Rings in the Sky: Orbital Data Centres and Potential Impacts to Astronomy and the Sky

Abstract

Megaconstellations of orbital data centres (ODCs) have the potential to fundamentally change the sky without a concerted mitigation effort. Potential changes include producing large coherent structures that would be visible during twilight and some portions of the night, as well as produce persistent infrared and radio source regions. We investigate the potential sky impacts of three ODC designs, as proposed by three companies. While more companies have proposed to launch megaconstellations of ODCs, other potential operators are expected to use the same design principles as presented here. These systems would produce large ring structures with each ring passing through the sky twice a day. The largest impacts are expected to occur during winter, where ring structures could be seen sweeping through otherwise dark skies. The confinement of the rings' orbital nodes will play a large role in determining whether the rings will be dense arcs in the sky or will produce sky-wide interference. The rings will persist throughout the day in polar regions, with the potential to interfere with polar science initiatives. Such structures will further have societal implications for high-latitude communities. We use simplified brightness models, which compare well with more detailed calculations, to show that brightness mitigation and/or hard limits on satellite numbers will be essential for preventing a future that has more visible satellites in the sky than visible stars during certain times of night.