The planet Mars might still conceal significant reserves of liquid water beneath its surface. A recent discovery, based on seismic data, opens new perspectives on the hydrological history of the Red Planet.
An international team of scientists analyzed seismic waves generated by meteorite impacts and a major Martian earthquake. Their findings, published in
National Science Review, suggest the presence of liquid water between 3.4 and 5 miles (5.4 to 8 kilometers) deep. This zone is characterized by a significant slowdown in seismic waves, a phenomenon often associated with the presence of liquid.
According to thermal gradient calculations, temperatures at depths greater than 3.1 miles (5 km) would exceed the freezing point, allowing for the storage of liquid water at the base of the upper crust.
Credit: NASA/JPL-Caltech The researchers used data from NASA's InSight mission to conduct their study. They identified a layer in Mars' upper crust where temperatures would allow water to remain in a liquid state. This discovery is based on precise calculations of thermal gradients and the thermal conductivity of the Martian crust.
The estimated amount of water in this zone is impressive. If the rock pores were completely filled with water, it would be equivalent to a layer 1,700 to 2,560 feet (520 to 780 meters) thick, evenly distributed across Mars' entire surface. However, these figures do not account for possible lateral structural variations.
This research has major implications for understanding Mars' evolution and the search for life. The presence of deep liquid water could influence future exploration missions, particularly those aimed at finding traces of past or present microbial life.
Scientists emphasize that their conclusions are based on localized data and require validation through future missions. Installing new seismometers on Mars would refine these results and allow exploration of other regions of the planet.
How do seismic waves reveal the presence of water?
Seismic waves propagate differently depending on the materials they pass through. In water-saturated rocks, their speed decreases, enabling scientists to detect liquid reservoirs.
This method, used on Earth to explore aquifers, has been adapted for Mars thanks to the InSight mission. Variations in wave speed provide valuable clues about subsurface composition.
On Mars, the presence of deep liquid water could be linked to internal heat sources, such as volcanism or the natural radioactivity of rocks. These conditions keep the water above its freezing point.
Future Martian missions could use these techniques to map water reserves more precisely—a crucial step for human exploration.
What is the impact of this discovery on the search for life?
Liquid water is essential for life as we know it. Its presence on Mars, even deep underground, strengthens the hypothesis of possible past or present habitability.
Subsurface environments could offer protection from surface radiation and extreme temperatures. These conditions might be favorable for the survival of microorganisms.
Scientists are now considering targeting these zones for future biosignature research. Drilling missions could be the key to accessing these hidden reservoirs.