NASA Marsquake Data Reveals Lumpy Nature of Red Planet's Interior

Rocky material that impacted Mars lies scattered in giant lumps throughout the planet's mantle, offering clues about Mars' interior and its ancient past.

Jet Propulsion Laboratory News Release

2025 August 28

What appear to be fragments from the aftermath of massive impacts on Mars that occurred 4.5 billion years ago have been detected deep below the planet's surface. The discovery was made thanks to NASA's now-retired InSight lander, which recorded the findings before the mission's end in 2022. The ancient impacts released enough energy to melt continent-size swaths of the early crust and mantle into vast magma oceans, simultaneously injecting the impactor fragments and Martian debris deep into the planet's interior.

There's no way to tell exactly what struck Mars: The early solar system was filled with a range of different rocky objects that could have done so, including some so large they were effectively protoplanets. The remains of these impacts still exist in the form of lumps that are as large as 2.5 miles (4 kilometers) across and scattered throughout the Martian mantle. They offer a record preserved only on worlds like Mars, whose lack of tectonic plates has kept its interior from being churned up the way Earth's is through a process known as convection.

The finding was reported Thursday, Aug. 28, in a study published by the journal Science.

"We've never seen the inside of a planet in such fine detail and clarity before," said the paper's lead author, Constantinos Charalambous of Imperial College London. "What we're seeing is a mantle studded with ancient fragments. Their survival to this day tells us Mars' mantle has evolved sluggishly over billions of years. On Earth, features like these may well have been largely erased."

InSight, which was managed by NASA's Jet Propulsion Laboratory in Southern California, placed the first seismometer on Mars' surface in 2018. The extremely sensitive instrument recorded 1,319 marsquakes before the lander's end of mission in 2022.

Quakes produce seismic waves that change as they pass through different kinds of material, providing scientists a way to study the interior of a planetary body. To date, the InSight team has measured the size, depth, and composition of Mars' crust, mantle, and core. This latest discovery regarding the mantle's composition suggests how much is still waiting to be discovered within InSight's data.

"We knew Mars was a time capsule bearing records of its early formation, but we didn't anticipate just how clearly we'd be able to see with InSight," said Tom Pike of Imperial College London, coauthor of the paper.

Quake hunting

Mars lacks the tectonic plates that produce the temblors many people in seismically active areas are familiar with. But there are two other types of quakes on Earth that also occur on Mars: those caused by rocks cracking under heat and pressure, and those caused by meteoroid impacts.

Of the two types, meteoroid impacts on Mars produce high-frequency seismic waves that travel from the crust deep into the planet's mantle, according to a paper published earlier this year in Geophysical Research Letters. Located beneath the planet's crust, the Martian mantle can be as much as 960 miles (1,550 kilometers) thick and is made of solid rock that can reach temperatures as high as 2,732 degrees Fahrenheit (1,500 degrees Celsius).

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