The characteristic dark streaks observed on some Martian slopes have nothing to do with water. This is according to a new study by planetary scientists from Brown University and the University of Bern.
Back in the 1970s, Viking vehicles photographed strange dark streaks tens of meters long, as if flowing down Martian rocks and crater walls. Some of them last for decades, while others disappear in a single season.
The most tantalizing theory attributed their origin to water. Although modern Mars is an arid planet where temperatures rarely rise above zero, it was thought that salt water could seep from underground sources (such as subsurface ice or aquifers) and briefly exist on the cold Martian surface. However, a new study points to a very different explanation: a dry process related to wind and dust activity.
Scientists were helped to come to this conclusion by machine learning algorithms. Having trained them on confirmed streak observations, they then used AI to scan 86,000 high-resolution satellite images. This work resulted in the first global map of the Martian streaks, containing information on more than 500,000 of their individual features. Next, scientists compared it to databases and catalogs of other Martian surface parameters such as temperature, wind speed, humidity, landslide activity, etc.
Geostatistical analysis showed that slope streaks did not appear in areas where evidence of liquid water or frost could be found. For example, watery slopes would have to face a certain direction, experience drastic temperature changes, or exist in a high humidity environment. Instead, the study found that such streaks are more common in areas with high winds and increased dust activity.
According to scientists, this indicates that the streaks are formed when thin layers of fine dust slide down a steep slope. The specific reasons may vary. Streaks on slopes are more common near recent impact craters where the shock wave may have disturbed surface dust. At the same time, recurring lines are commonly found in areas where dust devils or rockfalls are frequent.
This discovery has major implications for future Mars exploration. While habitable environments may seem like good targets for research, NASA prefers to keep its distance from them. Any Earth microbes left on the spacecraft could contaminate them, complicating the search for life on Mars. However, if the scientists are right, the risk of pollution at the sites of the streaks is not so great.
Earlier we reported on how the Perseverance rover photographed pre-dawn Mars.
According to Phys.org
