NASA’s InSight lander recorded a major marsquake on Dec. 24. After analyzing before-and-after images from NASA’s Mars Reconnaissance Orbiter (MRO), scientists learned the cause of the quake was a meteoroid strike. The meteoroid strike is estimated to be one of the biggest on Mars since NASA began exploring the cosmos.
A further revelation that has ramifications for NASA‘s future intentions to send astronauts to the Red Planet is that the meteoroid unearthed boulder-size chunks of ice buried closer to the Martian equator than ever before.
The event and its effects offer a rare opportunity to see how a large impact shook the ground on Mars.
The meteoroid’s estimated size is between 16 and 39 feet (5 and 12 meters), making it small enough to burn up in Earth’s atmosphere but too large to burn up in Mars’ thin atmosphere, which is only 1% as dense as our planet’s. The impact, which occurred in a region known as Amazonis Planitia, created a crater 70 feet (21 meters) deep and 492 feet (150 meters) broad. Some of the impact’s ejecta were launched up to 23 miles (37 kilometers) in the air. With images and seismic data documenting the event, this is believed to be one of the largest craters ever witnessed forming any place in the solar system. Many larger craters exist on the Red Planet but are significantly older and predate any Mars mission.
Ingrid Daubar of Brown University, who leads InSight’s Impact Science Working Group, said, “It’s unprecedented to find a fresh impact of this size. It’s an exciting moment in geologic history, and we witnessed it.”
The Context Camera (CTX) provides black-and-white, medium-resolution images, while the Mars Color Imager (MARCI) produces daily maps of the entire planet, allowing scientists to track large-scale weather changes like the recent regional dust storm that further diminished InSight’s solar power. The impact’s blast zone was visible in MARCI data, which allowed the team to pin down a 24-hour period within which the impact occurred. These observations correlated with the seismic epicenter, demonstrating that a meteoroid impact caused the large Dec. 24 marsquake.
Liliya Posiolova, who leads the Orbital Science and Operations Group at MSSS said, “The image of the impact was unlike any I had seen before, with the massive crater, the exposed ice, and the dramatic blast zone preserved in the Martian dust. I couldn’t help but imagine what it must have been like to witness the impact, the atmospheric blast, and debris ejected miles downrange.”
To improve the planet’s geologic history, it is essential to determine the pace at which craters occur on Mars. More craters can be found on older surfaces, like those of Mars and our Moon, than on Earth because of erosion and plate tectonics, which remove older features from the surface of our planet.
New craters also expose materials below the surface. In this case, large chunks of ice scattered by the impact were viewed by MRO’s High-Resolution Imaging Science Experiment (HiRISE) color camera.