Johnny T. Butler 
“A weak but distinct seismic signal” was detected on April 6th by the SEIS French seismometer deployed on Mars as part of NASA’s InSight mission.
This lander has been on the Martian surface since November 2018 after a journey of seven months and 485 million kilometers traveled.
On the 128th Martian day of the mission, the French instrument detected a seismic signal, similar to the seismic signals picked up on the surface of the Moon during Apollo missions.
It’s great to finally have the sign that there is still seismic activity on Mars. We look forward to providing detailed results as soon as we take a closer look and model our data.
Did you know?
- Images transmitted by the Mars Global Surveyor probe had revealed in 2005 that the surface of the planet next to Earth had changed since 2002.
- You could see new ditches and traces left by rocks on a hill.
- NASA specialists had at the time speculated that they would come from Mars tremors.
The event “Sol 128” would be the first detection of such a tremor whose origin would come from the inside of the planet, as opposed to a movement caused by the wind.
There is, however, a possibility that it comes from another source.
Scientists explain that the seismic event is too weak to provide useful data on the inside of Mars. Such a tremor would not have been detectable on Earth, but the Martian surface, which is extremely stable, allowed the very sensitive sensors of the seismometer to capture this weak signal.
Several characteristics of “Sol 128” correspond to the profile of the earthquakes detected on the lunar surface.
Between 1969 and 1972, NASA astronauts measured thousands of earthquakes by exploring the moon, revealing that the moon was still geologically active.
The analysis of the reflection of the seismic waves or the modification of their speed of propagation according to the materials crossed gave to the scientists information on the internal structure of the Moon, as well as the size of its nucleus.
This analysis of lunar seismic waves made it possible to better understand the process of impact between the Earth and the proto-Moon, as well as the formation of the Moon from debris put into orbit.
Thanks to the French seismometer, similar data can be collected on Mars, and will better understand the formation of the telluric planet.
The first data collected by InSight allow to continue the scientific advances that started with the Apollo missions.
“So far, we have collected background noise, but this first earthquake marks the official birth of a new discipline: Martian seismology,” says the scientist.
Three other signals that could also be of seismic origin were detected on March 14 (“Sol 105”), April 10 (“Sol 132”) and April 11 (“Sol 133”). The interpretation of these signals is still ambiguous for the InSight team, but for at least two of them, they do not seem to be due to the effect of wind or other sources of noise.
These signals are weaker than that of “Sol 128” and have only been detected by the ultra-sensitive sensors of the SEIS instrument.
The team is currently trying to clarify the origin of these other signals.
