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Geostationary orbit will remain in the near and far future one of the most frequently used for several applications including, mainly, telecommunications. For the time being the GEO satcoms are injected by intermediate, heavy or super heavy class launch vehicles, LV, using quasi standard procedures: low altitude injection on a geostationary transfer orbit, ballistic phase of at least five and a half hour, followed by an apogee manoeuvre (or boost) to reach GEO. Apogee boost is most of the time provided by the propulsive system of the satellite, if this one uses liquid propellant in an integrated system performing final injection and house-keeping for the whole life (up to 15 years) of the satellite. The current launch vehicle features generally a cryogenic (LOX/LH2) or semi-cryogenic (LOX/Kerosene) upper stage having a better Isp than the Isp of the satellite propulsive system: The possibility to provide the apogee boost by the LV upper stage seems attractive. Another possibility is to put on the top of the upper stage an other small stage, or module having the function of kick-stage, as it was done earlier when solid propellant stages were used for this apogee manoeuvre. This presentation will describe the pros and cons of this various choices for single but also dual launches in GTO/GEO, and also will address future new injection scheme, providing new transportation services to satellites featuring advanced propulsive systems such as electric, plasmic or thermo-solar thrusters, requiring other transfer orbits like MEO, GTO+ and super GTO+. |
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