Aerothermal effects of ablation on carbon-based space objects

The growing number of space objects is a potential risk not only for operational space systems but also for ground safety. To prevent possible collisions with the ground, it is necessary to accurately predict the trajectory and the survivability of space objects using re-entry analysis. Depending on the material of the space objects, ablation gas emissions should also be considered in re-entry analyses, because emissions can significantly affect the aerothermodynamics and gas-surface interaction. In this study, re-entry analyses of carbon-based space objects were performed, and ablation effects were analyzed. For the flow-field calculations, the trajectory of the space objects during re-entry was calculated based on three-degrees-of-freedom equations of motion. For the material response calculations, ablation modelling and quasi-one-dimensional in-depth temperature calculations for the ablating space objects were performed considering the surface energy balance. To independently consider the ablation effects of surface recession, ablation gas emission, and the chemical composition of the ablation gas, four space object models were considered. The re-entry of the space objects was analyzed under three trajectory scenarios, and then the effects of ablation on the trajectory and the survivability of the carbon-based space objects were assessed. Specifically, when considering the ablation gas emission, it was found that the maximum surface temperature and the final size of the space objects were different compared to that the predicted value only when melting was considered.