Perseverance rover will arrive at Mars with a bang: How NASA will listen – CNET


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Fernando and colleagues calculated the signals that might be produced from the sonic boom and found them unlikely to be detectable by Insight. However, the 154-pound (70-kilogram) CMBDs will be jettisoned over 620 miles (1,000 kilometers) above the surface of Mars, and should produce small craters when they impact the planet at high speed.
NASA

The actual touch down of Perseverance is meant to be a soft landing that shouldn’t be detectable over a long distance, but the more energetic parts of the process Fernando refers to include the sonic boom from the spacecraft as it decelerates during descent, and the impact of two large weights called Cruise Mass Balance Devices, aka CMBDs.

The Mars Insight lander is located less than 2,000 miles (about 3,000 kilometers) away from Jezero Crater, where Perseverance is set to land. Unlike the more charismatic rovers that are designed to roll around and explore the Martian landscape, one of Insight’s primary jobs is simply to sit in one spot and listen for marsquakes and other seismic activity.

An illustration of Perseverance during its descent to the Martian surface.
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“This will transmit a huge amount of energy into the ground, which will produce seismic waves,” Fernando explains. “We estimated that these signals will be ‘loud’ enough to be detected by InSight’s seismometers about 40% of the time in the best-case scenario. The uncertainties of our estimates are significant, mainly because no one has ever tried to detect an impact event at these distances before.”
Regardless of how well it works, even attempting to detect a spacecraft landing on Mars with another distant probe will be a first.

When NASA’s Mars 2020 Perseverance rover lands on the surface of the red planet Thursday, it will carry a microphone that will, hopefully, manage to capture the sounds of its descent and touchdown. But that won’t be the only device listening for the rover’s arrival.
Be sure to keep up with all our coverage of Perseverance’s arrival at Mars, which is set for 12:55 p.m. PT Thursday.
Now scientists are hoping to use the landing of Perseverance to get a better picture of the interior structure of Mars and how seismic waves propagate through it. The hope is that Insight will be able to pick up different phases of the landing with its sensors. In essence, this will be the first time that Insight will “hear” a “quake” and also know exactly where it’s coming from. This critical data will allow researchers to hone their models of the Martian interior and calibrate Insight’s seismic detection powers. Insight has already succeeded in detecting marsquakes. But as the lone seismic detection station on the planet, its science team has had trouble pinpointing the location and magnitude of the quakes. This is easier to do on Earth, where there is a whole network of seismic sensors making it easier to calibrate and calculate the particulars of a certain tremor.
“Luckily, the entry, descent and landing of the Perseverance rover is so energetic that it produces signals that are detectable by seismometers,” writes Ben Fernando, a member of the Insight science team, for The Conversation. 
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