A Proposed Geobiology-Driven Nomenclature for Astrobiological In Situ Observations and Sample Analyses

Scott M Perl; Aaron J Celestian; Charles S Cockell; Frank A Corsetti; Laura M Barge; David Bottjer; Justin Filiberto; Bonnie K Baxter; Isik Kanik; Sally Potter-McIntyre; Jessica M Weber; Laura E Rodriguez; Mohit Melwani Daswani

doi:10.1089/ast.2020.2318

A Proposed Geobiology-Driven Nomenclature for Astrobiological In Situ Observations and Sample Analyses

Astrobiology. 2021 Aug;21(8):954-967. doi: 10.1089/ast.2020.2318. Epub 2021 Aug 6.

Authors

Affiliations

¹ NASA Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA.
² Mineral Sciences, Natural History Museum of Los Angeles County, Los Angeles, California, USA.
³ Blue Marble Space Institute for Science, Seattle, Washington, USA.
⁴ School of Physics and Astronomy, University of Edinburgh, Edinburgh, Scotland.
⁵ Department of Earth Sciences, University of Southern California, Los Angeles, California, USA.
⁶ Lunar and Planetary Institute, Houston, Texas, USA.
⁷ Great Salt Lake Institute, Westminster College, Salt Lake City, Utah, USA.
⁸ School of Earth Systems and Sustainability, Southern Illinois University Carbondale, Carbondale, Illinois, USA.

Abstract

As the exploration of Mars and other worlds for signs of life has increased, the need for a common nomenclature and consensus has become significantly important for proper identification of nonterrestrial/non-Earth biology, biogenic structures, and chemical processes generated from biological processes. The fact that Earth is our single data point for all life, diversity, and evolution means that there is an inherent bias toward life as we know it through our own planet's history. The search for life "as we don't know it" then brings this bias forward to decision-making regarding mission instruments and payloads. Understandably, this leads to several top-level scientific, theoretical, and philosophical questions regarding the definition of life and what it means for future life detection missions. How can we decide on how and where to detect known and unknown signs of life with a single biased data point? What features could act as universal biosignatures that support Darwinian evolution in the geological context of nonterrestrial time lines? The purpose of this article is to generate an improved nomenclature for terrestrial features that have mineral/microbial interactions within structures and to confirm which features can only exist from life (biotic), features that are modified by biological processes (biogenic), features that life does not affect (abiotic), and properties that can exist or not regardless of the presence of biology (abiogenic). These four categories are critical in understanding and deciphering future returned samples from Mars, signs of potential extinct/ancient and extant life on Mars, and in situ analyses from ocean worlds to distinguish and separate what physical structures and chemical patterns are due to life and which are not. Moreover, we discuss hypothetical detection and preservation environments for extant and extinct life, respectively. These proposed environments will take into account independent active and ancient in situ detection prospects by using previous planetary exploration studies and discuss the geobiological implications within an astrobiological context.

Keywords: 954–967; Biogenicity; Evaporites. Astrobiology 21; Geobiology; Mars Sample Return; Nomenclature.

Publication types

Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

Earth, Planet
Exobiology
Extraterrestrial Environment*
Geology
Mars*
Planets