Tank passivation of geostationary satellites

CNES has adopted in October 2004 the European Code of Conduct on space debris, which is applicable to all new space projects of the French Space Agency. Concerning old satellites launched before any recommendation for space protection was established, CNES tries to adapt their end of life strategy in order to respect the mitigation guidelines as well as possible, like for example, when de-orbiting Spot1 or re-orbiting TDF2. Both major key points are then to dispose the satellite into a post-mission dedicated orbit zone and to minimize the potential for post-mission break-up. This paper deals with the specific question of depleting the residual propellant and other fluids in the case of geostationary satellites. Due to old designs not taking into account the need for emptying the tanks at end of life, a specific strategy has to be developed, in order to fulfill this objective and respect the other mitigation guidelines. But it is necessary to persuade the operator to authorise the emptying and the industrials to design an adapted strategy. In this context, CNES has decided to facilitate the depletion guideline respect by conducting activities of Research and Technology with industrials.