On Mars, a giant meteor impact was heard live

Mars-observing scientists got a Christmas present last year.

• Read more: Mars ‘not so dead’

On December 24, 2021, a meteorite hit its surface, causing a magnitude 4 tremor.

These were detected by the InSight probe and its seismograph, which landed on Mars nearly four years ago, about 3,500 kilometers from the impact site.

But the origin of this Martian tremor was confirmed only later by the Mars Reconnaissance Orbiter (MRO). In orbit around the planet, it took pictures of the newly formed crater within 24 hours of the event.

The picture is impressive: Ice blocks have been thrown to the surface, and a crater has been dug about 150 meters in diameter and 20 meters deep – the largest seen since the Orbiter MRO was launched 16 years ago.

While meteorite impacts are not uncommon on Mars, “we didn’t think we’d see something this big,” Ingrid Tauber, who works on the INSIDE and MRO missions, told a news conference Thursday.

The researchers estimated that the meteorite must have been about 12 meters – which would have disintegrated on Earth before it disintegrated in the atmosphere.

“This is the largest meteorite impact on Earth since we’ve been doing science with seismographs or seismographs,” explained AFP Philippe Lognonay, a professor of planetology who participated in two studies from these observations published Thursday. Journal of Science.

The recording of the earthquake, obtained by speeding up the vibrations collected by the seismometer and making them audible, was released by NASA.

The valuable information collected will help refine our knowledge of the Martian interior and its formation.

Ingrid Tauber, co-author of the two studies, underlined that the presence of snow in particular was “surprising”. “It’s the hottest place on Mars, so close to the equator, we’ve seen ice.”

In addition to the scientific interest of the discovery for Martian climate studies, the presence of water at this latitude will be “very useful” for future explorers, announced Lori Glaze, NASA’s director of planetary science.

“We want to land the astronauts as close to the equator as possible,” he said, citing warmer temperatures. However, the ice on the site can then be converted to water or oxygen.

The impact of the meteorite was powerful enough to generate both body waves (propagating through the nucleus) and surface waves (horizontally crossing the planet’s crust) – thus allowing detailed study of the internal structure of Mars.

Thus, the inboard crust was found to be less dense than the one passing through the collision site.

Additionally, in light of these data “current models on the deep structure of the Martian crust need to be slightly revised,” explained Philippe Lognon of the Paris Institute of Geophysics (IPGP). .

As expected, the InSight probe is running slowly due to dust accumulating on its solar panels. Bruce Bannert of NASA’s Jet Propulsion Laboratory said Thursday that communication would be lost “in about four to eight weeks,” adding that he was “sad” but welcomed the success of the mission.

Intelligence has detected a total of more than 1,300 “Marscats” — including some caused by smaller meteorites — and the data collected will be used by scientists around the world for years.