(NASA/JPL-Caltech/University of Arizona https://go.nasa.gov/3sG6Kqv)
A team of planetary scientists could connect two of the most powerful marsquakes with the fall of large meteorites on the Red Planet last year.
These two largest fresh impact craters were discovered by the Mars Reconnaissance Orbiter.
The team from the Institute of Geophysics at the Swiss Federal Institute of Technology in Zurich led by Doyeon Kim used the Mars InSight records to confirm them.
Impact events associated with meteorite falls are the most common process of change in the relief of bodies with a solid surface in the solar system.
However, seismic waves associated with the fall of a body on the planet's surface were reliably observed only on our planet, thanks to the craters left.
In the case of the Moon, although seismographs recorded tremors that were interpreted as falling meteorites we couldn't find craters.
However, in the case of Mars, the situation has recently changed for the better thanks to the joint work of the InSight station and the Mars Reconnaissance Orbiter
Both missions could successfully identify several events.
THE IMPACTS
Now, Kim’s team could establish a connection between the falls of large meteorites on Mars and two powerful magnitude 4 seismic events recorded by the SEIS seismograph.
As I’ve written before, the SEIS instrument is part of the InSight lander.
The CTX and HiRISE cameras of the Mars Reconnaissance Orbiter helped in detecting the impact craters.
The S1000a event was recorded on September 18, 2021 and was very powerful (magnitude 4.1), very long (93 minutes) and one of the first that occurred on the far side of the planet.
Because of this, in addition to PP and SS-waves, the probe detected Pdiff-wave (P-wave, which deviated from the mantle-core boundary).
The source of the shocks was presumably located to the west of the Patera volcano; the analysis of seismic data gave an estimate of the distance to it at 1000 kilometers.
The event was associated with the fall of a meteorite, which gave rise to several craters, located at a distance of 7460 kilometers from the station, in the Tempe Land region.
Unfortunately, the distance of the S1000a source from the station and the location of the craters on the slope did not make it easy to determine the parameters of the striker.
The impact zone was severely destroyed, and the seismic waves experienced additional attenuation and scattering on the way to the seismograph.
(JPLraw)
The second event identified by the researchers was designated S1094b: it was recorded on December 24, 2021, had a magnitude of 4 and lasted 108 minutes.
The source of shocks was located around 3000 kilometers away from the lander according to seismic data.
The crater, with a diameter of 150 ± 10 meters and a depth of 21 ± 3 meters, is located at a distance of 3460 kilometers on the Amazonian Plain.
It has an irregular shape, water ice ejected from the depths is observed next to it, while the main crater is surrounded by secondary craters.
In the case of S1094b, the researchers were able to determine some parameters of the impactor.
It had a diameter of several meters and a mass of more than a hundred tons, it fell at an angle of 30 ° relative to the surface of the planet.
This created two shock waves that propagated at least 18 kilometers in the transverse direction.
One formed when the meteoroid passed through the atmosphere, and the other due to its collision with Mars.
This information is of high value when humans finally decide to colonize the Red Planet.
(JPLraw)
Sources:
- Science: https://www.science.org/doi/10.1126/science.abq7704
- NASA: https://www.nasa.gov/feature/jpl/nasa-s-insight-lander-detects-stunning-meteoroid-impact-on-mars/
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