Ancient River System Discovered Under Mars’ Surface, Boosting Life Search

Data from the Perseverance rover has revealed evidence of a more extensive and long-lived ancient fluvial system hidden beneath the surface of Mars’ Jezero Crater, according to a study published in Science Advances. The discovery, made using the rover’s Radar Imager for Mars’ Subsurface Experiment (RIMFAX), indicates water was present on Mars for a longer period and in a more complex manner than previously understood.

For years, scientists have observed indications of past water on the Martian surface. However, the RIMFAX radar, capable of penetrating up to 35 meters below the surface, has provided a new perspective. Researchers have identified geological structures indicative of an ancient river system, including inclined and organized rock layers similar to those formed by sediment deposition in Earth-based deltas. Channels, lobes, and buried blocks further support the presence of ancient rivers.

“RIMFAX has revealed a prior deltaic environment beneath the current delta, expanding the period of potential habitability,” explained geomicrobiologist Emily Cardarelli of the University of California, Los Angeles. This suggests the water wasn’t present for a brief period, but flowed in different phases over millions of years. The activity of this system is estimated to have occurred between 4.2 and 3.7 billion years ago, a crucial period in the planet’s evolution.

The data indicates that some sediment deposits could reach thicknesses of 85 to 90 meters, suggesting multiple episodes of sedimentation and erosion. This reinforces the idea of a dynamic Mars with prolonged hydrological activity. The findings align with previous discoveries of ancient fluvial channels on Mars, as reported by NASA, indicating a planet with a wetter past than previously imagined.

This discovery has significant implications for the search for past life on Mars. The identified structures could have preserved chemical and mineral conditions favorable for microorganisms, making the subsurface of Jezero Crater a high-priority target for further exploration. NASA is currently working on plans to return samples collected by Perseverance to Earth for more detailed analysis, though challenges remain in executing this complex mission, as reported by Scientific American.

In March 2026, NASA announced a new finding from the Perseverance rover, indicating the potential presence of a “biosignature” in a rock sample. Details of this discovery are scheduled to be shared by NASA in the coming days, adding to the growing body of evidence suggesting Mars may have once been habitable.