The applications of satellite positioning in modern geodesy and navigation were presented at an academic conference held by the Faculty of Geodesy and Land Management of UWM on 23-25 June.
— The discussed applications are so varied and enormously diverse that the inventors of the first satellite navigation system could not even have dreamt of them — supposes Prof. of UWM, Paweł Wielgosz, PhD, a Vice Dean of the Faculty of G&LM, and the chairman of the scientific committee of the conference.
Contemporary satellite navigation systems originated from Transit system that was first used in 1964 by the United States Navy. It was applied in maritime navigation. Since 1967, Transit was also occasionally employed for civil purposes. At the beginning of 1980’s, it became publicly available. Transit system was used till the end of 1996. Its successor is known as GPS system. It was designed as a precise positioning system of global range for military purposes. Its Russian equivalent goes under the name of GLONASS, and it also fulfills military functions. GLONASS’ measurement method and applications are similar to the ones of GPS. China is another country that also has its own system (military too) — Compass/BeiDou. Moreover, twenty seven European countries are working on their own navigation system, Galileo. It is a civil system. Among people who are engaged in this project, there are scientists from UWM, for instance Prof. Stanisław Oszczak.
Does the world, especially Europe, need another navigation system? After all, it is very expensive.
— Yes, there is such a need, because other three systems are military ones, and due to some political decisions, they can be closed down for civil users. It would be a disaster for various fields of life and science — Prof. Wielgosz explains.
For which ones in particular? Except for aviation, maritime and land traffic.
— For agriculture, which currently is the main GPS user. However, the signals are also intensively used for example in satellite geodesy, a new branch of science that has been developed since 1990’s. One of its precursors was late Prof. Baran, in memory of whom we organized this conference — adds Prof. Wielgosz.
Determining water vapour concentration in the atmosphere is an example of a more precise GNSS application. Such measurements are useful for drawing up accurate weather maps. In Poland, we have two stations that take measurements of water vapour concentration using traditional methods. However, owing to the navigation system, a hundred more stations were set up. With the data from one hundred measurement stations, instead of only two, it is possible to make such a weather map more accurate, and a weather forecast – more trustworthy.
Another tool for precise weather forecasting is known as GPS radio occultation — a measurement of air temperature based on the refraction of GPS signals that pass through the atmosphere and are received by low-Earth orbit satellites.
Furthermore, at our faculty scientists conduct research into ionosphere – “cosmic weather”– that was initiated by Prof. Baran himself. Knowing the weather conditions and their influence on the satellite signal, we are able to determine an accurate position with GPS method. Currently, a standard signal enables positioning with the accuracy of 30cm up to 6 meters. We are already able to obtain the accuracy of 2mm — Prof. Wielgosz adds.
It’s not drivers who need such an accuracy, is it? Isn’t this needless?
— Definitely not. Such an accuracy is highly useful for mining. It is essential for mining services to know whether rock masses move relative to each other, or if the surface over a mine bends. We already take such measurements on various requests, as an example — for the Legnica-Głogów Copper Belt area. Such information is also desired by builders of highways or embankments.
GNSS signals are useful not only in applied science or global economy, but they also serve as auxiliary tools within natural science, for instance physics or astronomy. Interestingly, American scientists have observed that GPS signals generated by precise atomic clocks, undergo phase deviation. According to the scientists, it takes place because of dark matter. The deviation, in their opinion, constitutes an actual evidence of its existence.
— Inventors of the first satellite navigation system could not even have dreamt of its other numerous applications. I’m also unable to guess where else GNSS systems could be useful, but this subject is brought up at almost all conferences, which makes me really glad — Prof. Wielgosz concludes.