The US space agency announced Thursday, October 27, having discovered the largest meteorite crater ever observed on a planet. The story begins last year when scientists observing the planet Mars received a special Christmas present. On December 24, 2021, a meteorite hit its surface, causing tremors of magnitude 4. These were detected by the Insight probe and its seismometer, which landed on Mars almost four years ago, some 3,500 kilometers from the place. impact.
But the origin of this Martian tremor was only confirmed later, by the spacecraft called Mars Reconnaissance Orbiter (MRO). In orbit around the planet, it took pictures of the newly formed crater within 24 hours of the event.
Biggest ground meteorite impact heard
The image is impressive: blocks of ice were thrown on the surface, and a crater about 150 meters in diameter and 20 meters deep was dug – the largest ever observed since the commissioning of the orbiter MRO, 16 years ago.
Although meteor impacts on Mars are not uncommon, “we never thought we would see something so big”, said Thursday, October 28 during a press conference Ingrid Daubar, who works on the Insight and MRO missions. The researchers estimate that the meteorite itself must have been around 12 meters – which on Earth would have caused it to disintegrate in the atmosphere.
“This is quite simply the biggest meteorite impact on the ground that has been listened to since we have been doing science with seismographs or seismometers”explained Philippe Lognonné, professor of planetology who participated in two studies resulting from these observations, published Thursday in the journal Science.
An audio recording of the earthquake, obtained by accelerating the vibrations collected by the seismometer in order to make them audible, was released by NASA. The valuable information collected should help refine knowledge of the interior of Mars, and the history of its formation. The presence of ice, in particular, is “surprising”underlined Ingrid Daubar. “It’s the hottest spot on Mars, closest to the equator, where we’ve seen ice. »
In addition to the scientific interest of this discovery for the study of the Martian climate, the presence of water at this latitude could prove ” very useful “ for future explorers, said the director of planetary sciences at NASA.
The impact of the meteorite was powerful enough to generate both body waves (propagating to the core) and surface waves (crossing the planet’s crust horizontally) – thus making it possible to study details the internal structure of Mars.