Slope streaks are dark marks that appear on Martian slopes and gradually fade over time. Some scientists think they might form due to water or salty liquids moving on the surface, suggesting Mars still has small amounts of liquid water. This has significant implications for whether Mars could support life today.
A new study at Brown University and the University of Bern in Switzerland, suggests that Mars’ mysterious streaks aren’t caused by flowing water but by dry processes like wind and dust movement. Scientists analyzed a massive dataset using machine learning. They found that these streaks are likely formed by natural surface activity rather than liquid flows, meaning Mars may be drier than previously thought.
Scientists first noticed dark streaks on Mars in the 1970s. Some last for years, while others appear seasonally, leading to speculation that they might be linked to flowing water. If true, these streaks could indicate rare habitable spots.
However, many researchers believe dry processes like wind or rock cause them to fall. Scientists used machine learning to analyze over 86,000 satellite images to investigate further, creating a global map with more than 500,000 streak features. Their findings suggest that the streaks are more likely formed by dust and wind activity rather than liquid water.
First color image of the Martian surface
Scientists created a global map of slope streaks on Mars and compared it to various environmental factors like temperature, wind speed, and rock slide activity. They found no strong links to liquid or frost, but streaks were more common in areas with high wind and dust deposits, suggesting a dry origin.
The study concludes that the streaks likely form when fine dust slides down steep slopes, triggered by different events. Slope streaks often appear near impact craters, possibly shaken loose by shockwaves, while RSLs tend to form in areas with frequent dust devils or rockfalls.
These findings challenge the idea that these streaks indicate habitable environments on Mars. While NASA avoids potentially life-supporting regions to prevent contamination from Earthly microbes, this study suggests such concerns might not be necessary at slope streak sites.
Journal Reference:
- Bickel, V.T., Valantinas, A. Streaks on martian slopes are dry. Nat Commun 16, 4315 (2025). DOI: 10.1038/s41467-025-59395-w
