Speaker
Description
The risk of fragments surviving a destructive re-entry and impacting on ground, the state of the art around the turn of the millennium was based on thermal protection shield assumptions and limited material ablation testing. A significant amount of research in this field during the last decade indicated that the simplifying assumptions on shape and complex geometries lead to uncertainties of 50-100% and above when it comes the heating processes alone, and hence have a driving influence on the physical predictions of the demise behaviour. On-ground wind tunnel testing on spacecraft component indicated a strong dependency on flow based length-scale, i.e. local and global transition regimes, which even the most advance system level tools don’t account for.
The "Shape Effect Modelling for Risk Evaluation" project is dedicated to improving risk models with a critical dependency on shape assumption, and is embedded in the Agency’s Space Safety Programme. The general objective of the Space Safety Programme is to contribute to the protection of our planet, humanity and assets in space and on Earth from hazards originating in Space and to contribute to Europe, by providing safety from such hazards, as a service to its society. This activity focusses on analysing the probability of a hazard materialising and establishing its severity and magnitude; part of the Space Debris track of the Core Activities of the programme.
The top-level objective of the re-entry track of this activity is to increase the accuracy and the precision of the space debris risk methodologies in the field of destructive re-entry break-up modelling. This shall be done by improving the underlying physical response models used by such risk assessment methodology, rather than the methodologies that combine the likelihood of a physical response taking place with the severity of this event. E.g. it is envisaged to improve the aerothermodynamics coefficients in the transition regimes, but not the estimations of casualty areas.
The top-level objectives of the re-entry part of the activity are:
- Identify and assess the impact of shape assumptions, understood as the determination of characterising length scales and complex shape and behaviour in the transition regime, on the demise and fragmentation of spacecraft structures during destructive atmospheric re-entry.
- Develop a software library to implement the improved physics models into risk assessment methodologies.
These objectives shall be achieved by developing an "Aerodynamic/Aerothermodynamic Shape Effect Override (ASEO)" prototype. The ASEO prototype shall provide aerodynamic/aerothermodynamic coefficients derived from wind-tunnel experiments or high-fidelity CFD simulations for specific shapes.
