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Hundreds of basketball-sized space rocks crash into Mars every year, leaving impact craters behind and causing rumblings across the red planet, according to new research.
Mission planners could use the publications, recorded in data collected by the now-defunct NASA mission, when deciding where to land future robotic missions as well as astronaut crews on the red planet .
NASA’s InSight mission ended when the resident lander lost its battle due to the accumulation of Martian dust on its solar panels in December 2022, but the wealth of data collected by the spacecraft continues to inspire new research.
The lander carried the first seismometer to Mars, and the sensitive instrument was able to detect seismic waves occurring thousands of miles from InSight’s site in Elysium Planitia, a flat plain just north of the planet’s equator.
During its time on Mars, InSight used its seismometer to detect more than 1,300 earthquakes, which occur when the Martian subsurface cracks due to pressure and heat.
But InSight also captured evidence of meteorites crashing into Mars.
Meteoroids are space rocks that broke off from larger rocky bodies and range in size from dust grains to small asteroids, according to NASA. They are called meteoroids while they are still in space, they are called meteors when they pass through the atmosphere of the Earth or other planets.
Scientists have questioned why more impacts have not been found on Mars because the planet is located near the main asteroid belt of our solar system, where many space rocks emerge to hit the surface of Mars. The Martian atmosphere is only 1% the thickness of Earth’s atmosphere, meaning that more meteorites zip through it without disintegrating.
A meteoroid hit the Martian atmosphere on September 5, 2021, and then exploded into at least three shards, each leaving a crater on the red planet’s surface. And it was just the beginning.
Search for fresh craters
Since 2021, researchers have been looking at InSight data and have determined that space rocks hit Mars more often than previously thought, as much as two to 10 times higher than previous estimates, according to a study new published on 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 lead study author Ingrid Daubar, associate professor of Earth, environmental sciences and planetary at Brown University, in a statement. “Our results are based on a small number of samples available to us, but the current impact rate estimate suggests that the planet has been hit much more often than we can see using imaging alone.”
The team identified eight new impact craters created by meteorites from InSight data seen by orbiters that had previously circled the planet. Six of the craters were near the InSight landing site, and two of the distant impacts were some of the largest found by scientists observing the red planet, according to the study.
Both large impacts left craters the size of football fields, and occurred 97 days apart.
“An impact of this magnitude, we would expect it 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,” a Daubar said. “It could be a crazy coincidence, but there’s a very small probability that it’s just a coincidence. It’s more likely that the two major impacts are related, or that the impact rate is much higher for Mars than we thought.”
The team compared the data collected by InSight with data taken by NASA’s Mars Reconnaissance Orbiter to zero in on where the impacts occurred. Before and after images enabled the team to confirm eight of the craters. InSight may have registered more impacts during its mission, and the team plans to continue searching through the data and looking for orbital evidence of fresh craters.
“Planetary impacts are happening all over the solar system all the time,” Daubar said. “We are interested in studying that on Mars because then we can compare and contrast what is happening on Mars with what is happening on Earth. This is important for understanding our solar system, what it is and what the population of impactors in our solar system looks like – as hazards to Earth and historically to other planets as well.”
After seismic signals
A companion paper, published Friday in the journal Nature Communications, also examined seismic events recorded by InSight to determine that meteoroids about the size of a basketball crash into Mars almost daily.
Between 280 and 360 meteoroids hit the red planet each year, creating impact craters more than 26 feet (8 meters) across, according to the study. 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 imagery alone,” said co-lead study author Dr Géraldine Zenhäusern, a staff professor for seismology and geodynamics at Switzerland’s ETH Zürich , in a statement. “Along with orbital imaging, our results show that seismology is an excellent tool for measuring impact rates.”
By analyzing seismic events traced to meteoroids, the team identified about 80 earthquakes recorded by InSight that could have caused impacts. The odd tremors caused by meteoroid impacts occur at a higher frequency and are shorter than other tremors caused by subsurface activity.
“Although new craters are best seen on flat and dusty ground where they actually stand, this type of terrain covers less than half of the surface of Mars,” said Zenhäusern. “The sensitive InSight seismometer, however, could hear every impact within range of the landing.”
Seismic data of the smallest 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 build a timeline of the red planet’s geological history and evolution.” put together,” said study author co-citer Dr. Natalia Wojcicka, research. associate at Imperial College London’s Department of Earth Science and Engineering, in a statement. “You could think of it as a kind of ‘cosmic clock’ to help us date Martian surfaces, and perhaps, further down the line, other planets in the Solar System.”
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