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The Korean Astronomical Society (한국천문학회)
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SEARCH FOR BIOSIGNATURE IN THE SOLAR SYSTEM

태양계 내의 생명징후 탐사

  • Minsun Kim (Korea Astronomy and Space Science Institute) ;
  • Sun-Ju Chung (Korea Astronomy and Space Science Institute) ;
  • Min-Su Shin (Korea Astronomy and Space Science Institute) ;
  • Sungwook E. Hong (Korea Astronomy and Space Science Institute)
  • Received : 2022.12.22
  • Accepted : 2023.03.27
  • Published : 2023.08.31
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Abstract

"Are we alone in the universe?" is the fundamental question of mankind. To search for the life signatures in the universe, there have been a lot of researches and space explorations, especially in our solar system. In this review paper, we introduce the definition and characteristics of the "biosignature". The current situations and future plans for searching for biosignatures in our solar system are reviewed, especially at Venus, Mars, and Ocean Worlds such as Europa and Enceladus where life signatures are more likely to exist than in other places in the solar system. Finally, we discuss the opportunities and strategies for the Korean scientific society to participate in searching for biosignatures in the solar system.

Keywords

Acknowledgement

본 연구는 정부(과학기술정보통신부)의 재원으로 한국천문연구원 주요사업 및 기타사업의 지원을 받아 수행되었습니다 (우주생명현상탐색 기획연구(No. 2022E83090), 우주생명현상탐색(No. 2021184005), 우주거대구조를 이용한 암흑우주연구(No. 2022186903), 고밀도 천체의 물질 방출 및 자기장 연구(No. 2023184007)). 우주생명현상 탐색 연구를 함께 수행하고 있는 동료들(LiCE Team; 강현우, 권윤영, 김윤종, 손봉원, 이충욱, 정태현, 한정열, Thiem Hoang)과 익명의 심사위원께 감사드립니다.

References

  1. Alleon, J., Bernard, S., Remusat, L., & Robert, F., 2015, Estimation of nitrogen-to-carbon ratios of organics and carbon materials at the submicrometer scale, Carbon, 84, 290
  2. Arney, G. N., Domagal-Goldman, S. D., & Meadows, V. S., 2018, Organic haze as a biosignature in anoxic Earth-like atmospheres, Astrobiology, 18, 311
  3. Atreya, S. K., Mahaffy, P. R., & Wong, A. S., 2007, Methane and related trace species on Mars: Origin, loss, implications for life, and habitability, Planetary and Space Science, 55, 358
  4. Bains, W., Petkowski, J. J., Seager, S., Ranjan, S., SousaSilva, C., Rimmer, P. B., Zhan, Z., Greaves, J. S., Richards, A. M. S., 2021a, Phosphine on Venus Cannot Be Explained by Conventional Processes, Astrobiology, 21, 10, 1277
  5. Bains, W., Petkowski, J. J., Rimmer, P. B., & Seager, S., 2021b, Production of Ammonia Makes Venusian Clouds Habitable and Explains Observed Cloud-Level Chemical Anomalies, Proc. Natl. Acad. Sci., 118, 52, e2110889118
  6. Bains, W., Shorttle, O., Ranjan, S., Rimmer, P. B., Petkowski, J. J., Greaves, J. S., & Seager, S., 2022, Constraints on the Production of Phosphine by Venusian Volcanoes, Universe, 8, 54
  7. Bedrossian, M., Lindersmith, C., & Nadeau, J. L., 2017, Digital holographic microscopy, a method for detection of microorganisms in plume samples from Enceladus and other icy worlds, Astrobiology, 17, 9, 913
  8. Bell, E. A., Boehnke, P., Harrison, T. M., & Mao, W. L., 2015, Potentially biogenic carbon preserved in a 4.1 billion-year-old zircon. Proceedings of the National Academy of Sciences U.S.A., 112, 47, 14518
  9. Beyssac, O., Goffe, B., & Chopin, C., 2002, Raman spectra of carbonaceous material in metasediments: A new geothermometer, Journal of Metamorphic Geology, 20, 859
  10. Castro-Wallace, S. L., Chiu, C. Y., John, K. K., Stahl, S. E., Rubins, K. H., McIntyre, A. B. R., Dworkin, J. P., Lupisella, M. L., Smith, D. J., Botkin, D. J., Stephenson, T. A., Juul, S., Turner, D. J., Izquierdo, F., Federman, S., Stryke, D., Somasekar, S., Alexander, N., Yu, G., Mason, C. E., & Burton, A. S., 2017, Nanopore DNA sequencing and genome assembly on the International Space Station, Scientific Reports, 7, 18022
  11. Catling, D. C., Krissansen-Totton, J., Kiang, N. Y., Crisp, D., Robinson, T. D., DasSarma, S., Rushby, A. J., Del Genio, A., Bains, W., & Domagal-Goldman, S., 2018, Exoplanet Biosignatures: A Framework for Their Assessment, Astrobiology, 18, 6, 709
