Speaker
Description
Large-scale telecommunications constellations have contributed to the growing number of satellites in Low Earth Orbit (LEO), which has increased the demand for efficient Design-for-Demise (D4D) solutions to reduce the risk of on-ground casualties from debris surviving re-entry. Within this context, the D4D SAFER project (Structures with Advanced Demisability Function for Earth Re-entry), funded by ESA, focuses on the primary joints between main structural elements and aims to develop demisable alternatives. Early opening of the satellite structure at the joints increases the exposure of internal, often difficult to demise components, such as reaction wheels, thereby increasing their likelihood of a full demise and reducing the on-ground casualty risk.
This presentation shows the current status of the D4D SAFER project. First, a representative communications satellite use-case was developed, which serves as the baseline in the project for the evaluation of the demisable joints and their impact on the on-ground casualty risk. Re-entry simulations using SCARAB based on this use-case provided insights into thermal loading of the joints over the whole satellite, fragmentation behaviour, and remaining debris and their on-ground casualty risk. With this information, multiple demisable joint concepts were subsequently developed, using already known as well as new demise concepts aimed at enabling reliable separation under re-entry conditions. The concepts were tested in the re-entry chamber of AAC as well as in the L2K facility of DLR, showcasing both promising demise behaviour for some and limitations for others.
The presentation discusses the challenges encountered during the design and testing phases. In particular, these are contradicting requirements for the launch and in-orbit loads and early separation demands. During testing, several limitations have been observed. The existing testing methods use simplified static load cases, which are not representative of the tumbling and dynamic environment experienced during an actual satellite re-entry. This leads to the tests only demonstrating separation in pre-defined load cases. Additionally, investigating high break-up altitudes requires testing with very demanding test conditions in the L2K, which resulted in new challenges and insights.
Overall, the presentation highlights the potential of demisable joints and the current developments, while showing the challenges that need to be addressed in the next phases of the project.