The impact of space activities in Low Earth Orbit

Debris mitigation measures, gradually adopted since the 1980s, coupled with the end of the Cold War, at the beginning of the 1990s, have played a positive role over a couple of decades. Unfortunately, during the last 15 years, their benefits have been canceled by some major fragmentation events, by prolonged periods of extremely low solar activity and atmospheric drag, and by a dramatic increase in the launch rate of satellites. To aim for the goal of long -term sustainability of space activities, it is necessary to define an acceptable orbital debris environment. Of course, it is not immutable, but relies upon the technical solutions available at a certain time, and on how and for what the circumterrestrial space is used. Assuming the criteria identified more than 20 years ago to define a desirable , tolerable or unacceptable orbital debris environment, an acceptable one, at least in the medium term, should be characterized by a collision rate among objects > 10 cm as stable as possible compared to the current one, and in any case not more than 2or 3 times higher. Taking into account the present technological developments, and the deployment plans of mega-constellations and small satellites, the criticality threshold in LEO might be exceeded during the next ten years. The coming decade is therefore crucial for the future of space activities in LEO, and the widespread application of the debris mitigation measures recommended since the 2000s will probably not be enough. To counteract the negative trends, a combination of reinforced mitigation measures and operational capabilities, complemented by remediation initiatives, as the active removal of selected massive objects abandoned in critical regions of space, should be promoted and implemented.