Chapter 7b

Searching for Life

Synopsis

The search for life on other planets necessitates a rigorous and comprehensive examination of biosignatures, the types of signatures that life produces. Signatures can be chemical or physical features associated with past or present life, and may include the formation of elements, molecules, alone or in combination, or changes in structural components that would be distinct from an abiotic background. Efforts to look for in situ biosignatures on other planets have resulted in a multitude of space-capable techniques and instrumentation that are used to detect life on Earth as well as other planets such as Mars. Biosignatures can also be detected remotely. Evidence from spectral absorption, emission, or transmission features can be used to determine atmospheric composition of exoplanets or even potential biological pigments. Improving our understanding of these biosignatures, their production, transformation, or preservation on Earth can enhance our efforts to detect life on other planets. New perspectives towards agnostic biosignatures detection have also began to emerge, allowing for a broader more universal approach to potentially seeking life with exotic and unknown chemistry that is distinct from life as we know it on Earth.