Curiosity Rover Discovers What Made Mars Uninhabitable After Water Supported Life

NASA’s Curiosity rover is currently conducting research within Mars’ Gale Crater, shedding light on the planet’s climatic evolution from conditions that might have supported life to a state where life as we know it cannot survive.

Evidence suggests that Mars once harbored extensive liquid water. However, today’s Martian surface is harsh and inhospitable. Despite these conditions, NASA’s robotic missions continue to uncover signs that ancient Mars could have supported life.

Researchers utilizing Curiosity’s instruments have analyzed the isotopic composition of carbon-rich minerals found in the Gale Crater. Their findings provide new insights into the ancient Martian climate. According to David Burtt, the lead author of a study published in the Proceedings of the National Academy of Sciences and a researcher at NASA’s Goddard Space Flight Center in Maryland, the isotopic values of these carbonates indicate significant evaporation. This suggests that the carbonates formed in an environment with only fleeting occurrences of liquid water.

Burtt explained, “The isotope values point toward a climate that could only support transient liquid water, indicating a largely inhospitable environment.” He also noted that while the current findings don’t support the presence of a surface biosphere at the time these carbonates formed, they don’t entirely rule out the possibility of life existing underground or during an earlier period.

Isotopes are variants of an element that differ in mass. During the evaporation of water, lighter isotopes of carbon and oxygen tend to escape into the atmosphere, leaving behind heavier isotopes. These heavier isotopes accumulate and eventually become part of the carbonate rocks.

The study proposes two potential scenarios for the formation of carbonates at Gale. One scenario suggests that the carbonates were a product of repeated wet-dry cycles within the Gale Crater, while the other scenario posits that the carbonates formed in extremely salty water under cold, ice-forming conditions.

Jennifer Stern, a co-author of the paper and a researcher at NASA Goddard, commented on the implications of these findings for habitability. She noted that wet-dry cycling could suggest a fluctuation between more and less habitable conditions, whereas the cryogenic conditions would indicate an environment where water is predominantly trapped as ice, making it largely unsuitable for biological and chemical processes due to the extreme salinity and cold.