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Summary

To address the fundamental question of ‘Are we alone?’, a cornerstone of astrobiology, it is necessary to search for signatures of extraterrestrial life (biosignatures). This chapter is thus divided into two parts: in situ biosignatures and remote-sensing biosignatures. In the first, a variety of potential biomarkers are described, such as isotope ratios, individual and collective microfossils, homochirality (i.e., presence of molecules of the same handedness), distributions of biomolecular building blocks, and agnostic methods. In the second, the categories include gases (e.g., molecular oxygen and methane), surface components (e.g., pigments like chlorophylls), and temporal variations of certain features. This chapter concludes by delineating emerging criteria and techniques for evaluating the credibility of putative life detection.

The discovery of thousands of exoplanets in the last two decades has uncovered a wide diversity of planets that are very different from those in our own Solar System. Ideas for how to detect signs of life in the variety of planetary possibilities, by way of biosignature gases, are expanding, although they largely remain grounded in study of familiar gases produced by life on Earth and how they appear in Earth's spectrum as viewed as an exoplanet. What are the chances we will be able to observe and identify biosignature gases on exoplanets in the coming two decades? I review the status of the search for habitable planets and biosignature gases framed by a ‘Biosignature Drake Equation’.

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13 - Biosignatures

Summary

The search for habitable planets with biosignature gases framed by a ‘Biosignature Drake Equation’

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2 results

13 - Biosignatures

Summary

The search for habitable planets with biosignature gases framed by a ‘Biosignature Drake Equation’