Demisability and survivability sensitivity to design-for-demise techniques

Abstract

The paper is concerned with examining the effects that design-for-demise solutions can have not only on the demisability of components, but also on their survivability that is their capability to withstand impacts from space debris. First two models are introduced. A demisability model to predict the behaviour of spacecraft components during the atmospheric re-entry and a survivability model to assess the vulnerability of spacecraft structures against space debris impacts. Two indices that evaluate the level of demisability and survivability are also proposed. The two models are then used to study the sensitivity of the demisability and of the survivability indices as a function of typical design-for-demise options. The demisability and the survivability can in fact be influenced by the same design parameters in a competing fashion that is while the demisability is improved, the survivability is worsened and vice versa. The analysis shows how the design-for-demise solutions influence the demisability and the survivability independently. In addition, the effect that a solution has simultaneously on the two criteria is assessed. Results shows which, among the design-for-demise parameters mostly influence the demisability and the survivability. For such design parameters maps are presented, describing their influence on the demisability and survivability indices. These maps represent a useful tool to quickly assess the level of demisability and survivability that can be expected from a component, when specific design parameters are changed.  Abbreviations DRAMA: Debris Risk Assessment and Mitigation Analysis MASTER: Meteoroid and Space Debris Terrestrial Environment Reference MIDAS: MASTER-based Impact Flux and Damage Assessment Software LMF: Liquid Mass Fraction PNP: Probability of no-penetrationamong these mitigation measures is the limitation of the long-term presence of spacecraft and upper stages in the Low Earth Orbit (LEO) and Geostationary Orbit (GEO) protected regions [5]. This in turn means that a spacecraft has to be removed from its operational orbit after its decommissioning, either by placing it in a graveyard orbit or by allowing it to re-enter into the Earth's atmosphere. For LEO spacecraft, the preferred scenario is to design a disposal by re-entry within 25 years from its decommissioning in order for the mission to comply with the 25-year rule [6]. However, when a spacecraft is to be disposed through re-entry it has also to satisfy the requirement for the limitation of the risk of human casualty on the ground associated to the debris surviving the re-entry. This can be either achieved performing a controlled re-entry, where the spacecraft is guided to impact in the ocean or not populated areas, or through an uncontrolled re-entry, where the vehicle is left to re-enter without any guidance. In the latter case, the surviving mass of the spacecraft has to be low enough to comply with the regulation on the casualty risk expectation that has to be below the threshold of 10 -4 . Controlled re-entries ha...

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A Fast Thermal 1D Model to Study Aerospace Material Response Behaviors in Uncontrolled Atmospheric Entries

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