NASA’s Viking 2 lander recorded two candidate marsquakes in Utopia Planitia on sol 53 and sol 80 during its 1976 mission. Decades later, the InSight lander detected nearly 1,000 marsquakes between 2018 and 2022. A new study compares the historical and modern datasets to reexamine those early signals.
The findings appeared in AGU Advances on September 30, 2026, authored by a team led by Wanbo Xiao at Peking University. Matthew R. Francis detailed the results for Eos on October 21, 2026.
Utopia Planitia and the Viking 2 Lander
The Viking 2 spacecraft touched down on Mars on September 3, 1976, as the 4th spacecraft from Earth ever to land on Mars. Its mission in the Utopia Planitia region included searching for signs of Martian life and carrying a seismometer mounted on its top deck.
Winds across the Martian plains created vibrational noise that complicated data analysis. Researchers eventually identified two candidate events on sol 53 and sol 80, though scientists debated for nearly 50 years whether those signals reflected true Martian tectonics.
InSight Data and Regional Comparisons
NASA’s InSight lander arrived in Elysium Planitia in 2018 and operated a seismometer placed directly on the ground. It recorded nearly 1,000 marsquakes, providing a modern baseline for Martian seismology.
Wanbo Xiao and his colleagues reconstructed the original Viking workflow using contemporary knowledge from InSight. While one of the two detections by Viking 2 was dubious, the sol 80 event appears more credible and shares a geographic region with InSight’s seasonal northern-plains detections.
Instrument Differences and Alternative Origins
The study concludes that discrepancies between the Viking 2 and InSight recordings reflect differences in instrument response, sampling strategy, and the distinct spectral characteristics of Martian seismic events rather than a change in Martian activity alone. Viking carried a single deck-mounted instrument, whereas InSight utilized more advanced, ground-coupled equipment.
Researchers note that the sol 80 event decays faster than typical InSight marsquakes. This variation could imply lateral variations of structural energy absorption in the Martian subsurface, though a distant tectonic marsquake or a meteorite impact remain alternative explanations for the historical signal.
Common Questions About Martian Seismology
Did InSight confirm the 1976 Viking 2 marsquakes?
InSight did not exactly confirm the Viking 2 detections, but modern analysis shows the sol 80 event shares a source region with InSight’s seasonal northern-plains marsquakes.
When were the new findings published?
Wanbo Xiao and his research team published their peer-reviewed study in AGU Advances on September 30, 2026.
What caused the differences between Viking 2 and InSight data?
Researchers concluded that variations between the datasets reflect differences in instrument response, sampling strategy, and spectral characteristics rather than a change in Martian activity alone.
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