Recent seismic data from NASA’s InSight lander could provide answers to a 50-year-old puzzle concerning Mars’ unique structure. The planet is divided into the northern lowlands and southern highlands, separated by significant differences in elevation and crust thickness. This phenomenon, referred to as the “Martian dichotomy,” has perplexed scientists for decades. Clues from seismic activity suggest ancient processes within the planet’s interior may have caused this division, as opposed to external impacts like asteroid collisions.

Insights from Seismic Data

According to a study published in Geophysical Research Letters, seismic waves recorded by InSight were analysed to uncover differences between the planet’s hemispheres. Situated near the boundary of the dichotomy, the lander captured how seismic waves traveled through the mantle beneath both the northern and southern regions. Researchers observed that seismic energy dissipated more rapidly in the southern highlands, suggesting the mantle beneath is hotter than in the north.

The study points to ancient tectonic activity on Mars as a possible cause. Scientists believe that movements of tectonic plates in the planet’s early history, along with molten rock dynamics, could have shaped the dichotomy. When tectonic activity ceased, Mars transitioned to a “stagnant lid” structure, preserving the dichotomy over time.

Internal Processes or External Impact?

Lead researcher Dr. Benjamin Fernando noted in The Conversation that the findings support the theory of internal processes being responsible for the dichotomy. He explained that magma beneath the southern highlands was likely pushed upwards, while magma in the northern hemisphere sank toward the core. This difference aligns with the observed variations in crust thickness and mantle temperature.

Though the study favours an internal origin, researchers stress the need for additional seismic data and advanced planetary models to confirm these findings. External impacts, such as asteroid collisions, remain a possibility according to recent studies.

Further exploration of Mars’ geological history will be critical to definitively solving this enduring mystery.