Astrobiology

Amino-acid handedness can inform a search for life. A 60:40 example explains excess, while meteorite studies show why chemistry and contamination matter.

Atmospheric nitrogen is not automatically usable by life. Fixation changes its chemical form; Curiosity’s Mars samples show why accessible nitrogen is not proof of organisms.

Salt can favor liquid water while limiting biological use. A water-activity example and a scoped Mars climate study distinguish liquid stability from habitability.

Perseverance’s witness tubes record possible contamination around sampling. Their results would help establish a material’s origin, not automatically establish life.

Oxygen on an exoplanet could be a clue to life, but water loss and atmospheric chemistry can imitate it. Learn which observations help test those alternatives.

Discover why Europa and Enceladus are leading targets in the search for life, from their subsurface oceans to possible chemical energy and biosignatures.

Learn how parallax, standard candles, and redshift help scientists estimate distances across the universe—and why each method has limits.

Learn how extremophiles on Earth help scientists study habitability, biosignatures, and environments that could support life beyond our planet.

Explore why ocean worlds are important targets in the search for life beyond Earth and how scientists look for biosignatures from afar.