Recent seismic data from NASA’s InSight lander could provide answers to a 50-year-old puzzle about the unique structure of Mars. The planet is divided into northern lowlands and southern highlands, separated by significant differences in elevation and crustal thickness. This phenomenon, known as the “Martian dichotomy,” has perplexed scientists for decades. Clues from seismic activity suggest that ancient processes within the planet’s interior may have caused this split, as opposed to external impacts such as asteroid collisions.
Insights from seismic data
According to a study published in Geophysical Analysis Letters, seismic waves recorded by InSight were analyzed to discover differences between the planet’s hemispheres. Located near the boundary of the dichotomy, the lander captured how seismic waves traveled through the mantle beneath the northern and southern regions. The researchers observed that seismic energy was dissipating more rapidly in the southern highlands, suggesting that the underlying mantle is warmer than in the north.
The study points to ancient tectonic activity on Mars as a possible cause. Scientists believe that tectonic plate movements in the planet’s early history, along with the dynamics of molten rock, could have shaped the dichotomy. When tectonic activity ceased, Mars transitioned to a “waterlocked lid” structure, preserving the dichotomy over time.
Internal processes or external impact?
Lead researcher Dr. Benjamín Fernando noted in The Dialog that the findings support the theory that internal processes are responsible for the dichotomy. He explained that magma beneath the southern highlands was likely pushed upward, while magma in the northern hemisphere sank toward the core. This difference aligns with observed variations in crustal thickness and mantle temperature.
Although the study favors an internal origin, the researchers stress the need for additional seismic data and advanced planetary models to confirm these findings. According to recent studies, external impacts, such as asteroid collisions, remain a possibility.
Further exploration of the geological history of Mars will be essential to definitively solving this enduring mystery.
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