What happens to satellites orbiting Earth, and how does general relativity affect the satellites’ orbits and movement? It was comprehensively explained by scientists from the University of Life Sciences in Wroclaw and ESA.

The general theory of relativity, introduced by Albert Einstein more than 100 years ago, still contains many phenomena that are not described until now. Scientists from the Institute of Geodesy and Geographic Information at the University of Life Sciences in Wroclaw, along with representatives of the European Space Agency (ESA), provide some unexpected influences and predictions regarding the behavior of satellites orbiting the Earth, which have never been. Described in the literature before.

The results of the professor’s work. Krzysztof Sośnica presented in October 2020 and in March 2021 at the ESA Science Advisory Committee meeting (ESA GNSS Science Advisory Committee, GSAC) as part of the invited special papers, which have sparked heated debate and are now Published In the Journal of Celestial Mechanics and Dynamic Astronomy. The University of Life Sciences in Wroclaw also describes them in a popular science advertisement on the website.

Albert Einstein was able to explain disturbances in planetary motion through a theory describing the relationship between time, space, gravity and matter in a comprehensive manner. “But many other influences on the remaining orbital parameters have not been described in the literature yet. Our publication fills in this gap and provides a description of the perturbations of the orbital parameters and the change in the orbital period of the satellites orbiting the Earth.” – says the professor. Krzysztof Sośnica, quoted in the press release on the UPWr website.

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As the Head of Scientific Discipline for Civil Engineering and Transportation and the Division of Satellite Geodesy at UPWr illustrate in this popular science, relativity theory allows to distinguish three major influences that affect the motion of satellites. This is the Schwarzschild effect, which results from the deflection of space-time by the mass of the Earth (which is treated as a regular sphere), and the Linsa-Thering effect – the result of the rotation of the Earth around its axis, which generates the formation of so-called spacetime vortices, which are caused by satellites and the effect De Sitter, also known as the Geodesic Initiative, which results from the bending of space-time by the sun and the motion of satellites around the Earth reads moving around the sun – and thus the result of two movements “- in the press release.

Researchers (including from Poland) have described how these three influences affect the size and shape of the orbits and the direction of the orbit plane with respect to outer space. “We have presented for the first time how the size of the orbits of Earth satellites changes due to the curvature of space-time from the Earth” – says the professor. Susnica. It explains that scientists from UPWr and ESA have found that the longest half axis of the orbit of all Earth satellites has decreased by 17.7 mm.

“We were surprised that this value is constant, regardless of the altitude the satellite is orbiting at. It doesn’t matter whether it is 300 km for low-lying satellites or 36,000 km for geostationary satellites. We were also surprised by the value of a change in the long half axis of the orbit, because it is Exactly twice the Schwarzschild radius, that is, the radius of a black hole with the mass of the Earth, “- admits the professor. Krzysztof Sośnica.

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According to scientists from UPWr, if the entire mass of Earth could be compressed into a sphere of radius of 8.9 mm, the Earth would become a black hole. Nothing can go out of it, not even the light. The rays of a black hole are called the Schwarzschild, or event horizon, after which no information can escape. Scientists studying the general theory of relativity have found that the change in the radius of the main axis of all Earth satellites is exactly twice the Schwarzschild radius. “Even if the Earth collapses and turns into a black hole, the impact on all satellites on our planet will be -17.7 mm; it does not matter whether the satellites orbit at an altitude or low above the black hole” – says the professor. Susnica.

The second effect described for the first time in the work of scientists is the effect of changing the shape of the orbits of satellites. The UPWr and ESA researchers found that general relativity changes the shape of orbits in the same way as for elliptical and circular orbits. As a professor. Pine tree, all the orbits are flattened, “elliptical” and similarly.

In the third, unexpected effect of the team of scientists, the geodesic prefix value strongly depends on the angle of inclination of the sun relative to the plane of the satellite’s orbit. Scientists have shown that the impact of the geodetic initiative is greater for geostationary satellites orbiting around the equator. Previously, no one cared about it, because only the average effect was taken into account, not the real effect produced by the geometry of the satellite, the Earth and the sun.

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You can read more about the results of the work of a group of scientists from Poland, France, the Netherlands and Spain at: https://upwr.edu.pl/aktualnosci/naukowcy-z-upwr-i-esa-rozwiazali- zagadke-einsteina-3508.html

PAP – Science in Poland

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