. [14] Steele A. et al. (2000) MaPS 35, 237- sence of jarosite etc.), saline (presence of halite), and 241 [15] Bradley J.P. et al. (1997) Nature 390, 454- ranging from low to high oxidation states (ferrous 456. [16] Thomas-Keprta K.L. et al. (2000) GCA 64, carbonates to ferric-bearing phyllosilicates). These 4049-4081. [17] Thomas-Keprta K.L. et al. (2009) conditions are different from those inferred for the GCA 73, 6631-6677. [18] Golden D.C. et al. (2004) Gale Crater Lake – near-neutral, low salinity, low in Am. Min. 89, 681-695. [19] Treiman A.H. (2003) As- carbonate and of varying oxidation states [33-35]. The trobiology 3, 369-392. [20] Treiman A.H. & Essene oxygen isotope composition of the ALH 84001 car- E.J. (2011) GCA 75, 5324-5335. [21] Joseph R.G. et bonates indicates an atmospheric component [ak], al. (2019) J. Astrobiology Space Science Reviews 1, suggesting that the carbonate was remobilized from 40-81. [22] Corrigan C.M. & Harvey R.P. (2004) older sedimentary carbonate deposits [37]. MaPS 39, 17-30. [23] Niles P.B. et al. (2009) EPSL Later Desiccated Environment. There is minimal 286, 122-130. [24] Shearer C.K. et al. (1999) MaPS evidence that ALH 84001 encountered any liquid wa- 34, 331-339. [25] Treiman A.H. (2005) LPSC 36th, ter in the billions of years after its carbonate globules Abstr. 1107. [26] Thomas-Keprta et al. (2000) LPSC (and phyllosilicates) were deposited. The meteorite’s 31st, abstr. 1690. [27] Brearley A.J. (2000) LPSC 31st glasses, of plagioclase- and silica-rich composition, , Abstr. 1204. [28] Barker W.W. & Banfield, J.F. are intact. There have been no reports that the glasses (1999) GSA Annual Meeting, Abstract 51462. [29] have been altered (e.g. to form clay minerals) or de- Lee M.R. et al. (2015) GCA 154, 49-65. [30] Bridges vitrified (e.g., to form a crystalline silica phase). J.C. & Schwenzer S.P. (2012) EPSL 359, 117-123. Of similar significance is the preservation of high- [31] Schwenzer S.P. & Kring D.A. (2013) Icarus 226, ly strained orthopyroxene [5,6], recognized by spatial- 487-496. [32] Cockell C.S. et al. (2012) Icarus 217, ly varying optical extinction positions. Orthopyroxene 184-193. [ag] Grotzinger J.P. et al. (2014) Science 343, 1242777. [ah] Bristow T.F. et al. (2017) PNAS alters readily in aqueous environments [38], and one 114, 2166-2170. [aj] Hurowitz A.J. et al. (2017) Sci- would expect shock-strained opx to be even more ence 356, 922. [36] Farquhar J. et al. (1998) Science susceptible to aqueous alteration. 280, 1580-1582. [37] Michalski J.R. & Niles P.B. Conclusions: The enormous wealth of data col- (2010) Nature Geoscience 3, 751 [38] Phillips-Lander lected on the ALH 84001 martian meteorite provides C.M. et al. (2019) GCA 257, 336-353. a benchmark of sorts for investigating and understanding ancient habitable environments on Mars, and their potential or putative inhabitants. The long controversy about whether ALH 84001 preserves evidence of ancient martian life helps understand what type of evidence can be accepted as proof. Understanding the chemistry of the aqueous deposits in ALH 84001 pro- The First Billion Years: Habitability 2019 (LPI Contrib. No. 2134) 1022.pdf

Habitable zones : A new approach to physical factors. S.R. Valuri1 and V.T.Sangli2, 1RNSIT, ([email protected]), 2TISB ([email protected]).

Introduction: The long, detailed world of habitable planets has uprooted far more questions than has planted seeds of answers. As we push the boundaries for what we consider " Habitable," we start to spiral into problems of what can and cannot be regarded as life-supporting. As we look for planets that are like the earth and regularly refer to the "Earth Similarity Index," we tend to forget that not all parts of the planet are and were conducive for life to exist. Even the earth has its own Goldie locks zone. One of the main physical features the paper looks at is - Axis Inclination and inclination angles. We build a comparative study of earth and Earth-like planets that suggests that one of the main differentiating factors is the Axis Inclination and rotational rate. To combat the problem of - "Exoplanets with very similar physical features show no earth-like signs" (when it comes to life support systems), we suggest looking at new physical characteristics that contribute to concentrated habitable zones. To examine the formation of habitable zones on planets, we also look at orbital mechanics of early stellar system formations and dynamics. The paper mainly reviews the solar systems orbital mechanics that led to the tilt and inclination angle in the earth's axis and orbit. As we study and work through the planet and system's intertwining dynamics, we talk about the influence of different physical features that play a role in creating habitable zones. The article thoroughly examines the known primary 4 and sub two physical characteristics that help us speculate about habitable zones; introducing the roles of obliquity and the proposition of looking for these compartmentalized zones on exoplanets than ideal earth-like planets.

