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Spaceship interior3/27/2023 Other surface wave observations have since been made, in particular after a magnitude 4.7 earthquake detected on, which will allow these analyses to be completed.Ī few weeks before the fourth anniversary of its landing on Mars, the InSight mission and its main instrument, the SEIS seismometer, have made it possible to build the first models of the internal structure of Mars and to observe both the seismicity of the planet and the very strong impacts that a planet with a tenuous atmosphere can encounter. These crustal thickness measurements are fundamental to understanding the evolution of Mars and have so far only been possible under the InSight station thanks to the volume waves of earthquakes. This makes it possible to determine the average structure of the Mars crust between the point of impact and InSight“. Both released sufficient energy to generate both surface and volume waves that propagated down to the core of Mars.įor Eric Beucler, professor at Nantes Université and co-author of the articles, “ These are the first events for which surface waves are clearly visible. The larger one has an estimated mass of 250-650 tons, for an impact speed of 7.5 km/s. The two meteorites hit Mars 3500 km and 7500 km from the Insight landing site. In addition, we now have two seismic sources of equivalent magnitude greater than 4, whose position is perfectly known on Mars, and which allow us to validate our models of the internal structure of the upper mantle and the crust, developed in particular in the framework of the MAGIS project,” says Philippe Lognonné, scientific leader of the SEIS experiment at the Institut de Physique du Globe de Paris, second author of one of the two articles, coordinator of the MAGIS project financed by the French National Research Agency (ANR), and a professor at the Université Paris Cité. This allows us to better understand how the energy of such a bolide is distributed during the impact in the subsurface and in the atmosphere. The same is true on Mars, where no impact of this size had ever been detected by the Mars Reconnaissance Orbiter (MRO) mission since it began its orbital mission 16 years ago.īy combining seismic data from InSight’s SEIS and MRO’s CTX, MARCI and HiRISE cameras, the international teams of the two NASA missions have been able to pinpoint the precise location of these two events in time and space: “ The dynamics of the impact and the development of the shock wave have been documented by our seismometer and by the very high-resolution images from Mars Reconnaissance Orbiter. S1094b is even the largest impact crater of the last few centuries detected on a terrestrial planet, as its 150-metre diameter exceeds the 120-metre diameter of the Wabar crater in Saudi Arabia, which is considered to be the largest impact on the Earth’s surface during this period, several decades before the first seismographs were deployed at the beginning of the 20th century. Impacts S1000a and S1094b, on 18 September and 24 December 2021 respectively, left two footprints over 130 m in diameter on the surface of Mars. These data, via acoustic wave analysis, have already improved our knowledge of the local structure of the crust. On Mars, the impacts previously recorded by the SEIS instrument were within 300 km of the InSight lander and were associated with craters about 10 metres in diameter. Although natural impacts had already been recorded on the Moon, it was impossible to link the strongest of them to a crater image, which would have made it possible to determine their precise characteristics. And few other bodies in the solar system are equipped with seismometers. On Earth, our atmosphere protects us! Most meteorites burn up, end up as shooting stars or explode at altitude. While meteorite impacts shape planetary surfaces in the solar system, it is rare to be able to record signals from high energy impacts.
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