Recent research challenges long-held beliefs about the geological history of Mars, suggesting that liquid carbon dioxide (CO₂) could have played a significant role in shaping the planet's surface. This study, led by a team of scientists, posits that under Mars' dense atmosphere, CO₂ may have liquefied and flowed across the landscape, forming valleys and channels akin to those sculpted by liquid water.
Michael Hecht, principal investigator of the MOXIE instrument aboard NASA's Perseverance rover, stated, "The probability is high enough that it should not be ignored." The team examined mineral observations from Mars, including carbonates, phyllosilicates, and sulfates, alongside Earth-based experiments that demonstrated how liquid CO₂ can react chemically with minerals when saturated with water.
According to the authors, this reactivity could explain the presence of various minerals found on Mars today. They propose that CO₂ likely existed in the planet's history, particularly beneath glaciers or within sealed underground deposits. The dense and low-viscosity characteristics of liquid CO₂ would enable it to flow rapidly, potentially transporting sediment and carving deeper channels.
The traditional view of a warm, wet Mars is now being re-evaluated. The study suggests that the planet's early atmosphere, rich in CO₂, may not have produced enough heat to sustain stable bodies of liquid water. This new perspective indicates that a combination of transient geological processes could have contributed to Mars' current morphology.
Future Mars missions may need to adapt their instruments to search for signs of CO₂-related geological activity, such as unique mineral textures or specific chemical alterations. Additionally, climate models of Mars could be enhanced by incorporating scenarios involving interactions between liquid CO₂, water, and minerals.
Hecht emphasized the importance of expanding our understanding beyond Earth-centric paradigms to fully grasp Mars' geological history. "We must think creatively and explore possibilities that extend beyond traditional assumptions," he concluded, highlighting the ongoing quest to uncover Mars' mysteries.