The SEIS seismometer of the InSight mission detects a first Mars earthquake.

The “Sol 128” event (128th Martian day), detected by SEIS, is the first Martian earthquake whose origin is believed to come from within the planet – as opposed to a movement caused by wind – although scientists are still not entirely sure. The seismic event is too small to provide useful data on the interior of Mars, one of the main objectives of the mission. Such a tremor would not have been detectable on Earth, but the extremely stable Martian surface allowed the highly sensitive seismometer sensors to pick up this weak signal.

Several characteristics of “Sol 128” correspond to the profile of earthquakes detected on the lunar surface. NASA astronauts measured thousands of earthquakes while exploring the Moon between 1969 and 1972, revealing that it was still geologically active. The reflection of seismic waves or the modification of their propagation speed according to the materials traversed gave scientists information on the internal structure of the Moon, as well as the size of its nucleus. This has made it possible to better understand the impact process between the Earth and the proto-Moon, as well as the formation of the Moon from debris placed in orbit. With the SEIS seismometer, similar data can be collected on Mars to better understand the formation of such a telluric planet.

“The first data collected by InSight allows us to continue the scientific advances that began with the Apollo missions,” notes Bruce Banerdt, scientific head of the Insight mission at NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, California. “So far, we have collected background noise, but this first earthquake marks the official birth of a new discipline: Martian seismology. »