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Driven by debris mitigation requirements, satellite manufacturers have increasingly replaced titanium with aluminum in structural applications. Guidelines promoted by the European Space Agency (ESA) favor demisable designs, as uncontrolled atmospheric re-entry represents a comparatively simple and robust end-of-life strategy if ground risk can be excluded. Due to its high melting temperature and thermal stability, titanium has traditionally been considered non-demisable and therefore unsuitable for such concepts, despite offering clear advantages over aluminum in terms of specific strength, stiffness, and high-temperature capability.
The German Aerospace Center has been investigating two approaches to enable demisable titanium structures: (1) additively manufactured titanium with controlled, adjustable porosity, and (2) functional coatings applied to solid titanium components to promote material degradation under re-entry heat loads.
Manufacturing feasibility has been demonstrated for both approaches, confirming stable processing of porous titanium geometries as well as reliable coating application. Aerothermal performance was evaluated in plasma wind tunnel campaigns at the Plasmatron facility of the von Karman Institute for fluid Dynamics (VKI). Both porous and coated specimens showed significantly enhanced demisability compared to conventionally manufactured and fully dense additively manufactured titanium.
In addition, a comprehensive material characterization campaign was conducted on porous titanium samples with varying porosity levels. The results show that mechanical properties decrease in a predictable manner with increasing porosity while remaining comparable to conventional titanium at low porosity levels. This predictable behavior enables combined structural and demise-driven optimization, supporting topology optimization strategies that account for both mechanical loads and thermal re-entry constraints.
The paper presents the design of a representative reference bracket, the derived material properties from mechanical testing, and the results of the plasma wind tunnel investigations. The findings demonstrate that titanium can be engineered to meet debris mitigation requirements while retaining its structural performance advantages
The results challenge the long-standing assumption that titanium is incompatible with demisable design. By enabling controlled thermo-structural degradation, titanium can again become a competitive material for satellite structures. The industry can now combine high performance with compliant end-of-life behavior without compromising demisability.