Mars is shaking, and we’d never know were it not for the trailblazing InSight lander. This mission touched down on the red planet in 2018, making history by deploying the first and only seismometer on another planet. NASA has been listening for rumbles ever since, and it just heard some big ones.
NASA reports that InSight detected two strong quakes, originating in a region with enormous surface fissures called Cerberus Fossae. The quakes had magnitudes of 3.3 and 3.1, similar to a pair of previous quakes from the same area of the planet that clocked in at 3.6 and 3.5. InSight has recorded hundreds of seismic events on Mars with its Seismic Experiment for Interior Structure (SEIS) package, but these are the most significant.
Scientists hope that by studying the way seismic waves reverberate through Mars, they’ll be able to characterize its interior. So far, the mission has identified quakes that are like those detected on the Moon, which are gentler and more frequent than the other, more Earth-like kind. The newly detected events, as well as the previous Cerberus Fossae shaking, are the latter type.
The InSight team predicted this time of year would be ideal for listening for quakes because it’s summer in the northern hemisphere, and that means less wind to interfere with readings. However, temperature extremes on the surface have complicated matters — it can get as cold as -148 degrees Fahrenheit (-100 degrees Celsius) at night and then skyrocket to 32 degrees Fahrenheit (0 degrees Celsius) during the day. NASA believes the temperature swings are causing the SEIS cable to expand and contract, causing anomalous data spikes.
Currently, InSight is attempting to mitigate this effect by using its arm to dump soil on the Wind and Thermal Shield that covers the SEIS. It cascades down to cover the base of the shield where it connects to the cable, hopefully adding some insulation against temperature changes. Eventually, the probe may be able to bury the entire tether to further insulate it.
NASA has extended InSight’s mission for a least two more years, but the probe is about to go into a hibernation phase. Its solar panels are drawing less power as we move toward another Martian winter. The team will have to begin shutting down systems, including SEIS, in the coming months. When it awakens next spring, NASA will be able to continue studying the planet’s seismic activity. Its temperature, not so much.
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