Based on soil analysis from Gale Crater, the study suggests that Mars had a cold subarctic climate similar to that of Newfoundland. The discovery provides new insights into the preservation of amorphous matter and the possibility of Mars supporting life. (Artist’s concept) Credit: SciTechDaily.com
A new study has uncovered important clues hidden in Martian soil.
Recent studies comparing soils on Earth and Mars “The study suggests that Mars’ historical climate was cold and subarctic, similar to that of Newfoundland. This study focuses on amorphous material in the soil of Gale Crater that may have been preserved in near-freezing conditions, providing new insights into the environmental conditions on Mars and the possibility of the existence of life on the planet.”
Exploring past climates on Mars from Earth’s soil
The question of whether there was life on Mars has intrigued scientists and the general public for decades. At the heart of this discovery is gaining insight into the past climate of our planetary neighbour. Was Mars warm and wet, with oceans and rivers like Earth’s? Or was it frigid and icy, making life as we know it unlikely to exist?
A new study finds evidence to support the latter, identifying similarities between soils found on Mars and those of the cold, sub-Arctic climate of the Canadian island of Newfoundland.
The rim and floor of Gale Crater as seen from NASA’s Curiosity rover. Courtesy of NASA/JPL-Caltech
Insights from Gale Crater soil analysis
The study was published in the journal Communication Earth and the Environment July 7, We searched for soils on Earth that contain materials comparable to those in Gale Crater on Mars. Scientists often use soils to map environmental history, as the minerals they contain can show how the landscape has changed over time. Better understanding of how these materials formed could help answer long-standing questions about Mars’ historical conditions. The soils and rocks in Gale Crater are a record of a climate that was relatively wet on Mars 3 to 4 billion years ago, a time when life first emerged on the planet.
“Gale Crater is an ancient lake bed that clearly had water present, but what were the environmental conditions like when the water was there,” said Anthony Feldman, a soil scientist and geomorphologist now at DRI. “The conditions on Mars are so different from those on Earth that we’ll never find a direct analog on the Martian surface, but we can look at trends under Earth conditions and apply those to questions about Mars.”
Research site on the Newfoundland Tablelands. Photo credit: Anthony Feldman/DRI
Challenges in analyzing Martian materials
NASA’s Curiosity rover has been investigating Gale Crater since 2011 and has discovered large amounts of soil material known as “X-ray amorphous material.” These soil components cannot be easily characterized by traditional techniques such as X-ray diffraction because they lack the typical repeating atomic structure that defines minerals. For example, when a crystalline material like diamond is irradiated with X-rays, the X-rays scatter at characteristic angles based on the internal structure of the mineral. X-ray amorphous material, however, does not produce these characteristic “fingerprints.” This X-ray diffraction method was used by the Curiosity Rover to reveal that between 15 and 73 percent of the soil and rock samples examined in Gale Crater are composed of X-ray amorphous material.
“X-ray amorphous materials are like jelly,” Feldman said, “and jelly is like a soup of different elements and chemicals that slide around one another.”
The Curiosity rover also performed chemical analysis of soil and rock samples, finding that the amorphous material is rich in iron and silica and deficient in aluminum. Beyond the limited chemical information, scientists still don’t understand what the amorphous material is or what its presence suggests about Mars’ historical environment. Uncovering more information about how these enigmatic materials formed and persist on Earth could help answer long-standing questions about the Red Planet.
Field research mimicking the Martian environment
Feldman and his colleagues visited three locations in the plateau of Gros Morne National Park in Newfoundland, the Klamath Mountains in Northern California, and western Nevada to search for similar X-ray amorphous material. The three locations contain serpentinite soils that the researchers predicted would be chemically similar to the Gale Crater X-ray amorphous material — rich in iron and silicon but low in aluminum. The three locations also have wide ranges of rainfall, snowfall, and temperatures, which could provide insight into the types of environmental conditions that create and promote the preservation of amorphous material.
At each site, the team examined the soil using X-ray diffraction analysis and transmission electron microscopy, allowing them to see the soil material at a more detailed level. Newfoundland’s subarctic climate produced materials that were chemically similar to those found at Gale Crater, but lacked crystalline structure. Soils from warmer climates, such as California and Nevada, did not show any crystalline structure.
“This tells us that water is needed there to form these materials,” Feldman says, “but to preserve the amorphous materials in the soil, you need cold conditions with average annual temperatures close to freezing.”
Amorphous materials are often thought of as relatively unstable, meaning that at the atomic level, the atoms have not yet organized into a final crystalline structure. “There’s something going on in the reaction rates, or kinetics, that slows down the reactions so that these materials can be preserved over geological timescales,” Feldman says. “What we’re suggesting is that very low temperatures, close to freezing, are a particular kinetic limiting factor that allows these materials to form and be preserved.”
“This study improves our understanding of the Martian climate,” Feldman said, “and the results suggest that the abundance of this material in Gale Crater is consistent with subarctic conditions similar to those found in Iceland, for example.”
Reference: “Iron-rich X-ray amorphous material records past climate and persistence of water on Mars,” Anthony D. Feldman, Elizabeth M. Hausradt, Elizabeth B. Lampe, Valerie Tu, Tanya S. Pelletiazko, Christopher DeFelice, Thomas Sharp, 7 July 2024; Communication Earth and the Environment.
Publication date: 10.1038/s43247-024-01495-4
