Millions of dark "slope streaks" on Mars, first observed in the 1970s, have finally been explained. While previously thought to be caused by landslides involving water, a new analysis of over 2 million streaks from NASA's Mars Reconnaissance Orbiter indicates that the vast majority are formed by seasonal wind and dust erosion. These streaks are dark albedo features on Martian topographical slopes.
A recent study suggests that these landslides are dry and not water-related, narrowing down potential causes. While some streaks on specific features like the Apollinaris Mons volcano were linked to rare events like meteoroid impacts or marsquakes, this new research shows these are globally insignificant drivers. The study author estimates less than 0.1% of new streaks are caused by such seismic or impact events.
The new theory posits that seasonal wind speeds exceeding a threshold for "dust mobilization" are the main cause. When winds are strong enough, landslides can occur more easily on the slopes, similar to how high winds create dust devils on Mars. The reason these events were hard to observe is that they most likely occur at sunrise and sunset, when they are obscured by darkness.
This discovery suggests slope streaks may play a much larger role in Mars' dust cycle than previously understood. With an estimated 1.6 million existing streaks and a formation rate of around 80,000 new ones per year, these features could be a significant contributor to atmospheric dust. Understanding their role is important for future Mars missions and understanding the planet's dynamic processes.
