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Bains W, Petkowski JJ, Seager S. Venus' Atmospheric Chemistry and Cloud Characteristics Are Compatible with Venusian Life. ASTROBIOLOGY 2024; 24:371-385. [PMID: 37306952 DOI: 10.1089/ast.2022.0113] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Venus is Earth's sister planet, with similar mass and density but an uninhabitably hot surface, an atmosphere with a water activity 50-100 times lower than anywhere on Earths' surface, and clouds believed to be made of concentrated sulfuric acid. These features have been taken to imply that the chances of finding life on Venus are vanishingly small, with several authors describing Venus' clouds as "uninhabitable," and that apparent signs of life there must therefore be abiotic, or artefactual. In this article, we argue that although many features of Venus can rule out the possibility that Earth life could live there, none rule out the possibility of all life based on what we know of the physical principle of life on Earth. Specifically, there is abundant energy, the energy requirements for retaining water and capturing hydrogen atoms to build biomass are not excessive, defenses against sulfuric acid are conceivable and have terrestrial precedent, and the speculative possibility that life uses concentrated sulfuric acid as a solvent instead of water remains. Metals are likely to be available in limited supply, and the radiation environment is benign. The clouds can support a biomass that could readily be detectable by future astrobiology-focused space missions from its impact on the atmosphere. Although we consider the prospects for finding life on Venus to be speculative, they are not absent. The scientific reward from finding life in such an un-Earthlike environment justifies considering how observations and missions should be designed to be capable of detecting life if it is there.
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Affiliation(s)
- William Bains
- Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
- School of Physics and Astronomy, Cardiff University, Cardiff, United Kingdom
| | - Janusz J Petkowski
- Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
- JJ Scientific, Warsaw, Poland
| | - Sara Seager
- Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
- Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
- Department of Aeronautics and Astronautics, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
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2
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Mráziková K, Knížek A, Saeidfirozeh H, Petera L, Civiš S, Saija F, Cassone G, Rimmer PB, Ferus M. A Novel Abiotic Pathway for Phosphine Synthesis over Acidic Dust in Venus' Atmosphere. ASTROBIOLOGY 2024; 24:407-422. [PMID: 38603526 DOI: 10.1089/ast.2023.0046] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/13/2024]
Abstract
Recent ground-based observations of Venus have detected a single spectral feature consistent with phosphine (PH3) in the middle atmosphere, a gas which has been suggested as a biosignature on rocky planets. The presence of PH3 in the oxidized atmosphere of Venus has not yet been explained by any abiotic process. However, state-of-the-art experimental and theoretical research published in previous works demonstrated a photochemical origin of another potential biosignature-the hydride methane-from carbon dioxide over acidic mineral surfaces on Mars. The production of methane includes formation of the HC · O radical. Our density functional theory (DFT) calculations predict an energetically plausible reaction network leading to PH3, involving either HC · O or H· radicals. We suggest that, similarly to the photochemical formation of methane over acidic minerals already discussed for Mars, the origin of PH3 in Venus' atmosphere could be explained by radical chemistry starting with the reaction of ·PO with HC·O, the latter being produced by reduction of CO2 over acidic dust in upper atmospheric layers of Venus by ultraviolet radiation. HPO, H2P·O, and H3P·OH have been identified as key intermediate species in our model pathway for phosphine synthesis.
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Affiliation(s)
- Klaudia Mráziková
- J. Heyrovský Institute of Physical Chemistry, Czech Academy of Sciences, Prague, Czechia
| | - Antonín Knížek
- J. Heyrovský Institute of Physical Chemistry, Czech Academy of Sciences, Prague, Czechia
- Department of Physical and Macromolecular Chemistry, Faculty of Science, Charles University, Prague, Czechia
| | - Homa Saeidfirozeh
- J. Heyrovský Institute of Physical Chemistry, Czech Academy of Sciences, Prague, Czechia
| | - Lukáš Petera
- J. Heyrovský Institute of Physical Chemistry, Czech Academy of Sciences, Prague, Czechia
- Department of Inorganic Chemistry, Faculty of Science, Charles University, Prague, Czechia
| | - Svatopluk Civiš
- J. Heyrovský Institute of Physical Chemistry, Czech Academy of Sciences, Prague, Czechia
| | - Franz Saija
- Institute for Physical-Chemical Processes, National Research Council of Italy (IPCF-CNR), Messina, Italy
| | - Giuseppe Cassone
- Institute for Physical-Chemical Processes, National Research Council of Italy (IPCF-CNR), Messina, Italy
| | - Paul B Rimmer
- University of Cambridge, Cavendish Astrophysics, Cambridge, United Kingdom
| | - Martin Ferus
- J. Heyrovský Institute of Physical Chemistry, Czech Academy of Sciences, Prague, Czechia
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3
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Schulze-Makuch D, Irwin LN, Irwin T. Proposed Missions to Collect Samples for Analyzing Evidence of Life in the Venusian Atmosphere. ASTROBIOLOGY 2024; 24:397-406. [PMID: 37852009 DOI: 10.1089/ast.2022.0134] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/20/2023]
Abstract
The recent and still controversial claim of phosphine detection in the venusian atmosphere has reignited consideration of whether microbial life might reside in its cloud layers. If microbial life were to exist within Venus' cloud deck, these microorganisms would have to be multi-extremophiles enclosed within the cloud aerosol particles. The most straightforward approach for resolving the question of their existence is to obtain samples of the cloud particles and analyze their interior. While developing technology has made sophisticated in situ analysis possible, more detailed information could be obtained by examining samples with instrumentation in dedicated ground-based facilities. Ultimately, therefore, Venus Cloud-level Sample Return Missions will likely be required to resolve the question of whether living organisms exist in the clouds of Venus. Two multiphase mission concepts are currently under development for combining in situ analyses with a sample return component. The Venus Life Finder architecture proposes collection of cloud particles in a compartment suspended from a balloon that floats for weeks at the desired altitude, while the Novel solUtion for Venus explOration and Lunar Exploitation (NUVOLE) concept involves a glider that cruises within the cloud deck for 1200 km collecting cloud aerosol particles through the key regions of interest. Both architectures propose a rocket-driven ascent with the acquired samples transported to a high venusian orbit as a prelude to returning to Earth or the Moon. Both future conceptual missions with their combined phases will contribute valuable information relative to the habitability of the clouds at Venus, but their fulfillment is decades away. We suggest that, in the meantime, a simplification of a glider cloud-level sample collection scenario could be accomplished in a shorter development time at a lower cost. Even if the cloud particles are not organic and show no evidence of living organisms, they would reveal critical insights about the natural history and evolution of Venus.
