Unexpected asymmetries in Mars's interior and its moon Deimos
Planetary scientists analyzing decades of spacecraft tracking data have discovered that the interior beneath Mars's south pole is significantly hotter and partly molten compared to its northern hemisphere. In a separate study, hydrodynamic simulations suggest that the oddly smooth surface and prominent crater of the Martian moon Deimos could be the result of a single large asteroid impact that globally redistributed debris without shattering the small satellite.
Science··Midday
Hot patch beneath Mars
Decades of spacecraft tracking data have allowed researchers to measure the seasonal tidal pull of the Sun on Mars, revealing that the planet's interior is not spherically symmetric. The analysis, which utilized a technique known as tidal tomography, indicates that the southern interior is between 200 and 400 degrees Celsius hotter than the north and remains partly molten. This asymmetry could help explain long-standing mysteries regarding magnetic patterns found in southern iron minerals and the uneven propagation of seismic waves across the Martian surface.[1]
Connecting to early history
While the exact cause of the substantial temperature difference within the Martian interior remains unidentified, the findings rule out the standard modeling shortcut that assumes a spherically symmetric rock structure. Researchers note that this localized heat anomaly narrows down candidate explanations tied to the planet's early geological history, including the ancient giant impacts that are widely thought to have shaped the expansive northern lowlands and influenced the water that once flowed across the southern basins.[1]
An impact on Deimos
Separate observations of the Martian moon Deimos have prompted a reevaluation of its unusually smooth, dusty appearance and prominent southern depression. Planetary scientists combined data from the recent ESA Hera flyby with around 100 hydrodynamic simulations running on computing clusters. The results indicate that an asteroid roughly 320 meters wide striking the south polar region at a 45-degree angle could produce the current crater while distributing enough ejecta to globally bury older terrain under a 200-meter-thick debris layer, without shattering the satellite.[2]
