Creating Habitable Zones, at all Scales, from Planets to Mud Micro-Habitats, on Earth and on Mars
Résumé
The factors that create a habitable planet are considered at all scales, from plan- etary inventories to micro-habitats in soft sediments and intangibles such as habitat link- age. The possibility of habitability first comes about during accretion, as a product of the processes of impact and volatile inventory history. To create habitability water is essential, not only for life but to aid the continual tectonic reworking and erosion that supply key redox contrasts and biochemical substrates to sustain habitability. Mud or soft sediment may be a biochemical prerequisite, to provide accessible substrate and protection. Once life begins, the habitat is widened by the activity of life, both by its management of the greenhouse and