Scientists uncover ancient mantle fragments on Mars, revealing how colossal impacts shaped the planet's deep interior. (Image Source: NASA)
Mars has preserved rocky remains from colossal impacts that struck it around 4.5 billion years ago while scientists have discovered giant mantle fragments buried deep inside the planet. These relics, some as large as 4 kilometers, provide a pristine record of Mars’ early history. Unlike Earth, Mars never erased them because it lacks tectonic plate activity. The breakthrough came through NASA’s InSight lander, which used seismic investigations before its mission ended in 2022 and the findings reveal Mars as a planetary time capsule, holding rare evidence of its violent beginnings.
Mars endured cataclysmic collisions in its infancy and enormous rocky bodies, including potential protoplanets, bombarded the young world. These mega strikes released staggering energy, and they melted vast regions of the crust and mantle into magma oceans and rocky debris from those collisions sank into the mantle, embedding deep within the planet. Unlike Earth, where geological recycling wipes away such traces, Mars preserved them for billions of years.
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The newly discovered mantle fragments are remarkable. Some measure up to 4 kilometers across. These massive lumps survived untouched because Mars’ interior evolved sluggishly. Earth’s vigorous internal churning erased similar features long ago. Lead author Constantinos Charalambous from Imperial College London confirmed the significance. He explained that scientists have never seen a planetary interior in such clarity. The survival of these features proves that Mars has remained geologically quiet for ages.
NASA’s InSight lander made this discovery possible and from 2018 to 2022, it recorded 1,319 marsquakes using its ultra-sensitive seismometer. Seismic waves revealed the size, depth, and composition of the crust, mantle, and core. Among them, eight marsquakes proved critical. Their altered and delayed signals pointed to denser regions inside the mantle. Planetwide simulations confirmed that these zones contained buried impact fragments. Only in those areas did high-frequency seismic signals slow significantly.
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These findings show Mars as a unique planetary archive. The mantle fragments date back to the earliest bombardments. They remain as embedded pockets of shattered rock within the planet’s deep layers. Their persistence makes Mars a time capsule of planetary formation. Scientists now gain a rare opportunity to study early solar system history, and the insights may also apply to other rocky worlds without plate tectonics, such as Venus and Mercury.
