The structure of the interior of Mars was analyzed for the first time through seismic information captured by the seismometer of the NASA Mars probe ‘InSight’. Science provided
Scientists from Germany and Switzerland have discovered for the first time the internal structure of Mars using seismometers installed on the American Mars Orbiter Insight. Mars’ crust consists of at least two layers, and for the first time it has been confirmed that the mantle between the crust and the core is divided into upper and lower parts like Earth’s. In addition, the radius of the core at the very center of Mars was 1830 km, which is 60% of the Earth’s, which was larger than scientists expected. It is the first time that seismic waves have been used to determine the internal structure of a planet other than Earth.
A research team from the University of Cologne in Germany and the Federal Institute of Technology Zurich in Switzerland published three research papers in the international scientific journal Science on the 23rd that analyzed the Mars seismic wave records sent by NASA’s Mars probe Insight and revealed the structure of Mars in detail.
The speed of seismic waves generated by tectonic motion depends on the density of the objects passing through them. Geologists are using this principle to determine the internal structure of the Earth and the types and locations of the materials that make up it.
According to scientists, there is no tectonic motion or earthquakes on Mars like Earth does. However, the crust cracks as it cools, and an earthquake with a magnitude of about 4 occurs 30 km below the surface of the earth. InSight, which left Earth in May 2018, traveled 480 million km and landed on the Elysium Plain near the equator of Mars in November of the same year. InSight placed a dome-shaped seismograph on the surface of Mars shortly after landing. Scientists have observed more than 500 earthquakes of magnitude 2-4 through this seismometer until April this year. Seismic waves in the form of P-waves (longitudinal waves) and S-waves (transverse waves) commonly observed on Earth were also detected on Mars.
Brigitte Knafmeier-Endren, a team of researchers at the Bensberg Observatory at the University of Cologne, Germany, synthesized seismic wave information and estimated the thickness of the Martian crust to be at least 20 km and at most 72 km. The research team confirmed that there is a layer of about 8 km thick and a layer of about 12 km thick just below the landing site of InSight, and there is a mantle that is the same crust or rock layer with a thickness of 19 km below it. It is concluded that the Earth’s crust is slightly thicker than the Earth’s, compared to the point that the thickness of the Earth’s crust is about 5-10 km on the ocean plate and 40-50 km on the continental plate.
Amir Khan, a team of researchers from the Department of Earth Sciences at the Federal Institute of Technology Zurich, found that the mantle beneath Mars’ crust extends to a depth of about 800 kilometers. As a result of analyzing eight seismic waves collected by the Insight seismograph, it was found that the lithosphere with the hardened mantle exists up to 500 km below the crust, and there is a fluid layer below it. The research team analyzed that the mantle of Mars is likely to be moving in the same way as the Earth’s mantle is moving the lithosphere at the top and the tectonic plate at the bottom.
Simon Staler, a senior researcher in the Department of Earth Sciences at the Federal Institute of Technology Zurich, measured the radius of the Martian core to be about 1830 km. Although it is smaller than the Earth’s core, it is larger than the 1400 km scientists had predicted. Scientists have predicted that Mars’s density is lower than Earth’s, so the proportion of Mars’ core with heavy elements such as iron and nickel will be smaller than that of Earth. The team speculated that light elements such as oxygen were included between iron and nickel.
Scientists hope that the X-band antenna installed on the InSight will be able to take a closer look inside Mars. InSight was due to end its mission in November of last year. However, NASA has decided to extend the mission further until December 2022. “As more Martian earthquakes are collected over the next few years, we expect scientists to refine the Mars model and uncover more mysteries,” said Sane Kothar, professor of Earth Sciences at the University of Cambridge, UK.