Seismic waves produced by meteoroid impact events on Mars have been detected by NASA’s InSight lander and traced to the associated, newly formed impact craters by NASA’s Mars Reconnaissance Orbiter, according to a study published in Nature Geoscience. The study presents the first detections of seismic and acoustic waves from impacts on another planet that have been linked to the source craters.
The atmospheric entry and surface collision of a meteoroid at high speeds generates shock waves. These decay into seismic and acoustic waves that can be detected by seismometers. Such waves have been recorded for airburst events — where the impactor breaks up before reaching the surface — in Earth’s atmosphere, and for the formation of a single small impact crater on Earth. However, geophysical observations of new crater formation on other planets have been limited.
Raphael Garcia and colleagues analysed seismometer data from the InSight lander and identified seismic and acoustic waves from four events. The authors used the arrival times of the waves to calculate the location of each of these four events, and then requested imaging from the Mars Reconnaissance Orbiter to confirm the impact sites for three of them (the fourthwas a seismic event associated to an impact previously detected by imaging). With the source craters known, the impact-induced waves can be used to provide information about the cratering process and the properties of the Martian atmosphere and crust.
The authors conclude that these findings demonstrate the value of planetary seismology for studying impact processes on other worlds.
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