On the Quantification of Habitability: Current Approaches

In this chapter, we outline general ideas to quantify habitability, starting with a general abiogenesis–biogenesis conceptual model. We connect this model with the approach of the astrobiological school of quantitative habitability, specifically with quantitative habitability theory, to devise habitability indexes. We present two indexes devised by us: the Aquatic Primary Habitability for photosynthesis-based ecosystems, and the Chemosynthetic Habitability Index for chemoautotrophy-based ones. As a case study, we present the application of the last one to hydrothermal vents. It is also mentioned the possibility of embedding parameters such as net primary productivity, calculated using habitability indexes, into greater ecological models with several trophic models, making a clear connection between the astrobiological and ecological approaches of quantitative habitability.