§ 5.1 Prerequisites for a Product to be Made from Lunar and/or Asteroidal Material
All products from lunar and near-Earth asteroidal materials must satisfy 3 criteria in the initial stages of a PERMANENT program :
Initially, few systems will be made from 100% lunar and asteroidal materials. But most systems consist mostly of simple components, "mostly" in terms of weight percent, which can be made from lunar and asteroidal materials. For example, the electronics and precision components can be launched from Earth to a space station and incorporated into a large structure built from lunar and asteroidal materials.
Of course, the product must be made of materials which can be readily derived from asteroidal and/or lunar materials in a near term program, but this does not appear to pose a problem for the vast majority of products.
Later, as space infrastructure and industry matures, it will become economically attractive to make the more sophisticated components in space.
One example of a near-term product is fuel propellant. When the Space Shuttle launches a communications satellite, the cargo in the Shuttle's bay consists of the satellite itself and the rocket needed to boost it to geosynchronous orbit. The fuel propellant and next stage rocket make up about 70% of the mass of the satellite in the cargo bay. The fuel propellant can be easily derived from lunar or asteroidal material instead of being launched up from Earth, thereby tripling the Shuttle's capability to launch satellites and reducing the cost of putting a communications satellite into geosynchronous orbit.
A second example is the communications satellite itself. Larger communications satellites -- with larger antennas and power sources -- are feasible once we have asteroidal or lunar materials in hand. Platforms can be built to mount and support multiple satellites (also known as "orbital antenna farms", or OAF's). The satellites on a farm can even be connected together by fiber optics, making for more capable and cheaper global communications networks, and reducing the number of relays and potential for interference ever more crowded space. The bigger antennas and power sources will allow smaller, cheaper receiving and transmitting stations on Earth. Bigger antennas mean more focussed, smaller "footprints" on Earth, relieving many interference issues with the limited radio spectrum. Most of what's needed to bring this to fruition is the capability to make beams from asteroidal or lunar materials (and the fuel propellant to put it into place).
Note: In the near-term stage, the satellite electronics will still be made and assembled on Earth and launched up, but the platforms, antennas, and power supplies will be made of mostly lunar and near-Earth asteroidal materials. The latter simple-but-massive components will make up most of the weight of future communications systems. Hence, most of future communications systems can be produced from asteroidal and lunar materials.
For another example, consider space stations, factory facilities and habitats. Most of their mass will consist of:
The above components can be made from lunar fiberglass, lunar glass-ceramics, and asteroidal or lunar iron or other metals. Beams, walls, and radiation shielding are simple, mass producible parts which would constitute the vast majorith of the weight of many large products in orbit.
What is the equivalent of concrete and steel beams in space? The Moon is abundant in minerals readily usable to produce "lunarcrete" (a concrete-like structural item like granite or marble produced from thermal melts of lunar materials), ceramic beams, iron beams, fiberglass, some composites of these, glasses, and refractories. All of these can be produced in orbit using solar ovens and casting.
Metal from asteroids is readily available, especially iron and nickel. It's also not too difficult or expensive to produce metals from lunar material in the early stage of such a scenario, e.g., the lunar-abundant metals iron, aluminum, calcium, titanium, and magnesium.
Windows can easily be made from lunar glass.
Mirrors for thermal heat can be made from asteroidal nickel or lunar aluminum, on lunar glass substrate.
You get the idea...
However, don't underestimate the value of the space-based infrastructure. For example, if something goes wrong with a satellite, there will be people, fuel propellant and infrastructure there to go fix it. No more lost satellites in Earth orbit, as it will no longer be so remote. Indeed, maintenance contracts (thereby lowering the cost of insurance contracts), refuelling tankers, and entrepreneurial construction workers will have many a field day...