The Mars InSight lander detected seismic and acoustic waves created when four space rocks slammed into the Red Planet’s surface.
InsightThe seismometer felt vibrations from the impacts in 2020 and 2021, marking the first detections of meteoroids hitting the planet since the lander began collecting data after landing in 2018. The meteoroid impacts occurred between 53 miles (85 kilometers) and 180 miles (290 km) from InSight’s location in the Elysium Planitia region of Marcha vast plain that stretches across the Martian equator.
One of the space rocks, the first scientists detected, made a dramatic and violent entrance on September 5, 2021, exploding into pieces. At least three separate fragments hit the Martian surface, each leaving a crater.
Related: NASA’s InSight Mars lander spotted from orbit covered in dust
NASA’s Mars Reconnaissance Orbiter (MRO) confirmed the location of these impacts from orbit. The spacecraft, which launched in 2005, first took black-and-white images of the regions with its pop-up camera, revealing dark spots on the Martian surface. After identifying these impact sites, MRO then collected color images and close-ups using its High-Resolution Imaging Science Experiment camera (HIRISE). The meteoroids may have left additional craters around these impact sites that are too small for even HiRISE to spot.
A search of past data collected by InSight revealed that the lander’s seismometer had already detected three previous impacts on May 27, 2020, February 18, and August 31, 2021. All four impacts produced small earthquakes of a magnitude not exceeding 2.0.
“After three years of waiting for InSight to detect an impact, these craters were magnificent,” said Ingrid Daubar, a planetary scientist at Brown University in Rhode Island and a member of the team that made the discovery. statement.
Why so little impact?
Planetary scientists aren’t sure why InSight hasn’t detected more space rock impacts on the Red Planet. Not only does Mars sit next to the solar system’s main asteroid belt, a hotspot for space rocks, but its thin atmosphere should allow meteoroids to pass through it without destroying them. These factors mean that a higher proportion of space rocks should reach the Martian surface than, say, Earth.
The researchers are fairly confident that the lack of detections is not a sign that InSight’s seismometer is faulty. During its nearly four years on the Red Planet, the instrument detected more than 1,300 marsquakes and was sensitive enough to detect seismic waves thousands of miles away.
InSight scientists believed the impacts could be hidden by wind noise on the Red Planet or by seasonal changes in the atmosphere. Researchers will now revisit InSight data to search for seismic footprints of other space rock impacts.
Any such impact could help scientists better understand the age of the Martian surface. Counting impact craters is one way scientists can date the age of a planet’s surface, meaning the new discovery and any additional impacts could be key to establishing a timeline for Mars.
“Impacts are the clocks of the solar system,” Raphael Garcia, a planetary scientist at the Institut Supérieur de l’Aéronautique et de l’Espace in France and lead author of the new research, said in the same statement. “We need to know the impact rate today to estimate the age of the different surfaces.”
By combining InSight data about the shock waves created when space rocks hit the atmosphere with data collected from orbit, scientists may also be able to reconstruct the incoming trajectory of a specific meteoroid.
“We’re learning more about the impact process itself,” Garcia said. “We can now match different sizes of craters to specific seismic and acoustic waves.”
And researchers have a bit more time to collect data with InSight than they thought. Dust accumulation on the lander’s solar panels reduces its power supply and will eventually force it to shut down; previous estimates suggested this would happen in late summer, but now mission staff believe it will only happen between October 2022 and January 2023.
An article detailing InSight’s findings was published Monday, September 19 in the journal nature geoscience (opens in a new tab).
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