Fig. 8. Synergistic Moon and low Earth orbit program to start growing space industry. industries in space? No, I don't think so. Rather, let us find moon/LEO projects that are of about the same scale as the present space program. Initially, this new approach can concentrate on building small but flexible production systems and making simple products which are valuable in space. If there is much traffic to geosynchronous orbit or beyond, then one-half to two-thirds of the traffic from Earth to LEO can be propellant. On a weight basis, much of the remaining mass can be relatively simple structural components which can be fabricated in LEO. Lunar materials delivered to LEO could yield liquid oxygen and structural materials suitable for major mass fractions of many space payloads. This approach would free the shuttle capacity for other uses. In effect, use of lunar materials could leverage STS effectiveness. Rapid accumulation of productive experience in space can reveal reliable options for growth with minimal theoretical debate. What is that scale of entry? An intuitive approach is to approximately match the scale of transport of mass to LEO by the present Space Transportation Sytem. In the mid-to-late 1980s STS traffic is projected to be 30 to 40 flights per year with average payloads of 20,000 kg (maximum is 30,000 kg). Steady mass flow is therefore 70 kg/hour (19 grams/second; 6 U.S. pennies have a mass of 19 grams) to 140 kg/hour (38 grams/second). Assuming an average of 100 M$/flight (mission and payloads), the cash flow would be about 3 B$/year to 5 B$/year. This corresponds to steady production cash flows of 340,000 $/hour (95$/second or 5 $/gram or 16 $ per penny mass) to 570,000 $/hour (160 $/second). Mass flows matching the operation of one shuttle (about '/s the previous estimates; about 1 penny per second) might be the lower limit for starting lunar industries. Figure 8 depicts a general approach for starting growing cis-lunar industries (31,77). A small dust gathering-and-ejection system could be placed on the moon at one of the Apollo sites. Likely it would be an unmanned system, probably powered by solar energy and scaled to eject one to a few 10s of grams per second on average
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