Mars’ mantle might be lumpy—and those lumps could be fossils from the solar system’s chaotic youth. Using seismic data from NASA’s InSight lander, researchers have uncovered signs of localized structures deep inside the Red Planet, likely formed by colossal collisions around 4.5 billion years ago.
InSight spent four years listening for marsquakes, recording 1,319 events between 2018 and 2022. Seismic waves generated by these quakes travel through the planet’s interior and change speed and shape depending on the materials they pass through. By studying how those signals were altered, scientists can map what lies far beneath the surface.
A new analysis zeroed in on eight marsquakes that produced unusually high-frequency energy. As these waves dove deep into the mantle, they slowed and returned scrambled—evidence that they encountered something distinct from the surrounding rock. Planet-wide computer simulations trace this slowdown to a small, localized region, revealing clumps of material embedded within the mantle.
The team’s leading explanation is dramatic: these mantle lumps are ancient debris left behind by asteroid-scale impacts during the early days of the solar system, when collisions between forming worlds were common. Unlike Earth, Mars doesn’t have moving tectonic plates to churn and recycle its interior. Without that geologic conveyor belt, these structures have likely remained preserved for billions of years, acting as a time capsule of Mars’ violent beginnings.
The findings also hint at what might be hidden inside other rocky worlds that lack plate tectonics, such as Venus and Mercury. If similar relics exist there, they could help scientists piece together how early impacts shaped the evolution of terrestrial planets.
Key takeaways
– InSight detected 1,319 marsquakes from 2018 to 2022.
– Eight quakes with strong high-frequency signals flagged an anomaly deep in the mantle.
– Seismic waves slowed and scattered in a small region, pointing to compositionally distinct lumps.
– These structures likely formed from massive collisions about 4.5 billion years ago.
– Mars’ lack of plate tectonics helped preserve these ancient features, offering clues to the interiors of Venus and Mercury.
Why it matters: Mapping these hidden mantle structures refines our picture of Mars’ formation and thermal evolution. It also provides a rare, preserved record of the early impact era—insight that’s difficult to obtain on Earth, where plate tectonics erases the oldest traces. As researchers continue to mine InSight’s data, we can expect a sharper view of how violent beginnings left lasting fingerprints inside the rocky worlds of our solar system.
