realistic even in the very, very optimistic scenario described above. The cost to build a Powersat that can simultaneously supply power to 30 or 40 comsats positioned several thousands of kilometres away - if. indeed, it is technically feasible at all - would, in fact, turnout to be much greater than the cost to build one comsat. Although it is impossible to estimate accurately, a cost in the region of "hundreds of millions of AUs” is probably realistic. This example also brings up other important issues, particularly those relating to spacecraft missions and launch costs. While the launch costs in Figure 3-3 were calculated on the basis of cost per kilogramme, this can be misleading. Most launch vehicles do not charge precisely on the basis of how much the satellite weighs, but rather what mass range it falls into. For example, a dedicated Ariane 44L vehicle can carry up to 4.3 tonnes into GTO, but it costs a discrete amount more than an Ariane 44LP booster that can carry 3.7 tonnes. Further, the cost per kilogramme of an Ariane 44LP is more than an Ariane 44L. Hence, it costs more per kilogramme to launch a smaller satellite than a larger one, minimising the benefits of saving relatively small amounts of mass. The same distinction is true between an Atlas 2AS and an Atlas 2A. Thus, although a satellite which uses a Powersat might weigh 280 kg less than a satellite that doesn’t use a Powersat, the launch costs might still be about the same. In some cases, such as with a dual launch or where a 280 kg reduction makes the difference between two different types of launchers, there might be a launch cost savings, but these are unlikely to be as large as suggested by Figure 3-3. Further, this saving is effectively spread over the 10+ years lifetime of the comsat. If the launch cost savings shown in Figure 3-3 could be realised, this would lead to an amortised savings of 560,000 AU per year. (i.e. [280 kg x 20.000 AL/kg]10 years). By the same token, the cost to the user of not needing to be equipped to carry a full-sized solar array, batteries and other
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