Unraveling Mars’ Wet History

In a groundbreaking revelation, scientists have uncovered vast networks of ancient riverbeds sprawling across the southern highlands of Mars, suggesting the planet was once a lush, water-rich environment—much wetter than previously assumed!

In stunning high-resolution images captured by Mars orbiters, researchers identified nearly 10,000 miles (16,000 km) of ancient watercourses, dated to be over 3 billion years old. While many of these riverbeds appear short, some extend over 100 miles, indicating a once-thriving system of rivers that may have been sustained by regular rainfall or snowfall.

The Surprising Findings of Noachis Terra

The discovery is particularly striking in the Noachis Terra region—an area long viewed as arid due to a lack of evidence for ancient water. Adam Losekoot, a PhD student at the Open University, expressed excitement over the findings. “What we found is that this area did have water, and it was very distributed,” he stated. This challenges long-held beliefs that certain areas of Mars were devoid of water sources.

Computer models of Mars’ ancient climate suggested that Noachis Terra should have experienced considerable precipitation, shaping its terrain over time. After noticing a gap in evidence, Losekoot and his team turned to detailed images from NASA's Mars Reconnaissance Orbiter (MRO) and Mars Global Surveyor, covering an expanse nearly four million square miles—an area bigger than Australia!

The Evidence: Inverted Channels and Fluvial Ridgelines

The detailed images revealed an array of geological wonders known as fluvial sinuous ridges or inverted channels. These features form when sediments from ancient rivers solidify and are left exposed as the softer earth erodes away. While many segments are only a few hundred meters wide, some stretch over a mile!

One striking image from the MRO showcases a network of winding tributaries and evidence of water overtopping ancient riverbanks—visuals that strongly suggest a dynamic aquatic past. Two rivers are even seen funneling into a crater, likely filling it up before spilling over the other side.

A Promising Glimpse into Mars’ Aquatic Past

These exciting discoveries will be shared at the Royal Astronomical Society’s national meeting in Durham, revealing a compelling narrative of Mars’ history—a planet once brimming with surface water in its Noachis Terra region around 3.7 billion years ago. With every finding, our understanding of Mars as a former watery paradise continues to expand!