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.
Highlights
IntroductionIntroduction and MotivationAs the discipline of astrobiology is increasing in its parameters and practice for planetary missions, the definitions and usage of terminology that allows for proper differentiation of features from life or modified from life do not yet exist
Introduction and MotivationAs the discipline of astrobiology is increasing in its parameters and practice for planetary missions, the definitions and usage of terminology that allows for proper differentiation of features from life or modified from life do not yet exist
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
Summary
Introduction and MotivationAs the discipline of astrobiology is increasing in its parameters and practice for planetary missions, the definitions and usage of terminology that allows for proper differentiation of features from life or modified from life do not yet exist. If an independent origin of life did start separately on Mars, a planet without plate tectonics for most of its history, these contamination caveats would be used as supporting arguments for the preservation of ancient organics or perhaps extant life in the subsurface, providing we were able to prove that a positive signature and/or marker were indigenous to the sample and/or site. This is not to say that these efforts are unwarranted, quite the contrary
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