Scientists observing the planet Mars received an extraordinary Christmas present last year.
• Read also: The planet Mars “is not so dead”
On December 24, 2021, a meteorite hit its surface causing earthquakes of magnitude 4.
These were detected by the Insight probe and its seismometer, which landed on Mars nearly four years ago, some 3,500 kilometers from the impact site.
But the origin of this Martian tremor was only confirmed later, by the spacecraft called the Mars Reconnaissance Orbiter (MRO). Orbiting the planet, it took photos of the newly formed crater within 24 hours of the event.
The image is impressive: blocks of ice have been thrown to the surface and a crater approximately 150 meters in diameter and 20 meters deep has been excavated, the largest ever observed since the commissioning of the MRO orbiter 16 years ago.
Although meteorite impacts on Mars are not uncommon, “we never thought we would see something this big,” Ingrid Daubar, who works on the Insight and MRO missions, said Thursday.
Researchers estimate that the meteorite itself must have been about 12 meters, which on Earth would have caused it to disintegrate in the atmosphere.
“It is simply the largest meteorite impact on the ground that has been heard since we have done science with seismographs or seismometers,” Philippe Lognonné, a professor of planetology who participated in two studies from these observations, told AFP. the Science magazine.
An audio recording of the earthquake was released by NASA, obtained by accelerating the vibrations collected by the seismometer to make them audible.
The valuable information gathered should help sharpen knowledge of the interior of Mars and the history of its formation.
The presence of ice, in particular, is “surprising”, said Ingrid Daubar, also co-author of the two studies. “It’s the hottest point on Mars, closest to the equator, where we’ve seen ice.”
In addition to the scientific interest of this discovery in studying the Martian climate, the presence of water at this latitude could prove “very useful” for future explorers, said Lori Glaze, director of planetary sciences at NASA.
“We would like to land astronauts as close to the equator as possible,” he said, due to the warmer temperatures. However, the ice on site could then be turned into water or oxygen.
The impact of the meteorite was powerful enough to generate both body waves (which propagate to the core) and surface waves (which cross the planet’s crust horizontally), thus enabling a detailed study of the internal structure of Mars.
The crust on which Insight is located was therefore less dense than that crossed by the collision site.
Furthermore, the current models “of the deep structure of the mantle of Mars will deserve to be re-analyzed a little” in the light of these data, explained Philippe Lognonné, of the Institute of Physics of the Globe in Paris (IPGP). .
As expected, the Insight probe is now running in slow motion due to the dust that has accumulated on its solar panels. Contact is likely to be lost within “about four to eight weeks,” Bruce Banerdt of NASA’s Jet Propulsion Laboratory said Thursday, who said he was “sad” but welcomed the mission’s success.
Insight has detected more than 1,300 “marsquakes” in total, including some caused by smaller meteorites, and the data collected will be used by scientists around the world for many years to come.
