Austrian researchers repurpose Starlink satellites to monitor Earth in novel approach

Accurate data is crucial in scientific research, as access to more data sources leads to more precise results. Until recently, experts in navigation and satellite geodesy saw a missed opportunity—thousands of satellites in mega-constellations were orbiting Earth for communication but their signals were not utilized for positioning or Earth observation.

Through the FFG project Estimation, researchers at the Institute of Geodesy at the Technical University Graz (Austria) have found a way to use these previously untapped signals.

As defined in an article by The Debrief,  they aim to enhance Earth monitoring with greater accuracy by combining them with data from navigation and research satellites. Using the Doppler effect, scientists have begun analyzing signals from Starlink and similar satellite networks, uncovering valuable insights into climate, sea levels, and weather patterns. Though improving precision remains a challenge, the potential for global environmental monitoring is significant.

Earth observation via satellites involves detecting changes in sea levels, groundwater, and other environmental factors that subtly shift satellite trajectories due to variations in Earth's gravitational field. By studying these orbital shifts, researchers can extract critical data about planetary changes.

“The rise of satellite internet has given us an abundance of communication signals, far surpassing those from navigation satellites in both number and signal strength,” says Philipp Berglez from the Institute of Geodesy. “If we can integrate these signals into our measurements, we gain not only better signal availability but also enhanced temporal resolution, allowing us to observe short-term changes. This means we can track not just Earth’s gravitational field and climate-related shifts but also real-time weather phenomena like heavy rainfall or sea level fluctuations.”

Challenges in signal processing

One obstacle in this research is that satellite operators such as Starlink, OneWeb, and Amazon’s Project Kuiper do not publicly share details about their signal structures, which are constantly changing. Additionally, the lack of precise orbit data and distance measurements adds potential errors to calculations.

Despite these challenges, researchers have found a way to use Starlink signals by identifying consistent sound patterns within them. By leveraging the Doppler effect, they examined frequency shifts as satellites moved toward and away from receivers, allowing them to determine position with an accuracy of 54 meters. While this is not yet sufficient for geodetic applications, initial experiments confirmed the feasibility of this measurement technique using only a commercially available fixed satellite antenna.

The next goal is to improve accuracy to just a few meters. This will be achieved by using antennas that track satellites or receive signals from multiple directions, along with taking measurements from multiple locations to minimize errors. With more data, researchers can refine orbital calculations, leading to better positioning accuracy and more precise measurements of Earth’s gravitational field. Additionally, the navigation research team aims to develop advanced signal processing techniques to extract more precise data from signals that were previously unsuitable for geodetic applications.

By Nazrin Sadigova