Analysis of NASA InSight data suggests Mars hit by meteoroids more often than thought

How InSight Detected Hidden Impacts

The InSight lander, which operated on Mars from November 2018 to December 2022, was primarily designed to measure seismic activity beneath the planet's surface. While its main mission focused on marsquakes and internal structure, its highly sensitive seismometer also proved capable of detecting the distinct vibrations caused by meteoroid impacts. This provided a new method for identifying collisions that might not leave immediately visible traces or occur in areas not regularly imaged by orbiting spacecraft.

Researchers analysed seismic signals recorded by InSight and matched them with before-and-after images from NASA's Mars Reconnaissance Orbiter. This combined approach allowed them to confirm eight new impact craters that had not been previously detected through visual surveys alone. Six of these craters were located relatively close to the lander's landing site, while two were farther away and represented the largest impacts ever recorded by scientists using InSight data.

The ability to detect impacts through seismic data marks a significant advancement in planetary science. Traditional methods rely heavily on optical imaging, which can miss small craters or those obscured by dust and weathering. By combining seismic monitoring with orbital imagery, scientists can build a more complete picture of impact frequency and distribution across the Martian surface.

Implications for Martian Geology and Surface Age

The findings suggest that Mars is being hit by meteoroids more often than current models predict. Depending on the size of the space rocks, impact rates could be anywhere from two to ten times higher than previously estimated. This has direct consequences for how scientists interpret the age and evolution of the Martian surface, as crater counting is a primary method used to estimate how long a planetary surface has been exposed.

Lead researcher Ingrid Daubar, an associate professor at Brown University, noted that the results imply Mars may be more geologically active than earlier assumptions allowed. If impacts are occurring more frequently, surfaces may be younger than crater counts suggest, requiring a reevaluation of timelines for volcanic activity, erosion, and other geological processes on the planet.

The study also highlights the role of smaller meteoroids in continually reshaping the Martian landscape. While large, football-field-sized impacts are rare, the cumulative effect of numerous smaller strikes contributes significantly to surface alteration over time. This ongoing bombardment means the Martian surface is not static but is constantly being modified by incoming space debris.

Challenges to Existing Cratering Models

One of the most striking observations from the study was the timing of two large impacts, each creating a crater roughly the size of a football field. These events occurred just 97 days apart—a frequency that, under previous models, would be expected only once every few decades or even once in a lifetime. While the researchers acknowledge this could be a statistical anomaly, they consider it unlikely given the low probability of such a coincidence.

Daubar suggested that either the two large impacts are somehow related—perhaps originating from the same breakup event in space—or that the overall impact flux on Mars is substantially higher than believed. Either scenario would necessitate a revision of current cratering models used to date planetary surfaces not just on Mars, but across the solar system.

The implications extend beyond Mars. Accurate impact rate models are essential for understanding the history and hazard potential of celestial bodies throughout our solar neighbourhood. If Mars is experiencing more frequent strikes than thought, similar reassessments may be needed for the Moon, Mercury, and even asteroids, affecting how scientists interpret surface ages and impact histories elsewhere.

Relevance for Future Space Exploration

Understanding impact frequency is not only a matter of scientific curiosity but also has practical implications for future missions to Mars. As NASA and other space agencies plan for extended robotic exploration and potential human landings, knowing how often the surface is struck by meteoroids helps assess risks to equipment, habitats, and astronauts.

The data from InSight contributes to a broader effort to characterise the impact environment across planetary bodies. A companion study published in Nature Communications on the same date used additional InSight data to analyse high-frequency seismic events, arriving at impact rate estimates that align with those from the Science Advances paper. This independent verification strengthens confidence in the findings.

Looking ahead, researchers hope to use machine learning techniques to conduct more thorough searches of orbital imagery, potentially uncovering even more impacts that were missed initial surveys. Confirming additional events could further refine impact rate models and reveal other seismic signals currently attributed to non-impact sources.

What this means

The revelations from InSight's seismic data underscore the value of persisting with scientific analysis long after a mission's operational end. By revealing a more dynamic impact environment on Mars, the study prompts a necessary reconsideration of how we date planetary surfaces and interpret geological activity. For scientists, it highlights the importance of multi-method approaches in planetary research. For space agencies and mission planners, it offers critical data for safeguarding future explorers. Ultimately, the findings remind us that even seemingly quiet worlds like Mars are subject to constant change from the cosmos above—a process that continues to shape not just our neighbouring planet, but the broader story of our solar system.