Space debris modelling in the NewSpace era: how changes in the use of the space environment will impact the space debris environment and how it is modelled

Over the last two decades the rise of NewSpace has led to a transition away from traditional space operations altering the characteristics of the spacecraft population. An analysis of the physical and orbital characteristics of spacecraft from 1957 to 2020 identified trends consistent with the increase in NewSpace spacecraft. A divergence was discovered between the physical characteristics of spacecraft in Low Earth Orbit (smaller, lower mass) and those in Geosynchronous Orbit (larger, higher mass). A shift was also found towards greater spatial organisation in orbit with spacecraft becoming clustered into similar orbits and less uniformly distributed. Both trends have the potential to invalidate the assumptions made in debris model components. An implementation of the NASA Standard Breakup Model was created to investigate the impact of the changing physical characteristics of spacecraft and upper stages on breakup modelling. Validating the model against recent observed breakup events indicated an over-estimation of large debris released and an under-estimation of the number of small debris. A collision tool-set using the Cube and Orbit Trace collision algorithms was developed to study the consequences of increased spatial organisation. Collision probabilities were generated and compared to SOCRATES reports (https://celestrak.com/SOCRATES/) for specific populations of spacecraft and debris. Collision probabilities calculated using the models were reduced relative to the SOCRATES probabilities for scenarios with greater clustering of objects. The model implementations were combined to perform 25 year simulations of a NewSpace constellation comparing the use of the original models against collision and fragmentation models adjusted to account for NewSpace. The results showed that the reaction of the environment to breakups was sensitive to updates made to component models. In scenarios with an initial collision event the adjusted models led to a 250% increase in the final debris population and a 1564% increase in the cumulative collision probabilities of the constellation. These results suggested that current models underestimate the risk associated with NewSpace leading to the conclusion that modifications to account for NewSpace will be a crucial part of the next generation of space debris models. These models will be essential to ensure that appropriate measures are taken to control debris growth and mitigate the risk to future operations