Amino Acids
Organic molecules that serve as the building blocks of proteins; central target molecules in astrobiology because they have been detected both in known life and in abiotic chemistry (interstellar ice analogues, carbonaceous meteorites, asteroid-sample returns).
Astrobiology relevance
- Biological signature: All known life uses a specific set of ~20 proteinogenic amino acids, with strong homochirality (L-handed dominance).
- Abiotic delivery: Meteorites (Murchison, Bennu returned samples) contain dozens of amino acids in distinctly different distributions than biology — flatter, more racemic, including many non-biological species.
- Statistical-diversity biosignature (src-alien-biology-detection-method-2026-05): Yoffe & Klenner (2026) show that biological amino-acid pools are systematically more diverse (high richness) and more even (uniform distribution) than abiotic pools. Combined with fatty-acid data — which show the inverse pattern — this provides an instrument-agnostic classifier.
- Mars context: Detection of amino acids on Mars remains a key goal; ice-soil chemistry may destroy amino acids 10× faster than pure ice (src-mars-ancient-life-ice-survival-2026-02). Ice-drilling missions are recommended. The “organics-forward” Mars strategy (src-organics-forward-mars-life-search-2026-05) leans on the homochiral-20 biological signature vs. racemic abiotic mixtures as a structural discriminator for a Martian biosignature.