Speakers
Description
The deployment of large non geostationary satellite constellations introduces new environmental impacts on the observable sky that require systematic consideration early in mission design. Building on the current regulatory and technical groundwork, the work to be presented develops an integrated approach for minimising both optical and radio interference, aligned with the evolving regulatory landscape governing space systems and passive scientific services.
For the optical (Dark Sky) domain, there is currently no binding international regulations on satellite brightness despite the rapidly emerging expectations from scientific stakeholders and space agencies, including ESA’s own sustainability-driven recommendations. Leveraging on these expectations and recommendations, and in collaboration with the astronomical community, a set of requirements for LEO constellations was crafted. A comprehensive modelling chain was then implemented to assess its compliance, incorporating the spacecraft’s detailed geometry, material properties derived from BRDF based characterisation, attitude dynamics, solar array articulation, and full constellation visibility modelling. This analysis identified the surfaces, configurations, and orientations that most strongly contribute to observed brightness and evaluated targeted mitigation strategies – such as surface darkening, specularity tuning, equipment relocation, and solar array orientation techniques – taking into account feasibility, manufacturability, and mission level constraints.
For the radio (Quiet Sky) domain, an in-depth analyse of the applicable ITU Radio Regulations, CEPT deliverables, and the general European spectrum management context provides a sufficient regulatory foundation for the protection of radioastronomy. The Radio Regulations in particular identify the protected Radio Astronomy Service (RAS) bands, their associated protection criteria, and the obligations placed on satellite operators. Building on these requirements, a statistical epfd based methodology consistent with ITU R RA.769, RA.1513, and S.1586 was developed to assess constellation level interference into radio telescopes. The approach takes into account out of band emissions, platform generated unintended radiation, antenna off axis behaviour, and long duration integration effects. This enables the derivation of satellite level emission limits and EMC driven design constraints that are technically and regulatory coherent with the general regulatory framework.
Together, these analyses embed Dark & Quiet Skies protection into early architectural requirements for future satcom constellations, supporting ESA’s Clean Space ambitions and proposing leads for the long term preservation of the astronomical environment.