Washington (AFP)

NASA's InSight robot arrived in November 2018 on Mars recorded multiple earthquakes that Earth can now listen to.

NASA put on line Tuesday two sound files of two jolts dating from May 22 and July 25, recorded thanks to the ultrasensitive seismometer provided by the French space agency CNES and who listens since the beginning of the year the basement of the planet, in search of its "heartbeat" to discover clues of the history of its formation.

Because the planet is not dead and "breathes" still in a tenuous way, explains the CNES.

The vibration frequency is too low for the human ear, and the shaking is too weak to be felt.

The recordings were thus "slightly" processed and accelerated to become audible thanks to a so-called "sonification" technique, carried out by researchers from the Institute of Physics of the Globe of Paris. They are representative of 21 events that scientists are almost sure earthquakes, about a hundred events detected.

With headphones, we hear a light rumble, a buzz that is not spectacular at first sight, but which scientists are already drawing conclusions about the composition of the Martian crust.

This crust is probably comparable to "a mixture of the crust of the Earth and that of the Moon," writes the Jet Propulsion Laboratory (JPL) of NASA. Faults in the Earth close relatively quickly due to water infiltration, allowing the waves to cross the old fractures without interruption and to spin through the crust.

Conversely, the lunar crust is "drier", the faults do not close quickly and the waves propagate for tens of minutes instead of going in a straight line.

Mars looks more like the Moon, and the seismic waves propagate there for about a minute, "while earthquakes can appear and disappear in seconds," says JPL.

The teams managing the seismometer are only at the beginning of their exploration of the subsoil, of which they intend one day to discover the complete composition, in particular of the nucleus.

Both sounds are available at the following addresses:

© 2019 AFP