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Affiliation(s)
- Dirk Schulze-Makuch
- Astrobiology Group, ZAA, Technical University Berlin, Berlin, Germany
- Section Geomicrobiology, GFZ German Research Center for Geosciences, Potsdam, Germany
- Department of Experimental Limnology, Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB), Stechlin, Germany
- School of the Environment, Washington State University, Pullman, Washington, USA
| | - Louis N Irwin
- Department of Biological Sciences, University of Texas at El Paso, El Paso, Texas, USA
| | - Troy Irwin
- Oasis Systems, LLC, San Antonio, Texas, USA
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4
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Petkowski JJ, Seager S, Grinspoon DH, Bains W, Ranjan S, Rimmer PB, Buchanan WP, Agrawal R, Mogul R, Carr CE. Astrobiological Potential of Venus Atmosphere Chemical Anomalies and Other Unexplained Cloud Properties. ASTROBIOLOGY 2024; 24:343-370. [PMID: 38452176 DOI: 10.1089/ast.2022.0060] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/09/2024]
Abstract
Long-standing unexplained Venus atmosphere observations and chemical anomalies point to unknown chemistry but also leave room for the possibility of life. The unexplained observations include several gases out of thermodynamic equilibrium (e.g., tens of ppm O2, the possible presence of PH3 and NH3, SO2 and H2O vertical abundance profiles), an unknown composition of large, lower cloud particles, and the "unknown absorber(s)." Here we first review relevant properties of the venusian atmosphere and then describe the atmospheric chemical anomalies and how they motivate future astrobiology missions to Venus.
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Affiliation(s)
- Janusz J Petkowski
- Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
- Faculty of Environmental Engineering, Wroclaw University of Science and Technology, Wroclaw, Poland
- JJ Scientific, Mazowieckie, Warsaw, Poland
| | - Sara Seager
- Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
- Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
- Department of Aeronautics and Astronautics, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | | | - William Bains
- Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
- School of Physics and Astronomy, Cardiff University, Cardiff, UK
| | - Sukrit Ranjan
- Lunar and Planetary Laboratory, Department of Planetary Sciences, University of Arizona, Tucson, Arizona, USA
| | - Paul B Rimmer
- Department of Earth Sciences, University of Cambridge, Cambridge, UK
- Cavendish Laboratory, University of Cambridge, Cambridge, UK
- MRC Laboratory of Molecular Biology, Cambridge, UK
| | - Weston P Buchanan
- Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
- School of Aeronautics and Astronautics, Purdue University, West Lafayette, Indiana, USA
| | - Rachana Agrawal
- Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Rakesh Mogul
- California Polytechnic University, Pomona, California, USA
| | - Christopher E Carr
- School of Aerospace Engineering and School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, Georgia, USA
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5
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Lingam M. Information Transmission via Molecular Communication in Astrobiological Environments. ASTROBIOLOGY 2024; 24:84-99. [PMID: 38109216 DOI: 10.1089/ast.2023.0069] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2023]
Abstract
The ubiquity of information transmission via molecular communication between cells is comprehensively documented on Earth; this phenomenon might even have played a vital role in the origin(s) and early evolution of life. Motivated by these considerations, a simple model for molecular communication entailing the diffusion of signaling molecules from transmitter to receiver is elucidated. The channel capacity C (maximal rate of information transmission) and an optimistic heuristic estimate of the actual information transmission rate ℐ are derived for this communication system; the two quantities, especially the latter, are demonstrated to be broadly consistent with laboratory experiments and more sophisticated theoretical models. The channel capacity exhibits a potentially weak dependence on environmental parameters, whereas the actual information transmission rate may scale with the intercellular distance d as ℐ ∝ d-4 and could vary substantially across settings. These two variables are roughly calculated for diverse astrobiological environments, ranging from Earth's upper oceans (C ∼ 3.1 × 103 bits/s; ℐ ∼ 4.7 × 10-2 bits/s) and deep sea hydrothermal vents (C ∼ 4.2 × 103 bits/s; ℐ ∼ 1.2 × 10-1 bits/s) to the hydrocarbon lakes and seas of Titan (C ∼ 3.8 × 103 bits/s; ℐ ∼ 2.6 × 10-1 bits/s).