The First Billion Years: Habitability 2019 (LPI Contrib. No. 2134) 1018.pdf

ROLE OF IONS IN THE SORPTION OF AMINO ACIDS ONTO SERPENTINITE: ESSAYS OF PREBIOTIC CHEMISTRY. S. Villafañe-Barajas1, M. Colín-Garcia.2, A. Negrón-Mendoza3, F. Ortega2 and A. Becerra Bracho4 1Posgrado en Ciencias de la Tierra, Universidad Nacional Autónoma de México, Ciudad Universi- taria, 04510 Cd. Mx., México, [email protected] 2 Instituto de Geología, Universidad Nacional Autóno- ma de México, Ciudad Universitaria, 04510 Cd. Mx., México [email protected] [email protected] 3, Insti- tuto de Ciencias Nucleares, Universidad Nacional Autónoma de México, Ciudad Universitaria, 04510 Cd. Mx., Mé- xico, [email protected] 4 Facultad de Ciencias, Universidad Nacional Autónoma de México, Ciudad Uni- versitaria, 04510 Cd. Mx., México, [email protected]

Introduction: The sorption process of organic mole- the result of the formation of "bridges", mediated by cules is fundamental to understand the mechanisms that the cations present in solution, between the COO- could happen during the early stages of the primitive group of the amino acids and the negative surface Earth. Although several experiments have shown the charge of the serpentine. In addition, the formation of sorption capability of different minerals, most of the hydrogen bonds and other types of interactions may be simulations have been performed using distilled water relevant in the interaction between amino acids and or simple models of sea-water as reaction milleus1. In minerals at different pH values. this way, performing experiments that take into account some of the geochemical variables that were present in The sorption experiments of Gly, Ala, Glu and Asp in a possible "primitive environment" allows one to un- serpentinite showed: derstand the sorption processes that led to greater molecular complexity. In this work, the sorption of glycine 1. The presence of dissolved ions (HWM) favors sorp- (Gly), alanine (Ala), glutamic acid (Glu) and aspartic tion in all cases. Particularly, the divalent cations can acid (Asp) onto serpentinite was performed considering act as bridges between the negative charge of the COO- a “hydrothermal water model” (HWM). In the same group and the surface oxygens. way, the experiments were performed at different pH values. Our HWM is based in the recipe of Zaia1, 2. At acid, natural and basic pH the sorption is relative- which is mainly enriched in Na+, Cl- and Ca2+ ions. ly low (<≈20%). In this way, electrostatic interactions are not the dominant sorption mechanism.

3. The formation of hydrogen bonds and / or covalent bonds may be other mechanisms that participate in the sorption process.

Figure 1. Percentage of amino acid sorption at acid, natural, basic pH and in the presence of dissolved ions, HWM.

Results: The results suggest that dissolved ions im- Figure 2. Speciation of the amino acids used and the serpentinite. prove the sorption of amino acids, even at basic conditions (Fig. 1). On the other hand, at natural and acidic References: pH, the sorption in considerably low (20 %) in all cases. According to Figure 2, the four amino acids are [1] Lambert, J. F. (2008) Origins Life Evol B, 38(3), predominantly in their anionic form at basic pH 211-242. (pH≈12). Similarly, at that pH the surface charge of [2] Zaia, D. A. (2012). Int J Astrobiol 11(4), 229-234. the serpentinite is strongly negative. Consequently, the interaction by electrostatic charges cannot be the Acknowledgment mechanism that dominates the sorption process and SAVB thanks CONACyT for the grant, Posgrado Ciencias therefore, the percentage of sorption does not exceed de la Tierra and technical support of Chem. Claudia Ca- margo Raya. This work was performed at the laboratory of 15% (Fig. 1). However, in the presence of dissolved Chemical Evolution of the Instituto de Ciencias Nucle- ions, the sorption increases considerably. This can be ares,UNAM. The First Billion Years: Habitability 2019 (LPI Contrib. No. 2134) 1019.pdf

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