Powerful seismic waves
Probing the Mars core: that was the goal of the InSight mission. Whereas the mission has not been operational on Mars since last December, the information transmitted by the SEIS seismometer has allowed scientists to characterize the composition of the red planet’s core more precisely. This is fundamental information for geophysicists, who can constrain their planetary models with these new data and better understand the processes by which Mars was formed and evolved.
In 2021, the seismometer detected two high intensity seismic events: a marsquake and a meteorite impact causing a second marsquake. The scientists picked up the seismic waves, which then propagated through the Martian core.
Raphael Garcia, Researcher at ISAE-SUPAERO, a specialist in planetary cores, participated alongside researchers from various international laboratories in analyzing the signals received to determine the distances traveled by the waves. The farther a marsquake occurs from the InSight Station, the deeper the seismic waves can penetrate the planet before being detected. A huge stroke of luck for certain!
Seismic waves travel to the Mars core
Until then, discoveries about the core of the red planet were based on seismic waves that reflected off its outer boundary with the mantle, and these waves provided information that was much less precise.
“We had only been able to constrain the internal structure of the planet Mars up to the surface of the core. We had to wait for days 976 and 1000, i.e., more than two Earth years after the start of the mission, to obtain the last piece of the puzzle and probe the inside of the Martian core,” said a beaming Mélanie Drilleau, researcher in seismology and member of the ISAE-SUPAERO Space Systems for Planetology and its Applications research group. “We used the data provided by the seismometer, in particular the times the seismic waves took to propagate inside the core compared to those propagating only in the mantle, to constrain the properties of the core and build the first models of the elastic properties of the entire planet. ” she went on to say.
Analysis of the data enabled the researchers to infer that the Mars core was composed not only of iron but also light elements such as oxygen, sulfur, carbon, and hydrogen and this could suggest that the core base is liquid.
The analytical work will continue over the coming years. With more than 1,300 seismic events recorded over the four years of the mission, scientists hope to make further progress in understanding the structure of Mars.
*Proceedings of the National Academies of Sciences
Learn more about the InSight mission:
Insight is part of NASA’s Discovery Program, managed by the agency’s Marshall Space Flight Center in Huntsville, Alabama. Lockheed Martin Space in Denver built the InSight spacecraft, including its cruise stage and lander, and supported spacecraft operations for the mission. Several European partners, including the French National Centre for Space Studies (CNES) and the German Aerospace Centre (DLR), support the InSight mission.
CNES provided the SEIS (Seismic Experiment for Interior Structure) instrument to NASA, with the principal researcher at IPGP (Institut de Physique du Globe de Paris). Important contributions to SEIS have come from IPGP; Max Planck Institute for Solar System Research (MPS) in Germany; ETH Zurich in Switzerland; Imperial College London and Oxford University in the UK; and JPL.
The Marsquake Service is led by ETH Zurich, with important contributions from IPGP; Bristol University; Imperial College; ISAE-SUPAERO; MPS; and JPL. DLR provided the Heat Flow and Physical Properties Package (HP3), with significant contributions from the Space Research Centre (CBK) at the Polish Academy of Sciences and Astronika in Poland. The Spanish Centro de Astrobiología (cab) supplied the temperature and wind sensors.
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