Image Courtesy: NASA
Mars may be cold and barren on the surface, but new research suggests its interior is not cooling evenly. Scientists have found evidence that the planet’s southern hemisphere could be up to 400 degrees Celsius hotter deep below the surface than its northern hemisphere, revealing a major difference in Mars’s internal structure.
An international research team reached the conclusion by analyzing archival data from NASA’s Mars Global Surveyor, Mars Odyssey, and Mars Reconnaissance Orbiter. The researchers combined subtle changes in the spacecrafts’ orbital velocities with information about Mars’s orbit and planetary tilt to create a gravitational model of the planet’s interior using a technique known as tidal tomography.
The results suggest that the southern hemisphere’s interior could be approximately 200 to 400 degrees Celsius hotter than the northern hemisphere. The findings also support earlier observations made by NASA’s InSight lander, which found that seismic waves traveling through Mars’s southern interior weakened more quickly than waves passing through the north.
The study challenges the common assumption that planetary interiors are largely symmetrical. Dr. Alexander Berne, a postdoctoral associate at the University of Arizona and lead author of the research, said that increasing amounts of gravity data could help scientists build more detailed three-dimensional models of planetary interiors.
“Scientists usually assume that the interiors of planetary bodies are generally spherically symmetric, but this is not necessarily true,” Berne said. “As we get more gravity data, we can determine the three-dimensional intricacies of a planet’s interior structure.”
The temperature difference may be connected to Mars’s dramatically uneven landscape. The planet’s southern highlands have a much thicker crust than the relatively low and flat northern hemisphere. Researchers suggest that this thicker southern crust may have acted as an insulating layer, trapping heat that would otherwise have escaped as Mars gradually cooled over billions of years.
Mars was once far more geologically active than it is today. Its warmer interior fueled volcanism, helped sustain a magnetic field, and contributed to conditions that allowed liquid water to exist on the surface. Because Mars is smaller than Earth, however, it lost much of its internal heat more rapidly, leading to the decline of its magnetic field and widespread geological activity.
The new findings suggest that this cooling process may not have occurred uniformly across the planet. A hotter southern interior could preserve clues about Mars’s geological evolution and help scientists plan future missions designed to investigate what remains hidden beneath the Red Planet’s surface.
