Reno, Nev. (July 10, 2024) – The question of whether Mars ever supported life has captivated scientists and the public for decades. Central to this inquiry is understanding the planet’s past climate: was it warm and wet with seas and rivers, or frigid and icy? A new study supports the latter hypothesis by identifying similarities between soils found on Mars and those in Newfoundland, Canada, a region with a cold subarctic climate.
The study, published on July 7th in Communications Earth and Environment, examined Earth’s soils with materials comparable to those in Mars’ Gale Crater. Soil minerals can depict environmental history by revealing landscape evolution over time. Understanding these materials could help answer questions about historical conditions on Mars.
Gale Crater’s soils provide a record of Mars’ climate from 3 to 4 billion years ago when water was relatively abundant—a period that coincides with the emergence of life on Earth.
“Gale Crater is a paleo lakebed—there was obviously water present. But what were the environmental conditions when the water was there?” said Anthony Feldman, a soil scientist and geomorphologist at DRI. “We’re never going to find a direct analog to the Martian surface because conditions are so different between Mars and Earth. But we can look at trends under terrestrial conditions and use those to try to extrapolate to Martian questions.”
NASA’s Curiosity Rover has been investigating Gale Crater since 2011, discovering numerous soil materials known as “X-ray amorphous material.” These components lack the typical repeating atomic structure defining minerals, making them difficult to characterize using traditional techniques like X-ray diffraction.
“You can think of X-Ray amorphous materials like Jello,” Feldman explained. “It’s this soup of different elements and chemicals that just slide past each other.”
Curiosity also conducted chemical analyses on soil samples, finding that amorphous material was rich in iron and silica but deficient in aluminum. Scientists do not yet fully understand what this material implies about Mars’ historical environment.
Feldman and his colleagues visited three locations searching for similar X-ray amorphous material: Gros Morne National Park in Newfoundland, Northern California’s Klamath Mountains, and western Nevada. These sites had serpentine soils expected to be chemically similar to those at Gale Crater: rich in iron and silicon but lacking aluminum.
At each site, researchers used X-ray diffraction analysis and transmission electron microscopy for detailed examination. Subarctic conditions in Newfoundland produced chemically similar materials lacking crystalline structure found at Gale Crater; warmer climates like California and Nevada did not produce such results.
“This shows that you need the water there in order to form these materials,” Feldman noted. “But it needs to be cold, near-freezing mean annual temperature conditions in order to preserve the amorphous material in the soils.”
Amorphous material is often considered unstable because its atoms have not organized into their final crystalline forms. “There’s something going on in the kinetics—or the rate of reaction—that is slowing it down so that these materials can be preserved over geologic time scales,” Feldman added. “What we’re suggesting is that very cold, close-to-freezing conditions are one particular kinetic limiting factor allowing these materials to form and be preserved.”
“This study improves our understanding of Mars’ climate,” Feldman concluded. “The results suggest that this material’s abundance in Gale Crater aligns with subarctic conditions similar to Iceland.”
– @driscience –
More information: The full study “Fe-rich X-Ray amorphous material records past climate and persistence of water on Mars” is available from Communications Earth & Environment at https://www.nature.com/articles/s43247-024-01495-4
Study authors include Anthony Feldman (DRI/UNLV), Elisabeth Hausrath (UNLV), Elizabeth Rampe (NASA), Valerie Tu (NASA), Tanya Peretyazhko (NASA), Christopher DeFelice (UNLV), Thomas Sharp (ASU).
About DRI
DRI is Nevada’s non-profit research institute founded in 1959 focusing on science addressing pressing issues globally. With more than 600 scientists across Reno and Las Vegas campuses conducting over $47 million worth of sponsored research focused on improving lives annually.
