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Hundreds of basketball-sized space rocks crash into Mars every year, leaving behind impact craters and causing rumbles across the Red Planet, new research shows.
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 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 on Mars, and the sensitive instrument was able to detect seismic waves that occurred thousands of miles from InSight’s location in Elysium Planitia, a smooth plain just north of the planet’s equator.
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 as they crashed into Mars.
Meteoroids are space rocks that have broken off from larger rocky bodies and range in size from a speck of dust to a small asteroid, 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.
NASA/JPL-Caltech/University of Arizona
NASA’s Mars Reconnaissance Orbiter captured an image of a meteoroid impact that was later linked to a seismic event detected by the agency’s InSight lander. This crater was formed on May 27, 2020.
Scientists wonder why more impacts haven’t been detected on Mars, since the planet is located near our solar system’s main asteroid belt, where many space rocks emerge to strike the Martian surface . The Martian atmosphere is only 1% as thick as Earth’s atmosphere, meaning more meteorites pass through it without disintegrating.
A meteoroid struck the Martian atmosphere on September 5, 2021, then exploded into at least three fragments, 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 impact craters created by meteorites from InSight data, which probes orbiting the planet had already spotted. Six of these craters were near 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.
NASA/JPL-Caltech/University of Arizona
The orbiter spotted a meteoroid impact that occurred on February 18, 2021. InSight tracked a seismic signal from the event.
Each of the two large impacts left behind craters the size of football fields, and they occurred 97 days apart.
“We would expect an impact of this magnitude to happen maybe once every couple of decades, maybe even once in a lifetime, but here we have two of them within a little over 90 days of each other,” Daubar said. “It could just be a crazy coincidence, but there’s a very, very small chance that it’s just a coincidence. What’s more likely is that either the two major impacts are related, or the impact rate on Mars is much higher than we thought.”
The team compared data collected by InSight with data 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 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 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 crash into Mars almost daily.
Between 280 and 360 meteoroids hit the Red Planet each year and form impact craters more than 8 meters in diameter, according to the study. Larger craters spanning 30 meters occur about once a month, the study authors said.
“This rate is about five times higher than the number estimated from orbital imagery alone,” said study co-lead author Dr. Géraldine Zenhäusern, professor of seismology and geodynamics at ETH Zurich in Switzerland, in a statement. “In line with orbital imagery, 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.
NASA/JPL-Caltech/University of Arizona
Data from InSight was compared to photos taken by orbiters, such as this one of an impact crater created on August 30, 2021, to determine when and where meteor impacts occur on the Red Planet.
“The new craters are most visible on flat, dusty terrain, where they really stand out, but this type of terrain covers less than half of the surface of Mars,” Zenhäusern said. “The very sensitive InSight seismometer, however, could hear every impact within range of the landers. »
Seismic data of the slightest ground movements on Mars may be the most direct way to understand the number of impacts that 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 in a statement the study’s co-lead author, Dr. Natalia Wojcicka, a research associate in the Department of Earth Sciences and Engineering at Imperial College London. “We could think of this as a sort of ‘cosmic clock’ that would help us date Martian surfaces and perhaps, later, other planets in the solar system. »