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Hundreds of basketball-sized space rocks crash into Mars every year, leaving behind impact craters and causing rumblings across the red planet, according to new research.
Mission planners could use the revelations, recorded in data collected by a now-retired 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 accumulation of martian dust on its solar panels in December 2022, but the wealth of data collected by the probe is still fueling new research.
The probe carried the first seismograph to Mars, and the sensitive instrument was able to detect seismic waves that occurred thousands of kilometers away from InSight’s location on Elysium Planitia, a smooth plain north of the planet’s equator.
During its stay on Mars, InSight used its seismometer to detect more than 1,300 earthquakesthat occur when the Martian subsurface cracks due to pressure and heat.
But InSight also captured evidence of meteoroids as they collided with 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 while still in space, they are called meteors as 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 emerge to reach the Martian surface. The Martian atmosphere is only 1% as thick as Earth’s atmosphere, which means more meteoroids pass through it without disintegrating.
A meteoroid hit the Martian atmosphere on September 5, 2021 and then exploded into at least three fragments, each leaving behind a crater on the surface of the red planet. And it was just the beginning.
Looking for fresh craters
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 previous estimates, according to a new study published Friday. fair in the magazine. Advances in Science.
“It’s possible that Mars is more geologically active than we thought, which has implications for the age and evolution of the planet’s surface,” said study lead author Ingrid Daubar, associate professor of Earth, environmental and planetary sciences at the University of California. Brown, in a statement. . “Our results are based on a small number of examples we have, but the current impact rate estimate suggests the planet is being hit much more frequently than we can see using images alone.”
The team identified eight new impact craters created by meteoroids from InSight data that orbiters orbiting the planet had previously detected. Six of the craters were near InSight’s landing site, 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 football fields and occurred 97 days apart.
“We expected this impact to happen maybe once every two decades, maybe even once in a lifetime, but here we have two of them just over 90 days apart,” Daubar said. “It could just be a crazy coincidence, but there’s a very, very small probability that it’s just coincidence. What is more likely is that either the two large impacts are related, or the impact rate is much higher for Mars than we thought it would be.”
The team compared the data collected by InSight with that obtained 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 more impacts during its mission, and the team plans to continue combing through the data and looking for orbital evidence of new craters.
“Planetary impacts are happening throughout the solar system all the time,” Daubar said. “We’re interested in studying this on Mars because we can then compare and contrast what’s happening on Mars with what’s happening on Earth. This is important for understanding our solar system, what is in it and what the population of impacting bodies in our solar system is like – both as hazards to Earth but also historically to other planets.”
Following seismic signals
A complementary article, published Friday in the magazine Nature Communicationsalso explored seismic events recorded by InSight to determine that basketball-sized meteoroids fall on Mars almost daily.
Between 280 and 360 meteoroids hit the Red Planet every year and form impact craters more than 8 meters in diameter, according to the study. Larger craters, measuring 30 meters, 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-lead author Dr. Géraldine Zenhäusern, professor of seismology and geodynamics at ETH Zürich in Switzerland, said in a statement. “Aligned with orbital images, our findings demonstrate that seismology is an excellent tool for measuring impact rates.”
By analyzing seismic events traced back to meteoroids, the team identified about 80 earthquakes recorded by InSight that may have been caused by impacts. Marsquakes resulting from meteoroid impacts occur at a higher frequency and have a shorter duration than other marsquakes caused by underground activity.
“Although new craters can be 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 seismograph, however, could hear every impact within range of the landers.”
Seismic data from the slightest ground motions on Mars may 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 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 study co-lead author Dr. associate in the department of Earth sciences and engineering at Imperial College London, in a statement. “We could think of it as a kind of ‘cosmic clock’ to help us date the Martian surfaces and perhaps, further down the line, other planets in the Solar System.”
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