Synthesis, synchrotron characterization and astrobiological implications of biotic and abiotic carbonates at the nanoscale

• Grant number: 25/08031-0
• Support Opportunities: Scholarships in Brazil - Master
• Start date: October 01, 2025
• End date: September 30, 2027
• Field of knowledge: Physical Sciences and Mathematics - Geosciences
• Principal Investigator: Douglas Galante
• Grantee: Debora Aparecida Steffler
• Host Institution: Instituto de Geociências (IGC). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

At the beginning of its geological history, Mars had environmental conditions similar to those of the primitive Earth, and it is possible to hypothesize that, just like here, life may have arisen on the red planet. In this context, microbial mats played a fundamental role in biogeochemical cycles and in oxygenating the Earth's atmosphere, having the ability to precipitate calcium carbonates such as calcite and aragonite, which are possible biosignatures of life existing on Mars in the past. However, as these minerals can also be formed by abiotic processes, it is essential to differentiate between biosynthesized and inorganically synthesized carbonates in order to detect life outside the Earth.This project therefore aims to chemically, structurally and morphologically characterize calcium carbonates precipitated by microorganisms and compare them to those synthesized in the laboratory by abiotic means. The use of advanced synchrotron radiation techniques, such as nano-diffraction, ptychographic tomography and X-ray absorption spectroscopy, will allow the identification of chemical, morphological and structural patterns typical of biominerals, with high resolution and sensitivity, as well as enabling the non-destructive analysis of samples. By establishing more robust criteria for differentiating minerals of biotic and abiotic origin, this study could contribute to the detection of potential traces or signs of life on Mars. (AU)