The surface of Mars may seem barren and lethargic, but the red planet seems to have many secrets hidden from prying human eyes. Fortunately, we have the technology, and a new radar study of the Medusae Fossae formation region at the Martian equator has revealed what appear to be giant layered slices of buried water ice several kilometers thick.

This is the most water ever found at the center of Mars, and suggests that the dry, ancient dust ball is not as devoid of this material as we thought. According to scientists, enough water is buried there to be found in Earth’s Red Sea; If it were brought to the surface and melted, it would cover Mars with a shallow ocean 1.5 to 2.7 meters (4.9–8.9 ft) deep.

Traces of buried sediment were first discovered in 2007 at a depth of 2.5 kilometers (1.6 miles), but scientists did not know what it was. New data and new tools used to analyze that data have revealed much more about deposits than expected.

“Using new data from the MARSIS Mars Express radar, we reexamined the formation of Medusae Fossae and found that the deposits were thicker than we thought: up to 3.7 kilometers (2.3 miles) thick,” says Smithsonian geologist Thomas Watters.

“What’s exciting is that the radar signals match the signals we expect to see from layered ice and are similar to the signals we see from the polar caps of Mars, which we know are quite rich in ice.”

The Medusae Fossae Formation is a vast collection of sediments that extends approximately 5,000 kilometers (3,107 miles) along the Martian equator, marking the boundary between the plains of the northern hemisphere and the cratered highlands of the south. It is unknown what formed these deposits, but they are very large, several kilometers high, and shaped by the strong winds that scoured the Martian surface.

Since the region is so little studied, scientists are naturally eager to learn more about it. In 2007, Watters and his team collected radar data that clearly showed the presence of something buried underground.

What was unclear was the nature of the thing. Considering how dusty the Medusae Fossae Formation is, it is conceivable that the deposits may have formed from buried dust. This could also be volcanic material, rainy deposits from bygone eras, or interestingly, water ice.

So the researchers collected new radar data from the area, analyzed the results, and ran simulations to try to understand what was hidden beneath the windblown dust and rocks. And the only thing that fit the data well was water ice.

“Given how deep it is, if the MFF were a giant pile of dust, we would expect it to compress under its own weight,” says physicist Andrea Cicchetti of the National Institute of Astrophysics in Italy.

“This would create something much denser than what we actually saw in MARSIS. When we modeled how different materials would behave without ice, nothing could replicate the properties of MFF; we needed ice.”

Over the past few decades, as research on Mars has increased, our previous understanding of the dead dust ball has changed dramatically. Everywhere we look on Mars, there is evidence of ancient water flowing across the surface in rivers or collecting in lakes or oceans.

There is currently no liquid water on Mars as we know it. Where all this water went is a mystery: Did it disappear into space as vapor, or was it trapped somewhere inside the planet where we can’t see it? It is possible to find the definitive answer to this question in the formation of Medusae Fossae.

Scientists want to know where water would be found on Mars for another practical reason. When humans are eventually sent to the red planet, they will need water to survive. If there is already water there, the amount of water they need to carry with them will be minimized.

Unfortunately, access to water is prohibited in the Medusae Fossae formation; It is buried under several hundred meters of Martian dust that we cannot reach. Still, this discovery gives hope that water is hiding somewhere on Mars. It also gives scientists new information in their quest for the mysterious history of Mars and its evolution to its present state.

“This latest analysis challenges our understanding of the formation of Medusa’s dimples and raises as many questions as it answers,” says planetary scientist Colin Wilson of the European Space Agency.

“How long ago did these ice deposits form, and what was Mars like at the time? If confirmed to be water ice, these massive deposits would change our understanding of Mars’ climate history. Any ancient water reservoir could become a fascinating target for human or robotic exploration.” The study was published on: Geophysical Research Letters .