When the Perseverance Rover departs for Mars on Thursday, another NASA spacecraft will already be listening to the rumble that will result when the newcomer arrives.
The hope is that these bumps will create enough tremors to be detected by InSight, a stationary NASA probe that arrived in 2018 to listen to marsquakes with an extremely sensitive seismometer. The InSight lander sits more than 2,000 miles east of where endurance should land.
“We have a fair chance of seeing it,” said Benjamin Fernando, a graduate student at the University of Oxford in England and a member of the InSight Science team.
Unless something goes catastrophically wrong, the seismic signals that InSight can hear will not come from the rover. Endurance must be lowered from a hovercraft to the surface, which bumps softer against the ground at less than 2 miles per hour.
Scientists would rather examine the seismic data from InSight to give evidence of the impact of two 170-pound blocks of tungsten metal that helped keep endurance in a stable, balanced turn during the 300 million mile ride from Earth. At an altitude of 900 miles above Mars, they will be chased as debris, and without parachutes or right-handers to slow it down, they will strike the surface at about 9,000 km / h.
“This enormous velocity means they will make a significant crater,” Fernando said. In 2012, similar tungsten blocks from the Curiosity rover, which had almost the same design as Perseverance, left scars visible from the track.
If an angle of ten degrees enters, the impact of the blocks will be to the east, which will create a shot of seismic energy towards InSight that will detect the chance of vibrations.
If the impact waves are detected, it is not just a technical skill. The data may help to elucidate the structure of the crust of Mars.
The main purpose of the seismometer on InSight is to record marsquakes, and the spacecraft has so far recorded more than 400 such tremors. Scientists also expected InSight to detect earthquakes caused by space rocks that sometimes crashed into Mars.
But so far the number of recorded meteor impacts is zero. Or at least there is no wrapper that the scientists could confidently deduce that it was caused by such collisions. The lack of clear signals suggests that the crust of Mars may be more similar to that of the earth’s moon than to the earth.
Seismic waves move further through solid rock like a heap of loose material like sand. On Earth, the constantly carved plate tectonics generate new solid rocks at the surface. On the moon there are no more lava eruptions, and over the billions of years the bombardment of meteors has broken the old lunar crust into small pieces. The result is a loose top layer, which explains why the astronauts left so many boot prints during their visits.
“Mars is probably somewhere between the moon and the earth,” Fernando said.
With perseverance, however, the exact time and location of the landing will be known, and so InSight scientists will know where to look in the seismic data and extract a small signal that would normally be overlooked.
This is similar to how scientists decades ago were able to calibrate the seismometers left on the moon by NASA’s Apollo astronauts when pieces of rockets and lunar landers crashed into the moon.
With the knowledge, they can then search data earlier and look for similar patterns that could be meteor impact.
Mr. Fernando and the other InSight scientists also considered other signals that could pick up the seismometer. Perhaps waves of air pressure from the sonic surge of impending perseverance are enough. Or the sonic surge would shake the ground and generate a wave that would move to InSight.
But their calculations showed that the rumble would be too small to detect.
They also considered looking at larger pieces of the spacecraft, such as the heat shield that would also fall to the ground. But it will be detected at lower altitudes and not move as fast and generate small seismic waves.
Weather can cause another complication. If the wind on Mars on Thursday is too strong, it could break down the InSight seismometer, which could create noise that could also obscure the signal of Perseverance’s arrival.
What lies beneath the surface of Mars remains largely a mystery. Indeed, the inner parts of the planet thwarted the other main purpose of InSight, to insert a heat probe, nicknamed the mole, which would hammer itself about 16 feet into the Martian soil. But sin jumped back.
The sand around the mole exhibits an unexpected clump of property and it prevents friction from being sufficient to propel the device more than 14 inches below the surface.
In January, NASA announced that they were giving up the mole. Nevertheless, the Insight mission has been extended to December 2022 with the aim of collecting more seismic data.
Now InSight will have to survive the Mars winter. The solar panels, which are covered with dust, now produce only 27 percent as much power when they were new and clean. None of the hundreds of dust devils – essentially small tornado storm winds – came close enough to blow the dust away. The managers of the mission are therefore finding out how the spacecraft can be used with less energy, among other things by eliminating scientific instruments. That should be enough to prevent it from freezing to death, which was the fate of NASA’s Opportunity Rover in 2018 after being shrouded in a global dust storm.