Biosignatures & Paleobiology

Exoplanet Biosignatures: Future Directions

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.

Astrochemistry

Study Shows How Radioactive Decay Could Support Extraterrestrial Life

In the icy bodies around our solar system, radiation emitted from rocky cores could break up water molecules and support hydrogen-eating microbes. To address this cosmic possibility, a University of Texas at San Antonio (UTSA) and Southwest Research Institute (SwRI) team modeled a natural water-cracking process called radiolysis

Biosignatures & Paleobiology

Exoplanet Biosignatures: Understanding Oxygen as a Biosignature in the Context of Its Environment

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).

Astrochemistry

Production of Complex Organic Molecules: H-atom Addition Versus UV Irradiation

Complex organic molecules (COMs) have been identified in different environments in star- forming regions. Laboratory studies show that COMs form in the solid state, on icy grains, typically following a non-energetic (atom-addition) or energetic (UV-photon absorption) trigger. So far, such studies have been largely performed for single processes.

Extrasolar Planets

Neutron Star Planets: Atmospheric Processes and Habitability

Of the roughly 3000 neutron stars known, only a handful have sub-stellar companions. The most famous of these are the low-mass planets around the millisecond pulsar B1257+12. New evidence indicates that observational biases could still hide a wide variety of planetary systems around most neutron stars.

Biosignatures & Paleobiology

Exoplanet Biosignatures: Observational Prospects

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.

Astrobiology (general)

Before Astrobiology There Was Aстробиология

Contrary to what NASA may want you to think, the word "Astrobiology" was used decades before NASA began using it to describe the study of extraterrestrial life.

This book "Astrobiology" - "Aстробиология" was published (in Russian) in 1953 in the USSR.

The photos below illustrate the topics that the book covered.

Origin & Evolution of Life

Sea Level as a Metronome of Earth's History

Sedimentary layers record the history of the Earth. They contain stratigraphic cycles and patterns that precisely reveal the succession of climatic and tectonic conditions that have occurred over millennia, thereby enhancing our ability to understand and predict the evolution of our planet.

Biosignatures & Paleobiology

Exoplanet Biosignatures: A Framework for Their Assessment

Finding life on exoplanets from telescopic observations is the 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 found in future data must be expressed with probabilities, requiring a framework for biosignature assessment.

Habitable Zones & Global Climate

A Super-Earth on the Inner Edge of the Habitable Zone of the Nearby M-dwarf GJ 625

We report the discovery of a super-Earth orbiting at the inner edge of the habitable zone of the star GJ 625 based on the analysis of the radial-velocity (RV) time series from the HARPS-N spectrograph, consisting in 151 HARPS-N measurements taken over 3.5 yr. GJ 625 b is a planet with a minimum mass M sin i of 2.82 ± 0.51 M⊕ with an orbital period of 14.628 ± 0.013 days at a distance of 0.078 AU of its parent star.

Astrobiology (general)

A Statistical Comparative Planetology Approach to the Hunt for Habitable Exoplanets and Life Beyond the Solar System

The search for habitable exoplanets and life beyond the Solar System is one of the most compelling scientific opportunities of our time.