  12. Chan, M. A., Hinman, N. W., Potter-McIntyre, S. L., Schubert, K. E., & Gillams, R. J., 2019, Deciphering Biosignatures in Planetary Contexts, Astrobiology, 19, 9, 1075
  13. Cole, D. B., Reinhard, C. T., Wang, X., Gueguen, B., Halverson, G. P., Gibson, T., Hodgskiss, M. S. W., McKenzie, N. R., Lyons, T. W., & Planavsky, N. J., 2016, A shale-hosted Cr isotope record of low atmospheric oxygen during the Proterozoic, Geology 44, 7, 555
  14. Djokic, T., Van Kranendonk, M. J., Campbell, K. A., Walter, M. R., & Ward, C. R., 2017, Earliest signs of life on land preserved in ca.3.5 Ga hot spring deposits, Nature Communications, 8, 15263
  15. Delarue, F., Robert, F., Sugitani, K., Tartese, R., Duhamel, R., & Derenne, S., 2017, Investigation of the geochemical preservation of ca.3.0 Ga permineralized and encapsulated microfossils by nanoscale secondary ion mass spectrometry, Astrobiology, 17, 12, 1192
  16. Des Marais, D. J., Allamandola, L. J., Benner, S. A., Boss, A. P., Deamer, D., Falkowski, P. G., Farmer, J. D., Hedges, S. B., Jakosky, B. M., Knoll, A. H., Liskowsky, D. R., Meadows, V. S., Meyer, M. A., Pilcher, C. B., Nealson, K. H., Spormann, A. M., Trent, J. D., Turner, W. W., Woolf, N. J., & Yorke, H. W., 2003, The NASA Astrobiology Roadmap, Astrobiology, 3, 2, 219
  17. Des Marais, D. J., Nuth III, J. A., Allamandola, L. J., Boss, A. P., Farmer, J. D., Hoehler, T. M., Jakosky, B. M., Meadows, V. S., Pohorille, A., Runnegar, B., & Spormann, A. M., 2008, The NASA Astrobiology Roadmap, Astrobiology, 8, 715
  18. Dodd, M. S., Papineau, D., Grenne, T., Slack, J. F., Rittner, M., Pirajno, F., O'Neil, J., & Little, C. T. S., 2017, Evidence for early life on Earth's oldest hydrothermal vent precipitates, Nature, 543, 60
  19. Duzdevich, D., in preparation, Formation of lipid vesicles in 70% sulfuric acid
  20. Eid, J., Fehr, A., Gray, J., Luong, K., Lyle, J., Otto, G., Peluso, P., Rank, D., Baybayan, P., Bettman, B., Bibillo, A., Bjornson, K., Chaudhuri, B., Christians, F., Cicero, R., Clark, S., Dalal, R., Dewinter, A., Dixon, J., Foquet, M., Gaertner, A., Hardenbol, P., Heiner, C., Hester, K., Holden, D., Kearns, G., Kong, X., Kuse, R., Lacroix, Y., Lin, S., Lundquist, P., Ma, C., Marks, P., Maxham, M., Murphy, D., Park, I., Pham, T., Phillips, M., Roy, J., Sebra, R., Shen, G., Sorenson, J., Tomaney, A., Travers, K., Trulson, M., Vieceli, J., Wegener, J., Wu, D., Yang, A., Zaccarin, D., Zhao, P., Zhong, F., Korlach, J., & Turner, S., 2009, Real-time DNA sequencing from single polymerase molecules, Science, 323, 5910, 133 https://doi.org/10.1126/science.1162986
  21. Ehlmann, B. L., & Edwards, C. S., 2014, Mineralogy of the martian surface, Annual Review of Earth and Planetary Science, 42, 291
  22. Ehlmann, B. L., Anderson, F. S., Andrews-Hanna, J., Catling, D. C., Christensen, P. R., Cohen, B. A., Dressing, C. D, Edwards, C. S., Elkins-Tanton, L. T., Farley, K. A., Fassett, C. I., Fischer, W. W., Fraeman, A. A., Golombek, M. P., Hamilton, V. E., Hayes, A. G., Herd, C. D. K., Horgan, B., Hu, R., Jakosky, B. M., Johnson, J. R., Kasting, J. F., Kerber, L., Kinch, K. M., Kite, E. S., Knutson, H. A., Lunine, J. I., Mahaffy, P. R., Mangold, N., McCubbin, F. M., Mustard, J. F., Niles, P. B., Quantin-Nataf, C., Rice, M. S., Stack, K. M., Stevenson, D. J., Stewart, S. T., Toplis, M. J., Usui, T., Weiss, B. P., Werner, S. C., Wordsworth, R. D., Wray, J. J., Yingst, R. A., Yung, Y. L., & Zahnle, K. J., 2016, The sustainability of habitability on terrestrial planets: Insights, questions, and needed measurements from Mars for understanding the evolution of Earth-like worlds, Journal of Geophysical Research, 121, 10, 1927
  23. Etiope, G., Oehler, D. Z., & Allen, C. C., 2011, Methane emissions from Earth's degassing Implications for Mars, Planetary and Space Science, 59, 2-3, 182
  24. Farquhar, J., Savarino, J., Airieau, S., & Thiemens, M. H., 2001, Observation of wavelength-sensitive massindependent sulfur isotope effects during SO2 photolysis: Implications for the early atmosphere, Journal of Geophysical Research, 106, E12, 32829
