On Mars, a giant meteorite impact heard live

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On Mars, a giant meteorite impact listened to live

Representation of the meteorite impact of December 24, 2021 (S1094b) on the planet Mars and the propagation of surface waves to the SEIS seismometer of the InSight mission.

Scientists who observe the planet Mars received a remarkable Christmas present last year. On December 24, 2021, a meteorite slammed into 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 impact site.

Artist's impression of the December 24, 2021 meteorite impact in the Amazon Plains, on Mars. We distinguish the shock waves in the atmosphere, whose imprint on the ground was visualized by the Mars Reconnaissance Orbiter satellite and which characterizes the seismic source measured by the SEIS seismometer, as well as ice ejecta, observed in the images. very high resolution of MRO.

But the origin of this Martian tremor was not confirmed until a second time by the Mars Reconnaissance Orbiter (OMR). Orbiting the planet, it took snapshots of the newly formed crater within 24 hours of the event.

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 commissioning from the OMR orbiter 16 years ago.

Although meteorite impacts on Mars are not uncommon, we never thought we would see something big, said Ingrid Daubar, who works on the InSight and OMR missions, at a press conference on Thursday.

Representation of the meteorite impact of September 18, 2021 (S1000a) observed by the satellite of the Mars Reconnaissance Orbiter mission and of the propagation, within the mantle and up to the mantle/core interface of the planet Mars, of the different types of waves detected by the SEIS seismometer of the InSight mission.

Researchers estimate that the meteorite itself must have been around 12 meters – which on Earth the most. would have led to disintegration in the atmosphere.

It is quite simply the biggest meteorite impact on the ground that has been listened to since we did science with seismographs or seismometers, explained to AFP Philippe Lognonné, professor in 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 make it possible to refine knowledge of the interior of Mars, and the #x27;history of its formation.

The presence of ice, in particular, is surprising, underlined Ingrid Daubar, also co-author of the two studies. It is the hottest point on Mars, closest to the equator, where we have seen ice.

Besides 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 Lori Glaze, director of planetary sciences at NASA.

We would like to land astronauts as close to the equator as possible, she said, due to warmer temperatures. However, the ice present on site could then be transformed into water or oxygen.

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 allowing the internal structure of Mars to be studied in detail.

The crust on which InSight is located was thus found to be less dense than that traversed from the site of the collision.

In addition, 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 Institut de physique du globe de Paris (IPGP).

As expected, the InSight probe is operating in slow motion today due to dust that has accumulated on its solar panels. Contact will likely be lost in about four to eight weeks, said Bruce Banerdt of NASA's Jet Propulsion Laboratory on Thursday, who said he was sad but welcomed the success of the mission.

InSight has detected more than 1,300 Marsquakes in total – including some caused by smaller meteorites – and the data collected will continue to be used by scientists around the world for further research. many years.

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