Ancient Mars had sprawling river networks far larger than believed

A new study has revealed that ancient Mars once hosted vast, interconnected river systems. These networks were far more extensive than previously thought, covering 5% of the planet’s surface. The findings challenge earlier assumptions about the red planet’s watery past. For years, scientists believed Mars only had isolated gullies and small streams billions of years ago. But this research, published in the Proceedings of the National Academy of Sciences, shows a different picture. The study identified 19 major river clusters and 16 watersheds, each spanning over 100,000 square kilometres.

These river systems carried water and nutrients across long distances, creating conditions that may have supported life. Though they covered just 5% of Mars, they accounted for 42% of all river-transported sediment deposits. The lack of plate tectonics on Mars helped preserve these ancient drainage systems, offering a detailed record of the planet’s history. The researchers suggest that future Mars missions should focus on these 16 mega-basins. They believe these areas hold the best chance of uncovering signs of past life. The study will also help refine models of Martian river activity, clarifying when and how water once flowed across the surface.

The discovery reshapes our understanding of Mars’ ancient water systems. By pinpointing key river basins, the study provides new targets for exploration. Future missions may now prioritise these regions in the search for evidence of past life.