2023-06-26 13:45:57
The pioneering observation of free oscillations on Mars generated by atmospheric phenomena and by the world’s largest earthquake ever recorded by NASA’s InSight space probe will provide revealing information about the internal dynamics and composition of the Red Planet.
The study of this observation has the participation of the Higher Council for Scientific Research (CSIC) of Spain.
Martin Schimmel, a researcher at the CSIC’s Geosciences Barcelona (GEO3BCN), is one of the main authors of the study, along with Philippe Lognonné and Eleonore Stutzmann, from the Paris Globe Physics Institute in France.
“Free oscillations are a fundamental measurement to determine the average structure, especially at great depths. These measurements will allow us to determine the physical properties of the main layers and build reference models that cover the entire planet”, explains Schimmel.
In this study, the research team detected 60 normal mode frequencies, thanks to the magnitude 4.7 marsquake (Martian earthquake) that occurred at the end of December 2022, and the low noise level at low frequencies of the InSight seismometer with which the vibrations were recorded.
Mars. (Image: NASA JPL/Caltech)
the martian buzz
This work also shows evidence of continuous vibrations on Mars, known as the “mars hum,” since several of the eigenfrequencies were present before the quake occurred on Mars. The red planet thus becomes the second terrestrial-type planet, after Earth, in which these vibrations are observed.
Using a technique called phasor shift analysis, the science team was able to identify hidden vibration patterns in the seismic records of Mars. “The signals were very weak and cannot be detected using conventional methods”, underlines the GEO3BCN scientist. For this reason, the research team also used old methodologies, some of them developed more than 20 years ago: “The key technique in this study dates back to before the era of the creation of computers.”
In fact, Schimmel already used phasor displacement analysis in a biomedical study published in 2002 that showed circadian rhythms (the physical, mental, and behavioral changes that follow a 24-hour cycle) with temperature measurements of premature babies.
By capturing the free oscillations in the planet, this research opens the door to gain insight into the seismology of Mars and gain more insight into how the planet works internally.
All this information adds to what has already been published in academic journals by the InSight project team in recent years. The most recent publication, in which Schimmel has also collaborated, shows the detection for the first time of seismic waves traveling through the core of the Red planet. From the results, the research team concluded that, in addition to iron, the interior of Mars also contains large amounts of sulfur and, to a lesser extent, oxygen, carbon and hydrogen.
The study is titled “Detection of Mars Normal Modes From S1222a Event and Seismic Hum”. And it has been published in the academic journal Geophysical Research Letters. (Source: GEO3BCN / CSIC)
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