  25. Flannery, D. T., Allwood, A. C., Summons, R. E., Williford, K. H., Abbey, W., Matys, D. E., & Ferralis, N., 2018, Spatially-resolvedisotopic study of carbon trapped in ~ 3.43 Ga Strelley Pool Formation stromatolites, Geochimica et Cosmochimica Acta, 223, 21
  26. French, R., Mandy, C., Hunter, R., Mosleh, E., Sinclair, D., Beck, P., Seager, S., Petkowski, J. J., Carr, C. E., Grinspoon, D. H., & Baumgardner, D. 2022, Rocket lab mission to Venus, Aerospace, 9(8), 445
  27. Gelino, D., Wright, J., Batalha, N., Berdyugina, S., Enriquez, E., Kanodia, S., Siemion, A., Wright, J., & Wright, S., 2018, NASA and the Search for Technosignatures: A Report from the NASA Technosignatures Workshop, arXiv:1812.08681
  28. Glein, C. R., & Waite, J. H., 2020, The carbonate geochemistry of Enceladus' ocean, Geophysical Research Letters, 47, e2019GL085885
  29. Goodwin, S., Gade, A. M., Byrom, M., Herrera, B., Spears, C., Anslyn, E. V., & Ellington, A. D., 2015, Next-generation sequencing as input for chemometrics in differential sensing routines, Angewandte Chemie, 127, 6437 https://doi.org/10.1002/ange.201501822
  30. Goudge, T. A., Fassett, C. I., Head, J. W., Mustard, J. F., & Aureli, K. L., 2016, Insights into surface runoff on Mars from paleolake basin morphology and stratigraphy, Geology, 44, 6, 419
  31. Gough, R. V., Tolbert, M. A., McKay, C. P., & Toon, O. B., 2010, Methane adsorption on a martian soil analog: An abiogenic explanation for methane variability in the Martian atmosphere, Icarus, 207, 1, 165
  32. Greaves, J. S., Richards, A. M. S., Bains, W., Rimmer, P. B., Sagawa, H., Clements, D. L., Seager, S., Petkowski, J. J., Sousa-Silva, C., Ranjan, S., Drabek-Maunder, E., Fraser, H. J., Cartwright, A., Mueller-Wodarg, I., Zhan, Z., Friberg, P., Coulson, I., Lee, E., & Hoge, J., 2021a, Phosphine gas in the cloud decks of Venus, Nature Astronomy, 5, 655
  33. Greaves, J. S., Richards, A. M. S., Bains, W., Rimmer, P. B., Clements, D. L., Seager, S., Petkowski, J. J., SousaSilva, C., Ranjan, S., & Fraser, H. J., 2021b, Reply to: No evidence of phosphine in the atmosphere of Venus from independent analyses, Nature Astronomy, 5, 636
  34. Greaves, J. S., Richards, A. M. S., Bains, W., Rimmer, P. B., Sagawa, H., Clements, D. L., Seager, S., Petkowski, J. J., Sousa-Silva, C., Ranjan, S., Drabek-Maunder, E., Fraser, H. J., Cartwright, A., Mueller-Wodarg, I., Zhan, Z., Friberg, P., Coulson, I., Lee, E., & Hoge, J., 2021c, Addendum: Phosphine gas in the cloud deck of Venus, Nature Astronomy, 5, 726
  35. Greaves, J. S., Rimmer, P. B., Richards, A. M. S., Petkowski, J. J., Bains, W., Ranjan, S., Seager, S., Clements, D. L., Sousa-Silva, C., & Fraser, H. J., 2022, Low levels of sulphur dioxide contamination of Venusian phosphine spectra, MNRAS, 514, 2, 2994
  36. Grotzinger, J. P., Gupta, S., Malin, M. C., Rubin, D. M., Scheiber, J., Siebach, K., Summer, D. Y., et al., 2015, Deposition, exhumation, and paleoclimate of an ancient lake deposit, Gale crater, Mars, Science, 350, 6257, acc7575
  37. Ha, H. K., Kim, Y. H., Lee, H. J., Hwang, B., & Joo, H. M., 2015, Under-ice measurements of suspended particulate matters using ADCP and LISST-Holo, Ocean Science Journal, 50, 1, 97
  38. Hand, K. P., & German, C. R., 2018, Exploring ocean worlds on Earth and beyond, Nature Geoscience, 11, 2
  39. Hand, K. P., Phillips, C. B., Murray, A., et al., 2022, Science Goals and Mission Architecture of the Europa Lander Mission Concept, The Planetary Science Journal, 3, 22
  40. Hansen C. J., Esposito L., Stewart A. I. F., Colwell, J., Hendrix, A., Pryor, W., Shemansky, D., & West, R., 2006, Enceladus' Water Vapor Plume, Science 311, 1422
  41. Hassanalian, M., & Abdelke, D. R. A., 2018, Evolution of space drones for planetary exploration: A review, Progress in Aerospace Sciences, 97, 61
  42. Hendrix, A. R., Hurford, T. A., Barge, L. M., Bland, M. T., Bowman, J. S., Brinckerhoff, W., Buratti, B. J., Cable, M. L., Castillo-Rogez, J., Collins, G. C., Diniega, S., German, C. R., Hayes, A. G., Hoehler, T., Hosseini, S., Howett, C. J. A., McEwen, A. S., Neish, C. D., Neveu, M., Nordheim, T. A., Patterson, G. W., Patthoff, D. A., Phillips, C., Rhoden, A., Schmidt, B. E., Singer, K. N., Soderblom, J. M., & Vance, S. D., 2019, The NASA Roadmap to Ocean Worlds, Astrobiology, 19, 1, 1 https://doi.org/10.1089/ast.2018.1955
