The NASA landing, the mission of which is to record seismic waves in order to study the internal structure of the red planet, detected the acoustic waves produced by the arrival of meteoroids in the atmosphere.
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Arrived on March on November 26, 2018, the NASA Insight Lander was given the main objective of examining the Red Planet. Its main instrument is indeed the Seis seismometer (provided by France, thanks to the National Center for Spatial Studies), whose mission consists in recording Martian seismic waves in order to deduce the internal structure of the planet. But just like, with his stethoscope, a doctor does not just listen to beat the hearts of his patients, scientists hoped to detect these other cosmic events that are weather falls. And they were not disappointed: in a study, published Monday September 19 in Nature Geoscience, they announce that they have “heard” falling from celestial rocks. Exactly three, in 2021.
Professor at the Higher Institute of Aeronautics and Space (Isae-Supaéro, Toulouse) and first author of this article, Raphaël Garcia explains that Seis is so sensitive that he has not only perceived seismic waves Linked to collisions, but also the acoustic waves produced by the arrival of meteoroids in the tenuous Martian atmosphere: “In one of the three events, we have the whole film. First, the entrance to the meteoroid in the atmosphere, several kilometers away per second, creates a shock wave. Then, as it rubs a lot in the air and heats up, the meteoroid fragments between 13 and 16 kilometers above sea level, in a sort of explosion which releases a lot of energy. Finally, we have the rock ends which crash on the ground. “The device could even record reflected echoes on mountains or craters.
Small new craters
With these data, the researchers calculated the probable place where these large pebbles of a few tens of kilograms were pampered and they asked the team of another NASA machine, the orbiter Mro, which Turns around March since 2006, to check it by robbing your cameras on the areas in question. And bingo! By comparing them to old photographs taken by MRO, the new images have shown the presence of brand new craters, only a few meters in diameter, surrounded by dark tablecloths – in reality dust and ground material raised by The impact. A fourth event had been recorded, but, despite extensive research, no crater was identified, probably because the meteoroid had disintegrated before arriving on the ground.
This result interests astronomers in more ways than one. First of all because it is the first time that, on another planet, the drop in meteoroids has been located using a seismometer. On our land, however covered with these devices, it only happened once, in 2007, in Peru. In addition, having determined the exact location of the craters with MRO and their size makes it possible to refine the models from the interior of Mars.
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