Biosignatures on Mars: Habitability Variability, Preservation Pathways, and Earth-Analog Guidance for In Situ Detection

To the point

To search for life on Mars, scientists argue that ancient habitability varied greatly, life if it existed would likely have been chemotrophic and anaerobic around hydrothermal systems, preservation would require rapid mineralization to lock in microfossils and textures, Earth analogs help distinguish biosignatures from abiotic features, and mission designs must consider various outcomes and seek both morphological fossils and chemical biomarkers with careful interpretation.