  43. Hays, L. et al., 2015, NASA Astrobiology Sterategy 2015
  44. Hickman-Lewis, K., Garwood, R. J., Brasier, M. D., Goral, T., Jiang, H., McLoughlin, N., & Wacey, D., 2016, Carbonaceous microstructures from sedimentary laminated chert within the 3.46 Ga Apex Basalt, Chinaman Creek locality, Pilbara, Western Australia, Precambrian Research, 278, 161
  45. Hogan, J. 2005, A whiff of life on the Red Planet, New Scientist, http://www.newscientist.com/article.ns?id=dn7014
  46. Hong, S. E., Kwon, R.-Y., Kim, Y., Kang, H., & Kim, M., 2023a, Exoplanets and Habitability, PKAS, accepted
  47. Hong, S. E., Sohn, B. W., Jung, T., Shin, M. -S., Kang, H., & Kim, M., 2023b, Searching for Technosignature, PKAS, submitted
  48. Howell, S., Sotin, C., Carpenter, K., et al., 2020, Diving into Ocean Worlds, Environment Coastal & Offshore, May/June, 26
  49. Hsu H.-W., Postberg F., Sekine Y., Shibuya, T., Kempf, S., Horanyi, M., Juhasz, A., Altobelli, N., Suzuki, K., Masaki, Y., Kuwatani, T., Tachibana, S., Sirono, S., MoragasKlostermeyer, G., & Srama, R., 2015, Ongoing hydrothermal activities within Enceladus, Nature, 519, 207
  50. Hussmann, H. & Spohn, T., 2004, Thermal-orbital evolution of Io and Europa, Icarus, 171, 391
  51. Iess, L., Stevenson, D. J., Parisi, M., Hemingway, D., Jacobson, R. A., Lunine, J. I., Nimmo, F., Armstrong, J. W., Asmar, S. W., Ducci, M., & Tortora, P., 2014, The gravity field and interior structure of Enceladus, Science, 344, 78
  52. Imken, T., Castillo-Rogez, J., He, Y., Baker, J., & Marinan, A., 2017, CubeSat flight system development for enabling deep space science, IEEE aerospace conference, 1
  53. Jain, S., Wheeler, J. R., Walters, R., Agrawal, A. K., Barsic, A., & Parker, R., 2016, ATPase-modulated stress granules contain a diverse proteome and substructure, 2016, Cell, 164, 3, 487
  54. Johnson, S. S., 2018, Agnostic Approaches to Life Detection, Presentation to the Committee on An Astrobiology Science Strategy for Search for Life in the Universe
  55. Johnson, S. S., Anslyn, E. V., Graham, H. V., Mahaffy, P. R., & Ellington, A. D., 2018a, Fingerprinting Non-Terran Biosignatures, Astrobiology, 18, 7, 915
  56. Johnson, S. S., Graham, H., Anslyn, E., Conrad, P., Cronin, L., Ellington, A., Elsila, J., et al. 2018b, Agnostic Biosignatures: Towards a More Inclusive Life Detection Strategy, White paper submitted to the Committee on an Astrobiology Science Strategy for the Search for Life in the Universe
  57. Keppler, F., Vigano, I., McLeod, A., Ott, U., Fruchtl, M., & Rockmann, T., 2012, Ultraviolet-radiation-induced methane emissions from meteorites and the Martian atmosphere, Nature, 486, 7401, 93
  58. Kereszturi, A., Bradak, B., Chatzitheodoridis, E., & Ujvari, G., 2016, Indicators and methods to understand past environments from ExoMars rover drills, Origins of Life and Evolution of Biospheres, 46, 4, 435
  59. Khawaja, N., Postberg, F., Hillier, J., Klenner, F., Kempf, S., Nolle, L., Reviol, R., Zou, Z., Sramaet, R., 2019, Lowmass nitrogen-, oxygen-bearing, and aromatic compounds in Enceladean ice grains, MNRAS, 489, 5231
  60. Kim, M., Kwon, R. Y., Hoang, T., & Hong, S. E., 2023a, The Prospect of Interstellar Object Explorations for Searching Life in Cosmos, PKAS, accepted
  61. Kim, M., Hong, S. E., Jung, T., Kang, H., Shin, M.-S., & Sohn, B. W., 2023b, Searching for Radio Technosignature from the Farside of the Moon, PKAS, submitted
  62. Klein, F., Humphris, S. E., Guo, W., Schubotz, F., Schwarzenbach, E. M., & Orsi, W. D., 2015, Fluid mixing and the deep biosphere of a fossil Lost City-type hydrothermal system at the Iberia margin, Proceedings of the National Academy of Sciences U.S.A., 112, 12036
  63. Knollenberg, R. G. & Hunten, D. M., 1979, Clouds of Venus: Particle Size Distribution Measurements, Science, 203, 792
  64. Knollenberg, R. G. & Hunten, D. M., 1980, The microphysics of the clouds of Venus: Results of the Pioneer Venus Particle Size Spectrometer Experiment, J. Geophys. Res. Sp. Phys., 85, 8039
