Last December 24, NASA’s InSight lander recorded a magnitude 4 marsquake. However, scientists only learned the cause of that quake later: a meteoroid impact estimated to be one of the biggest seen on Mars since NASA began exploring the cosmos. Furthermore, the meteoroid strike excavated boulder-size chunks of ice buried closer to the Martian equator than ever found before – a discovery with implications for NASA’s future plans to send astronaut explorers to the Red Planet. Researchers determined the quake resulted from a meteoroid impact when they spotted a new, yawning crater in before-and-after images from NASA’s Mars Reconnaissance Orbiter (MRO). Offering a rare opportunity to see how a large impact shook the ground on Mars, the event and its effects are detailed in two scientific papers published on Thursday, October 27, in the peer-reviewed journal Science. 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 they are significantly older and were formed before any Mars mission. “It’s unprecedented to find a fresh impact of this size,” said Ingrid Daubar of Brown University, who leads InSight’s Impact Science Working Group. “It’s an exciting moment in geologic history, and we got to witness it.” Due to dust settling on its solar panels, InSight has seen its power drastically decline in recent months. Currently, the spacecraft is expected to shut down within the next six weeks, bringing the mission’s science to an end. This video includes a seismogram and sonification of the signals recorded by NASA’s InSight Mars lander, which detected a giant meteoroid strike on December 24, 2021, the 1,094th Martian day, or sol, of the mission. Credit: NASA/JPL-Caltech/CNES/Imperial College London InSight is studying the planet’s crust, mantle, and core. Seismic waves are key to the mission and have revealed the size, depth, and composition of Mars’ inner layers. Since landing in November 2018, InSight has detected 1,318 marsquakes, including several caused by smaller meteoroid impacts. However, the quake resulting from last December’s meteoroid strike was the first observed to have surface waves. This is a kind of seismic wave that ripples along the top of a planet’s crust. The second of the two Science papers related to the big impact describes how scientists use these waves to study the structure of Mars’ crust. Crater Hunters In late 2021, InSight scientists reported to the rest of the team they had detected a major marsquake on December 24. On February 11, 2022, the crater was first spotted by scientists working at Malin Space Science Systems (MSSS), which built and operates two cameras aboard MRO. 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, conclusively demonstrating that a meteoroid impact caused the large marsquake on December 24. This animation depicts a flyover of a meteoroid impact crater on Mars that’s surrounded by boulder-size chunks of ice. The animation was created using data from the High-Resolution Imaging Science Experiment (HiRISE) camera aboard NASA’s Mars Reconnaissance Orbiter. Credit: NASA/JPL-Caltech/University of Arizona “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,” said Liliya Posiolova, who leads the Orbital Science and Operations Group at MSSS. “I couldn’t help but imagine what it must have been like to witness the impact, the atmospheric blast, and debris ejected miles downrange.” Establishing the rate at which craters appear on Mars is critical for refining the planet’s geologic timeline. On older surfaces, such as those of Mars and our Moon, there are more craters than here on Earth. This is because on our planet, the processes of erosion and plate tectonics erase older features from the surface. 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. Subsurface ice will be a vital resource for astronauts, who could use it for a variety of needs, including drinking water, agriculture, and rocket propellant. Buried ice has never been spotted this close to the Martian equator. This is especially important because, as the warmest part of Mars, it is an appealing location for astronauts to land. References: “Largest recent impact craters on Mars: Orbital imaging and surface seismic co-investigation” by L. V. Posiolova, P. Lognonné, W. B. Banerdt, J. Clinton, G. S. Collins, T. Kawamura, S. Ceylan, I. J. Daubar, B. Fernando, M. Froment, D. Giardini, M. C. Malin, K. Miljkovic, S. C. Stähler, Z. Xu, M. E. Banks, É. Beucler, B. A. Cantor, C. Charalambous, N. Dahmen, P. Davis, M. Drilleau, C. M. Dundas, C. Durán, F. Euchner, R. F. Garcia, M. Golombek, A. Horleston, C. Keegan, A. Khan, D. Kim, C. Larmat, R. Lorenz, L. Margerin, S. Menina, M. Panning, C. Pardo, C. Perrin, W. T. Pike, M. Plasman, A. Rajšic, L. Rolland, E. Rougier, G. Speth, A. Spiga, A. Stott, D. Susko, N. A. Teanby, A. Valeh, A. Werynski, N. Wójcicka and G. Zenhäusern, 27 October 2022, Science.DOI: 10.1126/science.abq7704 “Surface waves and crustal structure on Mars” by D. Kim, W. B. Banerdt, S. Ceylan, D. Giardini, V. Lekic, P. Lognonné, C. Beghein, É. Beucler, S. Carrasco, C. Charalambous, J. Clinton, M. Drilleau, C. Durán, M. Golombek, R. Joshi, A. Khan, B. Knapmeyer-Endrun, J. Li, R. Maguire, W. T. Pike, H. Samuel, M. Schimmel, N. C. Schmerr, S. C. Stähler, E. Stutzmann, M. Wieczorek, Z. Xu, A. Batov, E. Bozdag, N. Dahmen, P. Davis, T. Gudkova, A. Horleston, Q. Huang, T. Kawamura, S. D. King, S. M. McLennan, F. Nimmo, M. Plasman, A. C. Plesa, I. E. Stepanova, E. Weidner, G. Zenhäusern, I. J. Daubar, B. Fernando, R. F. Garcia, L. V. Posiolova and M. P. Panning, 27 October 2022, Science.DOI: 10.1126/science.abq7157 More About the Missions JPL manages InSight and the Mars Reconnaissance Orbiter for NASA’s Science Mission Directorate. InSight is part of NASA’s Discovery Program, managed by the agency’s Marshall Space Flight Center in Huntsville, Alabama. Lockheed Martin Space in Denver built the Mars Reconnaissance Orbiter, InSight spacecraft (including its cruise stage and lander), and supports spacecraft operations for both missions. Malin Space Science Systems in San Diego built and operates the Context Camera and MARCI camera. The University of Arizona built and operates the HiRISE camera. A number of European partners, including France’s Centre National d’Études Spatiales (CNES) and the German Aerospace Center (DLR), are supporting the InSight mission. CNES provided the Seismic Experiment for Interior Structure (SEIS) instrument to NASA, with the principal investigator at IPGP (Institut de Physique du Globe de Paris). Significant contributions for SEIS came from IPGP; the Max Planck Institute for Solar System Research (MPS) in Germany; the Swiss Federal Institute of Technology (ETH Zurich) in Switzerland; Imperial College London and Oxford University in the United Kingdom; and JPL. DLR provided the Heat Flow and Physical Properties Package (HP3) instrument, with significant contributions from the Space Research Center (CBK) of the Polish Academy of Sciences and Astronika in Poland. Spain’s Centro de Astrobiología (CAB) supplied the temperature and wind sensors, and the Italian Space Agency (ASI) supplied a passive laser retroreflector.
