Mars, the Red Planet, may have been much wetter in the distant past than scientists ever imagined. A groundbreaking discovery has revealed more than 15,000 kilometers of ancient riverbeds in Mars’ Noachis Terra region, suggesting that flowing water, driven by precipitation, once spread across a vast part of the planet.
A Hidden Martian Landscape Unveiled
The research, led by PhD student Adam Losekoot from the Open University, uncovers a network of fluvial sinuous ridges—also known as inverted channels—spread throughout the Noachis Terra region. These ridges are believed to have formed when sediment deposited by rivers hardened, later becoming exposed as the surrounding material eroded away. What’s striking about this discovery is the sheer size of the riverbeds, which stretch over 15,000 kilometers, and the evidence they provide of a once-wet Mars.
Unlike the valley networks studied in other regions of Mars, these ridges indicate a prolonged history of surface water, challenging previous assumptions about the planet being cold and dry for most of its history. The water source for these ancient riverbeds is thought to have been precipitation.
Mars’ Ancient Climate Revealed
Mars has long been a planet of interest for scientists studying the potential for past life. Until now, much of the evidence pointing to ancient water activity came from valley networks. These branching erosional features were thought to be the result of historical rainfall and runoff. However, Noachis Terra, where this new discovery was made, has not been as extensively studied.
One reason for this is that it contains few valley networks. Instead, researchers focused on the fluvial sinuous ridges, which offer a different but equally compelling form of evidence for the existence of ancient surface water.
The team’s research suggests that surface water may have been stable in Noachis Terra during the Noachian-Hesperian transition, a period that occurred around 3.7 billion years ago. This period marks a significant change in Mars’ geological and climatic history. The findings imply that the region could have experienced prolonged wet conditions, which could have played a vital role in shaping the planet’s surface.
Advanced Tools and Methodology
To uncover this hidden landscape, the research team used three key orbital instruments: the Context Camera (CTX), the Mars Orbiter Laser Altimeter (MOLA), and the High-Resolution Imaging Science Experiment (HiRISE). These tools allowed the researchers to map the locations, lengths, and morphologies of the ridge systems across the vast Noachis Terra region. Many of these ridges appear as isolated segments, while others stretch for hundreds of kilometers, rising tens of meters above the surrounding terrain.
The distribution of these ridges, along with their size and form, suggests that the surface conditions on Mars were relatively stable for a geologically significant period. This indicates that water, likely in the form of precipitation, flowed over the surface of Mars for much longer than previously thought, pointing to a far more dynamic environment.
Mars Wasn’t Always a Desert
This new discovery challenges the widely accepted theories about Mars’ history. For years, scientists have believed that the planet was largely cold and dry, with only brief, sporadic periods of warmth that could have supported liquid water. The newly discovered ridges, however, indicate that Mars might have experienced more sustained periods of warm and wet conditions.
Losekoot expressed the excitement of working on this research, noting that studying regions like Noachis Terra, which have been largely unchanged for billions of years, is like looking at a time capsule.
