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“ The design and construction of a fully self-replicating factory system will be a tremendously complicated and difficult task. It may also be fairly expensive in the near-term. Before embarking upon such an ambitious undertaking it must first be shown that machine self-replication and growth is a fundamentally feasible goal. ”

“ If the manufacture of each part requires, on average, the addition of >1 new parts to product it, then an infinite number of parts are required in the initial system and complete closure cannot be achieved. On the other hand, if the mean number of new parts per original part is <1, then the design sequence converges to some finite ensemble of elements and bounded replication becomes possible.
The central theoretical issue is: can a real machine system itself produce and assemble all the kinds of parts of which it is comprised? ”

“ Closure engineering In actual practice, the achievement of full closure will be a highly complicated, iterative engineering design process. Every factory system, subsystem, component structure, and input requirement (Miller and Smith, 1979) must be carefully matched against known factory output capabilities. Any gaps in the manufacturing flow must be filled by the introduction of additional machines, whose own construction and operation may create new gaps requiring the introduction of still more machines. ”

“ The basic concept of physical machine systems capable of self-replication appears credible both from a theoretical and a practical engineering standpoint. It is reasonable to begin designing replicating systems based on current knowledge and state-of-the-art technology, but final design definition will require significant further research. Complete systems closure is achievable in principle, though partial closure may be more feasible from an economic and pragmatic engineering standpoint in the near term. ”

“ For instance, the in situ computer could be used simply as a teleoperation-management system for operations controlled directly by Earth-based workers. Material factory replication would proceed, but information necessary to accomplish this would be supplied from outside. An intermediate alternative would permit the on-site computer to handle mundane tasks and normal functions with humans retaining a higher-level supervisory role. Yet another possibility is that people might actually inhabit the machine factory and help it reproduce - manned machine economies can also self-replicate. ”

“ When the output stream is identical to the machine processing system itself, then the system is manufacturing more of itself - self-replicating - and the extraction ratio becomes an index of system materials closure on an element-by-element basis. ”

“ In addition to all Phase C capabilities, the Phase D system must be able to prepare industrial feedstock for input to the fabrication machines. Successful completion of Phase D is expected to be the most difficult of all because, in addition to the parts closure problem represented by the addition of materials processing machines, all chemical elements, process chemicals, and alloys necessary for system construction and operation must be extracted and prepared by the materials processing machines. ”

“ If allowed to expand for 18 years without diversion to production, the factory output could exponentiate to more than 4 X 109 tons per year, roughly the entire annual industrial output of all human civilization. ”

“ Computer control is nominally located at the hub of the expanding LMF disk, and commands in hierarchical fashion a distributed information processing system with sector computers at each node and sector subsystems at the next hierarchical level of control. ”

“ The master control and command system, located within the stationary universal constructor, is programmed to supervise the total SRS operation and to communicate both with the peripheral controls of the mobile universal constructors during the selfreplication phase and with the replicated stationary universal constructor during the transfer of command and control for the operation of the new SRS unit. ”

“ Mining robots equipped with grading tools proceed to the construction site and level the local surface. Five paving robots disembark and begin laying down the seed platform in square grids. This requires one working year for completion. When a sufficiently large platform section has been completed, seed mobile robots transfer the main computer to a place prepared for it at the center of the expanding platform disk. Erection of the solar canopy begins, followed by each of the seed sectors in turn, starting with the chemical processing. ”

“ Growth is quadratic from that time on. However, in real physical systems such as the developing LMF, enclosure need not preclude material communication with exterior units. Selected ramification of communication, control, and materials transportation channels or internal component rearrangement, reconfiguration, or specialization can prevent "starvation" in the inner regions of the expanding system. ”

“ Hence, SRS exponential growth may continue until limited either by purposeful design or by the - specific configuration of the external environment. Assuming that a 100-ton seed produces 100 tons/year of the same materials of which it is composed, then if T is elapsed time and N is number of seed units or seed mass-equivalents generated during this time, T = I + log2 N for simple exponential "doubling" growth. (There is no replication in the first year, the time required for initial setup.) ”

