NASA’s InSight Mars lander may be retired on the Red Planet, but data from the robotic explorer is still leading to seismic discoveries on Earth. In one of the latest studies using data from the spacecraft, an international team of scientists led by a Brown University researcher found that Mars may be being bombarded by space rocks at a more frequent rate than previously thought. Impact rates could be two to 10 times higher than previously estimated, depending on the size of the meteoroids, according to the study published in 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 researcher Ingrid Daubar, an associate professor of Earth, environmental and planetary sciences at Brown. “Our results are based on a small number of examples that we have available, but the current impact rate estimate suggests that the planet is being hit much more frequently than we can see using images alone.” As part of the study, the research team used InSight’s highly sensitive onboard seismometer to identify eight new meteorite impact craters not previously seen from orbit. The frequency of these cosmic collisions challenges existing notions about how often meteoroids strike the Martian surface and suggests the need to revise current models of Martian crater formation to incorporate higher impact rates, especially from smaller meteorites. Ultimately, the findings could reshape current understanding of the Martian surface (as strikes from small meteorites continue to sculpt it) and the impact history of not just Mars, but other planets. “This will require us to reconsider some of the models that the scientific community uses to estimate the age of planetary surfaces across the solar system,” Daubar said. Six of the craters the researchers detected were near where the stationary InSight lander touched down. The two distant impacts they identified from the data were the two largest impacts ever detected by scientists, even after decades of observation from orbit. The largest impacts, each of which left a crater roughly the size of a football field, occurred just 97 days apart, underscoring the increased frequency of such geological events. “We would expect an impact of this size to happen maybe once every couple of decades, maybe even once in a lifetime, but here we have two of them just 90 days apart,” Daubar adds. “It could just be a crazy coincidence, but there’s a very, very small chance that it’s just a coincidence. Most likely the two large impacts are related, or the impact rate is much higher on Mars than we thought.” NASA’s InSight mission was active from November 2018 to December 2022. One of its main goals was to measure seismological shaking on the planet. Previously, new impacts on Mars were detected with before-and-after images taken by cameras in orbit around the planet. The seismometer provided a new tool to find and detect these impacts, many of which might otherwise have gone unnoticed. “Planetary impacts happen throughout the solar system all the time. We’re interested in studying that 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’s in it, and what the population of impacting bodies in our solar system looks like, both as hazards to Earth and historically to other planets,” she insists. The rates are also important for assessing the potential hazards that impacts pose to future exploration missions when NASA sends rovers or even human missions into space. To determine when and where the impacts on Mars occurred, Daubar and the research team analyzed seismic signals from InSight and then compared that seismic data to images taken by NASA’s Mars Reconnaissance Orbiter. The team visually confirmed eight of the events as new craters by examining before-and-after images. This dual approach of using seismic data and orbital imagery allowed them to confirm that the seismic signals were caused by impacts and to verify their findings to ensure accuracy. The InSight lander thus collected seismic data from its landing until its solar panels, as expected, became covered in dust to the point that the lander could no longer generate power. “It’s possible that more events that InSight detected during its mission were actually impacts,” Daubar muses. “The next steps are to perform more detailed orbital searches to try to confirm this using machine learning techniques. If we can confirm even more impacts, we may also be able to find other seismic signals that were caused by impacts.”
