Planetary Analog Sites In The Indian Subcontinent And The Indian Ocean: Underexplored Environments Suited For Astrobiological And Space Research

The central objective of astrobiology is to evaluate the habitability of other planetary bodies and given the high cost and logistical complexity of space missions, preliminary investigations of planetary analog sites are a critical step in supporting and de-risking future exploration efforts.

Planetary analog sites are extreme environments on Earth that exhibit one or more environmental, geological, geochemical, or biological characteristics that are analogous to conditions expected on other planetary bodies. Understanding how life persists in planetary analog sites is essential for advancing our knowledge of extraterrestrial habitability. They provide valuable opportunities to study life’s resilience and to test life-detection instruments in realistic settings.

In this review, we present the first comprehensive synthesis of over 30 planetary analog field sites located across the Indian subcontinent and the surrounding Indian Ocean region. These include high-altitude glaciers, alkaline lakes, hypersaline basins, hot springs, and cold desert ecosystems.

Although these environments remain largely underexplored in the context of astrobiology, they exhibit strong environmental parallels to planetary conditions and offer significant potential for advancing microbial ecology, biosignature detection, and geobiological research.

As the scientific community prepares for the next generation of deep space missions focused on the search for life beyond Earth, we call for a broader geographical and conceptual inclusion of analog sites. By highlighting the environmental diversity and scientific value of these under-characterized regions in South Asia and their marine periphery, this review contributes a vital and previously underrepresented perspective to planetary analog research.

This review fills a critical gap in the global planetary analog landscape and aims to stimulate interdisciplinary investigations across planetary science, microbiology, and life-detection technology development.

Planetary analog environments across the Indian subcontinent and the Indian ocean basins that represent planetary bodies of astrobiological interest. — eartharxiv.org

Geographic distribution of extreme environments, that can serve as planetary analogues, overlaid on a hypsometric map of the Indian subcontinent and adjoining Indian Ocean. The left panel illustrates the regional distribution of terrestrial and marine sites across diverse ecosystems, while the right panel provides a detailed view of the Himalaya and Tibetan Plateau, highlighting clusters of high-altitude and glacial environments. The underlying topography and bathymetry emphasize the environmental gradients that shape the diversity of analogue sites. Geological base map compiled from GEBCO Compilation Group (2025) — eartharxiv.org

Geographic distribution of extreme environments, that can serve as planetary analogues, overlaid on a generalized geological map of the bed rock of the Indian subcontinent. The underlying geological framework (Cenozoic, Mesozoic, Paleozoic, and Precambrian units) highlights the lithological diversity associated with these analogue sites. Geological base map compiled fromWandrey, C.J., 1998, Geologic map of South Asia (geo8ag) — eartharxiv.org

Planetary analog sites in the Indian subcontinent and the Indian Ocean: Underexplored environments suited for astrobiological and space research, eartharxiv.org

Astrobiology, Astrogeology,