Understanding the Search for Life
How science asks whether we are alone — how life might begin, where it could survive, and how we would recognise its signs without being fooled. Built on real astrobiology; no claim of alien life is asserted.
Related entities
- Astrobiology discipline
Ocean Worlds
The icy moons with liquid-water oceans beneath their shells — Europa, Enceladus, and Titan — now the most promising places to search for life in the Solar System, targets of the Europa Clipper and Dragonfly missions.
- Biosignature
Atmospheric Biosignature
Gases in a planet's atmosphere that life could produce and maintain — especially a chemical disequilibrium, like oxygen and methane together, that non-living chemistry would quickly erase. Detected by the spectroscopy of a planet's light.
- Habitability factor
Liquid Water
The one requirement every known form of life shares — a liquid solvent for its chemistry. The habitable zone is defined by where a planet could hold liquid water on its surface, but subsurface oceans extend the possibilities far beyond it.
- Planetary protection
Forward Contamination
The risk of carrying Earth microbes to another world on a spacecraft, which could harm any native biosphere or, worse, be mistaken for alien life. Missions to Mars and the ocean worlds are cleaned and sterilised to strict standards to prevent it.