The Curiosity Mars rover has discovered its most diverse and abundant trove yet of organic molecules needed to sustain life.
The molecules, which contain the sulphur and carbon that life would have needed if it ever existed on Mars, were well-preserved in the clay minerals of the Gale Crater, a 155-kilometre-wide suspected former lake.
These sulphur-bearing organics were found in the Glen Torridon region of the crater, which the Curiosity rover explored from 2019 to 2021. at the US Geological Survey Astrogeology Science Center in Arizona and her colleagues presented the findings at the in Texas on 9 March.
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鈥淲e identified the most clay minerals in a sample thus far observed in the mission and we observed the most organics [too],鈥� says Bennett. 鈥淚t really showed that [Gale Crater] was this habitable ancient environment with high organic preservation potential.鈥�
Curiosity collected and analysed 10 samples from Glen Torridon by drilling into the Martian rock and then heating the extracted material to determine its chemistry using an on-board sample-analysis machine.
While organic molecules have been found in Gale Crater before, the Glen Torridon region presented the greatest abundance. It also included several new molecules that can be found on Earth associated with biological processes.
杏吧原创s are now trying to identify the point of origin of these molecules. While they could indicate biological processes 鈥� for instance, they can be produced by heating coal or through the activity of sulphur-reducing bacteria 鈥� it is perhaps more likely that they are the product of non-biological processes such as impacting meteorites or volcanic activity.
鈥淚t鈥檚 going to take years before we can actually constrain, and maybe we never will, where this organic matter is coming from,鈥� says at聽 Versailles Saint-Quentin-en-Yvelines University, France, who is part of the team analysing these sulphur-bearing compounds.
There are several ingredients that go into a life-supporting environment in addition to sulphur organics, such as the presence of water with a neutral pH 聽and temperatures similar to those found on Earth鈥檚 surface. Many of these important preconditions for life have been found over the course of Curiosity鈥檚 time in the Gale Crater. But the clay minerals are of particular significance, because they can both preserve evidence of organic matter and serve as evidence itself of previously habitable conditions.
鈥淐lay minerals are an important marker for planetary scientists, because they require water to form,鈥� says Bennett. 鈥淚f the original goal of the Curiosity rover was to identify habitable environments, and water is a key indicator of a habitable environment, it follows that clay minerals that are water indicators are a good way to go about that.鈥�
While you could make a good case for Gale Crater being the most habitable spot on Mars, there are still many unexplored regions, such as river deposits and sites where glaciers have interacted with the rocky surface.
鈥淭here鈥檚 just such a diverse set of environments represented on Mars, so I鈥檓 not sure what the absolute best spot [for preserved signs of life] would be,鈥� says Bennett.
