Speaker
Description
The use of pyrotechnic formulations to assist spacecraft demise during re-entry has been investigated in the frame of the SPADEXO ESA-TRP project. The approach selected during this activity consisted in the direct integration of thermite powder in the structural voids of robust components, which could be passively ignited by the aerothermal heat experienced by the spacecraft during the re-entry process. The extra enthalpy released by the reaction could be exploited to induce or assist the demise, hence lowering the casualty risk on ground associated to uncontrolled re-entries. This concept, hereby named Thermite-for-Demise (T4D) was already presented in some papers [1-2] or preliminary studies [3], but this strategy was investigated for the first time in an extensive manner only during the SPADEXO project.
The activities of the project culminated in the experimental campaign performed at the L2K arc-heated hypersonic wind tunnel, located at DLR’s premises in Cologne. Steel mock-ups of particularly robust components were filled with thermite and exposed to the high-enthalpy hypersonic flow, to verify the thermite passive ignition and its effects on the samples. A dedicated extension of the SCARAB re-entry software was realized for the prediction and successive rebuilding of the results. After the experimental campaign, the samples were then analysed in detail at Politecnico di Milano, to characterize the combustion products and highlight the properties of the remaining slag.
The presentation will focus on the results obtained on the mock-ups of Solar Array Drive Mechanisms (SADM). These cylindrical samples were characterized by the possibility of embedding a thermocouple inside the lateral wall, whose data proved to be particularly valuable in quantifying the effectiveness of the thermite enthalpy release to the surrounding structure. The passive ignition verified in all the tested cases and the effectiveness of the heat transfer confirm the validity of the T4D concept, that is now looked with interest also for future commercial applications [4].
- D. Dilhan and P. Omaly, Élement de véhicule spatial a capacité d’autodestruction ameliorée et procedure de fabrication d’un tel elément, FR 2975080 B1, Filling year 2011.
- R. Seiler and G. Smet., Exothermic reaction aided spacecraft demise during re-entry, European Patent EP 3 604 143 A1, Filing year 2018.
- T. Schleutker, A. Guelhan, B. Esser and T. Lips, Exothermic Reaction Aided Spacecraft Demise - Proof of Concept Testing – Final Report, Contract No. 4000126547/19/NL/AR/ig, Issue 1, Revision 2.
- M. Ehinger et al., Design for Demise approaches for reaction wheels, Space Mechanisms Workshop on Clean Space, ESA/ESTEC, Noordwijk, The Netherlands, 2024.
