Recently in the Biosignatures & Paleobiology Category

This vegetation index, created using images taken by OSIRIS-REx's MapCam camera on Sept. 22, 2017, shows areas on Earth with abundant plant life.

A Review of Exoplanetary Biosignatures

We review the field of exoplanetary biosignatures with a main focus upon atmospheric gas-phase species. Due to the paucity of data in Earth-like planetary atmospheres a common approach is to extrapolate knowledge from the Solar System and Early Earth to Earth-like exoplanets.

Astronomers using the Atacama Large Millimeter/submillimeter Array (ALMA) have detected the faint molecular fingerprint of methyl chloride - a chemical commonly produced by industrial and biological processes here on Earth - around an infant star system known as IRAS 16293-2422.

In everyday life, ultraviolet, or UV, light earns a bad reputation for being responsible for sunburns and other harmful effects on humans. However, research suggests that UV light may have played a critical role in the emergence of life on Earth and could be a key for where to look for life elsewhere in the Universe.

Exoplanets: Possible Biosignatures

The ancestor philosophers' dream of thousands of new worlds is finally realised: about 3500 extrasolar planets have been discovered in the neighborhood of our Sun. Most of them are very different from those we used to know in our Solar System.

Transmission spectra of exoplanetary atmospheres have been used to infer the presence of clouds/hazes. Such inferences are typically based on spectral slopes in the optical deviant from gaseous Rayleigh scattering or low-amplitude spectral features in the infrared.

An instrument originally developed to search for organic molecules on Mars is being repurposed to potentially hunt for life on a handful of moons in the outer solar system that appear to host oceans, geysers and vents of ice volcanoes.

Exoplanet science promises a continued rapid accumulation of rocky planet observations in the near future, energizing a drive to understand and interpret an unprecedented wealth of data to search for signs of life. The large statistics of exoplanet samples, combined with the ambiguity of our understanding of universal properties of life and its signatures, necessitate a quantitative framework for biosignature assessment.

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), and provides an in-depth, interdisciplinary example of biosignature identification and observation that serves as a basis for the development of the general framework for biosignature assessment described in Catling et al., (2017).

We provide an overview of the prospects for biosignature detection and general characterization of temperate Earth-sized planets. We review planned space-based missions and ground-based projects as well as the basic methods they will employ, and summarize which exoplanet properties will become observable as these new facilities come on line.