Robert Salkeld

Robert Salkeld To estimate a common-based comparison of asteroidal and lunar materials costs, both are here placed on the same program basis as assumed, for the lunar case (ref. 9). That is, Earth launches are assumed to begin in 1985 using the first generation space shuttle (capacity 60 flights/yr), phasing in 1987 to a shuttle -derivative heavy-lift vehicle (SD/HLV) for unmanned cargo (capacity - 80 flights/yr), and finally phasing in 1991 to a second generation passenger-cargo single stage-to-orbit (SSTO) shuttle. Program duration is 10 years (1985-1994), during which about 1 million tons of asteroid material (from the capture of two 1-million-ton asteroids) are returned to the space manufacturing facility (SMF), compared with about 2.4 million tons of lunar materials.

Capture of two asteroids in this time period is based on the estimate of a 5-year out-and-back mission time, and is consistent with the maximumpaced program assumed for the lunar case. Thus, the first generation shuttle launches the asteroid miner and mass driver in sections during 198586, contributing in the process all of its external tanks for mass-driver reaction mass. The SD/HVL then phases in to launch a second miner and mass driver, and all the remaining reaction mass for two asteroid expeditions as well as chemical orbital transfer vehicles (OTV) and their propellants for establishing the SMF, during 1987-89. The first expedition leaves low-Earth orbit (LEO) early in 1987 and returns in 1992. When it has successfully reached its target and is homeward bound 1989, the second leaves to return in 1994. The SD/HVL, SSTO and OTV establish the SMF in 1989-92 so that it is ready to process the first returning asteroid. The chemical OTV is used for SMF rather than a smaller mass driver, to avoid a second mass driver development program, and because the OTV is required in any case for SMF personnel transfer. Use of a mass driver for deploying SMF would reduce total program cost only slightly.

The results of preliminary costing of the asteroid and lunar programs are summarized in table 3. A possible requirement for an LEO station has been included as one consideration, to maintain as comparable basis as possible with the lunar case. Several observations may be made:

  1. Costs of asteroidal materials are higher in table 3 than in figure 15 because of inclusion of the SMF and higher cost launch vehicles in the program, to be more comparable with the lunar case.
  2. Costs of asteroidal materials are not sensitive to the requirement for an LEO station, since its development, deployment and resupply costs are small in the total picture.
  3. The total program cost for the asteroid option is only about half that of the lunar case including nonrecurring research, development, test and engineering (RDT & E) costs; it is only about one-third that of the lunar case if RDT & E costs are excluded.
  4. Cost per delivered kg of material is 10-20 percent higher for asteroid materials if RDT & E are included, but 25-30 percent lower than lunar materials on a recurring cost basis. Reasons for this are the relatively high RDT & E costs, but the lower amount of massdriver throughput for the same delivered mass, for the asteroid than the lunar case. In addition, the asteroid operation is not burdened with the establishment and operation of anything akin to the mass-catcher or lunar orbit facilities and logistics.
  5. These results suggest that for comparable or better economics in terms of cost per kilogram delivered, the asteroid option is significantly more attractive than the lunar option in terms of front-end "price of admission." The relative attractiveness of the asteroid option would of course be further strengthened if asteroidal material compositions are found more favorable than those of lunar materials.
1.1X106 tons delivered
to SMF
2.4X106 tons
to SMF
No Yes Yes
Total program,
$ billions
27.7 31.2 57.0
11.9 12.6 37.0
Per kg
25.2 28.4 23.8
10.8 11.5 15.4

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Curator: Al Globus
NASA Responsible Official: Dr. Ruth Globus
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