Mars hit by space rocks more often than previously thought

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NASA’s Mars InSight Lander may be retired, but its data is still revealing new insights.

A team of scientists, led by Brown University, found that Mars is being bombarded by space rocks more frequently than previously believed.

According to their study in Science Advances, impact rates on Mars could be two to ten times higher than earlier estimates.

Ingrid Daubar, an associate professor at Brown University, led the research. She explains, “Mars might be more geologically active than we thought, which affects our understanding of the planet’s surface age and evolution.

Our findings suggest that Mars is getting hit more often than we can see with just images.”

Using InSight’s sensitive seismometer, the team identified eight new impact craters caused by meteoroids.

These impacts challenge current beliefs about how often meteoroids hit Mars, especially smaller ones.

The study suggests that current models of Martian cratering need to be updated to reflect these higher impact rates.

The results could change how scientists understand the Martian surface, as impacts from small meteoroids continuously shape it. This research also has implications for the impact history of other planets.

Daubar notes, “We may need to rethink the models used to estimate the age of planetary surfaces throughout the solar system.”

Six of the detected craters were near InSight’s landing site. Two distant impacts were the largest ever recorded by scientists, each creating craters about the size of a football field. These large impacts occurred just 97 days apart, highlighting the higher frequency of such events.

“We’d expect this size of impact to happen maybe once every few decades, but we had two within just over 90 days,” Daubar says. “This could be a coincidence, but it’s more likely that the impact rate on Mars is higher than we thought.”

InSight’s mission, active from November 2018 to December 2022, focused on measuring Mars’ seismic activity. Previously, new impacts were identified with before-and-after images from orbiting cameras. The seismometer provided a new way to detect impacts, many of which might have been missed otherwise.

“Impacts happen all across the solar system,” Daubar says. “Studying them on Mars helps us understand our solar system and the population of impacting bodies, which are hazards to Earth and historically to other planets.”

Impact rates are also crucial for assessing risks to future Mars missions. To pinpoint when and where impacts occurred, Daubar and her team analyzed seismic signals from InSight and compared them with images from NASA’s Mars Reconnaissance Orbiter. They visually confirmed eight new craters by examining before-and-after images.

InSight collected seismic data until its solar panels were covered in dust and it could no longer generate power. The current study aligns with a companion paper in Nature Communications, which also uses InSight data to look at high-frequency seismic events. Both studies reinforce each other’s findings.

“We might find even more impacts if we conduct detailed orbital searches using machine learning,” Daubar says.

Researchers from various institutions, including the Institut Supérieur de l’Aéronautique et de l’Espace, University of Oxford, Imperial College London, and NASA’s Jet Propulsion Laboratory, contributed to the study.