“ A finite number of parts involves a finite number of machine operations, this number being less than the number of parts because some machines can make more than one kind of parts. Therefore, the number of machines is finite and less than the number of operations. ”

“ Paving operations require a well graded surface, and cellar digging is necessary so that the LMF computer may be partially buried a short distance beneath the surface to afford better protection from potentially disabling radiation and particle impacts. Towing is needed for general surface transport and rescue operations to be performed by the mining robots. The robot design selected is a modified front loader with combination roll-back bucket/dozer blade and a capacity for aft attachments including a grading blade, towing platform, and a tow bar. ”

“ Figure 5.18 - LMF assembly sector: Operations. Computer control and communications. The seed computers must be capable of deploying and operating a highly complex, completely autonomous factory system. The original computer must erect an automated production facility, and must be expandable in- order to retain control as the LMF grows to its full "adult" size. The computer control subsystem coordinates all aspects of production, scheduling, operations, repairs, inspections, maintenance, and reporting, and must stand ready to respond instantly to emergencies and other unexpected events. ”

“ Expansion is radially outward with an accelerating radius during the growth phase. Original seed mass is 100 tons.
The replicating LMF design encompasses eight fundamental subsystems. Three subsystems are external to the main factory (transponder network, paving, and mining robots) . The LMF platform is divided into two identical halves, each comprised of three major production subsystems: (1) the chemical processing sector accepts raw lunar materials, extracts needed elements, and prepares process chemicals and refractories for factory use ”

“ Storage is in lots earmarked for specific facility construction sites. The replication parts depot also serves as buffer during interruptions in parts production plant or universal constructor operations.
Production facility. The production facility manufactures the desired products. Parts and subassemblies are picked up at the production parts depot and are transported to the production facility to be assembled into specific useful products. Finished products are then stored in the products depot. Ultimately these are collected by the product retrieval system for outshipment. ”

“ A given SRS design must be economically, politically, and socially feasible, or else it may never be translated into reality even if the technology to do so exists. A general discussion of the implications of replicating systems appears in section 5.5, but the team has arrived at no firm conclusions regarding concept feasibility in this area. More research is clearly required.
5.3.2 Concept Definition
In order to demonstrate SRS concept credibility, specific system designs and mission scenarios must be subjected to a detailed feasibility analysis. ”

“ Production - Generation of useful output from useful input. The unit machine remains unchanged in the process. This is a "primitive" behavior exhibited by all working machines including replicating systems.
Replication - Complete manufacture of a physical copy of the original unit machine, by the unit machine.
Growth - Increase in mass of the original unit machine by its own actions, retaining the physical integrity of the original design. ”

“ In our generalized terrestrial industrial economy manned by humans the answer clearly is yes, since "the set of machines which make all other machines is a subset of the set of all machines" (Freitas et al.,1981) . ”

“ The incremental gains in closure after 90% are purchased only at great price - from 1 to 3 orders of magnitude more raw materials mass must be processed to achieve the last bit of full materials autonomy. ”

“ If all existing machines were disassembled into their individual parts there would obviously be a finite number of parts, many of them identical, and a large number would be of common categories like shafts, motors, wiring, etc. ”

“ Mobile assembly and repair robots, assisted by mining robots, emerge from the landing pod and erect a small provisional solar array to provide interim power until the solar canopy is completed. LMF robots, with the computer, select the precise site where erection of the original seed will commence. ”

“ Growth and production of useful output may proceed sequentially, cyclically, or simultaneously, though the former is preferred if large subsystems of the lunar factory must be reconfigured to accommodate the change. ”

“ Note that 100% closure (C = 1) is achieved for the "U.S. Industrial" estimate (84 elements of the space probe "seed") at R = 2984; for "Demandite" (28 elements) at R = 1631; and for the appendix 5E "LMF" (18 elements) at R = 45. This suggests that the fewer the number of different elements, and the more common and more efficiently extractable are the elements the factory system needs for replication to occur, the lower will be the total mass of raw materials which must be processed by the LMF.
Figure 5.23 - Quantitative materials closure data for various self-replicating systems. ”