8.2.2 Present Status of Upper Stages/OTV's Current conventional launch systems (Ariane 4 for example) directly inject payloads into the envisaged target orbits of OTV's and don't need staging in Low Earth Orbit. This means that the upper stages work as OTV. But changes of strategy (as American NSTS or Ariane 5) with reusable orbiters requires a LEO staging. Consequently new upper stages (i.e. EPS-L9 for Ariane 5) are the first step in the OTV field. The Table 8.3 summarizes the main characteristics of OTV like vehicles currently in operation or in development (and available before 1997). Remark :The functions and characteristics of all these systems have three common features which are really typical of the current Space Transportation Systems i.e. 1. Dedicated to a particular payload transfer mission (Mass + AV) 2. Expendable 3. Using a chemical propulsion system (solid or liquid rocket engine). ____________Table 8.3; Main Characteristics of OTV-like vehicles 8.2.3 OTV Analysis Market Survey First of all let's present a rough near term market analysis to show that such vehicles have a real potential market outside the Space Solar Power Program needs. A dedicated study was performed in Europe (based on previous studies of Arianespace and satellite operating organizations) in order to identify the coming market. Eastern world needs (mainly former USSR and China) were not taken into account and it was assumed that total number of commercial
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