Biosignaturen

Biosignaturen, or biosignatures, are indicators that provide scientific evidence of past or present life. They can be chemical, isotopic, morphological, or contextual measurements whose occurrence would be unlikely under purely abiotic conditions. A robust biosignature is not a single feature but a line of evidence that supports an interpretation of biological activity.

Biosignaturen are commonly grouped into several categories. Chemical signatures include gases in a planetary atmosphere that would be out of equilibrium, such as oxygen and methane coexisting, or complex organic molecules associated with biology. Isotopic signatures rely on fractionation patterns produced by metabolism. Morphological signatures refer to preserved cellular structures or microfossil-like textures in rocks. Contextual or functional signatures consider the environmental setting and energy sources that could sustain life.

Detection methods span in situ analyses and remote sensing. In the solar system, landers and rovers analyze surface and subsurface materials and may return samples for laboratory study. In exoplanet science, spectroscopy aims to identify atmospheric constituents and their possible disequilibrium. Laboratory techniques include mass spectrometry, chromatography, isotopic ratio measurements, and high-resolution microscopy.

Challenges include distinguishing biotic from abiotic sources, requiring multiple lines of evidence and careful modeling. Contamination and instrument limitations can complicate interpretation. Biosignaturen are central to astrobiology and guide the search for life beyond Earth, while technosignaturen address signs of intelligent life.