Mars is hit by hundreds of basketball-sized space rocks every year

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Hundreds of basketball-sized space rocks crash into Mars every year, leaving impact craters and rumblings across the red planet, according to new research.

Mission planners could use the revelations recorded in data collected by NASA’s now-defunct mission when determining 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 its battle with Martian dust build-up on its solar panels in December 2022, but the amount of data the spacecraft collected is still fueling 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 where InSight is located in Elysium Planitia, a smooth plain north of the planet’s equator.

During its time on Mars, InSight used its seismometer to detect more than 1,300 tremors, which occur when subsurface cracks on Mars crack due to pressure and heat.

But InSight also picked up evidence of meteoroids when they hit Mars.

According to NASA, meteoroids are space rocks that have broken off from larger rocky bodies and range in size from dust grains to small asteroids. 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 have questioned why more impacts haven’t been detected on Mars because the planet is located next to our solar system’s main asteroid belt, where many of the space rocks that hit the Martian surface emerge. The Martian atmosphere is only 1% the thickness of Earth’s atmosphere, meaning that more meteoroids will pass through it without disintegrating.

The meteoroid hit the Martian atmosphere on September 5, 2021 and then exploded into at least three fragments, each of which left a crater on the red planet’s surface. And that was just the beginning.

Starting in 2021, researchers pored over InSight data and found that space rocks are bombarding Mars more often 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.

“It is possible that Mars is more geologically active than we thought, with implications for the age and evolution of the planet’s surface,” said study leader Ingrid Daubar, an associate professor of Earth, environmental and planetary sciences at Brown University. . “Our results are based on the small number of examples available to us, but the estimate of the current impact rate suggests that the planet is being hit much more frequently than we can see with imaging alone.”

The team identified eight new impact craters created by meteoroids from InSight data previously spotted by orbiters circling the planet. Six of the craters were located near the InSight landing site, and two of the distant impacts were among the largest ever observed by scientists observing the red planet, according to the study.

Each of the two major impacts left craters the size of football fields and occurred 97 days apart.

“We would expect an impact of this magnitude to happen maybe once every few 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, really small chance that it’s just a coincidence.” It is more likely that either the two large impacts are related, or that the impact rate at Mars is much higher than we thought.”

The team compared the data collected by the InSight system with data obtained by NASA’s Mars Reconnaissance Orbiter with ground zero at the site of the impacts. Before and after images allowed the team to confirm eight craters. It’s possible that InSight saw more impacts during its mission, and the team plans to continue scouring the data for orbital evidence of fresh craters.

“Planetary impacts happen all the time throughout the solar system,” 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 impactors in our solar system looks like – both as a threat to Earth and historically to other planets.”

A companion paper, published Friday in the journal Nature Communications, also examined seismic events recorded by InSight to find that basketball-sized meteoroids hit Mars almost daily.

According to the study, 280 to 360 meteoroids hit the Red Planet each year, creating impact craters larger than 26 feet (8 meters) in diameter. Larger 98-foot (30-meter) craters occur about once a month, the study authors said.

“This rate was about five times higher than the number estimated from orbital images alone,” study co-author Dr. Géraldine Zenhäusern, professor of seismology and geodynamics at the Swiss ETH Zürich. “Consistent with the orbital images, our findings show that seismology is an excellent tool for measuring impact rates.”

By analyzing seismic events traced to meteoroids, the team identified about 80 marsquash recorded by InSight that could have been caused by impacts. Shocks due to meteoroid impacts they occur with a higher frequency and have a shorter duration than other marsquakes caused by subsurface activity.

“While the new craters are best seen on flat and dusty terrain where they really stand out, this type of terrain covers less than half the surface of Mars,” Zenhäusern said. “But the sensitive InSight seismometer could hear every single impact within range of the landers.”

Seismic data on the tiniest ground motions on Mars could be the most direct way to understand how many impacts occur on Mars, 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 geologic history and evolution of the red planet,” said study co-author Dr. Natalia Wojcicka, researcher. associate in the Department of Earth Science and Engineering, Imperial College London, in a statement. “You can think of it as a kind of ‘cosmic clock’ that will help us date the surfaces of Mars and perhaps, beyond, other planets in the Solar System.”