The ESA Project for On-Board Autonomy – 3 (PROBA-3) mission is a technological demonstration for precise formation flying of two small spacecraft in a Highly elliptical Earth Orbit. The mission’s main objective is to demonstrate and validate formation flying techniques with high precision, performing formation control, collision avoidance, and rendezvous operations. In addition to the technological goals, PROBA-3 accommodates a scientific payload that takes advantage of the formation flying capabilities derived from the millimetre relative position precision. The Association of Spacecraft for Polarimetric and Imaging Investigation of the Corona of the Sun (ASPIICS) is a coronagraph system distributed over two satellites: the CSC (Coronagraph SpaceCraft) carrying a telescope imaging the corona in visible light, and the OSC (Occulter SpaceCraft) carrying the Sun occulter disk that will produce an artificial eclipse.