Size of Infrastructure

From "The Machine Stops" to Nano-assemblers

• There are two fictional visions of self-replicating industrial infrastructure that are near opposite ends in scale. In a story "The Machine Stops," E.M. Forster in 1909 depicted all people on Earth and all of their machines interconnected as one self sustaining growing unit. Eric Drexler and others suggested that a desk top scale nano-assembler (once one was perfected) could make other nano-assemblers. In this way a self replicating industrial infrastructure, with mining, chemical processing and manufacturing could fit into a moving van. Each module would fit on a desk top and be ready to work with the others. If electrical power water and feed stock are provided, one module could make all the others. God has already got one up on Drexler with the carrot seed.
• Opponents of putting industrial infrastructure on Luna tend toward Forster's vision. They seem to think that if an industrial infrastructure is not as big as the Earth including as many people as live today, it cannot sustain itself and produce product. Since it is impossible to ship such a thing to Luna, those against lunar colonies suggest people should not try.
• Some proponents of industrial infrastructure on Luna seem to think that fully self maintaining and self reproducing industrial equipment could be sent to Luna with (perhaps) a half dozen Ares V launches. These launches would include perhaps a half dozen astronauts. Three of them would arrive on the first Ares V. They would be living in locally built housing and running the show the first day. Supporters of this vision could be imagining an industrial base something like Drexler's table top nano-factories. The industrial infrastructure would be set up in hours. It would support all the needs of astronauts from the start. Alternatively, enthusiasts could imagine that congress will cheerfully keep sending tang and freeze dried filet mignon to Luna for as many years as it takes for astronauts to set up industry. A few hundred astronauts in space suits with picks, shovels and other basic tools could dig out mines and building foundations. They could hand lay sintered bricks and weave reinforcing glass cables through holes in the brick.
• Actually the way to kill a government funded space program is to insist that the program simply must have resources that are more expensive than congress is willing to provide. The job of engineers is to solve a problem while working within certain constraints. The tighter the constraints in which something can be accomplished, the more cost effective and/or profitable that accomplishment tends to be.
• Neither Drexler's nano-factories nor Ares V launchers are necessary to build a lunar base that can support people. Time and remote controlled equipment can establish the infrastructure. This equipment neither eats nor drinks nor breaths, but can be designed to stay on the job many years. Once established, industrial infrastructure can support people and allow the export of products that will pay for imports. It may be fifty years before there are profits, not quite so long before people arrive. With local resources supporting them, people's hands on work can aid the lunar enterprise.
• All necessary remotely operated devices can be sent to Luna on moderate size rockets. The Ares V was planned to put 350,000 pounds into low Earth orbit as compared to 19,000 pounds for the Delta IV heavy. A modest modification to make the Delta IV heavy more appropriate for the low Earth orbit mission than the Geostationary orbit mission could improve on that. A useful unmanned space station that would provide a platform for vehicle assembly and refueling would allow 19,000 pound payloads to be assembled with a fully fueled vehicle that would put 19,000 pounds on Luna. A useful unmanned space station might have these four sections: A) A nonrotating section connected to a nonrotating axel; B) A constantly rotating portion housing storage tanks, solar cells, communications equipment and if necessary some structure and ballast that would increase its moment of inertia; C) A spin up/spin down portion to rotate on the same axel. It would hold rockets that fuel up or unload fuel; D) A counter rotating section would balance the angular momentum of the spin up/spin down section without using rocket thrusters. The nonrotating section would have solar cells and communications equipment. Cargoes of fuel and rockets to be refueled or assembled would dock with the spin up/spin down portion while it is not rotating. Docking of two spacecraft was demonstrated early in the space program. The center of mass of the loaded platform would be adjusted to the common spin axis of the station. The platform would be spun up to a mere 20 centimeters per second squared radial acceleration and fuel would be transferred with no problem. Sections of the refueling station would be connected by magnetic bearings and electric motors. There would no solid surface contact between the two. Bearings, motors, and power transfer devices would be mounted part on the nonrotating axel and part on the rotating section. Magnetic bearings do not need lubricants.
• Savings come from not building the Ares V nor maintaining launching facilities for the Ares V nor any other excessively large and expensive vehicle. More savings come from a higher frequency of launch of medium lift rockets resulting (at least potentially) in lower unit cost. NASA does not do things this way because of an institutional bias toward using big rockets. There is some argument for using big rockets in all at once launches for manned Mars missions, but the expense should all be counted toward the manned Mars missions. A program of Bootstrapping Industry on Luna does not require such big rockets.
• This does not need to result in a smaller NASA. Spending the same money on cheaper per each missions results in more missions.

A Lack of Data

• There is good reason to believe that the Ares V was just too big and expensive for a practical space program, but how big should a rocket be to fit well with NASA's programs? Some might think that a rocket similar to the Ariane V ES with a 46,000 pound to LEO capability would be sufficient. Others might consider that the Falcon_9 Heavy with a planned 71,000 pound to LEO capability would be better. If people oppose space colonization on principal, they would say anything larger than needed for communications and military satellites is a waste. Numerical matching of requirements and the ways of meeting those requirements is needed to get a good general idea. All in one launch missions should be compared with multiple launch with assembly on orbit missions when these are alternatives. We should compare the service to the overall goal and the cost. Such comparisons usually must contain a considerable measure of executive judgment in the form of ground rules for comparison.
• How big does an industrial base on Luna need to be to be mostly self-replicating? The Advanced Automation for Space Missions starts to address this question and others.