Exciting flight results and lessons learned keep coming from the Starling FormationFlying Optical Experiment (StarFOX) which represents the first published demonstration of distributed optical navigation between multiple co-orbiting satellites in a swarm. The navigation system developed by the Space Rendezvous Laboratory is called Angles-only Absolute and Relative Trajectory Measurement System (ARTMS).
This video shows images produced by the on-board BCT star-tracker on Starling satellite Nr. 4 (left) with superimposed information generated by ARTMS. Note the autonomous object identification and tracking features. Here Starling satellites Nr. 2 and 3 are visible in the field of view at about 142 km and 79 km respectively. Reference truth data are available on the ground through GPS-based orbit determination which is not used by ARTMS on-board but only used to evaluate accuracy.
The ARTMS estimation errors for Starling satellite Nr. 3 orbit w.r.t. Nr. 4 are plotted in radial, along-track, and cross-track direction (right). At steady state, the residual errors standard deviation is less than 10m in radial and cross-track and less than 1km in along-track which is about 1.3% of the distance. This is achieved in the presence of sparse measurements and long data gaps due to eclipses (between vertical gray bars).
Note that NO a-priori information is used for the targets, instead bearing angles are accumulated over the first two orbits to generate a coarse state through nonlinear batch estimation to initialize the sequential unscented Kalman filter. In other words, ARTMS is a self-contained optical navigation system that can self-initialize as demonstrated in orbit.
Credits to Justin Kruger who created the video, to the NASA ARC Starling team (Howard Cannon), and to NASA SSTP (Roger Hunter) for the continued support.
