Multibody aerothermodynamics of space debris fragments

Kurzfassung

Due to the increasing space transportation activities and possible entry of the Near-Earth-Objects at very high velocities space debris became an issue of safety for our Earth. In order to satisfy the new requirement concerning risk mitigation of space debris, the design of the flight hardware has to consider a complete demise of the objects during atmospheric re-entry. Since the size, geometry, break-up-altitude and interaction of the space object have an influence on the ground impact, dedicated characterization tests are necessary. The evolution of the demise process and formation of fragments has a big influence on the prediction of the ground impact. The available numerical tools have still significant shortcomings in correct physical modelling of the demise and multibody interaction. In order to characterize proposed demise solutions and to create a reliable experimental data base the Supersonic and Hypersonic Technologies Department of DLR developed unique experimental skills. Both arc heated facilities L2K and L3K are qualified for demise testing at critical trajectory points of re-entry objects. The prediction of aerothermodynamic behaviour of space debris and their interaction with each other is another challenging task. Such objects may have complex non-aerodynamic shapes. Therefore the determination of aerodynamic and thermal behaviour of multi bodies requires an upgrade or development of new experimental and numerical tools. Since the standard aerodynamic measurement technique using high precision six component balances would cause undesired limitations with respect to the multi body motion, a new approach of free flight of multiple bodies in the hypersonic wind tunnel H2K has been developed. Experimental results on single and multi-bodies show significant differences in the aerothermodynamic process, which leads to differences in the demise behaviour, fragmentation and ground impact.