  65. Korablev, O. I., Ackerman, M., Krasnopolsky, V. A., Moroz, V. I., Muller, C., Rodin, A. V., & Atreya, S. K., 1993, Tentative identification of formaldehyde in the Martian atmosphere, Planetary and Space Science, 41, 6, 441
  66. Krasnopolsky, V. A., Bjoraker, G. L., Mumma, M. J., & Jennings, D. E., 1997, High-resolution spectroscopy of Mars at 3.7 and 8㎛: A sensitive search for H2O2, H2CO, HCl, and CH4, and detection of HDO, JGR, 102, E3, 6525
  67. Krasnopolsky, V. A., Maillard, J. P., & Owen, T. C., 2004, Detection of methane in the martian atmosphere: evidence for life?, Icarus, 172, 2, 537
  68. Kwon, R. Y., Kim, M., & Hoang, T., 2023, Detecting Interstellar Objects by using Space Weather Data, PKAS, in preparation
  69. Lovelock, J. E., 1965, A physical basis for life detection experiments, Nature, 207, 4997, 568
  70. Lovelock, J. E., 1975, Thermodynamics and the recognition of alien biospheres, Proceedings of the Royal Society B, 189, 1095, 167
  71. MacKenzie, S. M., Neveu, M., Davila, A. F., et al., 2021, The Enceladus Orbilander Mission Concept: Balancing Return and Resources in the Search for Life, The Planetary Science Journal, 2, 2, 77
  72. MacKenzie, S. M., Neveu, M., Davila, A. F., et al., 2022a, Science Objectives for Flagship-Class Mission Concepts for the Search for Evidence of Life at Enceladus, Astrobiology, 22, 6, 685
  73. MacKenzie, S. M., Kirby, K. W., Greenauer, P. J., et al., 2022b, Enceladus Orbilander: A Flagship Mission Concept for Astrobiology, Planetary Mission Concept Study for the 2023-2032 Decadal Survey
  74. Marshall, S. M., Murray, A. R. G., & Cronin, L., 2017, A probabilistic framework for identifying biosignatures using pathway complexity, Philosophical Transactions of the Royal Society A, 375, 20160342
  75. Effect of Enceladus's rapid synchronous spin on interpretation of Cassini gravity, McKinnon, W. B., 2015, Geophysical Research Letters, 42, 2137
  76. McMahon, S., Parnell, J., & Blamey, N. J., 2013, Sampling methane in basalt on Earth and Mars, International Journal of Astrobiology, 12, 2, 113
  77. Meadows, V.S., 2017, Reflections on O2 as a biosignature in exoplanetary atmospheres, Astrobiology, 17, 1022
  78. Meadows, V. S., Reinhard, C. T., Arney, G. N., et al., 2018, Exoplanet biosignatures: Understanding oxygen as a biosignature in the context of its environment, Astrobiology, 18, 630
  79. Meslin, P. Y., Gough, R., Lef'evre, F., & Forget, F., 2011, Little variability of methane on Mars induced by adsorption in the regolith, Planetary and Space Science, 59, 2-3, 247
  80. Morag, N., Williford, K. H., Kitajima, K., Philippot, P., Van Kranendonk, M. J., Lepot, K., Thomazo, C., & Valley, J. W., 2016, Microstructure-specific carbon isotopic signatures of organic matter from ~ 3.5 Ga cherts of the Pilbara Craton support a biologic origin. Precambrian Research, 275, 429
  81. Mumma, M. J., Novak, R. E., DiSanti, M. A., & Bonev, B. P., 2003, A sensitive search for methane on Mars, Bull. Am. Astron. Soc., 35, 937
  82. Mustard, J. F., Adler, M., Allwood, A., Bass, D. S., Beaty, D. W., Bell III, J. F., Brinckerhoff, W. B., et al., 2013, Report of the Mars 2020 Science Definition Team. Mars Exploration Program Analysis Group (MEPAG), http://mepag.jpl.nasa.gov/reports/MEP/Mars_2020_SDT_Report_Final.pdf
  83. NASEM (National Academies of Sciences, Engineering, and Medicine), 2017, Searching for Life Across Space and Time: Proceedings of a Workshop, The National Academies Press
  84. NASEM (National Academies of Sciences, Engineering, and Medicine), 2019, An Astrobiology Strategy for the Search for Life in the Universe, The National Academies Press
  85. Nivala, J., Marks, D. B. & Akeson, M., 2013, Unfoldase-mediated protein translocation through an α-hemolysin nanopore, Nature Biotechnology, 31, 3, 247 https://doi.org/10.1038/nbt.2503
  86. Nutman, A. P., Bennett, V. C., Friend, C. R. L., Van Kranendonk, M. J., & Chivas, A. R. 2016, Rapid emergence of life shown by discovery of 3,700-million-year-old microbial structures, 2016, Nature, 537, 535
