Page:Advanced Automation for Space Missions.djvu/282



5D.1 Mining Robot Functions

The requirements of seed mining robots which are components of the proposed growing, replicating Lunar Manufacturing Facility (LMF) include six basic functions:


 * Strip mining - Mining robots must be able to strip mine the lunar surface without the need for overburden removal down to a depth of at least 2-3m.
 * Hauling - Having "mined" a certain amount of unbeneficiated lunar regolith, mining robots must haul their loads back to the central LMF complex for further processing. It is possible that greater efficiency might be achieved by separating the hauling and excavating functions. Also, Carrier (1979) has pointed out that it may be more efficient to beneficiate raw materials at the pit site so that only useful soil components need be transported some distance to the LMF. This would reduce the mass of mining robots required, but would increase the mass of equipment located a distance from the base site.
 * Landfilling - On the return leg of each journey from the strip mining pit to the growing seed factory, each robot carries a load of unused slag or waste materials back to the pit where it is packed in as landfill. The pit might perhaps be excavated in a spiral pattern, with the fill site lagging the dig site by a gradually increasing amount.
 * Grading - Mining robots must be sufficiently general purpose to be capable of rough leveling of hilly terrain and then precision centimeter-level grading preparatory to paving robot activities.
 * Cellar digging - It is conceivable that the LMF computer at the center of the circular factory complex, and perhaps certain other LMF components as well, will need to be buried under a few meters of lunar topsoil for reasons of temperature control, radiation shielding, and so forth.
 * Towing -- Miners are the mobile workhorses of the growing LMF complex beyond the confines of the factory platform. When mining machines break down somewhere outside, miners must go to them and tow them back if they are immobilized. For example, if a robot has become trapped because of pit wall collapse, from a fall in loose lunar soil, or has become jammed into the surface or under fallen rocks, mining robots are ideal rescuers because they are also the LMF excavation machines and are smart and mobile enough to handle such tasks with ease.

Many additional mining-related functions conceivably could be performed by a robot system capable of the most general classes of excavation and mining activities. Indeed, such capacity might be absolutely essential if seed packages are dispatched to other planets than the Moon (e.g., Mars, Titan, Mercury, or Earth). These added functions include drilling, tunneling, blasting, and many others. But the basic six capabilities described above appear both necessary and sufficient for system survival and growth on the lunar surface.

5D.2 Design Alternatives

There exists a bewildering variety of mining and excavation machine technologies from which to draw in conceiving an autonomous vehicle (Nichols, 1976). The final design is a variant of the system devised by Carrier (1979) during a 1978 NASA-sponsored study on extraterrestrial materials processing and construction (Criswell, 1978).

In Carrier's system, strip mining proceeds in an annular sector ω radians wide as shown in figure 5.37. The total system is designed for gradual expansion. based on Earth supply or lunar colony supply, over a 30-year period. In the first few years of operation, all stripping and hauling to the central processing plant is performed by front-end loaders (also called, variously, the "shovel dozer." "dozer shovel," "tractor loader," "end loader," "front loader," or "loader"). These machines are used on Earth for digging, loading, rough grading, and limited hauling. In the lunar case, according to Carrier, the loader should be used at the outset for long hauling as the easiest way to start ore flowing into the central plant. After a few years the loaders may be augmented by a system of haulers, essentially large volume ore trucks carrying lunar topsoil back to the central plant. This permits the loaders to strip-mine full time.

While useful as a starting point in the present study, the Carrier system cannot perform all required LMF functions. Figure 5.38 shows the basic design for the LMF mining robot. This machine is a modified loader with a rollback bucket; has a dozer blade formed on the lower face of