Mars Gutters: Dry Ice Carving on Mars
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Martian Gullies: New Research Explains Recurring Slope Lineae formation
Updated October 27, 2025, 05:20:47 AM PST
The Mystery of Martian gullies
Since 2008, scientists have observed dark, narrow streaks called Recurring Slope Lineae (RSL) appearing and growing on steep slopes on Mars during warmer seasons. These features, frequently enough appearing on sun-facing slopes, suggest the possible presence of flowing liquid, but the source and composition of this liquid have remained a long-standing mystery. Initial hypotheses included briny water, but the extremely low temperatures and atmospheric pressure on Mars made this explanation challenging.
The RSL are typically less than 5 meters wide and can extend hundreds of meters downhill. They fade during colder periods, leading to the “recurring” aspect of their name.The Mars Reconnaissance Orbiter (MRO) has been instrumental in documenting these features, providing high-resolution images that have fueled the debate about their origin.
Dry Ice as a Potential Culprit
New research, published in Nature Communications on October 26, 2025, proposes a surprising alternative: the formation of RSL is driven by the sublimation of carbon dioxide (CO2) ice – commonly known as dry ice – rather than liquid water. Researchers at Utrecht University in the Netherlands conducted experiments simulating Martian conditions to test this hypothesis. Scinexx reports that the team focused on the unique properties of CO2 ice and its behavior under Martian atmospheric conditions.
Initially, the team conducted experiments under terrestrial conditions, dropping blocks of CO2 ice down slopes. They observed the formation of grooves similar to those seen in Martian RSL. However, these experiments didn’t fully replicate the Martian surroundings. “Though, we suspect that the thin Martian atmosphere is a crucial element in this phenomenon,” the researchers write, as reported by Scinexx. To address this, they repeated the experiments within a Mars simulation chamber, accurately replicating the planet’s atmospheric pressure.
