Needed on the Moon
If you tour any construction site or factory on Earth you will see a number of basic industrial mechanisms that are at the foundation of all processes. We must design lunar versions of these mechanisms if we are to build a successful settlement on the Moon. The harsh lunar environment makes many of these very challenging designs.
The factors making machine design difficult in the lunar environment include:
- Harsh UV sunlight
- Temperature extremes
- Radiation Problem
- No air
The familiarity of the Earth versions coupled with the harshness of the lunar environment make many of these redesigns excellent student projects. They are also a fertile field for entrepreneurs.
The following list covers basic mechanisms found in Earth industry that we must have for commercial operations on the Moon:
This is the seal on a spinning shaft such as a motor. It keeps dirt out of the bearings and the lubrication in. It must be flexible yet stand up in a long life of riding against a spinning shaft.
On Earth, these seals are made from rubber and plastic compounds and are highly successful in a wide range of environments.
On the Moon, the big challenges include the gritty dust and the lack of an atmosphere. This adaptation should not be too challenging but a great many materials may need to be tested in realistic lunar conditions.
These seals must slide across a polished metal rod as in hydraulic pistons. Look around an Earth construction site and you will see these pistons everywhere. These shafts move in and out exposing their surfaces first to the internal hydraulic oil and then to the environment. The seals must hold in the pressure while withstanding the ware of sliding.
On Earth, these seals are made from rubber and plastic compounds and, again, are highly successful in a wide range of environments. The gas shocks in modern cars are one good example.
On the Moon, this design problem is a killer that must be solved. The lunar dust is highly abrasive. The film of oil left on the rod holds the fine dust. The seals must push this mix out of the way or withstand this extremely abrasive paste for a very long time. A blow out of the oil would be a major break down.
Linear seals are one of the major design challenges for commercialization of the Moon.
Wire Rope Systems
Wire rope systems with there wenches, pulleys, and hooks, are one of the most useful devices in Earth industry. They are very widely used despite their inherent dangers. These systems are notorious for crushing off fingers and delivering slashing wounds when broken cable ends fly.
On the Moon, wire rope systems will have difficulty surviving in the dusty environment, but the chief design challenge is the danger they pose to a person working in a spacesuit.
The conveyor belt is the foundation mechanism of mass production. They move stuff. Typically they contain a large number of moving parts and joints. They are driven at one location and many have many support wheels and rollers along their length.
On the Moon, the primary challenge is wear from the dust.
Moving around a lunar settlement will require vehicles with wheels. These wheels must have tires of some sort. The ability to negotiate lunar slopes will be a major factor in lunar transportation. Good tires are the key to transversing these slopes.
On Earth, tires are universally made from synthetic rubber and inflated with air. This design is completely unsatisfactory for the lunar environment.
On the Moon, the Apollo rover tires were made from metal mesh and work reasonably well. They did however through up a lot of dust and were never pushed onto steep slops.
The Caterpillar or tank tread is used extensively in construction and mining on Earth to allow heavy equipment to move across open grown. They are massive and contain a very large number of joints and bearings.
Treads can be a difficult maintenance problem in dusty environments. One of Field Marshal Romel's great innovations in the WWII North Africa campaign was to load his tanks onto trucks for long hauls. This greatly reduced the break down rate of the treads.
On the Moon, the dust will be a server challenge for treads. It will simply wear them out. The mass of most tread designs is also a problem as long as that mass has to be shipped from Earth.
Power Distribution Cable
Lunar power generation stations, solar or nuclear, will need to be separated from both living areas and commercial operations. Distance is needed both for safety and to avoid the dust kicked up by human activity. Also the optimal site location for one activity is rarely the optimum location for another.
We will need a way to efficiently send electrical power over at least a few kilometers. This must be done safely and with a minimum of mass shipped from Earth.
How can we build a settlement without good cement? Both in the form of concrete and mortar it is the universal construction material on Earth.
Cement is a good example of a process we depend on on Earth that must be modified for the Moon. On Earth we heat limestone driving off the water to make slaked lime. We add a stabilizing mineral. The Romans used volcanic ash; we use gypsum. We mix this cement with sand to make mortar or with crushed rock to make concrete.
The cement has the amazing property when mixed with water it sticks to rock or brick and becomes stone hard. The water does not evaporate or dry. The water reacts chemically with the lime and remains. Every drop put in the wet mix is present in the finished product. This cannot happen in a vacuum.
The finished product has great compressive strength but little tensile strength. Fortunately when iron bars, which have great tensile strength, are placed inside concrete the cement coating both bonds strongly and protects the iron from rust.
On Earth, most of the minerals used to make cement are associated with water in some way. Limestone is laid down by living organisms at the bottom of shallow seas. Gypsum forms when an inland sea dries up. There is no water on the Moon and there never has been. No minerals of this type can be expected.
The Moon is cover with ground up rock and we will produce a number of interesting by-products when we harvest volatiles from it. We need to find a way to convert some of that particulate mater and some of those chemicals into a solid construction material. We need to do this with as little mass shipped from Earth as possible.
Steal rebar will be hard to manufacture on the Moon. On Earth it is made by recycling old cars. We may be able to make fiberglass on the Moon and use it to reinforce the cement.
With a decent mortar, stone masonry could become the defining architectural element of our lunar settlement. There is certainly no shortage of rocks.
Glue & Sealants
Outside on the Moon, we need to be able to glue things together and to seal leaky enclosures. This ability is life-or-death.
Color in Architecture
The Moon is gray. Asphalt parking lot gray. Monotonous, boring gray. We need to add color. We need paint. The bulk of the paint must come from lunar materials.
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