  87. Okon, A. B. 2010, Mars science laboratory drill, Proceedings of the 40th Aerospace Mechanisms Symposium, NASA/CP-2010-216272
  88. Olson, S. L., Schwieterman, E. W., Reinhard, C. T., Ridgwell, A., Kane, S. R., Meadows, V. S., & Lyons, T. W., 2018, Atmospheric seasonality as an exoplanet biosignature, ApJ Letters, 858, 2, L14
  89. Oze, C. & Sharma, M., 2005, Have olivine, will gas: Serpentinization and the abiogenic production of methane on Mars, Geophysical Research Letters, 32, L10203
  90. Paganini, L., Villanueva, G. L., Roth, L., Mandell, A. M., Hurford, T. A., Retherford, K. D., & Mumma, M. J., 2020, A measurement of water vapour amid a largely quiescent environment on Europa, Nature Astronomy, 4, 266
  91. Patthoff, D. A. & Kattenhorn, S. A.., 2011, A fracture history on Enceladus provides evidence for a global ocean, Geophysical Research Letters, 38, L18201
  92. Pavlov, A. A. & Kasting, J. F., 2002, Mass-independent fractionation of sulfur isotopes in Archean sediments: Strong evidence for an anoxic Archean atmosphere, 2002, Astrobiology, 2, 1, 27
  93. Pellenbarg, R. E., Max, M. D., & Clifford, S. M., 2003, Methane and carbon dioxide hydrates on Mars: Potential origins, distribution, detection, and implications for future in situ resource utilization JGR, 108, E4, GDS 23-1
  94. Pla-Garcia, J., Rafkin, S. C. R., Karatekin, O., & Gloesener, E., 2019, Comparing MSL Curiosity Rover TLSSAM Methane Measurements With Mars Regional Atmospheric Modeling System Atmospheric Transport Experiments, Journal of Geophysical Research: Planets, 124, 8, 2141
  95. Planavsky, N. J., Asael, D., Hofmann, A., Reinhard, C. T., Lalonde, S. V., Knudsen, A., Wang, X., et al., 2014a, Evidence for oxygenic photosynthesis half a billion years before the Great Oxidation Event, Nature Geoscience, 7, 283
  96. Planavsky, N. J., Reinhard, C. T., Wang, X., Thompson, D., McGoldrick, T., Rainbird, R. H., Johnson, T., Fischer, W. W., & Lyons, T. W., 2014b, Low Mid-Proterozoic atmospheric oxygen levels and the delayed rise of animals, Science, 346, 6209, 635
  97. Poch, O., Kaci, S., Stalport, F., Szopa, C., & Coll, P., 2014, Laboratory insights into the chemical and kinetic evolution of several organic molecules under simulated Mars surface UV radiation conditions, Icarus, 242, 50
  98. Porco, C. C., Helfenstein, P., Thomas, P. C., et al., 2006, Cassini Observes the Active South Pole of Enceladus, Science, 311, 5766, 1393
  99. Postberg, F., Schmidt, J., Hillier, J., Kempf, S. & Srama R., 2011, A salt-water reservoir as the source of a compositionally stratified plume on Enceladus, Nature, 474, 620
  100. Postberg, F., Khawaja, N., Abel, B., et al., 2018, Macromolecular organic compounds from the depths of Enceladus, Nature, 558, 564
  101. Russell, M. J., Murray, A. E., & Hand, K. P., 2017, The Possible Emergence of Life and Differentiation of a Shallow Biosphere on Irradiated Icy Worlds: The Example of Europa, Astrobiology, 17, 12, 1265
  102. Schaler, E. W., Ansari, A., Howell, S., Lee, H., Smith, M., Rajguru, A., Tosi, L., Hao, Z., & Kim, J., 2022, Earth and Space Science Open Archive, https://doi.org/10.1002/essoar.10511452.1
  103. Schwieterman, E. W., Kiang, N. Y., Parenteau, M. N., Harman, C. E., DasSarma, S., Fisher, T. M., Arney, G. N., et al., 2018, Exoplanet biosignatures: A review of remotely detectable signs of life, Astrobiology, 18, 6, 663
  104. Seo, E. Y., Ahn, T. S., & Zo, Y. G., 2010, Agreement, precision, and accuracy of epifluorescence microscopy methods for enumeration of total bacterial numbers, Applied and Environmental Microbiology, 76, 6, 1981
  105. Schuerger, A. C., Moores, J. E., Clausen, C. A., Barlow, N. G., & Britt, D. T., 2012, Methane from UV irradiated carbonaceous chondrites under simulated Martian conditions, Journal of Geophysical Research, 117, E08007
  106. Schmidt, J., Brilliantov, N., Spahn, F., & Kempf, S., 2008, Slow dust in Enceladus' plume from condensation and wall collisions in tiger stripe fractures, Nature 451, 685