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Affiliation(s)
- Manasvi Lingam
- Department of Aerospace, Physics and Space Sciences, Florida Institute of Technology, Melbourne, Florida, USA
- Department of Physics, The University of Texas at Austin, Austin, Texas, USA
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6
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Malaterre C, Ten Kate IL, Baqué M, Debaille V, Grenfell JL, Javaux EJ, Khawaja N, Klenner F, Lara YJ, McMahon S, Moore K, Noack L, Patty CHL, Postberg F. Is There Such a Thing as a Biosignature? ASTROBIOLOGY 2023; 23:1213-1227. [PMID: 37962841 DOI: 10.1089/ast.2023.0042] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
The concept of a biosignature is widely used in astrobiology to suggest a link between some observation and a biological cause, given some context. The term itself has been defined and used in several ways in different parts of the scientific community involved in the search for past or present life on Earth and beyond. With the ongoing acceleration in the search for life in distant time and/or deep space, there is a need for clarity and accuracy in the formulation and reporting of claims. Here, we critically review the biosignature concept(s) and the associated nomenclature in light of several problems and ambiguities emphasized by recent works. One worry is that these terms and concepts may imply greater certainty than is usually justified by a rational interpretation of the data. A related worry is that terms such as "biosignature" may be inherently misleading, for example, because the divide between life and non-life-and their observable effects-is fuzzy. Another worry is that different parts of the multidisciplinary community may use non-equivalent or conflicting definitions and conceptions, leading to avoidable confusion. This review leads us to identify a number of pitfalls and to suggest how they can be circumvented. In general, we conclude that astrobiologists should exercise particular caution in deciding whether and how to use the concept of biosignature when thinking and communicating about habitability or life. Concepts and terms should be selected carefully and defined explicitly where appropriate. This would improve clarity and accuracy in the formulation of claims and subsequent technical and public communication about some of the most profound and important questions in science and society. With this objective in mind, we provide a checklist of questions that scientists and other interested parties should ask when assessing any reported detection of a "biosignature" to better understand exactly what is being claimed.
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Affiliation(s)
- Christophe Malaterre
- Département de philosophie, Chaire de recherche du Canada en philosophie des sciences de la vie, Université du Québec à Montréal (UQAM), Montréal, Québec, Canada
- Centre interuniversitaire de recherche sur la science et la technologie (CIRST), Université du Québec à Montréal (UQAM), Montréal, Québec, Canada
| | - Inge Loes Ten Kate
- Department of Earth Sciences, Utrecht University, Utrecht, the Netherlands
| | - Mickael Baqué
- Planetary Laboratories Department, Institute of Planetary Research, German Aerospace Center (DLR), Berlin, Germany
| | - Vinciane Debaille
- Laboratoire G-Time, Université libre de Bruxelles, Brussels, Belgium
| | - John Lee Grenfell
- Department of Extrasolar Planets and Atmospheres, Institute of Planetary Research, German Aerospace Center (DLR), Berlin, Germany
| | - Emmanuelle J Javaux
- Early Life Traces & Evolution-Astrobiology, UR Astrobiology, University of Liège, Liège, Belgium
| | - Nozair Khawaja
- Institute of Geological Sciences, Freie Universität Berlin, Berlin, Germany
| | - Fabian Klenner
- Institute of Geological Sciences, Freie Universität Berlin, Berlin, Germany
- Department of Earth and Space Sciences, University of Washington, Seattle, Washington, USA
| | - Yannick J Lara
- Early Life Traces & Evolution-Astrobiology, UR Astrobiology, University of Liège, Liège, Belgium
| | - Sean McMahon
- UK Centre for Astrobiology, School of Physics and Astronomy, University of Edinburgh, Edinburgh, United Kingdom
- School of GeoSciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Keavin Moore
- Department of Earth & Planetary Sciences, McGill University, Montreal, Québec, Canada
- Trottier Space Institute, McGill University, Montreal, Québec, Canada
| | - Lena Noack
- Institute of Geological Sciences, Freie Universität Berlin, Berlin, Germany
| | - C H Lucas Patty
- Physikalisches Institut, Universität Bern, Bern, Switzerland
- Center for Space and Habitability, Universität Bern, Bern, Switzerland
| | - Frank Postberg
- Institute of Geological Sciences, Freie Universität Berlin, Berlin, Germany
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7
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Zorzano MP, Olsson-Francis K, Doran PT, Rettberg P, Coustenis A, Ilyin V, Raulin F, Shehhi OA, Groen F, Grasset O, Nakamura A, Ballesteros OP, Sinibaldi S, Suzuki Y, Kumar P, Kminek G, Hedman N, Fujimoto M, Zaitsev M, Hayes A, Peng J, Ammannito E, Mustin C, Xu K. The COSPAR planetary protection requirements for space missions to Venus. LIFE SCIENCES IN SPACE RESEARCH 2023; 37:18-24. [PMID: 37087175 DOI: 10.1016/j.lssr.2023.02.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Revised: 01/30/2023] [Accepted: 02/01/2023] [Indexed: 05/03/2023]
Abstract
