For years, scientists have been intrigued by mysterious dark streaks running down the slopes of Martian cliffs and craters. These marks, called slope streaks and recurring slope lineae (RSLs), have often been considered possible signs of water on Mars. That raised hopes that the Red Planet could support life or may have supported life in the past.
But new research is challenging that idea. A team from Brown University and the University of Bern used artificial intelligence to analyze over 86,000 high-resolution satellite images of the Martian surface.
Their findings, published in Nature Communications, suggest that wind and dust, not water, are likely responsible for the streaks. The researchers trained an algorithm to identify slope streaks, then compared their locations with environmental data such as wind speed, temperature, and dust patterns. They found no link between the streaks and moisture, frost, or any other clear signs of water on Mars.
Instead, the features were more common in areas with strong winds and high dust activity. This points to a dry process, where dust layers suddenly shift down slopes due to external forces like wind.
If these streaks had been caused by flowing water, NASA might have avoided sending rovers or landers to those areas. The concern is that microbes from Earth could contaminate regions that might host life. With the water theory now less likely, scientists have more freedom to explore these zones without that risk.
Although this study does not eliminate the possibility of water elsewhere on Mars, it does help narrow the search. Not every unusual surface feature is a sign of water on Mars, and studies like this one help clarify where and how we continue our search for signs of life.
In space exploration, ruling out possibilities is often just as valuable as confirming them, especially when we’re trying so hard to find signs of life on the Red Planet.
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