The red planet keeps its secrets in stone. New seismic evidence reveals that Mars’ mantle, locked beneath a stagnant crust, preserves a fractured record of the planet’s primordial past. In a study published in Science, researchers analyzing data from NASA’s InSight mission report that Mars’ mantle is riddled with fine-scale heterogeneities—irregularities that formed billions of years ago and remain frozen in place. By contrast, Earth’s dynamic plate tectonics would have erased such traces long ago.
Constantinos Charalambous of Imperial College London and colleagues studied seismic signals from eight well-recorded marsquakes, including those caused by meteorite impacts. They found a systematic delay in high-frequency P-wave arrivals as seismic energy traveled through the mantle. The delays, they argue, reflect kilometer-scale variations in composition that never smoothed out. Instead, they linger as evidence of violent beginnings.
“Whereas Earth’s early geological records remain elusive, the identification of preserved ancient mantle heterogeneity on Mars offers an unprecedented window into the geological history and thermochemical evolution of a terrestrial planet under a stagnant lid, the prevalent tectonic regime in our Solar System and beyond,” write the authors.
Shattered Beginnings
To understand the story, recall that Mars is a single-plate planet. Unlike Earth, which constantly recycles crust through subduction and volcanism, Mars has had a stagnant lid for billions of years. That stasis preserved chaotic patterns from an earlier era when the young planet endured colossal impacts and magma ocean crystallization. According to the study, those catastrophic events fractured the mantle and mixed crustal and foreign material into the planet’s interior on a planetary scale. When convection slowed, the disorder froze in place.
Angela Hessler, who authored the editor’s summary in Science, put it bluntly:
“Charalambous et al. detected marsquake waveforms arriving at NASA’s InSight lander and saw an apparent delay in the high-frequency arrivals that increased with travel distance through Mars’ mantle.”
Why It Matters
The findings shed light on how rocky worlds form and evolve. On Earth, geologists struggle to reconstruct early mantle conditions because tectonics has erased the evidence. Mars offers a natural laboratory. Its preserved interior suggests a mantle viscosity of 1021.3 to 1021.9 pascal-seconds and an effective activation energy of 70 to 90 kilojoules per mole—parameters that hint at deformation by dislocation creep. In other words, Mars froze young, and it stayed that way.
The implications ripple outward. Many exoplanets may also live under stagnant lids. If so, their interiors could retain equally ancient clues, helping astronomers and planetary scientists trace the conditions that make a world habitable. A static mantle, paradoxically, may preserve a planet’s most dynamic past.
For NASA, the result is also bittersweet. InSight ceased operations in 2022, its solar panels choked by Martian dust. Yet its legacy continues to shake the field. Each marsquake InSight captured is still speaking, still whispering stories of a planet that once convulsed with fire and collision, then cooled into silence.
Explainer: What Is a Mantle?
A planet’s mantle is the thick rocky layer sandwiched between the crust above and the core below. On Earth, convection in the mantle drives plate tectonics, volcanoes, and earthquakes. Mars, however, has no plate tectonics. Its mantle convects sluggishly, which means features formed early in its history were never erased. Studying seismic waves from marsquakes allows scientists to map mantle properties, much like doctors use ultrasound to see inside the human body.
Journal: Science
DOI: 10.1126/science.adk4292
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