Mars’s Dusty Mysteries: New Studies Reveal Ancient Water Pathways and Dry Surface Processes

Mars continues to captivate scientists with its complex geological history, from ancient water flows to modern dust avalanches. Three new studies published this month offer fresh insights into the Red Planet’s past and present conditions, challenging some long-held assumptions about Martian water.

Dark streaks on Mars likely dust avalanches, not water flows

Those mysterious dark streaks running down Martian slopes that have intrigued scientists for decades? They’re probably not signs of flowing water after all, according to a comprehensive new study published in Nature Communications on May 19.

Researchers from Brown University and the University of Bern used machine learning to analyze over 86,000 high-resolution satellite images, creating an unprecedented global map containing more than 500,000 streak features across Mars.

“A big focus of Mars research is understanding modern-day processes on Mars — including the possibility of liquid water on the surface,” said Adomas Valantinas, a postdoctoral researcher at Brown who coauthored the research with Valentin Bickel, a researcher at Bern. “Our study reviewed these features but found no evidence of water. Our model favors dry formation processes.”

The sinewy dark streaks, first observed by NASA’s Viking mission in the 1970s, had fueled speculation about possible liquid water on modern Mars. Some scientists theorized that small amounts of water mixed with enough salt could create flows even in Mars’s freezing conditions.

But when Bickel and Valantinas compared their massive dataset with factors like temperature, wind speed, and humidity, they found these features correlate more strongly with wind and dust activity than with water-related factors.

The researchers conclude these streaks most likely form when fine dust slides off steep slopes—triggered by impact shockwaves near recent craters, or by dust devils and rockfalls in other regions.

For future Mars exploration, this finding has practical implications. NASA carefully avoids potentially habitable environments to prevent contamination from Earth-based microbes.

“That’s the advantage of this big data approach,” Valantinas said. “It helps us to rule out some hypotheses from orbit before we send spacecraft to explore.”

Ancient Mars had “one-way” water cycle, UT Austin study finds

While modern Mars shows little evidence of flowing water, its ancient past was dramatically different. But even then, Mars’s water behaved quite unlike Earth’s, according to research published in Geophysical Research Letters by University of Texas at Austin graduate students.

The study reveals that on early Mars, surface water took between 50 to 200 years to percolate from the surface down to aquifers approximately a mile underground—a process that typically takes just days on Earth.

This dramatically slower infiltration helps explain a key mystery about Mars’s water cycle, providing insight into how water moved between the surface and underground reservoirs billions of years ago.

The researchers calculated that the water moving between surface and aquifer could have been enough to cover Mars with at least 300 feet of water—potentially representing a significant portion of the planet’s total available water.

The findings suggest that Mars had a fundamentally different water cycle than Earth’s. Unlike our planet’s dynamic cycle of evaporation, precipitation and surface flow, Mars’s water followed a more one-directional path.

“The way I think about early Mars is that any surface water you had—any oceans or large standing lakes—were very ephemeral,” said co-author Eric Hiatt, who recently completed his doctoral degree from UT’s Jackson School of Geosciences. “Once water got into the ground on Mars, it was as good as gone. That water was never coming back out.”

This new understanding helps scientists track Mars’s total water budget and may eventually aid future Mars explorers seeking buried water resources.

ESA’s Mars Express reveals crater’s complex history

While some researchers focus on water dynamics, others are examining the physical evidence of Mars’s geological processes. The European Space Agency’s Mars Express spacecraft recently captured striking images of Deuteronilus Cavus, a 120 km-wide depression that preserves evidence of volcanic, glacial, water and wind-related activity across four billion years.

The circular shape of this feature, situated between Mars’s rugged southern highlands and smoother northern lowlands, suggests an impact crater origin dating to 4.1–3.7 billion years ago. Over time, erosion by water and ice reshaped and enlarged the crater to nearly twice its initial size.

Channels cut into the crater rim may have formed from surface water flows or subsurface water drainage. Grooved textures indicate the past presence of glaciers, where boulders frozen into ice gouged out troughs visible today.

The crater’s interior contains a jumbled mixture of chunky rock formations, mesas, channels and smoother plains. Much of this interior is covered by dark deposits of wind-blown volcanic ash, while brighter deposits shining through contain clay minerals formed by volcanic ash mixing with water—suggesting liquid water once pooled in this location.

This feature-rich crater serves as a natural laboratory for studying Mars’s diverse geological processes, offering researchers a window into the planet’s complex history.

Building a complete picture

Together, these three studies help scientists construct a more complete picture of Mars’s hydrological history. From the slow one-way percolation of ancient surface water into deep aquifers, to the preservation of water-shaped features in craters like Deuteronilus Cavus, to the modern dust avalanches creating streaks on slopes, Mars continues to reveal its secrets.

While the current findings suggest limited potential for surface liquid water today, they add valuable context to our understanding of Mars’s past habitability and will guide future exploration efforts as humanity continues its fascination with the Red Planet.