This project is intended to enable future space exploration missions into our Solar System that have not been possible before. Re-entering spacecraft are exposed to extreme heat loads, which are mitigated by heat shields that continuously burn-up during flight. However, the physical processes of the extreme high-speed flow around the vehicle, and the influence of the ablating heat shield on the flow are still not well understood and result in exorbitant safety margins for the heat shield mass. Heat shields become too heavy and prevent missions that suffer from high heat loads like planet exploration or sample return scenarios. The project will utilise a newly developed ground-testing architecture to re-create this flight situation in a laboratory. A plasma-generator will heat sub-scaled models of re-entry capsules to extreme temperatures, as experienced in flight. After this phase, the model will start to decompose due to pyrolysis reactions inside the heat shield material. As a final step, the model will be exposed to a hypervelocity flow. This retains the characteristics of an ablation-flow coupling and allows for the first time a real ablating scaled model in an aerodynamically similar flow, enabling the investigation of physical effects that were previously inaccessible. The so created laboratory experiment allows us to investigate the flow and material response and therefore gives us insight into the physical and chemical effects occurring during re-entry. Several of these experiments are planned with varying test model size, temperature, material, and external flow condition. The flow around the models will be investigated using laser absorption spectroscopy and optical emission spectroscopy. The former of these techniques allows the measurement of temperature and concentration of the nitric oxide molecule, which is a strong indicator for the thermal and chemical state of the flow. The latter technique gives insight into various species and enables the measurement of excitation temperatures of different molecules and atoms. The combination of these approaches results a highly detailed characterisation of the flow around ablating test models. These data are extremely valuable for developing physical models of high-temperature flows, which in turn allows a better design of spacecraft and hypersonic vehicles. I will target flow conditions that replicate high-speed Earth re-entry, such as encountered during the re-entry of the US Space Shuttle or the European IXV mission. The final step in this programme is to use the gathered data of sub-scaled spacecraft models to develop a new theory relating ground-tests to flight scenarios. This endeavor will be accomplished by three interlinked methods. 1) A formulation of an analytical description of the problem utilising first principles of heat and mass transfer, fluid mechanics, and chemical kinetics. 2) The utilisation of the created experimental data spanning a large range of different conditions faced by spacecraft re-entry to ensure generality of the developed scaling approach. 3) A set of detailed numerical simulations rebuilding the experiments and beyond. These simulations will furthermore provide insight into flow physics not captured by the optical diagnostics, complementing the holistic methodology. This methodology will be used to identify dominating physical mechanisms, non-dimensionalise the problem, and generate a new ground-to-flight extrapolation theory that allows us to relate the ablating boundary layer flows directly to flight scenarios.