Environmental Impact of Large Constellations Through a Debris Index Analysis

In recent years, the number of objects orbiting around the Earth has experienced a continuous growth because of the increase in the number of launches and of space debris produced by fragmentation events. This growth will likely accelerate with the introduction of large constellations in Low Earth Orbit (LEO), unless mitigating measures will be taken. Despite the benefits they will introduce, large constellations will also have a massive influence on the short- and long-term stability of the space environment, by increasing the interaction with the background space debris population and, thus, the probability of hazardous collision events. New mitigation policies and a careful mission design including the post mission disposal are required for ensuring a future sustainable access to space. This work aims at analysing how the inclusion of large constellations will affect the population of objects already in-orbit. Indeed, the inclusion of a large number of objects in restricted region of the space will change the future population shape. Then, the impact of a constellation is evaluated taking as reference the OneWeb constellation, already being deployed. The evaluation is performed using the THEMIS software tool, developed at Politecnico di Milano in collaboration with Deimos Space within an ESA-funded project. In this frame, the impact of a mission on the space environment is assessed considering the likelihood and associated effects of fragmentations of the satellite(s) during each phase of the mission.