FLIGHT RESULTS FROM THE CANX-4 AND CANX-5 FORMATION FLYING MISSION

In November 2014, only five months following launch, the CanX–4 and CanX–5 dual-spacecraft formation-flying mission became the first nanosatellites to successfully demonstrate autonomous formation flight with sub-metre control error and centimetre-level relative position knowledge. This achievement was preceded by a rapid commissioning phase and orbit acquisition manoeuvres, which brought the two satellites from a maximum range of 2300 km to a closest controlled range of 50 m during formation flight. Launched on 30 June 2014 from Sriharikota, India on board the Polar Satellite Launch Vehicle (PSLV), CanX–4 and CanX–5 were deployed separately, after which a series of drift recovery manoeuvres were executed to bring the spacecraft within communications range of each other. Subsequently, the spacecraft used cold gas propulsion, an S-band intersatellite communications link, and relative navigation using carrier-phase differential GPS techniques to perform a series of precise, controlled, autonomous formations with separations from 1 km down to 50 m. The achievements of CanX–4 and CanX–5 have set the benchmark for small satellite formation flight, and the technologies and algorithms developed for this mission enable a number of future applications, from on-orbit inspection and repair to sparse aperture sensing, interferometry, and ground-moving target indication.