NASA’s InSight lander was deployed to listen out for seismic activity on Mars, and last year it picked up a marsquake so big it was suspected to be from a meteoroid impact. Now, thanks to the cooperation of all agencies with orbiters around Mars, the source has been tracked.
On May 4, 2022, InSight detected a marsquake with a magnitude of 4.7 – the strongest ever seen on Mars. Designated S1222a, the quake was five times stronger than the next-strongest, and released the equivalent combined energy of all other marsquakes it detected over its five-year lifespan.
Mars doesn’t have any active plate tectonics, so it wasn’t thought capable of producing quakes this powerful. As such, scientists suspected that S1222a was the result of a meteoroid striking the surface, which is a common occurrence that produces similar seismic waves. Based on its power, such an impact would have produced a crater measuring at least 300 m (984 ft) wide – so to put the matter to bed, the entire planet was scoured for any new craters that size or larger.
Such a massive undertaking required the cooperation of every agency operating a Mars orbiter – NASA, the European Space Agency (ESA), the Chinese National Space Agency (CNSA), the Indian Space Research Organization (ISRO), and the United Arab Emirates Space Agency (UAESA). Each group investigated data from their satellites, searching for a new crater that had appeared after the date of the quake, or other evidence like a dust cloud spotted within hours of it.
It took a few months to search it all, but in the end no such crater was discovered. The team has now concluded that the quake had to have been caused by tectonic forces inside the Red Planet, indicating it’s a more seismically active world than previously thought.
“We still think that Mars doesn’t have any active plate tectonics today, so this event was likely caused by the release of stress within Mars’ crust,” said Dr. Benjamin Fernando, lead author of the study. “These stresses are the result of billions of years of evolution; including the cooling and shrinking of different parts of the planet at different rates. We still do not fully understand why some parts of the planet seem to have higher stresses than others, but results like these help us to investigate further. One day, this information may help us to understand where it would be safe for humans to live on Mars and where you might want to avoid!”
After detecting S1222a, InSight went quietly into the night in December 2022. At least now it can sleep easy knowing it contributed some fascinating new information about Mars.
The research was published in the journal Geophysical Research Letters.
Source: Oxford University