Mars retains within it the traces of its violent past, a history of gigantic collisions that occurred approximately 4.5 billion years ago. Data from the InSight lander, analyzed in a study led by Constantinos Charalambous of Imperial College London and published in the journal Science, has identified the fragments of these primordial impacts that shaped the planet.
Shortly after their formation, all planets in the Solar System underwent a highly turbulent phase marked by violent collisions with asteroids and comets. These cataclysmic events were powerful enough to melt vast portions of the planetary surfaces, generating oceans of magma that gradually solidified. The data from InSight, the NASA probe designed to detect vibrations from faint Martian tremors and operational from 2018 to 2022, has allowed scientists to reconstruct the Martian depths in detail, uncovering the signs of these ancient impacts.
“The fact that we can still detect these traces after four and a half billion years shows just how slowly the interior of Mars has been churning since then,” said Charalambous. According to the study’s authors, those ancient violent impacts produced a large amount of debris, including some very large fragments, which then sank through the molten crust to the mantle—the layer separating the core from the crust.
These fragments remain detectable today through interference patterns recorded in seismic waves. “What happened on Mars is that after those initial events, the surface solidified into a tight lid that sealed the underlying mantle, trapping those ancient chaotic structures like a planetary time capsule,” Charalambous concluded. This phenomenon is not visible on Earth, where, unlike on Mars, continuous internal activity and mantle movements constantly recycle the crust, erasing all traces of that distant past.