Recent gravity studies of Mars have uncovered large, dense structures hidden beneath the planet's surface, offering new insights into the geological activity that may still be occurring on the Red Planet.
These findings were presented at the Europlanet Science Congress 2024, and they suggest that Mars could still be experiencing mantle processes—movements within the planet’s interior that influence its surface features, including the massive volcano Olympus Mons. The discoveries could reshape our understanding of the planet’s geological history and its potential for future volcanic activity.
A Revolutionary Look Beneath Mars’ Surface
The new gravity map, developed using data from multiple Mars missions, including NASA’s InSight mission, reveals dense structures buried deep beneath Mars' northern polar plains. These findings indicate that the planet's geological processes may be more active than previously thought. Dr. Bart Root, from Delft University of Technology, led the team responsible for this groundbreaking analysis.
Using tiny deviations in satellite orbits to map Mars' gravity field, the researchers were able to detect anomalies below the surface. These anomalies are approximately 300-400 kilograms per cubic meter denser than the surrounding terrain, and they are located beneath a layer of smooth sediment that may have settled on an ancient seabed. Dr. Root explained, “These dense structures could be volcanic in origin or compacted material from ancient impacts. We've identified around 20 features of various sizes surrounding the northern polar cap, including one with a striking resemblance to a dog.” The structures, which are invisible from the surface, provide a fascinating glimpse into Mars' hidden history.
Olympus Mons: Signs of Active Volcanism?
The study also uncovered intriguing new details about the Tharsis Rise, a massive volcanic region that includes Olympus Mons, the largest volcano in the solar system. Normally, such a massive volcanic feature would cause the surrounding surface to sink under its weight, in a process known as flexural isostasy, which occurs when a planet's lithosphere—the rigid outer layer—responds to the pressure of a large load. This can be seen on Earth, where the weight of Greenland’s ice sheet causes the land beneath it to sink.
However, the Tharsis region does not behave as expected. Instead of sinking, it remains elevated above the surrounding terrain. The gravity data suggest that this elevation is caused by a lighter mass—possibly a mantle plume, a large upwelling of molten rock—pushing the region upward from below. Dr. Root noted, “This suggests Mars may still have active processes in its interior, which could influence the formation of new volcanic features.” This finding challenges the assumption that Mars is geologically dead and raises the possibility of future volcanic activity.
Unraveling Mars’ Geological History
The newly discovered structures beneath Mars’ surface provide important clues about the planet's geological past. While the dense anomalies beneath the northern plains could be remnants of ancient volcanic activity or material from large impacts, their exact nature remains unclear. Understanding these hidden features will require further investigation, and scientists are already proposing missions to gather more data.
One such proposed mission is the Martian Quantum Gravity (MaQuIs) mission, which would use technology similar to that of the GRAIL and GRACE missions, which mapped the gravity fields of the Moon and Earth. Dr. Lisa Wörner from the German Aerospace Center (DLR) emphasized the importance of such a mission, stating, “MaQuIs would allow us to explore the Martian subsurface in greater detail, helping us understand these mysterious hidden features and the planet's ongoing mantle convection.” This mission could also shed light on other dynamic surface processes, such as seasonal atmospheric changes and the potential detection of groundwater reservoirs.
Implications for Future Exploration
These findings could have significant implications for the future exploration of Mars, particularly as we look toward human missions and the possibility of establishing colonies on the planet. If Mars is still geologically active, it could influence everything from the stability of future settlements to the availability of resources such as water. The presence of a mantle plume beneath Olympus Mons might also provide heat that could be used to generate power or even melt subsurface ice, creating potential sources of water.
Understanding Mars' internal dynamics is crucial for the long-term planning of space exploration and the potential for human habitation. As researchers continue to investigate the planet's gravity field and hidden structures, they are likely to uncover even more about the geological forces that have shaped Mars over billions of years and what the future holds for its evolving landscape.
The discoveries from the gravity study of Mars are a major leap forward in our knowledge of the Red Planet’s interior. The hidden structures and signs of ongoing mantle processes suggest that Mars is more geologically dynamic than previously thought, providing new avenues for exploration and understanding of this enigmatic world.