The InSight mission, initiated in November 2018, aims to study the composition of the inner layers of the planet Mars from seismic data. Since the start of the mission, more than 1,300 earthquakes have been recorded, most of which were caused by small impacts from meteorites. But the impact in question here is one of the most powerful ever observed on the red planet since the start of the space conquest: images from the Mars Reconnaissance Orbiter show that it formed a crater nearly 150 meters in height. diameter in the Amazonis Planitia region. But that’s not all: the collision made it possible to make a very important discovery for the future colonization of Mars.
An impact that illuminates the structure of the Martian crust
The new crater was spotted from space by the Mars Reconnaissance Orbiter on February 11. Scientists estimate that the meteorite measured between 5 and 12 meters in diameter. The images revealed the presence of a hole about 150 meters in diameter and 21 meters deep; some of the ejecta generated by the impact were projected up to 37 kilometers away! An audio recording of the earthquake generated by the impact – obtained by accelerating the vibrations collected by the seismometer – was released by NASA.
Meteorite impacts are not uncommon on Mars, but this one is particularly significant. It could be one of the largest craters ever seen forming in the solar system since man explored space. ” It is unprecedented to find a recent impact of this size. It’s an exciting time in geological history, and we got to witness it said Ingrid Daubar of Brown University, who leads the scientific working group on the impacts recorded by the InSight mission.
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This major impact is also distinguished by the fact that it is the first observed to present surface seismic waves – waves a little slower than the body waves which propagate inside the planet, but which present large amplitudes. ” These surface waves help unravel the structure of the Martian crust, which contains various amounts of volcanic and sedimentary rocks, as well as subterranean ice, in different regions of the planet. “, explain the researchers in Science.
Thanks to this new data, scientists have discovered that between the site of the impact and the InSight probe – located some 3,500 kilometers from the new crater – the Martian crust is denser than at the site of the lander. -same ; the models describing the deep structure of the Martian mantle will therefore have to be revised.
Water ice near the equator
Another meteorite impact occurred a few months before, on September 18, 2021, about 7450 kilometers from InSight. The event formed “a cluster of craters”, the largest measuring around 130 meters in diameter. It, too, caused a magnitude 4 seismic event. Both of these events could help solve a long-standing mystery about the geography of Mars. This planet indeed has two hemispheres with radically different topologies: the north is composed of low cratered plains, while the south is mountainous and has more impact craters.
The reason for this dichotomy is still debated. But one theory suggests that the northern and southern hemispheres are made up of two different types of rock; another argues that the planet’s crust is simply thicker in the south. InSight’s data does not definitively resolve the question, but supports the second theory.
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The collision also resulted in the excavation of huge chunks of water ice, which were previously deeply buried. This is the first time that ice has been spotted so close to the Martian equator, where temperatures are relatively warmer; this discovery is of capital importance for the future colonization of Mars by Man.
Indeed, the presence of water at such a low latitude (35°N) could be essential for future explorers – who will undoubtedly land as close as possible to the equator, where the temperatures are “milder”. The water ice can be used to produce drinking water, but also hydrogen and oxygen – essential to power the rocket engines for the return trip.
A mission that is coming to an end
The InSight probe has proven that Mars is a geologically active planet. Data collected so far suggests that it has a layered structure similar to that of Earth, with a core radius of about 1830 km, a mantle about 1500 km thick and a crust 20 to 70 km thick.
Unfortunately, the probe has seen its power drop considerably in recent months due to the dust that has accumulated on its solar panels throughout its mission. Scientists expect the spacecraft to cease all activity permanently by the end of the year. But InSight will have accomplished its mission brilliantly! It will have made it possible to identify the regions most prone to earthquakes, to shed light on the internal composition of the planet and to collect meteorological data.
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” InSight has transformed our understanding of the interiors of rocky planets and set the stage for future missions. We can apply what we’ve learned about the internal structure of Mars to Earth, the Moon, Venus, and even rocky planets in other solar systems. said Lori Glaze, director of NASA’s planetary science division.
When the probe is no longer operational, the recorded seismic data will continue to be analyzed and will undoubtedly provide new clues about the structure of Mars. Future Mars exploration missions, such as ExoMars led by the European Space Agency, which are expected to carry more sophisticated seismometers, will no doubt yield an even more detailed map of the structure of the Martian crust and upper mantle. .