Researchers have derived the first estimate of global meteorite impacts on Mars using seismic data. Their findings indicate between 280 to 360 meteorites strike the planet each year forming impact craters greater than about 26 feet across. Using data from the seismometer deployed during the NASA InSight Mission to Mars, researchers found that six seismic events recorded in the near proximity of the station had been previously identified as meteoric impacts. Now, researchers have found that these six seismic events belong to a much larger group of marsquakes, so called very high frequency events. The source process of these quakes occurs much faster than for a tectonic marsquake of similar size. Where a normal magnitude 3-quake on Mars takes several seconds, an impact-generated event of the same size takes only 0.2 seconds or less, due to the hypervelocity of the collision. By analysing marsquake spectra, a further 80 marsquakes were identified that are now thought to be caused by meteoroid strikes. The impact-generated seismic signals show meteorite impacts to be five times more abundant than previously thought. Seismic data offers a new tool, in addition to observational data, for calculating meteorite impact rates and planning future Mars missions.