The Committee on Space Research's (COSPAR) Planetary Protection Policy states that all types of missions to Venus are classified as Category II, as the planet has significant research interest relative to the processes of chemical evolution and the origin of life, but there is only a remote chance that terrestrial contamination can proliferate and compromise future investigations. "Remote chance" essentially implies the absence of environments where terrestrial organisms could survive and replicate. Hence, Category II missions only require simplified planetary protection documentation, including a planetary protection plan that outlines the intended or potential impact targets, brief Pre- and Post-launch analyses detailing impact strategies, and a Post-encounter and End-of-Mission Report. These requirements were applied in previous missions and are foreseen for the numerous new international missions planned for the exploration of Venus, which include NASA's VERITAS and DAVINCI missions, and ESA's EnVision mission. There are also several proposed missions including India's Shukrayaan-1, and Russia's Venera-D. These multiple plans for spacecraft coincide with a recent interest within the scientific community regarding the cloud layers of Venus, which have been suggested by some to be habitable environments. The proposed, privately funded, MIT/Rocket Lab Venus Life Finder mission is specifically designed to assess the habitability of the Venusian clouds and to search for signs of life. It includes up to three atmospheric probes, the first one targeting a launch in 2023. The COSPAR Panel on Planetary Protection evaluated scientific data that underpins the planetary protection requirements for Venus and the implications of this on the current policy. The Panel has done a thorough review of the current knowledge of the planet's conditions prevailing in the clouds. Based on the existing literature, we conclude that the environmental conditions within the Venusian clouds are orders of magnitude drier and more acidic than the tolerated survival limits of any known terrestrial extremophile organism. Because of this future orbital, landed or entry probe missions to Venus do not require extra planetary protection measures. This recommendation may be revised in the future if new observations or reanalysis of past data show any significant increment, of orders of magnitude, in the water content and the pH of the cloud layer.
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Affiliation(s)
- María Paz Zorzano
- Centro de Astrobiología (CAB), CSIC-INTA, Carretera de Ajalvir km 4, 28850, Torrejón de Ardoz, Madrid, Spain.
| | - Karen Olsson-Francis
- AstrobiologyOU, Faculty of Science, Technology, Engineering and Mathematics, The Open University, Milton Keynes, UK
| | - Peter T Doran
- Department of Geology and Geophysics, Louisiana State University, Baton Rouge, LA, USA
| | - Petra Rettberg
- Research Group Astrobiology, Institute of Aerospace Medicine, DLR, Koeln, Germany
| | - Athena Coustenis
- LESIA, Paris Observatory, CNRS, PSL Univ., 92195, Meudon Cedex, France
| | - Vyacheslav Ilyin
- Institute for Biomedical Problems, 123007, Khoroshevskoye shosse 76a, Moscow, Russia
| | - Francois Raulin
- Univ Paris Est Créteil and Université Paris Cité, CNRS, LISA, F-94010, Créteil, France
| | | | - Frank Groen
- NASA Headquarters, Washington, DC, 20546, USA
| | - Olivier Grasset
- Nantes Université, Univ Angers, Le Mans Université, CNRS, UMR 6112, Laboratoire de Planétologie et Géosciences, F-44000, Nantes, France
| | - Akiko Nakamura
- Department of Planetology, Kobe University, 657-8501, Kobe, Japan
| | - Olga Prieto Ballesteros
- Centro de Astrobiología (CAB), CSIC-INTA, Carretera de Ajalvir km 4, 28850, Torrejón de Ardoz, Madrid, Spain
| | - Silvio Sinibaldi
- Planetary Protection Officer, Independent Safety Office (TEC-QI), European Space Agency (ESA) - ESTEC, Keplerlaan 1, 2201, AZ, Noordwijk, the Netherlands
| | - Yohey Suzuki
- Department of Earth and Planetary Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan
| | | | - Gerhard Kminek
- European Space Agency (ESA) - ESTEC, Keplerlaan 1, 2201, AZ, Noordwijk, the Netherlands
| | - Niklas Hedman
- Committee, Policy and Legal Affairs Section, Office for Outer Space Affairs, United Nations Office at Vienna, Austria
| | - Masaki Fujimoto
- Japan Aerospace Exploration Agency (JAXA), Institute of Space and Astronautical Science (ISAS), Kanagawa, Japan
| | - Maxim Zaitsev
- Planetary Physics Dept., Space Research Inst. of Russian Acad. of Sciences, Moscow, Russia
| | - Alex Hayes
- Cornell University, Ithaca, NY, 14853-6801, USA
| | - Jing Peng
- China National Space Administration, Beijing, China
| | | | | | - Kanyan Xu
- Laboratory of Space Microbiology, Shenzhou Space Biotechnology Group, Chinese Academy of Space Technology, Beijing, China
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8
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De Mol ML. Astrobiology in Space: A Comprehensive Look at the Solar System. Life (Basel) 2023; 13:life13030675. [PMID: 36983831 PMCID: PMC10054531 DOI: 10.3390/life13030675] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2023] [Revised: 02/18/2023] [Accepted: 03/01/2023] [Indexed: 03/06/2023] Open
Abstract
The field of astrobiology aims to understand the origin of life on Earth and searches for evidence of life beyond our planet. Although there is agreement on some of the requirements for life on Earth, the exact process by which life emerged from prebiotic conditions is still uncertain, leading to various theories. In order to expand our knowledge of life and our place in the universe, scientists look for signs of life through the use of biosignatures, observations that suggest the presence of past or present life. These biosignatures often require up-close investigation by orbiters and landers, which have been employed in various space missions. Mars, because of its proximity and Earth-like environment, has received the most attention and has been explored using (sub)surface sampling and analysis. Despite its inhospitable surface conditions, Venus has also been the subject of space missions due to the presence of potentially habitable conditions in its atmosphere. In addition, the discovery of habitable environments on icy moons has sparked interest in further study. This article provides an overview of the origin of life on Earth and the astrobiology studies carried out by orbiters and landers.
