Evidence suggests liquid water still flows across the Martian surface

Space · Published 8 October 2026 Swipe more like this →

In short: For years, scientists suspected that liquid water might still move on the Red Planet. New data from NASA's Mars Reconnaissance Orbiter has provided the strongest evidence yet, revealing that briny flows are not just a relic of the past, but an active, seasonal occurrence today.

Researchers have identified specific features known as recurring slope lineae (RSL). These are darkish streaks on steep Martian slopes that appear to ebb and flow over time. They typically darken and move downhill during warmer seasons, only to fade away when temperatures drop. These observations have been documented at dozens of different sites across the planet using the High Resolution Imaging Science Experiment (HiRISE). To understand the mechanism behind these streaks, scientists used the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) to map minerals. They detected signatures of hydrated salts specifically on the slopes where the RSL appear. These salts are significant because they lower the freezing point of liquid brine, similar to how road salt prevents ice from forming on Earth.

This chemical presence suggests that the water is likely a briny liquid capable of remaining fluid in Mars' harsh environment. The current scientific consensus points toward a shallow subsurface flow. Rather than a massive river, it is believed that enough water wicks to the surface to create the visible darkening of the streaks. Evidence shows that hydrated salts appeared exclusively during the peak width of seasonal markings, proving water is essential to how these streaks develop. This discovery validates a long-held suspicion in the search for life: that water remains a dynamic, active component of the Martian landscape.

The discovery was spearheaded by Lujendra Ojha, who first noticed these puzzling features in 2010 while a student at the University of Arizona. The findings, published in Nature Geoscience, represent a major milestone in planetary science, confirming that the quest to 'follow the water' has led to a tangible, modern reality on the surface of our neighbor planet.

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