Introduction

Scientists are challenging the long-cherished belief that water was the primary liquid shaping the Martian landscape. For years, features such as massive outflow channels, ancient river valleys, and lakebeds led researchers to conclude that a watery past was the only explanation for Mars’ surface. However, recent studies reveal that this established view may be too simplistic.

The Role of Liquid Carbon Dioxide

An intriguing alternative has emerged: liquid carbon dioxide. In the dense atmosphere of early Mars, carbon dioxide could have existed in liquid form, flowing across the surface and carving features similar to those shaped by water on Earth. A new study suggests that our deep-rooted understanding of water-based systems may have led us to overlook this plausible scenario, which could have significantly impacted the planet's geological history.

Insights from NASA's MOXIE Experiment

Michael Hecht, principal investigator for the MOXIE experiment on NASA's Perseverance rover, spoke to MIT News about the potential implications of this fresh perspective. "While we can't ascertain the exact likelihood of these speculations about early Mars, we do believe that it's important enough to merit serious consideration."

Previous Carbon Sequestration Studies

The research team has drawn upon earlier experiments from carbon sequestration studies that examined how carbon dioxide interacts with minerals, particularly when supercritical or liquid carbon dioxide is present—states where carbon dioxide exhibits properties of both gas and liquid. These studies suggest that in conditions similar to those on ancient Mars, carbon dioxide could have had notable chemical reactions with minerals, leading to the formation of carbonates and other minerals we observe today.

Geological Evidence on Earth and Mars

Interestingly, geologic sequestration studies on Earth have revealed a high degree of reactivity between liquid carbon dioxide and minerals under various conditions. The findings in the study highlight how the resulting mineral alterations—which include carbonates, phyllosilicates, and possibly sulfates—are consistent with mineral evidence found on Mars.

A New Perspective on Martian Features

The researchers propose that Martian features could have formed from stable pockets of liquid carbon dioxide melting beneath glaciers or trapped in subsurface reservoirs. Instead of the conventional narrative of a single warm and wet environment, they emphasize a more dynamic and varied picture characterized by brief episodes of instability and subsurface activity.

The Interplay of Water and Carbon Dioxide

What's more, it's now possible that both liquid water and liquid carbon dioxide interacted to influence Mars' topography. This insight suggests that we may need to think outside conventional frameworks and consider a spectrum of conditions that could have existed on the planet.

Conclusion

Hecht encapsulated the central dilemma of Martian studies by stating, "Understanding how there was sufficient liquid water on early Mars to account for its current morphology and mineralogy is arguably the largest unresolved question in Mars science. There may not be a single answer, and we are proposing yet another possible piece of this intricate puzzle." As we delve deeper into Martian exploration, the implications of this research could redefine our understanding of planetary processes and lead to exciting new discoveries about our neighboring planet.