A study suggests that Mars had a cold subarctic climate similar to that of Newfoundland, based on soil analyses from Gale Crater. The discovery provides new insights into the preservation of amorphous materials and Mars’ potential to support life. (Artist’s concept.) Credit: SciTechDaily.com
A new study reveals crucial clues hidden in the soil of the Red Planet.
Recent research comparing Earth’s soils and
” data-gt-translate-attributes=”({“attribute”:”data-cmtooltip”, “format”:”html”})” tabindex=”0″ role=”link”>Mars The results of this study suggest that the historical climate of Mars was cold and subarctic, similar to that of Newfoundland. The study focused on amorphous materials from the soil of Gale Crater, potentially preserved by near-freezing conditions, providing new insights into the environmental conditions of Mars and its potential for life.
Exploring the past climate of Mars through terrestrial soils
The question of whether Mars ever supported life has captured the imagination of scientists and the public for decades. The discovery hinges on a better understanding of the past climate of Earth’s neighbor: Was the planet warm and wet, with seas and rivers very similar to those on our own planet? Or was it frigid and therefore potentially less likely to support life as we know it?
A new study provides evidence to support the latter hypothesis by identifying similarities between soils found on Mars and those in Newfoundland, Canada, a cold subarctic climate.
The rim and floor of Gale Crater as seen from NASA’s Curiosity rover. Credit: NASA/JPL-Caltech
Gale Crater Soil Analysis Overview
The study, published in the journal Earth and Environment Communications July 7th, Researchers have searched Earth for soils containing materials similar to those in Mars’ Gale Crater. Scientists often use soil to describe environmental history because the minerals present can tell the story of how the landscape changed over time. A better understanding of how these materials formed could help answer long-standing questions about historical conditions on the Red Planet. The soils and rocks in Gale Crater provide a record of Mars’ climate 3 billion to 4 billion years ago, a time when water was relatively abundant on the planet — and the same time that life emerged on Earth.
“Gale Crater is a paleo-lake bed: there was obviously water. But what were the environmental conditions like when the water was there?” says Anthony Feldman, a soil scientist and geomorphologist now at DRI. “We’ll never find a direct analogue of the Martian surface, because the conditions are so different between Mars and Earth. But we can look at trends in Earth conditions and use those to try to extrapolate to Martian questions.”
The study site in the Newfoundland Tablelands. Credit: Anthony Feldman/DRI
Challenges of analyzing Martian materials
NASA’s Curiosity rover has been studying Gale Crater since 2011 and has discovered a multitude of soil materials called “X-ray amorphous materials.” These soil components lack the typical repeating atomic structure that defines minerals and therefore cannot be easily characterized using traditional techniques like X-ray diffraction. When X-rays are shined on crystalline materials like a diamond, for example, the X-rays scatter at characteristic angles based on the mineral’s internal structure. However, X-ray amorphous materials do not produce these characteristic “fingerprints.” This X-ray diffraction method was used by the Curiosity rover to demonstrate that X-ray amorphous materials made up between 15 and 73 percent of the soil and rock samples tested in Gale Crater.
“You can compare amorphous materials to jelly in X-rays,” Feldman says. “It’s a kind of soup of different elements and chemicals sliding around on top of each other.”
The Curiosity rover also performed chemical analyses on soil and rock samples, and found that the amorphous material was rich in iron and silica, but poor in aluminum. Beyond the limited chemical information, scientists don’t yet understand what the amorphous material is, or what its presence implies about Mars’ historical environment. Uncovering more information about how these enigmatic materials form and persist on Earth could help answer lingering questions about the Red Planet.
Field studies reproducing Martian conditions
Feldman and his colleagues visited three sites looking for similar X-ray amorphous materials: the plateaus of Gros Morne National Park in Newfoundland, the Klamath Mountains of northern California, and western Nevada. All three sites had serpentine soils that the researchers expected to be chemically similar to the X-ray amorphous material in Gale Crater: rich in iron and silicon but lacking in aluminum. The three sites also had a range of precipitation, snowfall, and temperatures that could help us better understand the kinds of environmental conditions that produce amorphous materials and promote their preservation.
At each site, the research team examined the soils using X-ray diffraction analysis and a transmission electron microscope, which allowed them to observe the soil materials at a more detailed level. Newfoundland’s subarctic conditions produced materials that were chemically similar to those found in Gale Crater, but lacked a crystalline structure. Soils produced in warmer climates such as California and Nevada did not.
“This shows that water is necessary for the formation of these materials,” Feldman says. “But the annual average temperature needs to be close to freezing to preserve the amorphous material in the soils.”
Amorphous materials are often thought of as relatively unstable, meaning that at the atomic level, the atoms have not yet organized themselves into their final, more crystalline forms. “There’s something happening in the kinetics – or the rate of reaction – that slows it down so that these materials can be preserved over geological timescales,” Feldman says. “What we’re suggesting is that very cold conditions, close to freezing, are a particular kinetic limiting factor that allows these materials to form and be preserved.”
“This study helps us better understand the climate of Mars,” Feldman says. “The results suggest that the abundance of this material in Gale Crater is consistent with subarctic conditions, similar to those observed, for example, in Iceland.”
Reference: “Fe-rich X-ray amorphous material records past climate and persistence of water on Mars” by Anthony D. Feldman, Elisabeth M. Hausrath, Elizabeth B. Rampe, Valerie Tu, Tanya S. Peretyazhko, Christopher DeFelice, and Thomas Sharp, July 7, 2024, Earth & Environment Communications.
DOI: 10.1038/s43247-024-01495-4