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The search for a second instance of life is one of the greatest problems of modern science. Outside of creating an artificial origin of life on Earth, the primary targets for the search for life are planets inside or outside the solar…
Finding life on exoplanets from telescopic observations is an ultimate goal of exoplanet science. Life produces gases and other substances, such as pigments, which can have distinct spectral or photometric signatures. Whether or not life is…
Upcoming biosignature searches focus on indirect indicators to infer the presence of life on other worlds. Aside from just signaling the presence of life, however, some biosignatures can contain information about the state that a planet's…
Exoplanet science promises a continued rapid accumulation of new observations in the near future, energizing a drive to understand and interpret the forthcoming wealth of data to identify signs of life beyond our Solar System. The large…
The search for extraterrestrial (alien) life is one of the greatest scientific quests yet raises fundamental questions about just what we should be looking for and how. We approach alien hunting from the perspective of an experimenter…
One of the major goals for astronomy in the next decades is the remote search for biosignatures (i.e.\ the spectroscopic evidence of biological activity) in exoplanets. Here, we adopt a Bayesian statistical framework to discuss the…
We use a probability theory framework to discuss the search for biosignatures. This perspective allows us to analyse the potential for different biosignatures to provide convincing evidence of extraterrestrial life and to formalise…
Ocean worlds are considered as targets for life detection missions because they meet several key requirements for habitability. However, identifying potential life on other worlds requires observing clear and unambiguous biosignature…
Since its inception six decades ago, astrobiology has diversified immensely to encompass several scientific questions including the origin and evolution of Terran life, the organic chemical composition of extraterrestrial objects, and the…
Here we review how environmental context can be used to interpret whether O2 is a biosignature in extrasolar planetary observations. This paper builds on the overview of current biosignature research discussed in Schwieterman et al. (2017),…
A wide variety of scenarios for the origin of life have been proposed, with many influencing the prevalence and distribution of biosignatures across exoplanet populations. This relationship suggests these scenarios can be tested by…
After it was proposed that life on Earth might descend from seeding by an earlier civilization, some authors noted that this alternative offers a testable aspect: the seeds could be supplied with a signature that might be found in extant…
The ultimate goal of astrobiology is to determine the distribution and diversity of life in the universe. But as the word "biosignature" suggests, what will be detected is not life itself, but an observation implicating a particular process…
The probability that life spontaneously emerges in a suitable environment (abiogenesis) is one of the major unknowns in astrobiology. Assessing its value is impeded by the lack of an accepted theory for the origin of life, and is further…
The past five years has seen a surge in research and innovative ideas for the imaging of extrasolar planets, particular terrestrial ones. We expect that within the next decade a space observatory will be launched with the objective of…
The goals of the astrobiology community are focussed on developing a framework for the detection of biosignatures, or evidence thereof, on objects inside and outside of our solar system. A fundamental aspect of understanding the limits of…
Over the past two decades, enormous advances in the detection of exoplanets have taken place. Currently, we have discovered hundreds of earth-sized planets, several of them within the habitable zone of their star. In the coming years, the…
The search for life beyond the Earth is the overarching goal of the NASA Astrobiology Program, and it underpins the science of missions that explore the environments of Solar System planets and exoplanets. However, the detection of…
In the coming years and decades, advanced space- and ground-based observatories will allow an unprecedented opportunity to probe the atmospheres and surfaces of potentially habitable exoplanets for signatures of life. Life on Earth, through…
Ocean-atmosphere chemistry on Earth has undergone dramatic evolutionary changes through its long history, with potentially significant ramifications for the emergence and long-term stability of atmospheric biosignatures. Though a great deal…