Magnetofossils – fossilised remains of magnetic particles produced by magnetotactic bacteria – have been observed in rock varnish layers in Ladakh. Studies suggesting biological processes in the formation of rock varnish illustrate how life can exist in extreme environments, providing valuable insights for astrobiology as well as for planning future space missions with the goal of identifying habitable environments in space.
Ladakh, known as the “cold desert of India”, experiences extreme climatic conditions such as high ultraviolet (UV) radiation, significant temperature variation and limited water availability, making it a suitable terrestrial analogue for the study of Mars. Researchers from the Birbal Sahni Institute of Palaeosciences, Lucknow (BSIP), an autonomous institute of the Department of Science and Technology (DST), were inspired by the similarities between the rock varnish found in Ladakh and that observed during the Mars Perseverance rover operations.
They collected samples of rock varnish from the Ladakh region and selected and employed XPS to perform surface chemistry analysis of the rock varnish. The analysis carried out by lead authors Dr Amritpal Singh Chadha and Dr Anupam Sharma at BSIP along with Sophisticated Analytical Instrumentation Facility (SAIF) established by DST helped in identifying nanochains of magnetofossils.
Additionally, high concentrations of oxidized manganese (Mn4+) and carboxylic acid functionality were identified on the varnish surface, indicating organic presence. The study, published in Planetary and Space Science, showed that rock varnish from Ladakh, a potential Martian analogue site, contains rich concentrations of magnetic minerals derived from biological sources.
These findings highlight the potential of rock varnish as an archive of ancient environmental records and as a geomaterial for astronomical studies.
By identifying biological presence in rock varnish, scientists can better target potential biosignatures on Mars and other planetary bodies, thereby aiding in the search for extraterrestrial life. This information is critical for planning future space missions by ISRO and other space agencies, including Mars exploration, where identifying habitable environments is a primary goal.