The first of these confirmed impacts occurred on September 5, 2021, shattering into at least three large pieces that each made a crater. To confirm the strike, NASA’s Mars Reconnaissance Orbiter flew over the possible impact site and took pictures with the black-and-white Context Camera. Three new dark spots were photographed, so the next pass, they used HiRISE to capture high-resolution color images.
Of course, now that scientists had one example of what a confirmed impact looked like, they began combing through all the data. So far, they have found three other impacts that occurred between May 2020 and August 2021, and they think there are even more to be found.
And while Mars’s atmosphere may be much thinner than Earth’s, that atmosphere still exists, which means sound waves travel. NASA has included a sound file of the September 2021 event, which we’ll link to in our show notes.
NASA JPL press release
University of Maryland press release
“Newly formed craters on Mars located using seismic and acoustic wave data from InSight,” Raphael F. Garcia et al., 2022 September 19, Nature Geoscience