Mars keeps its secrets buried deep, but every meteorite that punches through its protective layers scatters evidence across the surface. Scientists from Brown University now believe the scattered debris around impact craters holds a coded message about what’s hiding beneath the Martian surface, including potentially life-sustaining ice deposits that future astronauts could tap into.
When meteorites strike Mars, they fling material outward in what scientists call an ejecta blanket. The distance this debris travels compared to the crater size (known as “ejecta mobility” or EM) works like a fingerprint that can identify what is beneath the planet’s surface. This could include ice resources that could be vital for future human missions.
According to new research published in the Journal of Geophysical Research: Planets, when solid ice lies just beneath the surface on Mars, the debris from crater impacts doesn’t spread as far, giving scientists a possible way to spot hidden ice from orbit.
This means we might be able to map underground ice deposits simply by analyzing crater patterns from spacecraft orbiting Mars, without needing to send expensive drilling equipment to the planet.
The international team, led by A.J. Sokolowska from Brown University, conducted sophisticated computer simulations of Martian impacts. Using a program called iSALE, they modeled what happens when meteorites hit different layers of material that might exist beneath Mars’ dusty exterior.
Their simulations focused on impacts creating craters roughly 50 meters across, similar to ones that have formed on Mars during the recent period of spacecraft observation. The team tested dozens of different underground setups, varying the materials, strengths, porosities, and layering patterns.
This study focuses on smaller, more common craters. These impacts probe the shallow subsurface that future explorers would need to access. They’re also “strength-dominated,” meaning the material’s physical properties have a stronger influence on the impact process than gravity does. This means that for smaller craters, the type of material under the surface matters more for how far debris flies than it does in larger craters, where gravity plays a bigger role.
Depending on what lies beneath the surface, ejecta can spread dramatically different distances. EM values ranged from as low as 7 to as high as 19 times the crater radius.
The team discovered that ejecta dynamics are affected by materials much deeper than previously thought, not just in the area directly carved out by the impact. This is because their dynamics are affected by what exists at deeper levels.
When impacts occur over areas with ice beneath the surface, the debris pattern looks distinctly different from impacts into purely rocky terrain. This difference is substantial enough that scientists could identify it in images from spacecraft like NASA’s Mars Reconnaissance Orbiter.
The researchers examined two small Martian impact craters with dramatically different ejecta patterns. One displayed an EM of approximately 19, while the other had an EM of just 11. The crater with the lower EM value is known to have excavated ice, exactly as the team’s models predicted.
If there is ice on Mars, that means there is water there, too. Finding water on Mars is crucial for any future human presence. Astronauts will need water not only for drinking but also for growing food and potentially producing rocket fuel for a return journey to Earth. Hauling all that water from Earth would be prohibitively expensive and logistically challenging.
The research also revealed interesting physics about how impact shocks move through different materials. When a meteorite hits Mars, it creates shock waves that behave differently depending on what materials they encounter. The researchers found that the contrast in acoustic impedance (how well sound waves move through a material) between different subsurface layers significantly affects how ejecta gets distributed.
Future missions to Mars could target areas where crater ejecta patterns suggest accessible ice deposits, potentially increasing the chances of mission success.
Source : https://studyfinds.org/underground-ice-on-mars-no-drills-required/