Scientists have learned all this thanks to the Insight probe.
TASS, February 24th. Instruments of the InSight landing platform recorded hundreds of tremors on Mars and localized their source, and also found traces of unexpectedly strong magnetization in the rocks of the planet. The mission participants spoke about this at a teleconference held by the editors of Nature magazine. Scientists also published these results in a series of journal articles ( 1 , 2 , 3 , 4 , 5 , 6 ).
"We proved that Mars is a seismically active planet. Its bowels turned out to be much more active than the Moon, but less hectic than on Earth. In general, Mars in this respect resembles those quiet corners of our planet that are far from faults and zones seismic stress, "said Bruce Banerdtt, the head of the InSight mission.
The InSight descent module landed on the surface of Mars in December 2018. His two main tasks are to search for traces of marsquakes and to study the internal structure of the Red Planet. His scientific work began last February, when German and American scientists completed the installation of the SEIS seismograph and began to deploy the HP3 drilling rig.
The problems with this device began on the very first day of work. Initially, it was supposed to plunge deep into Mars by 70 centimeters, but this did not happen: after passing about 35 centimeters, the drill stopped diving and began to "stagnate".
The following year, NASA and DLR scientists spent on understanding what exactly happened with the drill, and to figure out how to save it. So far they have not been able to do this, since the movement of the drill is prevented by a particularly dense layer of sintered sand, which does not break under HP3 impacts.
However, these problems, as Banerdt noted, did not interfere with the work of the seismograph, as well as other InSight tools that are designed to study the atmospheric processes and bowels of Mars. In particular, in the first six months of observations, SEIS recorded 174 marquakes. This confirmed that the bowels of the Red Planet are still seismically active.
Secrets of the depths of Mars
Most of these shocks, according to planetologists, were rather weak. The remaining 24 arose at great depths, 20-30 km, their magnitude was approximately 3-4 points. As planetologists explained, a person could notice such tremors only if he lived in the vicinity of their epicenter. In general, experts came to the conclusion that marquakes happen much more often than they thought.
In addition, scientists discovered two interesting and difficult to explain facts that are associated with the geology of Mars. Firstly, the landing module instruments recorded unusually high levels of remanent magnetization of the Martian crust, which do not fit into the idea that the Red Planet never had a powerful magnetic field. As scientists noted, the values measured by them were ten times higher than the data obtained by the orbiting satellites and which predict theories of planet formation.
Secondly, most of the marquakes that SEIS was able to catch were scattered across the bowels of the planet not randomly, but were concentrated in the so-called Cerberus Fissures. So, scientists call the set of clefts and faults, which is located at the equator of Mars, next to the plain of Elysius.
"Modern astronomers consider the Cerberus Furrows as the youngest geological region of Mars. The last outpourings of magma occurred here about 10 million years ago, and therefore the concentration of marsquake epicenters in this region that we discovered was especially interesting," commented Suzanne Smrecar, one of Banerdt’s deputies.
According to her, it is not yet clear what exactly generated these shocks and whether they can be associated with manifestations of modern tectonic and magmatic activity in the bowels of Mars. On the one hand, as Smrekar noted, this is impossible from the point of view of modern ideas about how the temperature in the bowels of Mars has changed since its birth.
On the other hand, the presence of relatively recent traces of volcanic activity, as well as the concentration of sources of marsquakes and the numerous traces of water flows in the Cerberus Fissures, do not preclude this hypothesis and compel scientists to look for plausible explanations for this. Subsequent InSight measurements, the mission hopes, will bring us closer to the answer to this riddle.