NASA’s Curiosity rover has provided new insights into how Mars became uninhabitable, shedding light on the planet’s ancient climate. The rover, currently exploring Gale crater, used its instruments to measure the isotopic composition of carbon-rich minerals and discovered evidence that suggests extreme evaporation occurred in a climate that could only support transient liquid water.
According to David Burtt, lead author of a paper published in the Proceedings of the National Academy of Sciences, the isotope values point towards an environment with little surface liquid water. “The isotope values of these carbonates point toward extreme amounts of evaporation,” said Burtt.
As water evaporated on Mars, light versions of carbon and oxygen were more likely to escape into the atmosphere, while heavy versions accumulated in rocks like carbonates. These minerals can retain signatures of the environment in which they formed, providing a record of the planet’s climate.
The study proposes two formation mechanisms for carbonates found at Gale: one through wet-dry cycles within the crater and another in very salty water under cold conditions. The findings suggest that both scenarios represent different climate regimes with varying habitability.
The heavy isotope values measured in Martian carbonates are significantly higher than those seen on Earth, indicating an extreme degree of evaporation that drove these changes. “This means two things: 1) there was an extreme degree of evaporation driving these isotope values to be so heavy, and 2) any processes creating lighter isotope values must have been significantly smaller in magnitude,” said Burtt.
The discovery was made using the Sample Analysis at Mars (SAM) and Tunable Laser Spectrometer (TLS) instruments aboard the Curiosity rover. The findings provide new insights into ancient Mars’ climate and shed light on the planet’s transformation from potentially suitable for life to an inhospitable environment.
Source: https://phys.org/news/2024-10-curiosity-rover-insights-mars-uninhabitable.html