for three plane change capabilities. To increase the plane change capability from 32 to 62 degrees (+93.8%) the OEW increases just 19.1%. OEW and dry weight determine the cost of the spacecraft. Gross weight determines the operational cost. In this case the gross weight is 57% greater. Designing for a larger plane change capability (62 degrees), but operating at a 32-degree plane change, has only a minimal increase in the resources required over a spacecraft specifically designed for a 32-degree plane change, see the last two rows of Table 5.11. It would be practicable to design for the greater operational capability. Since the hypersonic gliders are designed to operate with hydrogen/oxygen propellants, the availability of engines is not critical, and a number of engines from either the United States or Russia are suitable.

We now have both the quantity of launcher propellant required to deliver the OMV propellant to LEO, and the OMV propellant required in each of three orbital maneuver missions. So we can now determine the total mass units of propellant (launcher and OMV) required per unit mass of the satellite for each of the four space propulsion systems.

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