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Affiliation(s)
- Maarten L De Mol
- Centre for Industrial Biotechnology and Biocatalysis (InBio.be), Department of Biotechnology, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, 9000 Ghent, Belgium
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9
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Coleine C, Delgado-Baquerizo M. Unearthing terrestrial extreme microbiomes for searching terrestrial-like life in the Solar System. Trends Microbiol 2022; 30:1101-1115. [PMID: 35568658 DOI: 10.1016/j.tim.2022.04.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Revised: 04/03/2022] [Accepted: 04/11/2022] [Indexed: 01/13/2023]
Abstract
The possibility of life elsewhere in the universe has fascinated humankind for ages. To the best of our knowledge, life, as we know it, is limited to planet Earth; yet current investigation suggests that life might be more common than previously thought. In this review, we explore extreme terrestrial analogue environments in the search for some notable examples of extreme organisms, including overlooked microbial groups such as viruses, fungi, and protists, associated with limits of life on Earth. This knowledge is integral to provide the foundational principles needed to predict what sort of Earth-like organisms we might find in the Solar System and beyond, and to understand the future and origins of life on Earth.
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Affiliation(s)
- Claudia Coleine
- Department of Ecological and Biological Sciences, University of Tuscia, 01100 Viterbo, Italy.
| | - Manuel Delgado-Baquerizo
- Laboratorio de Biodiversidad y Funcionamiento Ecosistémico. Instituto de Recursos Naturales y Agrobiología de Sevilla (IRNAS), CSIC, Av. Reina Mercedes 10, E-41012, Sevilla, Spain; Unidad Asociada CSIC-UPO (BioFun). Universidad Pablo de Olavide, 41013 Sevilla, Spain.
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10
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Sasaki S, Yamagishi A, Yoshimura Y, Enya K, Miyakawa A, Ohno S, Fujita K, Usui T, Limaye S. In situ bio/chemical characterization of Venus cloud particles using Life-signature Detection Microscope for Venus (Venus LDM). Can J Microbiol 2022; 68:413-425. [PMID: 35235433 DOI: 10.1139/cjm-2021-0140] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Much of the information about the size and shape of aerosols forming haze and the cloud layer of Venus is obtained from indirect inferences from nephelometers on probes and from analysis of the variation of polarization with the phase angle and the glory feature from images of Venus. Microscopic imaging of Venus' aerosols has been advocated recently. Direct measurements from a fluorescence microscope can provide information on the morphology, density, and biochemical characteristics of the particles; thus, the fluorescence microscope is attractive for the in situ particle characterization of Venus' cloud layer. Fluorescence imaging of Venus' cloud particles presents several challenges due to the sulfuric acid composition and the corrosive effects. In this article, we identify the challenges and describe our approach to overcoming them for a fluorescence microscope based on an in situ bio/chemical and physical characterization instrument for use in the clouds of Venus from a suitable aerial platform. We report that a pH adjustment using alkali was effective for obtaining fluorescence images, and that fluorescence attenuation was observed after the adjustment, even when the acidophile suspension in the concentrated sulfuric acid was used as a sample.
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Affiliation(s)
- Satoshi Sasaki
- Tokyo University of Technology, 13097, Hachioji, Japan, 192-0914;
| | - Akihiko Yamagishi
- Tokyo University of Pharmacy and Life Sciences, 13115, Hachioji, Tokyo, Japan;
| | | | - Keigo Enya
- JAXA, 13557, Sagamihara, Kanagawa, Japan;
| | - Atsuo Miyakawa
- Tokyo University of Pharmacy and Life Sciences, 13115, Hachioji, Tokyo, Japan;
| | - Sohsuke Ohno
- Chiba Institute of Technology, 12829, Chiba, Chiba, Japan;
| | | | | | - Sanjay Limaye
- University of Wisconsin-Madison, 5228, Madison, Wisconsin, United States;
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11
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Cockell CS, Higgins PM, Johnstone AA. Biologically Available Chemical Energy in the Temperate but Uninhabitable Venusian Cloud Layer: What Do We Want to Know? ASTROBIOLOGY 2021; 21:1224-1236. [PMID: 33470900 DOI: 10.1089/ast.2020.2280] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The cloud layer has been hypothesized to be the most habitable region of Venus. In the lower clouds, both temperature and pressure fall within bounds that support reproduction of microbial life on Earth, although the water activity of the sulfuric acid cloud droplets makes the clouds uninhabitable to known life. In this study, we carried out an analysis of CHNOPS (carbon, hydrogen, nitrogen, oxygen, phosphorus, sulfur) elements and potential redox couples in the cloud layer, and we used a microbial energetic growth model to investigate quantitatively the chemical energy available for microbial growth from methanogenesis, sulfate reduction, and hydrogen oxidation at temperatures between 278 and 350 K. The purpose was to improve knowledge of how far the venusian cloud layer comes from being habitable. Hydrogen oxidation was favorable at all temperatures; however, negative Gibbs free energies for sulfate reduction and methanogenesis depended critically on the assumed concentrations of electron donors, acceptors, and products. Improved measurements and the investigation of new molecules will allow us to better assess quantitatively how far Venus comes from possessing a habitable cloud layer and what would need to be different to make it habitable. We identify specific required measurements. These data will advance our understanding of the habitability of planetary atmospheres on extrasolar greenhouse worlds and the habitability of Earth when the planet eventually enters a greenhouse state.
