METHODS FOR ESTIMATING COST AND TIME FOR SSPS AND MORE COLONIES
Column 3 of Table 6-12 gives the number of new terrestrial SSPS's produced per year. The program is set up so that from the first year of production the level of output is always equal to the demand for terrestrial SSPSs, which is calculated in appendix E. That appendix shows that the level of demand depends in part on the year in which production begins. To determine demand, year 1 of the program is assumed as 1976.
To avoid undue complexity, composite variables are used in the analysis for two major variables - SSPS's and all colonies other than the first. Costs of a composite are obtained by aggregating costs of its components, including a charge for use of capital and an adjustment for the cost of maintenance. Methodology and costs of the major components are set forth in appendix F.
Costs for each of the composites are expressed by 5 variables whose initial values are: for an SSPS, $9.73 billion plus the costs associated with obtaining 3,398 man-years of labor at L5; 700 man-years of labor on the Moon; and 557 manyears of labor in other locations in space. In addition, the costs of 2298 percent of a chemical processing and fabricating plant at L5 is charged to the SSPS. These costs decrease over time due to learning curves and the introduction of the second generation shuttle system. Second and later colonies are only produced after the second-generation shuttle system has been introduced. Their costs are also affected by learning curves. To begin with, colonies cost $9.24 billion, 20,946 man-years at L5 - 1759 man-years on the Moon, 626 man-years elsewhere in space, and a chemical processing and fabricating charge of 0.5741 L5 plants.
Man-year requirements for both SSPS's and colonies are assumed to decrease as additional units are produced with an 80 percent learning curve, found to be empirically valid in the aircraft industry (refs 5,6). The level of output of new terrestrial SSPS's coupled with the labor costs of an SSPS and the assumption that an SSPS is produced within 1 yr, determine the number of workers needed at L5 for SSPS construction, as given in column 4 of table 6-12. Column 5 of table 6-12 gives the number of new and old colonies. Columns 6 and 7 give the number of SSPS workers in colonies and construction shacks, respectively.
The timing of the nonlabor costs for building any particular colony other than the first is determined by assuming that expenditures are proportional to the labor input Column 9 gives the number of new chemical processing and fabricating plants that are needed for a given year at L5 to build the scheduled number of SSPS's and second and later colonies. The initial chemical processing and fabricating plant has a mass of 10,800 t. It all comes from Earth The cost of material purchased on Earth for all plants is assumed to be $600/kg. Taking into consideration the previously-mentioned learning curve and the cost of transportation for the year in question, the costs of all plants can be determined. Next, for each year, the average cost is computed of plants that have been placed at L5 during that year or any preceding year for the purpose of building terrestrial SSPS's or second and later colonies. Similarly for colonies, the total nonlabor costs in dollars of terrestrial SSPS's and of second and later colonies are given in columns 10 and 11.
Column 13 gives the costs of labor. It is assumed that every colonist obtains 100 kg from the Earth annually and that the purchase price on Earth is $5/kg. Luxury goods and various consumable goods produced within the colony make up the colonists' wages. The costs for a worker who is not a colonist consist of wages, crew rotation costs, and supplies from Earth. Wages cost $120,000 per worker for each year spent in space. Each noncolonist also requires 1.67 t of supplies from Earth per year, costing $5/kg purchase price on Earth plus transportation. Besides workers who live in construction shacks at L5 all workers not at L5 are assumed to be noncolonists. Column 14 gives the total costs.
The total of terrestrial SSPS's being used, column 15, is the sum of all terrestrial SSPS's built during the previous year or before, minus those worn out after an assumed lifetime of 30 yr. The derivation of the benefits listed in column 16 is discussed in appendix E.
The last column of table 6-12 gives the costs of the power produced after SSPS's come into commercial production. The cost of second and later colonies is thereby incorporated since they are needed to house the required labor. It is assumed that the resulting cost must be paid over the 30-year lifetime of the SSPS. A level charge for the 30-year period, which also covers interest at a real rate of 10 percent is then computed. The same procedure is followed so as to compute a level charge for all terrestrial SSPS's. To obtain the cost of electricity for a particular year, the level charges of all terrestrial SSPS's which produce electricity in that year are averaged.
TABLE 6-12, columns 1-9 (gif format)
|(1) (b) |
at L5, (d)
in colonies, (e)
shacks at L5
Labor at L5
used to build
second and later colonies, (d)
Number of new
chemical processing &
being used at L5
to build SSPS's & 2nd & later colonies (d)
SSPS costs, (d), (f)
Costs of second
Labor costs, (d)
Total costs, (h)
SSP's in use
Costs of space
(a) The analysis runs for 70 yr. The numbers for the last 25 yr corresponding to table 6-12 are not given. They may, however, be calculated by the reader if desired. All of the required data are given within this chapter.
(b) Indicates columnar numbers referred to in text.
(c) These costs are obtained by summing the costs in table 6-9.
(d) All learn curves with respect to SSPS's, colonies, and chemical processing and fabricating plants, have the first unit given in the table as the second unit in a learning curve since one colony, one SSPS, and one plant were produced previously and have their costs accounted for as part of the adjusted costs of figure 6-2.
(e) Second and later colonies which are finished in year X are assumed to provide their full complement of labor in year X-1. The first colony is assumed to be complete except for 37.5 percent of its radiation shield by the beginning of year 20. The colony is then slowly occupied. One-sixth of its full complement of export labor being available in year 20, one-half in year 21, five-sixths in year 22, and all of it thereafter. By the beginning of year 23 the colony has been completed
(f) The initial SSPS dollar costs can be divided into a constant cost of $2.48 billion and a variable cost of $7.26 billion. The introduction of the second-generation shuttle system reduces these numbers to 1.99 and 4.77, respectively. The variable cost falls in accordance with an 80 percent learning curve until it has decreased by a factor of six. (See footnote (d).)
(g) All numbers in this column can be calculated from information given in table 6-12 except for the entries for years 15 through 22. These use as additional inputs the amount of labor related directly or indirectly to the first colony. In chronological order these inputs are 2671, 3010, 3214, 3316, 3486, 1375, and 1375 man-years.
(h) To help maintain a reasonably smooth pattern of expenditures, $4 billion which, according to the algorithm, should have been spent in year 20 is moved to year 19. For similar reasons $2 billion is moved form year 25 to year 24. In practice these changes could be accomplished by purchasing on Earth some of the components for SSPS's the year before they are actually needed.
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