HABITABLE TRINITY

We propose a new concept of a habitable environment in the search for life beyond Earth that goes beyond the follow-the-water paradigm, newly named Habitable Trinity. Habitable Trinity is the coexistence of an atmosphere (consisting largely of C and N), an ocean (H and O), and a landmass (supplier of nutrients). It is the minimum requirement for the beginning of life to satisfy (1) formation of membrane, (2) metabolism, and (3) self-replication as we know it. A habitable planet, which has largely been defined as having an adequate climate, a sufficient atmosphere, and the presence of liquid water on its surface, is insufficient to meet the requirements to bear life.

Also, material circulation driven by the Sun must be maintained with Habitable Trinity to continue the supply of elements necessary to sustain organic radical reactions that is the basis of life. The Sun is the major engine that links the three components primarily through hydrological cycling, including weathering, erosion, and transport of nutrient-enriched landmass materials to the ocean via far-reaching river systems.

Habitable Trinity can be applied to other planets and moons to discuss the presence of extraterrestrial life. Mars is considered to be the best target to test the hypothesis of whether life exists elsewhere in our solar system, as it records an ancient Habitable Trinity (i.e., lakes and oceans which interacted with a landmass (cratered southern highlands) and an atmosphere). Other terrestrial planets, as well as satellites of the gaseous giants such as Europa and Titan, have little chance to harbor life as we know it because they lack Habitable Trinity.

Going beyond “the-follow-the-water-approach”, the Habitable-Trinity concept provides an index in the quest for life-containing planetary bodies beyond our solar system as the reconnaissance systems become increasingly autonomous and at higher resolution, affording greater perspective during this golden age of international and interdisciplinary exploration and discovery.