In-orbit flight results ALERT: our landmark paper on the initial flight results and lessons learned from the Starling Formation-flying Optical eXperiment (StarFOX) is out! Results demonstrate the applicability of angles-only navigation to future DistributedSpaceSystems (DSS) for Positioning, Navigation, and Timing (PNT) and Space-based Situational Awareness (SSA) as independent as possible from ground assets.
Justin Kruger, Sonny Hwang, Simone D'Amico;
Starling Formation-Flying Optical Experiment: Initial Operations and Flight Results;
38th Small Satellite Conference, Logan, Utah, August 3-8, 2024.
Redacted Abstract:
This paper presents initial flight results for distributed optical angles-only navigation of a swarm of SmallSats. StarFOX is a core payload of the NASA Starling mission, which consists of four CubeSats launched in 2023.
Angles-only methods apply inter-satellite bearing angles obtained by on-board cameras for navigation, increasing satellite autonomy and enabling new mission concepts. Nevertheless, prior flight demonstrations have only featured one observer and target and have relied upon a priori target orbit knowledge for initialization, translational maneuvers to resolve target range, and external absolute orbit updates to maintain convergence (see prior ARGON and AVANTI experiments).
StarFOX overcomes these limitations by applying the angles-only Absolute and Relative Trajectory Measurement System (ARTMS), which integrates three novel algorithms. Image processing detects and tracks multiple targets in images, using multi-hypothesis methods and kinematic modeling, and computes target bearing angles. Batch orbit determination computes initial swarm orbit estimates from bearing angle batches, via iterative batch least squares and sampling of the weakly observable target range. Sequential orbit determination leverages an adaptive, efficient unscented Kalman filter with nonlinear models to refine swarm state estimates over time. Multi-observer measurements shared over an inter-satellite link are seamlessly fused to enable robust absolute and relative orbit determination. StarFOX flight data and telemetry present the first demonstrations of autonomous angles-only navigation for a satellite swarm, including multi-target and multi-observer relative navigation; autonomous initialization of navigation for unknown targets; and simultaneous absolute and relative orbit determination. Relative positioning uncertainties of 1.3% of target range (1σ) are achieved for a single observer under challenging measurement conditions, reduced to 0.6% with multiple observers.
