Space Capacity Methodologies to Rank the Risk of Orbital Regions

The growth in the number of objects in Earth orbit poses a threat to space safety and space sustainability. The orbital space is not infinite, but it is a limited resource that must be properly managed and maintained. In this work, three approaches to assess the space consumed capacity are compared on the same object population with clear distinctions between operational and non-operational objects; the three methods are THEMIS space debris indicator (Tracking the Health of the Environment and Missions In Space), the Criticality of Spacecraft Index (CSI), and the Risk Balance Model. The evaluation is performed on specific altitude bins in the Low Earth Orbit (LEO), considering different bin sizes to investigate how this affects the evaluation of the capacity at different altitude shells. The numerical results are normalised to better compare the different approaches and the relative importance of the altitude bins, ranking them from highest to lowest.