  107. Schmidt, B. E., Kim, S., Walker, C. C., West, M. E., Meister, M. M., Spears, A., Buffo, J. J., Greenbaum, J. S., Skidmore, M., Barker, L., Burnett, J., Hynes, M., Echeverry, G., Soderlund, K. M., VanTil, E., Blankenship, D. D., Bramall, N., Doran, P., Johnson, A., Rack, F., Siegel, V., Stone, W. C., & Young, D. A., 2015, Sub-Ice Marine and Planetary Ecosystems: First Results from Below the McMurdo Ice Shelf, Proc. Astrobiol. Sci. Conf., 2015, 15
  108. Schwieterman, E. W., Kiang, N. Y., Parenteau, M. N., et al., 2018, Exoplanet Biosignatures A Review of Remotely Detectable Signs of Life, Astrobiology, 18, 6, 663
  109. Seager, S., Bains, W., & Petkowski, J. J., 2016, Toward a list of molecules as potential biosignature gases for the search for life on exoplanets and applications to terrestrial biochemistry, Astrobiology, 16, 6, 465
  110. Seager, S., Petkowski, J. J., Gao, P., Bains, W., Bryan, N. C., Ranjan, S., & Greaves, J., 2021a, The Venusian lower atmosphere haze as a depot for desiccated microbial life: A proposed life cycle for persistence of the Venusian aerial biosphere, Astrobiology, 21, 1206
  111. Seager, S., Petkowski, J. J., Carr, C. E., Grinspoon, D., Ehlmann, B., Saikia, S. J., Agrawal, R., Buchanan, W., Weber, M. U., French, R., Klupar, P., & Worden, S. P,. 2021b, Venus Life Finder Mission Study, arXiv:2112.05153
  112. Seager, S., Petkowski, J. J., Carr, C. E., Grinspoon, D. H., Ehlmann, B. L., Saikia, S. J., Agrawal, R., Buchanan, W. P., Weber, M. U., French, R. & Klupar, P., 2022, Venus life finder missions motivation and summary, Aerospace, 9(7), 385
  113. Siegel, V., Stone, W., Hogan, B., Richmond, K., Harman, J., Lelievre, S., Smith, J., Flesher, C., & Lopez, A., 2019, Project THOR: Design and Testing of a Full-Scale CCHWD Cryobot, American Geophysical Union, Fall Meeting 2019, abstract #P51B-08
  114. Snellen, I. A. G., Guzman-Ramirez, L., Hogerheijde, M. R., Hygate, A. P. S., & van der Tak, F. F. S., 2020, Re-analysis of the 267 GHz ALMA observations of Venus: No statistically significant detection of phosphine, A&A, 644, L2
  115. Summons, R. E., Albrecht, P., McDonald, G., & Moldowan, J. M., 2008, Molecular biosignatures, Part of the Space Sciences Series of ISSI book series, Vol. 25, pp 133-159
  116. Sousa-Silva, C., Seager, S., Ranjan, S., Petkowski, J. J., Zhan, Z., Hu, R., & Bains, W., 2020, Phosphine as a Biosignature Gas in Exoplanet Atmospheres, Astrobiology, 20, 2, 235
  117. Spacek, J. 2021, Organic Carbon Cycle in the Atmosphere of Venus, Venera-D: Venus Cloud Habitability System Workshop, LPI Contribution No. 2629, id.4052, arXiv2108.02286
  118. Spilker, T. R., Adler, M., Arora, N., Beauchamp, P. M., Cutts, J. A., Munk, M. M., Powell, R. W., Braun, R. D., & Wercinski, P. F., 2019, Qualitative Assessment of Aerocapture and Applications to Future Missions, Journal of Spacecraft and Rockets, 56, 2, 536
  119. Stone, W., Hogan, B., Richmond, K., Harman, J., Siegel, V., Lelievre, S., Flesher, C., Ralston, J., Tanner, N., Wright, N., Alexander, M., & Lopez, A., 2021, Project THOR - Test Results for a Full Scale Nuclear-compatible Cryobot, AGU Fall Meeting 2021, id. P25E-2195
  120. Sugitani, K., Mimura, K., Nagaoka, T., Lepot, K., & Takeuchi, M., 2013, Microfossil assemblage from the 3400 Ma Strelley Pool Formation in the Pilbara Craton, Western Australia: Results form a new locality, Precambrian Research, 226, 59
  121. Sugitani, K., Mimura, K., Takeuchi, M., Lepot, K., Ito, S., & Javaux, E. J., 2015, Early evolution of large microorganisms with cytological complexity revealed by microanalyses of 3.4 Ga organic-walled microfossils, Geobiology, 13, 6, 507
  122. Tang, D., Shi, X., Wang, X., & Jiang, G., 2016, Extremely low oxygen concentration in mid-Proterozoic shallow seawaters, Precambrian Research, 276, 145
  123. Thomas, P. C., Tajeddine, R., Tiscareno, M. S., Burns, J. A., Joseph, J., Loredo, T. J., Helfenstein, P., & Porcod, C., 2016, Enceladus's measured physical libration requires a global subsurface ocean, Icarus, 264, 37
  124. Thompson, M. A., 2021, The statistical reliability of 267- GHz JCMT observations of Venus: no significant evidence for phosphine absorption, MNRAS, 501, L18
  125. Truong, N. & Lunine, J., 2021, Volcanically extruded phosphides as an abiotic source of Venusian phosphine, Proc. Natl. Acad. Sci. USA, 118, e2021689118
