Collision Avoidance Practises for GEO Satellites in an Operational Control Centre

The protection of the geostationary ring has always been a big concern for CNES, in charge of geostationary station-keeping since 1974. In particular, protecting this unique resource implies to absolutely avoid any collision in this region, as it could generate debris that would pollute on a long term basis the whole geostationary ring and so threaten all current and future missions.This paper will focus on CNES recent experience concerning on-orbit collision avoidance for operational geostationary satellites. The different stages of risk mitigation will be discussed : specific practices to increase safety during longitude drift phases, daily screening for conjunctions detection, analysis of risk and decision of performing an avoidance manoeuvre with respect to mission constraints. This process will be illustrated by two examples of operational management for proximity situations.