2022-09-19
Meteorites frequently collide with Mars, creating its distinctive cratered landscape. This is because the Red Planet, compared to Earth, has a thin atmosphere and is closer to the asteroid belt in our solar system. Now, as part of NASA's InSight mission, with input from the Marsquake Service and ETH Zurich, researchers have been able to record the impacts of four meteorites using the seismometer on board the mission's spacecraft. These are the first measurements of ground tremors caused by such impacts on Mars.
Read more...The key to the discovery was a meteorite that penetrated the Martian atmosphere on 5 September 2021. Upon entry it split into at least three parts, which left craters when they hit the planet's surface. The craters are located in the area of Elysium Planitia, approximately 100 km from the InSight station, confirmed in a flight by NASA's Mars Reconnaissance Orbiter. The three impacts and the resulting pressure waves produced tremors that show up clearly in the seismic data. The researchers then analysed earlier seismic recordings again and discovered three more meteorite impacts. They suspect that other impacts have also occurred in the past, but these are hidden in the background noise of the seismic signals. This noise is caused by strong winds and seasonal changes in the atmosphere.
Meteorite impacts on the surface of Mars reveal a lot about the history of the Red Planet. By tracing how often craters of different sizes are created, it is possible to determine retrospectively how and over what period the present-day Martian surface formed. Drawing on satellite images as well, the trajectory of a meteorite and the size of the shock wave triggered can also be reconstructed. The findings are set out in a recent article in the journal Nature Geoscience.