Ground control to Elon Musk: Stability implications of satellite mega-constellations

Abstract Outer space is increasingly central to international security. The use of Starlink in the Russo–Ukrainian war has enabled Ukrainian operations while negating Russian interference. Having witnessed Starlink’s crucial impact in Ukraine, several states seek to emulate the system’s offensive and defensive advantages. This article analyses how the onset of mega-constellations – satellite systems consisting of very high numbers of smaller satellites – will affect stability in the space domain. As states are increasingly dependent on space for both nuclear and conventional operations, the stability of the space domain is a key concern for international security. Showing how mega-constellations can mitigate existing vulnerabilities in space while generating offensive advantages on earth, this article shows that their proliferation is likely to make conventional counterspace attacks ineffective and costly. Therefore, mega-constellations will have a stabilising effect between states equally dependant on space. However, under conditions of asymmetric dependence, less space-reliant states may find incentives to employ highly destructive weapons, including nuclear weapons, to disable adversary mega-constellations. Accordingly, the proliferation of mega-constellations may act in a destabilising manner, especially if under conditions of asymmetry in space.