  126. Ueno, Y., Yoskioka, H., Maruyama, S., & Isozaki, Y., 2004, Carbon isotopes and petrography of kerogens in 3.5-Ga hydrothermal silica dikes in the North Pole area, Western Australia, Geochimica et Cosmochimica Acta, 68, 3, 573
  127. Vance, S. D., 2018, The Habitability of Icy Ocean Worlds in the Solar System, In Deeg, H., Belmonte, J. (eds) Handbook of Exoplanets, Springer, Cham
  128. Vago, J. L., & Westall, F., 2017, Habitability on early Mars and the search for biosignatures with ExoMars Rover, Astrobiology, 17, 6, 471
  129. Villanueva, G. L., Cordiner, M., Irwin, P. G. J., et al., 2021, No evidence of phosphine in the atmosphere of Venus from independent analyses, Nature Astronomy, 5, 631
  130. Wacey, D., Kilburn, M. R., Saunders, M., Cliff, J., & Brasier, M. D., 2011, Microfossils of sulphur-metabolizing cells in 3.4-billion-year-old rocks of Western Australia, Nature Geoscience, 4, 698
  131. Waite Jr., J. H., Lewis, W. S., Magee, B. A., Lunine, J. I., McKinnon, W. B., Glein, C. R., Mousis, O., Young, D. T., Brockwell, T., Westlake, J., Nguyen, M.-J., Teolis, B. D., Niemann, H. B., McNutt, R. L., Perry, M., & Ip, W. -H., 2009, Liquid water on Enceladus from observations of ammonia and 40Ar in the plume, Nature, 460, 7254, 487
  132. Waite, J. H., Glein, C. R., Perryman, R. S., Teolis, B. D., Magee, B. A., Miller, G., Grimes, J., Perry, M. E., Miller, K. E., Bouquet, A., Lunine, J. I., Brockwell, T., & Bolton, S. J., 2017, Cassini finds molecular hydrogen in the Enceladus plume: Evidence for hydrothermal processes, Science, 356, 6334, 155
  133. Walker, S. I., Bains, W., Cronin, L., DasSarma, S., Denielache, S., Domagal-Goldman, S., Kacar, B., Kiang, N. Y., Lenardic, A., Reinhard, C. T., Moore, W., Schwieterman, E. W., Shkolnik, E. L., & Smith, H. B., 2018, Exoplanet biosignatures: Future directions, Astrobiology, 18, 6, 779
  134. Wang, A., Freeman, J. J., Jolliff, B. L. & Chou, I. -M., 2006, Sulfates on Mars: A systematic Raman spectroscopic study of hydration states of magnesium sulfates, Geochimica et Cosmochimica Acta, 70, 24, 6118
  135. Webster, C. R., Mahaffy, P. R., Atreya, S. K., Flesch, G. J., Mischna, M. A., Meslin, P. Y., Farlye, K. A., et al., 2015, Mars methane detection and variability at Gale crater, Science, 347, 6220, 415
  136. Webster, C. R., Mahaffy, P. R., Atreya, S. K., Moores, J. E., Flesch, G. J., Malespn, C., McKay, C. P., et al., 2018, Background levels of methane in Mars' atmosphere show strong seasonal variations, Science, 360, 6393, 1093
  137. Webster, C. R., Mahaffy, P. R., Pla-Garcia, J., Rafkin, S. C. R., Moores, J. E., Atreya, S. K., Flesch, G. J., Malespin, C. A., Teinturier, S. M., Kalucha, H., Smith, C. L., Viudez-Moreiras, D., & Vasavada, A. R., 2021, Day-night differences in Mars methane suggest nighttime containment Gale crater, A&A, 650, A166
  138. Wilhelm, M. B., Davila, A. F., Parenteau, M. N., Jahnke, L. L., Abate, M., Cooper, G., Kelly, E. T., Garcia, V. P., Villadangos, M. G., Blanco, Y., Glass, B., Wray, J. J., Eigenbrode, J. L., Summons, R. E., & Warren-Rhodes, K., 2018, Constraints on the metabolic activity of microorganisms in Atacama 1 surface soils inferred from refractory biomarkers: Implications for martian habitability and biomarker detection, 2018, Astrobiology, 18, 7, 955
  139. Yung, Y. L., Chen, P., Nealson, K., Atreya, S., Beckett, P., Blank, J. G., Ehlmann, B., et al., 2018, Methane on Mars and habitability: challenges and responses, Astrobiology, 18, 10, 1221
  140. Zacny, K., Bar-Cohen, M., Brennan, G., Briggs, G., Cooper, K., Davis, B., Dolgin, D., Glaser, D., Glass, B., Gorevan, S., Guerrero, J., McKay, C., Paulsen, G., Stanley, S., & Stoker, C., 2008, Drilling systems for extraterrestrial ubsurface exploration, Astrobiology, 8, 3, 665
  141. Zahnle, K., Claire, M., & Catling, D., 2006, A loss of massindependent fractionation in sulfur due to a Palaeoproterozoic collapse of atmospheric methane, Geobiology, 4, 271
  142. Zolotov, M. Y. & Shock, E. L., 2001, Composition and stability of salts on the surface of Europa and their oceanic origin, JGR, 106, 32815