New Delhi: Over 6,000 confirmed exoplanets have been discovered by humans so far. Worlds in the mass gap between Earth and Neptune dominate the discovered population, but no such worlds exist in the Solar System. The conventional approach for assessing exoplanet habitability is to find a rocky exoplanet in orbit around a Sun-like star, in the habitable zone, with an atmosphere that contains biosignatures of life. In 2019, scientists published an essay in Science magazine urging researchers to factor in the interior dynamics of a planet when assessing habitability.
Earth has a geomagnetic field that protects the surface from radiation harmful to cells, plate tectonics that continuously recycles the crust, and has liquid water on the surface, all of which support life. The process by which planets form, including the abundances of chemical ingredients, the heating and cooling experienced in their infancies together influence the chemistry of the planet, which in turn determines ocean volume and atmospheric composition. An interdisciplinary team of researchers are investigating if the geologic and dynamic features that makes Earth habitable, can also be produced on exoplanets with different compositions. The scientists work under the Atmospheric Empirical, Theoretical, and Experimental Research (AEThER) project to explore the habitability of Sub-Neptune exoplanets.
A roadmap for discovering aliens
The group has published at least 60 research papers in major research journals so far. Much of the early efforts were focused on modelling and lab experiments. The researchers have been able to determine that the water on Earth could have emerged from interactions between primitive hydrogen-rich atmospheres and magma oceans when Earth was in an embryonic stage. Lab experiments have also demonstrated that large quantities of water are created as a natural consequence of planet formation. The researchers are probing the interior dynamics of planets and bulk compositions using models and lab experiments, characterising the diversity of exoplanet atmospheres using space and ground based astronomical instruments, and are conducting observational as well as analytical efforts to understand how planets acquire and retain volatiles that evaporate easily, but are necessary to support life.