NASA’s InSight lander installed a seismograph on Mars, recording three large 'marsquakes' that have since helped scientists gain a better understanding of what lies below the Martian surface. It's been exactly three years since the InSight lander touched down on Mars on November 26, 2018. The lander carries a seismograph that has recorded multiple marsquakes, which are earthquakes on Mars.

Three of the marsquakes in August-September 2021 were among the largest that NASA ever recorded, with each of them registering above 4.0 on the Richter scale. The biggest and longest one was rated at 4.2 and it lasted for about an hour and a half. Two of the other quakes detected by the seismograph measured 4.2 and 4.1. All of them were significantly more powerful than the 3.7 magnitude quake detected in 2019.

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The data from the seismic activity has been extensively studied by scientists and they have provided some answers on the makeup of the Martian core. The researchers have now published a report in the journal Nature about what the marsquakes have revealed about the structure of the Red Planet, and according to the report, the lander was sitting directly above a "low-velocity sedimentary unit" sandwiched between two large basalt layers. Above the lava stacks and closest to the surface, the data suggests the presence of a thin regolith layer that researchers say "cannot be thicker than 1-1.5 m." Further below the surface, researchers believe there's a layer of basaltic bedrock at a depth of about 3 meters. According to estimates, the basalts are of Amazonian and Hesperian vintage and are between 160 and 180 meters thick. Beneath the basalts, there are layers of physically weak sedimentary rocks, likely of the Noachian age. Below that are further volcanic deposits.

The Quakes Almost Went Undetected

Photo of Mars from space

Data from the seismograph has revealed much information about the Martian core, but the quakes might not have been detected at all had NASA not optimized the energy consumption of the InSight lander earlier in the year. According to a press release by NASA back in September, it had to reduce InSight’s power consumption just a few months earlier by temporarily turning off certain instruments after Mars moved farther away from the Sun. That reduced the temperatures, which led to extensive use of the heater to keep the lander warm.

The lander's solar panels also gathered a lot of dust over the past three years, which also reduced its power levels significantly. However, NASA was able to clear out some of the dust from the panels using innovative methods, which boosted the power levels in the lander somewhat. Mars has since moved closer to the Sun once again as part of its orbital revolution, thereby increasing InSight's energy levels significantly.

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Source: Nature, NASA