Habitability Study of Terrestrial Planets: Application to Venus-like Worlds

TL;DR

This paper introduces the Venus Similarity Index (VSI) to identify Venus-like exoplanets and explores habitability evolution through AVSI and FESI indices, advancing planetary habitability assessment methods.

Contribution

The paper presents the VSI, AVSI, and FESI indices, providing new tools for comparative habitability studies of Venus-like worlds and planetary evolution.

Findings

VSI ranges from 0 to 1, indicating dissimilarity to Venus.

VSI helps identify Venus-like exoplanets.

Indices enable study of habitability evolution over time.

Abstract

The study of planetary habitability beyond Earth remains a central and challenging project in planetary science. Analysis of large volumes of planetary data from space missions such as CoRoT, Kepler, and JWST is directed ultimately at finding a planet similar to Earth, the Earth's twin, and answering the question of potential exo-habitability. The Earth Similarity Index (ESI) is a first step in this quest, ranging from 1 (Earth) to 0 (totally dissimilar to Earth). To identify planets that may be habitable to the extreme forms of life, we introduce the Mars Similarity Index (MSI). However, extreme forms of life have also been hypothesized under specific conditions in the upper atmosphere of Venus, motivating comparative habitability studies beyond Earth and Mars. The Venus Similarity Index (VSI), introduced here, is defined as the geometric mean of radius, density, escape velocity, and surface temperature, normalized in Venus units (VU). VSI values range from 0 (complete dissimilarity) to 1 (maximum similarity). The VSI provides a comparative framework for identifying Venus-like planetary environments within exoplanet populations. To explore habitability evolution, we further introduce the Ancient Venus Similarity Index (AVSI) and the Future Earth Similarity Index (FESI) to examine early Venusian conditions relative to ancient Earth and to assess potential future evolutionary pathways for Earth-like planets.