It is the first time a mission has been recorded both seismic and acoustic waves from an impact on Mars; and InSight’s first detection of impacts since landing on the red planet in 2018.
Luckily, InSight didn’t get in the way of these meteoroids, the name for space rocks, before they hit the ground. The impacts ranged from 53 to 180 miles (85 to 290 kilometers) from the stationary lander’s position in Elysium Planitia on Mars, a smooth plain north of the equator.
A meteoroid struck the Martian atmosphere on September 5, 2021 and 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 had landed and spotted three dark areas. The orbiter’s color imager, the camera on the High-Resolution Imaging Science Experiment, took detailed close-up pictures of the craters.
“After waiting three years for InSight to spot an impact, these craters looked beautiful,” said study co-author Ingrid Daubar, assistant professor of Earth, Environmental and Planetary Sciences at Brown University in Providence, Rhode Iceland, 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 record of a meteor impacting Mars on Monday. During the clip, listen three times for a very sci-fi sounding “bloop” as the space rock enters the atmosphere, explodes into pieces, and hits the surface.
Scientists have actually questioned why no more impacts have been detected on Mars because the planet is adjacent to our solar system’s main asteroid belt, where many space rocks emerge to meet the Martian surface. The Martian atmosphere is only 1% the thickness of Earth’s atmosphere, meaning more meteoroids fly through it without dissipating.
During its time on Mars, InSight’s seismometer has detected more than 1,300 marsquakes, which occur when the Martian subsurface cracks due to pressure and heat. The sensitive instrument can detect seismic waves occurring thousands of kilometers away from InSight’s site – but the September 2021 event is the first time scientists have made use of it the waves to confirm an impact.
It’s possible that the whooshing of the Martian winds or seasonal changes occurring in the atmosphere are hiding the additional effects. Now that researchers understand what an impact’s seismic signature looks like, they expect to find more as they comb through InSight’s data for the past four years.
Impact craters help scientists understand the age of a planet’s surface. Researchers can also determine how many of the craters formed early in the Solar System’s turbulent history.
“Impacts are the clocks of the solar system,” said lead author Raphael Garcia, an academic researcher at the Institut Supérieur de l’Aéronautique et de l’Espace in Toulouse, France, in a statement. “Today, we need to know the impact rate to estimate the age of different surfaces.”
Examining the data from InSight may provide researchers with an opportunity to analyze the trajectory and magnitude of the shock wave produced as the meteoroid enters the atmosphere and impacts the ground.
“We’re learning more about the impact process itself,” Garcia said. “We can now associate different crater sizes with specific seismic and acoustic waves.”
The latest readings suggest it could close between next October and January 2023.
Until then, the spacecraft still has the opportunity to expand its research portfolio and its impressive collection of discoveries on Mars.