Fig. 5. PDV for all space operations (billions of dollars). This relationship can be incorporated into the cash flow equation as follows: The PDV can be evaluated by applying the discount factor e~r<, and integrating over the period in question. For a 100,000 T SMF using the base case technology, the PDV of 50 years of net revenues is approximately one trillion dollars, discounted at 10% per year to the time at which production of Q begins. These benefits are introduced to the total project value at the times specified in Fig. 4. The result of adding the appropriately discounted revenues to the isocost curves of assembling the SMF is shown in Fig. 5. The length of time required to develop the capital obviously exerts the dominant influence. However, the cost of establishing the SMF (Fig. 3) adds a slight bias toward the origin. Figure 5 still does not tell the whole story. It demonstrates the PDV from the first launch of terrestrial materials, but ignores the costs incurred prior to space operations. Perhaps the most important of these factors is the cost of the transport fleet. Indeed, it is the neglect of this expense which allows the peak PDV to stay at the maximum M. It has been previously suggested that the optimal fleet for bootstrapping would consist of numerous small vehicles (11). In this case, the fleet cost is roughly proportional to the transport capacity and can be viewed on a relief diagram as a plane
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