Covariance-based estimation performance for in-flight calibration of NASA’s ACS3 solar sail

Abstract

Solar sailing exploits solar radiation pressure to generate propellantless thrust, enabling mission applications beyond the capabilities of conventional propulsion systems. Despite this potential, the lack of in-flight validation for solar-sail force models has limited confidence in applying solar sailing beyond technology demonstration missions. This study presents the first comprehensive investigation into the potential of solar-sail performance characterisation from flight data by applying a covariance-based estimation framework using simulated GNSS observations for NASA’s ACS3 mission.A set of calibration steering laws is proposed to facilitate the in-orbit estimation of the parameters governing the solar-sail acceleration. The study focuses on the sail frontside reflectivity and specularity, the optical coefficients exerting the strongest influence on the solar-sail dynamics. For each steering law, the covariance analysis quantifies the achievable estimation accuracy of these coefficients as a function of measurement noise, observation arc length, sampling rate, and ACS3 expected orbital evolution over the coming year. The operational feasibility of the calibration steering laws is also assessed through the evaluation of power budget, ground station communication, altitude maintenance, sail material degradation, and attitude rate limitations.For the 10-meter observation noise level expected in ACS3 telemetry, results indicate that a dedicated in-flight calibration can reduce the formal errors of the optical coefficients in the (Formula presented) to (Formula presented) range, an improvement of two to three orders of magnitude compared to pre-flight ground characterisation. When estimation performance is evaluated against operational constraints, the power budget is identified as the main limiting factor, and the fixed in-plane pointing steering law emerges as the most robust strategy, consistently delivering high-accuracy estimates while satisfying all operational constraints across diverse orbital geometries.