CRC ATLAS brings satellites closer to earth

Earth's orbits are increasingly crowded, with collision warnings and actual collisions disrupting the routine operation of satellites on a daily basis. "At altitudes of 500 kilometers and above, we are now tracking tens of thousands of satellites. Space is getting tight up there,” says Prof. Stefanos Fasoulas at the start of the 2nd International VLEO Symposium. “A sensible alternative is to get closer to the earth.”

At the symposium hosted by the Collaborative Research Centre 1667 ATLAS (Advancing Technologies of Very Low Altitude Satellites) at the University of Stuttgart, scientists and early-career researchers presented innovative solutions to help satellites withstand the challenging conditions of the Very Low Earth Orbit (VLEO). Professor Manfred Bischoff, Vice Rector for Research and Sustainable Development: “As Vice Rector, I am proud that we have such an internationally visible center of excellent research and spaceflight technologies at this university. Naturally, I am also proud that we have the opportunity to host such a prestigious conference. With this conference, the DFG-funded Collaborative Research Center 1667 ATLAS is promoting the international exchange of knowledge and strengthening its international network.”

These technologies are the product of interdisciplinary collaboration between scientists and early-career researchers within the ATLAS CRC. For instance, researchers are exploring innovative control systems and concepts that enable satellites to maneuver in orbit with the fuel efficiency of aircraft. "We don’t view the atmospheric conditions in the VLEO merely as a disturbance; instead, we aim to harness lift and drag to serve our purposes," explain Friedrich Tuttas and Fabian Geyer, doctoral researchers at the Institute of Flight Mechanics and Control (IFR). This makes it possible to align satellites in a controlled manner - for data transmission to a ground station, for example.

However, sending large amounts of data to Earth in a short time is tricky. "In VLEO, satellites orbit much closer to Earth, resulting in significantly higher relative speeds. This means more Earth orbits per day with extremely short time windows for data transmission,” says Mark Neff, PhD student at the Institute of Robust Power Semiconductor Systems (ILH). At the ILH poster stand, Neff presented previous research work on modulation processes and broadband technologies. Satellite constellations that communicate with each other via radio play a central role in the development of modern mobile communications. In this way, satellites can provide a global network that ensures data and fast internet are available anytime and anywhere.

Professor Michael Saliba and his team rely on two-layer perovskite and silicon solar cells to supply energy: Thinner than a human hair, they can be flexibly integrated into the satellite structure and also withstand extreme radiation exposure. “Solar cells are usually encapsulated with glass or plastic film,” says Andreas Pahler, PhD student at the Institute for Photovoltaics (ipv). "However, for use in VLEO, we require exceptionally robust materials that can provide long-term protection for solar cells—this is the focus of our research."

The Collaborative Research Center 1667 “Advancing Technologies of Very Low Altitude Satellites” (ATLAS) has received funding from the German Research Foundation (DFG) since April 2024 and this funding will continue for an initial period of four years. The goal is to establish the scientific foundation for exploring Earth's low orbit. Led by the University of Stuttgart, 13 institutes and the German Aerospace Center (DLR) are actively involved. The CRC receives support from non-university partners from research and industry, such as the European Space Agency (ESA), Stuttgart-based Astos Solutions GmbH and Luleå University of Technology in Sweden.