ESTIMATION - Enhancing Satellite Geodesy Using Mega Constellations

The commercialization of the space sector, referred to as "New Space", is characterized by growing investments on the part of private actors, new business models and procurement approaches. This transformation of the space sector has led to the trend of building, launching and operating smaller satellites and results in a faster and more flexible deployment of satellites. In recent years, instead of launching few, complex, large, and expensive satellites, the trend is towards the deployment of large amounts of smaller, simpler, and less expensive satellites flying in LEO. To provide global coverage using LEOs large number of satellites are required; thus, satellite mega constellations are used. Mega constellations are currently showing their potential in the communication field. The biggest drawback, from the satellite geodesy (SG) point of view, is that although thousands of satellites are in orbit and their transmitted signal power is much higher than GNSS, their signals are designed for communication purposes and no ranging or precise orbit information is available. They are mainly focusing on providing high data communication bandwidths. However, recent research, investigated the unknown communication signals, and revealed that, such signals could be used to generate pseudorange and Doppler measurements. Such an understanding of the signal is essential to emerging efforts that seek to dual-purpose mega constellation signals for SG. Recently researchers began to study potential non-telecommunication applications of these mega constellations, because they do have a huge potential in SG, especially in positioning, navigation and timing, global monitoring of Earth, enhancing space observation as well as other geodetic applications. By using mega constellations in the field of position, navigation and timing the availability as well as robustness can be significantly improved, especially in challenging environments, by having numerous observations simultaneously available. Since the signals, emitted from those communication satellites, are thousand times stronger than GNSS signals, an increase in robustness against interference can be achieved. They also could be used as a back-up or alternate to GNSS. In case of scientific applications such mega constellations can provide valuable information for space weather, variations of the Earth’s gravity field, ionospheric modelling, or early warning in case of space debris. Consequently, to benefit from such commercial mega constellations, scientific research is necessary, not only to obtain precise measurements based on the communication signal, but also to investigate and estimate precise orbits. Within this activity both research fields will be addressed to access the possibilities and advantages of mega constellations in the field of SG.