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Affiliation(s)
- Charles S Cockell
- UK Centre for Astrobiology, School of Physics and Astronomy, University of Edinburgh, Edinburgh, United Kingdom
| | - Peter M Higgins
- UK Centre for Astrobiology, School of Physics and Astronomy, University of Edinburgh, Edinburgh, United Kingdom
- Institute for Astronomy, University of Edinburgh, Blackford Hill, Edinburgh EH9 3HJ, UK
| | - Andrew A Johnstone
- UK Centre for Astrobiology, School of Physics and Astronomy, University of Edinburgh, Edinburgh, United Kingdom
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12
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Limaye SS, Zelenyi L, Zasova L. Introducing the Venus Collection-Papers from the First Workshop on Habitability of the Cloud Layer. ASTROBIOLOGY 2021; 21:1157-1162. [PMID: 34582698 DOI: 10.1089/ast.2021.0142] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
We introduce the collection of papers from the first workshop on the habitability of the venusian cloud layer organized by the Roscosmos/IKI-NASA Joint Science Definition Team (JSDT) for Russia's Venera-D mission and hosted by the Space Research Institute in Moscow, Russia, during October 2-5, 2019. The collection also includes three papers that were developed independently of the workshop but are relevant to venusian cloud habitability.
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Affiliation(s)
- Sanjay S Limaye
- Space Science and Engineering Center, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Lev Zelenyi
- Space Research Institute, Russian Academy of Sciences, Moscow, Russian Federation
| | - Ludmilla Zasova
- Space Research Institute, Russian Academy of Sciences, Moscow, Russian Federation
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13
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Kotsyurbenko OR, Cordova JA, Belov AA, Cheptsov VS, Kölbl D, Khrunyk YY, Kryuchkova MO, Milojevic T, Mogul R, Sasaki S, Słowik GP, Snytnikov V, Vorobyova EA. Exobiology of the Venusian Clouds: New Insights into Habitability through Terrestrial Models and Methods of Detection. ASTROBIOLOGY 2021; 21:1186-1205. [PMID: 34255549 PMCID: PMC9545807 DOI: 10.1089/ast.2020.2296] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2020] [Accepted: 04/16/2021] [Indexed: 06/13/2023]
Abstract
The search for life beyond Earth has focused on Mars and the icy moons Europa and Enceladus, all of which are considered a safe haven for life due to evidence of current or past water. The surface of Venus, on the other hand, has extreme conditions that make it a nonhabitable environment to life as we know it. This is in contrast, however, to its cloud layer, which, while still an extreme environment, may prove to be a safe haven for some extreme forms of life similar to extremophiles on Earth. We consider the venusian clouds a habitable environment based on the presence of (1) a solvent for biochemical reactions, (2) appropriate physicochemical conditions, (3) available energy, and (4) biologically relevant elements. The diversity of extreme microbial ecosystems on Earth has allowed us to identify terrestrial chemolithoautotrophic microorganisms that may be analogs to putative venusian organisms. Here, we hypothesize and describe biological processes that may be performed by such organisms in the venusian clouds. To detect putative venusian organisms, we describe potential biosignature detection methods, which include metal-microbial interactions and optical methods. Finally, we describe currently available technology that can potentially be used for modeling and simulation experiments.
