Thermite-for-Demise (T4D): Concept Definition for Exothermic Reaction-Aided Spacecraft Demise during Re-entry
Creators: name:  A. FINAZZI 
name:   F. MAGGI 
name:   C. PARAVAN 
name:   L. GALFETTI 
name:   S. DOSSI 
name:   A. MURGIA 
name:   T. LIPS 
name:   G. SMET 
Publisher: name: Proceedings of  the 9th European Conference for Aerospace Sciences. Lille, France, 27 June - 1 July, 2022
Year: 2022
Subjects: SPACE DEBRIS MODELING
REENTRY

description: Design-for-Demise (D4D) is one of the main topics currently under investigation to improve space exploitation sustainability and to reduce on-ground risks related to spacecraft re-entry. It is rather common, especially when dealing with relatively small satellites, to consider an uncontrolled re-entry to reduce operational costs. The main drawback of this option is that the heat generated by the interaction with the atmosphere is often not enough to demise completely all spacecraft components. Titanium tanks, reaction wheels and similar high-melting parts are the main sources of on-ground risks related to spacecraft re-entry. It has been estimated that 10-40% of the satellite mass can impact on the ground [1]. One of the possible solutions to limit these risks is the use of energetic materials to provide additional heat. Such a technique could improve demisability with potential limited costs. Thermites, a particular class of energetic materials made by a combination of a metal and a metal oxide, are particularly interesting for such an application. The main features of these powders are their capability to release a high amount of enthalpy upon reaction and their relative safety with respect to other propellants or explosive materials. In D4D frame, different uses can be outlined for thermites [2-3]. Their embodiment into a re-entering satellite could provide the missing heat to promote complete melting and ablation. Another option is to use thermites to provoke controlled break-up, generating more easily demisable fragments. An overview of the main possible design concepts will be presented, highlighting major benefits and constraints of each solution. In this context, the identification of the most effective sequence of events during the re-entry is a problem of central importance. This topic, strictly connected to thermite ignition and thermite-spacecraft heat transfer effectiveness, is one of the main design choices that must be defined. This parameter will have a paramount effect on this innovative technique efficacy. Moreover, the selection of the re-entry phase in which the thermite ignition should occur is one of the main drivers that guides the choice between the possible concepts. The discussion will focus on this investigation, currently in development in the frame of SPADEXO ESA-TRP project. [1] M. Trisolini et al., Demisability and survivability sensitivity to design-for-demise techniques, Acta Astronautica 145 (2018) 357-384 [2] R. Seiler and G. Smet, Exothermic reaction aided spacecraft demise during re-entry, European Patent EP 3 604 143 A1, Filing year 2018 [3] D. Dilhan and P. Omaly, Element de vehicule spatial a capacite d\'autodestruction amelioree et procede de fabrication d\'un tel element, Patent FR 2975080 A1, 2012