A large underground water deposit has been identified beneath the Medusae Fossae Formation (MFF) on Mars. Located nearly two miles below the surface, this ice-rich region could be the most significant non-polar water reservoir ever detected on the planet.
The discovery was made using data from the MARSIS radar on ESA’s Mars Express. The radar signals resemble those observed at Mars’s polar ice caps, indicating the presence of thick ice layers beneath the dusty surface. Scientists previously believed the MFF consisted mostly of windblown dust and volcanic ash.
If fully melted, the ice trapped beneath the MFF could cover the entire Martian surface with 5 to 9 feet of water. This volume is similar to Earth’s Red Sea, suggesting Mars once had far more water than previously estimated.
The presence of ice near the equator, rather than at the poles, makes this discovery significant for human exploration. The region’s lower latitudes are more accessible for potential crewed missions, offering a strategic water resource for long-term stays.
For years, scientists debated the composition of the MFF. Radar data now indicate that ice must be present, as alternative materials such as compacted dust or volcanic deposits would not produce the observed density patterns. This changes previous assumptions about the region’s formation.
The existence of deep equatorial ice raises new questions about Mars’s past. Scientists are investigating how water accumulated and remained preserved so far from the poles, potentially offering insights into periods of increased atmospheric moisture or past climate shifts.
The ice beneath the MFF may have been buried for millions of years, shielding it from surface radiation and preserving potential organic material. If microbial life once existed on Mars, these frozen deposits could serve as a record of the planet’s biological and environmental history.