store the fuel, as well as periodically service the generator, are likely to be significantly greater and less convenient than receiving energy from a centrally supplied power station. The above terrestrial analogy might be considered obvious. However, in the first three and a half decades on orbit the only facility that has been deliberately expanded and supported in space on a continuous basis over many years is the Mir Space Station. This is a very important point, considering that Europe will not obtain any similar experience until the first servicing mission to the Columbus Free-Flyer in 2004. The high cost and limited opportunities to access and return from space severely prohibits such activities. 4.1.1 Example of Space Station Freedom The deployment of Freedom sometime in the next 10 years will provide the West's first experience with the problems of supporting a very large, high- power system in space. Freedom's current logistics support planning is an instructive guide in understanding the impacts on a large space facility that must provide its own large solar panels for power. The principal impacts are felt in two key areas: Starion-Keeping Propellant Freedom will be located in an approximately 400 km low Earth orbit where it is in easy reach of the Space Shuttle, but where atmospheric drag remains significant. Unfortunately, this high drag conflicts strongly with the desire to increase the power capability of the station: the larger the solar arrays, the higher the drag. The current version of Freedom (Figure 4.1-1) at the Permanently Manned Capability (PMC) will have two solar array wings capable of producing 37.5 kW of user power. These wings represent a total surface area of the solar array of about 1,300 m2. Originally, the plan was to
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