Attitude control recovery of the CERISE microsatellite following an in-orbit collision

The first ever credited collision between two catalogued space objects has been detected in low Earth orbit. After one year of operation in space, controllers at the Mission Control Centre, Guildford, Surrey, observed a sudden change to the attitude of the CERISE microsatellite as it tumbled rapidly end-over-end in its 700 km polar Earth orbit. After initial investigations, a collision with a piece of space debris was suspected. Despite the impact the CERISE microsatellite and its payloads continued to operate under full ground control. In the process of the mission recovery, Surrey mission control engineers re-programmed the microsatellite's advanced on-board computer with new attitude control software allowing it to continue its mission, relying solely on the on-board electromagnets since there is now little gravity stabilisation due to the loss of the boom in the impact. The paper describes the determination of the new moment of inertia following the loss of the gravity gradient boom in the collision, and also the estimation of the attitude state before and after the collision. A number of new attitude control algorithms were considered to provide a way to continue the mission. The simulation of one possible algorithm is described, which aims to recover the nadir pointing attitude without the gravity gradient boom. Preliminary verification of this possibility is shown using in-orbit results from the UoSAT-5 spacecraft.