NASA’s Curiosity rover has been exploring the Gale crater on Mars, uncovering new information about how the Red Planet went from being a place with liquid water to a harsh, uninhabitable world.
Although Mars is cold and barren today, scientists believe that it may have supported life billions of years ago.
By studying rocks and minerals, Curiosity is helping scientists understand how the Martian climate changed and why the planet became inhospitable.
Curiosity has been using its instruments to analyze carbon-rich minerals, called carbonates, in the Gale crater.
These carbonates are important because they can act as records of the climate when they formed.
Recently, researchers found that the isotope composition of these carbonates points to an ancient Martian climate marked by extreme evaporation, which would have only allowed for temporary bodies of liquid water.
According to David Burtt, a scientist from NASA’s Goddard Space Flight Center and the lead author of the study, these findings suggest that Mars didn’t have the kind of stable environment necessary to support life on the surface.
However, this doesn’t completely rule out the possibility that life could have existed underground or that surface life could have appeared and disappeared before the carbonates formed.
Isotopes are different versions of the same element, but they have slightly different masses. Scientists use isotopes to study ancient environments because their ratios can change depending on conditions like temperature and the presence of water.
As water evaporates, lighter versions of carbon and oxygen tend to escape into the atmosphere, while the heavier versions stay behind. This process can leave behind minerals, like carbonates, with high levels of heavy isotopes.
By measuring the isotopes in Martian carbonates, scientists can learn about the conditions under which these minerals formed. On Earth, carbonates can reveal details about ancient climates, including the temperature of the water they formed in and the composition of the atmosphere.
The research team suggests two different climate scenarios based on the carbonates found in the Gale crater.
In the first scenario, the climate went through cycles of wet and dry periods, meaning there were times when Mars had liquid water and times when it didn’t. This would have created a mix of habitable and less-habitable conditions.
In the second scenario, the carbonates formed in very salty water under freezing conditions. This would have created a much less hospitable environment, as most of the water would have been trapped in ice, and any liquid water would have been too salty for most forms of life to survive.
Both of these climate scenarios have been proposed in the past, but this study provides new evidence based on isotope measurements to support them.
The isotopic values in the Martian carbonates were found to be much heavier than anything seen on Earth or in other Martian samples, suggesting that these processes happened to an extreme degree on ancient Mars.
The Curiosity rover used two special tools to study the carbonates: the Sample Analysis at Mars (SAM) and the Tunable Laser Spectrometer (TLS). SAM heats rock samples to very high temperatures, up to nearly 1,652 degrees Fahrenheit (900°C), and then TLS analyzes the gases produced to measure the isotopes.
This combination allowed scientists to get a detailed look at the composition of the carbonates and gain new insights into Mars’ ancient climate.
This research is helping scientists piece together the puzzle of why Mars lost its liquid water and became the dry, cold planet we see today.
The findings could also guide future missions as they continue the search for signs of life on Mars.
Source: NASA.
