TOPEX/Poseidon was launched on August 10, 1992 and decommissioned 13 years later on October 9, 2005. Considering the satellite mission's age, its primary mission lifetime design of 5 years, and its decreasing mission budget profile, TOPEX/Poseidon posed significant navigation challenges during the latter part of its lifetime. This paper describes the navigation products and services required to maintain TOPEX/Poseidon in its operational orbit given the primary science requirement that 95% of all TOPEX/Poseidon equatorial crossings occur within +1 km of a pre-defined reference ground track. The paper also talks about the navigation strategies, the Orbital Maintenance Maneuver (OMM) history of TOPEX/Poseidon, and the TOPEX/Poseidon Orbit Transfer Maneuvers (TOTM) campaign. Finally, several cost cutting initiatives are discussed as well as the orbit disposal and decommissioning strategy. Nomenclature AOP = Argument of Perigee β' = angle between the orbital pane and Earth-Sun line e = eccentricity SAPB = Solar Array Pitch Bias SMA = Semi-Major Axis

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This paper describes some of the operations experience of the ESA flight dynamics and NASA/JPL navigation teams on the Ulysses mission. It provides an overview of the major mission milestones and key dates for Ulysses and brief introductions to the attitude and orbit control systems on-board the spacecraft and the on-ground flight dynamics and navigation systems. A section of the paper discusses some aspects of attitude manoeuvre operations while another discusses the orbit determination strategy employed on the mission. There is also a discussion of the solar heating induced spacecraft nutation and the techniques employed to control it. Finally some low cost operations practices are presented.