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Hundreds of basketball-sized space rocks crash into Mars every year, leaving impact craters and causing rumbles across the red planet, according to a new study.
Mission planners could use the findings, recorded in data collected by a now-retired NASA mission, as they determine where to land future robotic missions and astronaut crews on the red planet.
NASA’s InSight mission ended when the stationary spacecraft lost a battle to an accumulation of Martian dust on its solar panels in December 2022, but the wealth of data collected by the spacecraft is still fueling new research.
The lander carried the first seismometer on Mars, and the sensitive instrument was able to detect seismic waves that occurred thousands of miles away from InSight’s location on Elysium Planitia, a flat plain north of the planet’s equator.
During its time on Mars, InSight used its seismometer to detect more than 1,300 Martian earthquakes, which occur when the Martian subsurface cracks due to pressure and heat.
But InSight also captured evidence of meteoroids as they crashed into Mars.
Meteoroids are space rocks that have broken off from larger bodies of rock and range in size from dust grains to small asteroids, according to NASA. Known as meteoroids while still in space, they are called meteors after they pass through the atmosphere of Earth or other planets.
Scientists have questioned why more impacts have not been detected on Mars because the planet is located near our solar system’s main asteroid belt, where many space rocks come out to hit the Martian surface. The Martian atmosphere is only 1% the thickness of Earth’s atmosphere, meaning that more meteoroids pass through it without disintegrating.
A meteorite hit the Martian atmosphere on September 5, 2021 and then exploded into at least three pieces, each leaving behind a crater on the red planet’s surface. And it was just the beginning.
Since 2021, researchers have pored over InSight data and determined that space rocks bombard Mars more often than previously thought, two to 10 times more than previously estimated, according to a new study published Friday in the journal Science Advances.
“It’s possible that Mars is geologically more active than we thought, which has implications for the age and evolution of the planet’s surface,” said lead study author Ingrid Daubar, an associate professor of Earth, environmental and planetary sciences at Brown University. , in a statement. . “Our results are based on a small number of examples available to us, but estimating the actual impact rate suggests that the planet is being hit much more often than we can see using images alone.”
The team identified eight new meteoroid impact craters from InSight data that orbiters circling the planet had previously seen. Six of the craters were close to where InSight landed, and two of the distant impacts were some of the largest ever detected by scientists observing the red planet, according to the study.
Each of the two large impacts left craters the size of a football field, and they occurred 97 days apart.
“An impact of this size, we would expect to happen maybe once every two decades, maybe even once in a lifetime, but here we have two of them that are just over 90 days apart,” Daubar said. “It could just be a crazy coincidence, but there’s a really small chance that it’s just a coincidence. What is more likely is that either the two large impacts are related, or the magnitude of the impact is much higher for Mars than we thought it was.”
The team compared data collected by InSight with that taken by NASA’s Mars Reconnaissance Orbiter at ground zero of where the impacts occurred. Before and after images enabled the team to confirm eight of the craters. It’s possible that InSight recorded more impacts during its mission, and the team plans to continue searching through the data and look for orbital evidence of fresh craters.
“Planetary impacts are happening throughout the solar system all the time,” Daubar said. “We’re interested in studying it on Mars because then we can compare and contrast what’s happening on Mars with what’s happening on Earth. This is important for understanding our solar system, what’s in it, and what the population of bodies that affect our solar system looks like — as a risk 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 crash into Mars almost every day.
According to the study, between 280 and 360 meteoroids hit the red planet each year, and they form impact craters larger than 8 meters. Larger craters that span 98 feet (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,” study co-lead author Dr. Géraldine Zenhäusern, staff professor of seismology and geodynamics at ETH Zürich, Switzerland. “Consistent with orbital imaging, our findings show that seismology is an excellent tool for measuring impact rates.”
By analyzing the seismic events traced to the meteoroids, the team has identified about 80 earthquakes recorded by InSight that could have been caused by the impacts. Earthquakes as a result of meteoroid impacts occur at a higher frequency and have a shorter duration than other earthquakes caused by underground activity.
“While the new craters are best seen on flat, dusty terrain, where they really stand out, this type of terrain covers less than half the surface of Mars,” Zenhäusern said. “The sensitive InSight seismometer, however, could hear any impact within range of the earth.”
Seismic data of smaller ground motions 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 hit Mars and how these impacts change its surface, we can begin to piece together a timeline of the geological history and evolution of the Red Planet,” said co-author -director of the study, Dr. Natalia Wojcicka, researcher. fellow in the department of Earth science and engineering at Imperial College London, in a statement. “You can think of it as a kind of ‘cosmic clock’ to help us date Martian surfaces, and perhaps, further down, other planets in the Solar System.