The atmosphere of the Archean eon—one-third of Earth's history—is important for
understanding the evolution of our planet and Earth-like exoplanets. New geological proxies …

Prokaryotic life has dominated most of the evolutionary history of our planet, evolving to
occupy virtually all available environmental niches. Extremophiles, especially those thriving …

Extreme environments on Earth are typically devoid of macro life forms and are inhabited
predominantly by highly adapted and specialized microorganisms. The discovery and …

Methane has been proposed as an exoplanet biosignature. Imminent observations with the
James Webb Space Telescope may enable methane detections on potentially habitable …

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 …

NASA's Dragonfly mission will send a rotorcraft lander to the surface of Titan in the mid-
2030s. Dragonfly's science themes include investigation of Titan's prebiotic chemistry …

The early Earth's environment is controversial. Climatic estimates range from hot to glacial,
and inferred marine pH spans strongly alkaline to acidic. Better understanding of early …

We describe how environmental context can help determine whether oxygen (O2) detected
in extrasolar planetary observations is more likely to have a biological source. Here we …

The search for life in the Universe is a fundamental problem of astrobiology and modern
science. The current progress in the detection of terrestrial-type exoplanets has opened a …

Understanding the impact of active M dwarf stars on the atmospheric equilibrium and
surface conditions of a habitable zone Earth-like planet is key to assessing M dwarf planet …