If you’ve ever wondered how different marsquakes are from earthquakes, we now have the answer thanks to NASA and Swiss research university ETH Zurich. NASA delivered the first-ever seismometer to the red planet aboard the InSight lander last year, and it’s now deployed and sending back data. Researchers from ETH Zurich have used that data to reconstruct a marsquake here on Earth, and it’s not what anyone expected.
InSight touched down on Mars back in November of 2018. The robotic lander’s goal is to study the interior of Mars, which has not been possible with past missions like Curiosity. Among InSight’s instruments is the Seismic Experiment for Interior Structure (SEIS).
NASA successfully deployed the sensor in December of 2018 (see above) after building a model of InSight’s landing zone on Earth to rehearse the delicate process. InSight placed the instrument about 5.3 feet (1.6 meters) away, close to the maximum reach of its robotic arm. If SEIS didn’t make good contact with the ground, its data wouldn’t be useful. Luckily, the sensor works perfectly and detected its first marsquake in April 2019.
In a new video, ETH Zurich scientists demonstrate the differences between seismic events on Earth, the moon, and Mars. They have a quake simulator that can reproduce a seismic event from data as you’d get from an instrument like SEIS or the seismometer deployed on the moon by Apollo 11 50 years ago.
Seismic waves are affected by the composition of a planet or moon, so you’d expect different worlds to have different quakes. Indeed, quakes on Earth feature strong initial P-wave arrival followed by a stronger S-wave. To experience moonquakes, the team had to scale the signal up by one million times. Seismic waves on the moon have much smaller attenuation with strong scattering. So a moonquake could last an hour or more.
For the marsquake simulation, the team had to increase the InSight signal by 10 million times. The lander has so far detected two “families” of marsquakes. There’s a high-frequency version and the low-frequency version demonstrated in the video. The lower-frequency quakes may originate farther from InSight. The waves aren’t the same as on Earth, but they’re not like the moon either. ETH Zurich researchers believe Mars will end up having seismic properties in between the two. In time, the seismic data from Mars could help us better understand its composition without cracking it open to take a peek.
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