Researchers from the University of Graz have found a way to use signals from communication satellites to study climate change and track weather phenomena in real time. This innovation opens up new perspectives for monitoring our planet.
Traditionally, communication satellites, such as those from Starlink or OneWeb, are used to transmit data. However, a team from the Institute of Geodesy at the University of Graz has managed to harness their signals for scientific applications. By analyzing frequency variations due to the Doppler effect, they can now measure changes in the Earth's gravitational field and observe climate events in real time.
The Doppler effect at the service of science
Earth observation by satellite relies on a simple principle: variations in sea level or groundwater levels alter the gravitational field, thereby influencing satellite trajectories. By studying these changes, scientists obtain valuable data on the evolution of our environment.
Signals from communication satellites, which are more numerous and powerful than those from navigation satellites, offer much higher temporal resolution. This allows for the detection of short-term changes, such as heavy rainfall or variations in sea level. This information is essential for climate research.
However, satellite operators do not disclose the structure of their signals, which complicates their use. Despite this, researchers have identified constant tones in Starlink signals. By measuring their frequency shift using the Doppler effect, they were able to determine positions with an accuracy of 177 feet (54 meters).
Towards increased accuracy
Although this accuracy is insufficient for advanced geodetic applications, it demonstrates the feasibility of the method. Researchers are currently using a fixed satellite antenna but are considering improving their results with mobile antennas capable of tracking satellites.
By multiplying measurement points, they hope to reduce errors and refine their calculations. The goal is to achieve an accuracy of a few meters, which would allow for a better understanding of changes in the Earth's gravitational field and refine climate models.
Researchers are also developing new signal processing methods to extract more precise data. These advances could improve the study of our planet by providing more effective tools for monitoring its evolution.
To go further: What is the Doppler effect?
The Doppler effect is a physical phenomenon where the frequency of a wave changes according to the relative motion between the source and the observer. It is often illustrated by the change in pitch of an ambulance siren as it approaches and then moves away.
For satellites, this effect allows for the measurement of frequency shifts in emitted signals. By analyzing these variations, researchers can determine the speed and position of satellites, as well as changes in the Earth's gravitational field.
This technique is already used in astronomy to study the motion of stars and galaxies. Its application to Earth observation opens up new possibilities for climate and meteorological research.
Article author: Cédric DEPOND