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Affiliation(s)
- Oleg R. Kotsyurbenko
- Yugra State University, The Institute of Oil and Gas, School of Ecology, Khanty-Mansiysk, Russian Federation
- Network of Researchers on the Chemical Evolution of Life, Leeds, UK
| | - Jaime A. Cordova
- Laboratory of Genetics, University of Wisconsin, Madison, Wisconsin, USA
| | - Andrey A. Belov
- Network of Researchers on the Chemical Evolution of Life, Leeds, UK
- Moscow State University, Faculty of Soil Science, Moscow, Russian Federation
| | - Vladimir S. Cheptsov
- Network of Researchers on the Chemical Evolution of Life, Leeds, UK
- Moscow State University, Faculty of Soil Science, Moscow, Russian Federation
- Space Research Institute, Russian Academy of Sciences, Moscow, Russian Federation
| | - Denise Kölbl
- Space Biochemistry Group, Department of Biophysical Chemistry, University of Vienna, Vienna, Austria
| | - Yuliya Y. Khrunyk
- Department of Heat Treatment and Physics of Metal, Ural Federal University, Ekaterinburg, Russian Federation
- M.N. Mikheev Institute of Metal Physics of the Ural Branch of the Russian Academy of Sciences, Ekaterinburg, Russian Federation
| | - Margarita O. Kryuchkova
- Network of Researchers on the Chemical Evolution of Life, Leeds, UK
- Moscow State University, Faculty of Soil Science, Moscow, Russian Federation
| | - Tetyana Milojevic
- Space Biochemistry Group, Department of Biophysical Chemistry, University of Vienna, Vienna, Austria
| | - Rakesh Mogul
- Chemistry and Biochemistry Department, California State Polytechnic University, Pomona, California, USA
| | - Satoshi Sasaki
- School of Biosciences and Biotechnology/School of Health Sciences, Tokyo University of Technology, Hachioji, Tokyo, Japan
| | - Grzegorz P. Słowik
- Institute of Materials and Biomedical Engineering, Faculty of Mechanical Engineering, University of Zielona Góra, Zielona Góra, Poland
| | - Valery Snytnikov
- Boreskov Institute of Catalysis, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russian Federation
- Novosibirsk State University, Novosibirsk, Russian Federation
| | - Elena A. Vorobyova
- Network of Researchers on the Chemical Evolution of Life, Leeds, UK
- Moscow State University, Faculty of Soil Science, Moscow, Russian Federation
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14
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Mogul R, Limaye SS, Lee YJ, Pasillas M. Potential for Phototrophy in Venus' Clouds. ASTROBIOLOGY 2021; 21:1237-1249. [PMID: 34569810 DOI: 10.1089/ast.2021.0032] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
We show that solar irradiances calculated across Venus' clouds support the potential for Earth-like phototrophy and that treatment of Venus' aerosols containing neutralized sulfuric acid favor a habitable zone. The phototrophic potential of Venus' atmosphere was assessed by calculating irradiances (200-2000 nm, 15° solar zenith angle, local noon) using a radiative transfer model that accounted for absorption and scattering by the major and minor atmospheric constituents. Comparisons to Earth's surface (46 W m-2, 280-400 nm) suggest that Venus' middle and lower clouds receive ∼87% less normalized UV flux (6-7 W m-2) across 200-400 nm, yet similar normalized photon flux densities (∼4400-6200 μmol m-2 s-1) across 350-1200 nm. Further, Venus' signature phototrophic windows and subwindows overlap with the absorption profiles of several photosynthetic pigments, especially bacteriochlorophyll b from intact cells and phycocyanin. Therefore, Venus' light, with limited UV flux in the middle and lower clouds, is likely quite favorable for phototrophy. We additionally present interpretations to refractive index and radio occultation measures for Venus' aerosols that suggest the presence of lower sulfuric abundances and/or neutralized forms of sulfuric acid, such as ammonium bisulfate. Under these considerations, the aerosols in Venus' middle clouds could harbor water activities (≥0.6) and buffered acidities (Hammett acidity factor, H0 -0.1 to -1.5) that lie within the limits of acidic cultivation (≥H0 -0.4) and are tantalizingly close to the limits of oxygenic photosynthesis (≥H0 0.1). Together, these photophysical and chemical considerations support a potential for phototrophy in Venus' clouds.
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Affiliation(s)
- Rakesh Mogul
- Chemistry & Biochemistry Department, California State Polytechnic University, Pomona, California, USA
| | - Sanjay S Limaye
- Space Science and Engineering Center, University of Wisconsin, Madison, Wisconsin, USA
| | - Yeon Joo Lee
- Zentrum für Astronomie und Astrophysik, Technische Universität Berlin, Berlin, Germany
| | - Michael Pasillas
- Chemistry & Biochemistry Department, California State Polytechnic University, Pomona, California, USA
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15
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Omran A, Oze C, Jackson B, Mehta C, Barge LM, Bada J, Pasek MA. Phosphine Generation Pathways on Rocky Planets. ASTROBIOLOGY 2021; 21:1264-1276. [PMID: 34551269 DOI: 10.1089/ast.2021.0034] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The possibility of life in the venusian clouds was proposed in the 1960s, and recently this hypothesis has been revived with the potential detection of phosphine (PH3) in Venus' atmosphere. These observations may have detected ∼5-20 ppb phosphine on Venus (Greaves et al., 2020), which raises questions about venusian atmospheric/geochemical processes and suggests that this phosphine could possibly be generated by biological processes. In such a claim, it is essential to understand the abiotic phosphorus chemistry that may occur under Venus-relevant conditions, particularly those processes that may result in phosphine generation. Here, we discuss two related abiotic routes for phosphine generation within the atmosphere of Venus. Based on our assessment, corrosion of large impactors as they ablate near Venus' cloud layer, and the presence of reduced phosphorus compounds in the subcloud layer could result in production of phosphine and may explain the phosphine detected in Venus' atmosphere or on other rocky planets. We end on a cautionary note: although there may be life in the clouds of Venus, the detection of a simple, single gas, phosphine, is likely not a decisive indicator.
