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NASA’s InSight Lander has “heard” and detected the vibrations of four space rocks as they slammed into Mars over the past two years.
It’s the first time a mission has taken off both seismic and acoustic waves from an impact on Mars, and InSight’s first impact detection since landing on the Red Planet in 2018.
Fortunately, InSight was not in the path of these meteoroids, the name given to space rocks, before they hit the ground. The impacts ranged from 85 to 290 kilometers from the stationary lander’s position in Mars’ Elysium Planitia, a flat plain just north of the equator.
A meteoroid hit the Martian atmosphere on September 5, 2021, then exploded into at least three fragments, each leaving a crater on the Red Planet’s surface.
The Mars Reconnaissance Orbiter then flew over the site to confirm where the meteoroid landed, spotting three dark areas. The orbiter’s color camera, the High-Resolution Imaging Science Experiment camera, captured detailed close-up images of the craters.
Researchers shared their findings about the new craters in a study published on Monday in the journal Nature Geoscience.
“After three years with InSight and waiting to detect an impact, these craters looked beautiful,” study co-author Ingrid Daubar, assistant professor of Earth, Environmental and Planetary Sciences at Brown University in Providence, Rhode Island, said in a statement.
Data from InSight also revealed three other similar impacts, one on May 27, 2020, and two more in 2021 on February 18 and August 31.
The agency released a recording of a Martian meteorite impact on Monday. During the clip, you can listen for a very science fiction-sounding “bloop” three times as the space rock enters the atmosphere, explodes into pieces, and hits the surface.
Indeed, scientists have questioned why more impacts have not been detected on Mars because the planet is adjacent to the Solar System’s main asteroid belt, where many space rocks emerge to hit the Martian surface. The Martian atmosphere is only 1% the thickness of Earth’s atmosphere, meaning that several meteoroids slip through it without disintegrating.
During its time on Mars, InSight has used its seismometer to detect more than 1,300 Martian earthquakes, which occur when the Martian subsurface cracks due to pressure and heat. The sensitive instrument can detect seismic waves that occur thousands of miles away from InSight’s location — but the September 2021 event is the first time scientists have used the waves to confirm an impact.
It is possible that the noise of the Martian wind or seasonal changes occurring in the atmosphere obscured the additional influences. Now that scientists understand what an impact’s seismic signature looks like, they expect to find more when they comb through InSight’s data from the past four years.
Seismic waves help scientists unlock additional information about the interior of Mars because they change as they move through different materials.
The meteoroid impacts create earthquakes with a magnitude of 2.0 or less. So far, InSight’s largest detected earthquake was a magnitude 5 event in May.
Impact craters help scientists understand the age of a planet’s surface. Scientists can also determine how many of the craters formed early in the solar system’s tumultuous history.
“Impacts are the clocks of the solar system,” lead author Raphael Garcia, an academic researcher at the Institut Supérieur de l’Aéronautique et de l’Espace in Toulouse, France, said in a statement. “We need to know the impact rate today to estimate the age of different surfaces.”
Studying InSight’s data could give scientists a way to analyze the path and size of the shock wave produced when the meteoroid enters the atmosphere, as well as when it hits the ground.
“We’re learning more about the impact process itself,” Garcia said. “We can match different sizes of craters to specific seismic and acoustic waves now.”
InSight’s mission is nearing its end as dust builds up on its solar panels and reduces power. Eventually the spacecraft will shut down, but the team is unsure when that will happen.
The latest measurements have suggested that it may be closed between the coming October and January 2023.
Until then, the spacecraft still has a chance to add to its research portfolio and the amazing collection of discoveries on Mars.