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Every year, hundreds of basketball-sized space rocks crash into Mars, leaving behind impact craters and causing rumbles across the Red Planet, a new study suggests.
Mission planners could use the revelations, recorded in data collected by a now-abandoned NASA mission, to determine where to land future robotic missions as well as astronaut crews on the Red Planet.
NASA’s InSight mission ended when the stationary lander lost a battle to a buildup of Martian dust on its solar panels in December 2022, but the wealth of data collected by the spacecraft continues to fuel new research .
The lander carried the first seismometer to Mars, and the sensitive instrument was able to detect seismic waves that occurred thousands of miles from InSight’s location at Elysium Planitia, a smooth plain just north of Mars. equator of the planet.
During its stay on Mars, InSight used its seismometer to detect more than 1,300 earthquakes, which occur when the Martian subsurface cracks under pressure and heat.
But InSight also captured evidence of meteoroids when they crashed into Mars.
Meteoroids are space rocks that have broken off from larger rocky bodies and range in size from dust grains to small asteroids, according to NASA. Known as meteoroids when they are still in space, they are called meteors when they pass through the atmosphere of Earth or other planets.
Scientists wonder why more impacts haven’t been detected on Mars because the planet is located near our solar system’s main asteroid belt, from which many space rocks emerge to strike the Martian surface. The Martian atmosphere is only 1% as thick as Earth’s, meaning more meteorites pass through it without disintegrating.
A meteoroid struck the Martian atmosphere on September 5, 2021, then exploded in at least three bursts, each leaving behind a crater on the surface of the red planet. And that was only the beginning.
Since 2021, researchers have studied InSight data and determined that space rocks bombard Mars more frequently than previously thought, up to two to ten times more than previous estimates, according to a new study published Friday in the journal Science Advances.
“Mars may be more geologically active than we thought, which has implications for the age and evolution of the planet’s surface,” said Ingrid Daubar, lead author of the study and associate professor of Earth, environmental and planetary sciences at Brown University, in a statement. “Our results are based on a small number of examples that we have, but the estimate of the current impact rate suggests that the planet is being struck much more frequently than we can see using imaging alone.”
The team identified eight new meteoroid-created impact craters from InSight data that orbiters circling the planet had already spotted. Six of the craters were close to InSight’s landing site, and two of the distant impacts were among the largest ever detected by scientists observing the Red Planet, according to the study.
Each of the two large impacts left behind craters the size of a football field, and they occurred 97 days apart.
“You would expect an impact of this magnitude to happen once every 20 years, or even once in a lifetime, but here we have two of them just over 90 days apart,” Daubar said. “It could be a coincidence, but there’s a very, very small chance that it’s a coincidence. What’s more likely is that the two big impacts are related, or that the impact rate is much higher on Mars than we thought.”
The team compared the data collected by InSight with that taken by NASA’s Mars Reconnaissance Orbiter to determine where the impacts occurred. Before-and-after images allowed the team to confirm eight of the craters. It’s possible that InSight recorded other impacts during its mission, and the team plans to continue searching the data for orbital evidence of new craters.
“Planetary impacts are happening all the time throughout the solar system,” Daubar said. “We want to study this on Mars because then we can compare what’s happening on Mars with what’s happening on Earth. This is important for understanding our solar system, what it contains, and what the population of impacting bodies in our solar system looks like – both as dangers to Earth and also historically to other planets.
A companion paper, published Friday in the journal Nature Communications, also explored seismic events recorded by InSight to determine that basketball-sized meteoroids are crashing into Mars almost daily.
Between 280 and 360 meteoroids strike the Red Planet each year, forming impact craters larger than 8 meters in diameter, the study said. Larger craters spanning 30 meters occur about once a month, the study authors said.
“This rate was about five times higher than the number estimated from orbital imaging alone,” Dr. Géraldine Zenhäusern, co-senior author of the study and professor of seismology and geodynamics at ETH Zürich, said in a statement. in Swiss. “Aligned with orbital imaging, our results demonstrate that seismology is an excellent tool for measuring impact rates.”
By analyzing seismic events attributed to meteoroids, the team identified about 80 earthquakes recorded by InSight that may have been caused by impacts. Earthquakes due to meteorite impacts They occur at a higher frequency and have a shorter duration than other earthquakes caused by underground activity.
“Although the new craters are best seen on flat, dusty terrain where they really stand out, that type of terrain covers less than half of Mars’ surface,” Zenhäusern said. “The sensitive InSight seismometer, however, could hear every impact within range of the landers.”
Seismic data from the smallest ground movements on Mars may be the most direct way to understand how many impacts occur on Mars, the researchers said.
“By using seismic data to better understand how often meteorites strike Mars and how these impacts change its surface, we can begin to piece together a timeline of the Red Planet’s geological history and evolution,” said Dr. Natalia Wojcicka, co-lead author of the study and associate professor in the Department of Earth Science and Engineering at Imperial College London, in a statement. “You could think of it as a kind of cosmic clock to help us date the surfaces of Mars and perhaps, later, other planets in the Solar System.”