NASA’s InSight detects two major earthquakes on Mars

NASA’s InSight lander detected two strong, clear earthquakes originating in a place on Mars called Cerberus Fossae – the same location where two strong earthquakes were observed earlier in the mission. The new earthquakes have magnitudes of 3.3 and 3.1; previous earthquakes were of magnitude 3.6 and 3.5. InSight has recorded over 500 earthquakes to date, but due to their clear signals, these are four of the best earthquake recordings for probing the interior of the planet.

Studying marsquakes is one of the ways the InSight science team seeks to develop a better understanding of the mantle and core of Mars. The planet does not have tectonic plates like Earth, but it does have volcanically active regions that can cause rumblings. The earthquakes of March 7 and 18 add weight to the idea that Cerberus Fossae is a center of seismic activity.

“During the mission, we saw two different types of earthquakes: one that is more ‘lunar’ and the other, more ‘Earth-like’,” said Taichi Kawamura of the Institute of Physics of the Globe of France. Paris, which helped supply InSight’s seismometer and disseminate its data with the Swiss research university ETH Zurich. Earthquake waves travel more directly across the planet, while moonquake waves tend to be widely scattered; earthquakes fall somewhere in between. “Interestingly,” Kawamura continued, “these four larger earthquakes, which originate from Cerberus Fossae, are” Earth-like. “

The new earthquakes have something else in common with InSight’s previous major seismic events, which occurred almost a full Martian year (two Earth years) ago: they occurred during the northern Martian summer. Scientists had predicted that this would once again be a great time to listen to earthquakes, as the winds would become calmer. The seismometer, called the Seismic Experiment for Interior Structure (SEIS), is sensitive enough that even though it is covered by a dome-shaped shield to block it from the wind and keep it from getting too cold, the wind causes still enough vibration to obscure it. some marsquakes. During the last Nordic winter season, InSight did not detect any earthquakes.

“It’s wonderful to see earthquakes again after a long period of wind noise recording,” said John Clinton, a seismologist who heads InSight’s Marsquake service at ETH Zurich. “A Martian year later, we are now much faster at characterizing seismic activity on the Red Planet.”

Better detection

The winds may have calmed down, but scientists still hope to improve their ability to “listen” even further. Temperatures near the InSight lander can drop from almost minus 148 degrees Fahrenheit (minus 100 degrees Celsius) at night to 32 degrees Fahrenheit (0 degrees Celsius) during the day. These extreme temperature variations can cause the cable connecting the seismometer to the lander to expand and contract, resulting in noises and spikes in the data.

The mission team therefore began to try to partially insulate the cable from the elements. They started by using the shovel at the end of InSight’s robotic arm to deposit dirt on top of the dome-shaped wind and heat shield, allowing it to sink onto the cable. This allows the ground to get as close to the shield as possible without interfering with the shield’s seal with the ground. Burying the seismic tie is actually one of the goals of the next phase of the mission, which NASA recently extended by two years, until December 2022.

Despite the winds shaking the seismometer, InSight’s solar panels remain covered in dust, and the power decreases as Mars moves away from the Sun. Energy levels are expected to improve after July, when the planet begins to approach the Sun again. Until then, the mission will successively shut down the lander’s instruments so that InSight can hibernate, periodically waking up to check on its health and communicate with Earth. The team hopes to keep the seismometer on for another month or two before needing to turn it off temporarily.

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