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Affiliation(s)
- Arthur Omran
- Department of Geosciences, University of South Florida, Tampa, Florida, USA
| | - Christopher Oze
- Geology Department, Occidental College, Los Angeles, California, USA
| | - Brian Jackson
- Department of Physics, Boise State University, Boise, Idaho, USA
| | - Chris Mehta
- Department of Geosciences, University of South Florida, Tampa, Florida, USA
| | - Laura M Barge
- NASA Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
| | - Jeffrey Bada
- Scripps Institution of Oceanography Department, University of California at San Diego, La Jolla, California, USA
| | - Matthew A Pasek
- Department of Geosciences, University of South Florida, Tampa, Florida, USA
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16
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Milojevic T, Treiman AH, Limaye SS. Phosphorus in the Clouds of Venus: Potential for Bioavailability. ASTROBIOLOGY 2021; 21:1250-1263. [PMID: 34342520 DOI: 10.1089/ast.2020.2267] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Aerosol phase elements such as phosphorus (P), sulfur (S), and metals including iron (Fe) are essential nutrients that could help sustain potential biodiversity in the cloud deck of Venus. While the presence of S and Fe in the venusian cloud deck has been broadly discussed (Zasova et al., 1981; Krasnopolsky, 2012, 2013, 2016, 2017; Markiewicz et al., 2014), less attention has been given to the presence of P in the aerosols and its involvement in the multiphase chemistry of venusian clouds and potential sources of P deposition in the venusian atmosphere. A detailed characterization of phosphorus atmospheric chemistry in the cloud deck of Venus is crucial for understanding its solubility and bioavailability for potential venusian cloud microbiota (Schulze-Makuch et al., 2004; Grinspoon and Bullock, 2007; Limaye et al., 2018). We summarize our current understanding of the presence of P in the clouds of Venus and its role in a hypothetical atmospheric (bio)chemical cycle. The results of the VeGa lander measurements are put into perspective with regard to nutrient limitation for a potential biosphere in venusian clouds. Our work combines the results of the VeGa measurements and focuses on P as an inorganic nutrient component and its potential sources and chemical behavior as part of multiple transformations of atmospheric chemistry. The VeGa data indicate that a plentiful phosphorus layer exists within a layer that reaches into the lower venusian clouds and exceeds minimum P abundances for terrestrial microbial life. Extreme acidification of airborne phases in the atmosphere of Venus may facilitate P solubilization and its bioavailability for a potential ecosystem in venusian clouds. Further sampling and P abundance measurements in the atmosphere of Venus would improve our knowledge of P speciation and facilitate determination of a bioavailable fraction of P detected in venusian clouds. The previous results deserve further experimental and modeling analyses to diminish uncertainties and understand the rates of atmospheric deposition of P and its role in a potential venusian cloud ecosystem.
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Affiliation(s)
- Tetyana Milojevic
- Space Biochemistry Group, Department of Biophysical Chemistry, University of Vienna, Vienna, Austria
| | | | - Sanjay S Limaye
- Space Science and Engineering Center, University of Wisconsin, Madison, Wisconsin, USA
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17
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Baines KH, Nikolić D, Cutts JA, Delitsky ML, Renard JB, Madzunkov SM, Barge LM, Mousis O, Wilson C, Limaye SS, Verdier N. Investigation of Venus Cloud Aerosol and Gas Composition Including Potential Biogenic Materials via an Aerosol-Sampling Instrument Package. ASTROBIOLOGY 2021; 21:1316-1323. [PMID: 33944604 DOI: 10.1089/ast.2021.0001] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
A lightweight, low-power instrument package to measure, in situ, both (1) the local gaseous environment and (2) the composition and microphysical properties of attendant venusian aerosols is presented. This Aerosol-Sampling Instrument Package (ASIP) would be used to explore cloud chemical and possibly biotic processes on future aerial missions such as multiweek balloon missions and on short-duration (<1 h) probes on Venus and potentially on other cloudy worlds such as Titan, the Ice Giants, and Saturn. A quadrupole ion-trap mass spectrometer (QITMS; Madzunkov and Nikolić, J Am Soc Mass Spectrom 25:1841-1852, 2014) fed alternately by (1) an aerosol separator that injects only aerosols into a vaporizer and mass spectrometer and (2) the pure aerosol-filtered atmosphere, achieves the compositional measurements. Aerosols vaporized <600°C are measured over atomic mass ranges from 2 to 300 AMU at <0.02 AMU resolution, sufficient to measure trace materials, their isotopic ratios, and potential biogenic materials embedded within H2SO4 aerosols, to better than 20% in <300 s for H2SO4 -relative abundances of 2 × 10-9. An integrated lightweight, compact nephelometer/particle-counter determines the number density and particle sizes of the sampled aerosols.
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Affiliation(s)
- Kevin H Baines
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
| | - Dragan Nikolić
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
| | - James A Cutts
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
| | | | | | - Stojan M Madzunkov
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
| | - Laura M Barge
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
| | - Olivier Mousis
- Aix Marseille Université, CNRS, CNES, LAM, Marseille, France
| | | | - Sanjay S Limaye
- Space Science and Engineering Center, University of Wisconsin-Madison, Wisconsin, USA
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