Lunar colonization, in my opinion, will be a very difficult challenge
for mankind, but it is a very important step in the overall colonization
of the solar system. Since there is no air or water obviously available
to people on the moon, alot of preliminary work will need to be completed
before lunar colonies will be built and able to sustain human life.
Some important questions need to be addressed. Let's speculate
on some criteria for starting and operating a lunar colony, and on some
potential first steps in that effort.
COLONY CRITERIA
First off let's determine what would be needed to successfully start and operate a colony.
Self-Sustainability: A lunar colony absolutely needs to be self-sustaining. Although the initial lunar settlement could get away with receiving resources from earth for awhile, eventually it would have to be completely independent from earth. This is because transportation costs would be so fantastically high that the colony would quickly go broke if it were dependent on earth for any length of time. Food needs to be grown locally, air and water absolutely needs to be recycled. Sewage needs to be dealt with as well.
Continuous Power: This is one of the greatest obstacles to lunar colonization. At some point, the people on the moon will need to confront the lunar night. If the first colony can be located at the lunar pole, this can be avoided for a time. But eventually, people will want to explore other areas. Additionally, landing on the lunar poles is not particularly fuel efficient, and is probably not the best place for the eventual construction of a mass driver. Nuclear energy may be the easiest route at first.
Available Mineral Resources/Mining Technology: For expansion purposes, and any big construction projects, the local resources will need to be used. Developing plastics from the lunar resources may be impossible, consequently a lunar colony will need to find alternative solutions.
Available Water/Gas Resources: It has been proposed that oxygen can be released from metal oxides in the lunar soil. Additionally, the polar water ice will take care of the colony's water needs. One notable concern is where on the moon could you find nitrogen and other gases? Nitrogen may not be necessary in the lunar atmosphere at first, but plants need nitrogen (at least in the form of nitrates and ammonium) to produce amino acids and other compounds. Initial sources of nitrogen may be available as by-products from the breakdown of some of the fuel components used to move spacecraft to the moon, such as nitrogen tetroxide N2O4(a highly toxic oxidizer which obviously needs to be modified) and hydrazine N2H4(a highly toxic fuel source).
These two chemicals were the oxidizer/fuel components used in the Apollo
lunar excursion modules. Similarly, water and oxygen are the natural
byproducts of the decomposition of hydrogen peroxide H202
(a fairly benign oxidizer/monopropellant that is favored by many space
entrepreneurs).
Lunar Industrial Technology: The large scale refining of ore into pure glass, ceramics, and metals in a vacuum (hopefully using solar energy) will need to be worked out. Although this may not be needed right away, if the colony is going to expand, it is vital.
Profit Motive: A colony might or might not be required to return
a profit. It would be nice to start a colony on the basis that it
would be a profitable business, but with so many unknowns, that might not
be a valid expectation. It is reasonable to believe that a lunar
settlement would eventually hit pay dirt: the moon has roughly the
same land surface area as the african continent and is essentially unexplored,
and of course it's resources have never been tapped. Earth, on the
other hand, has tapped into and used up much of the easily accessible ore
bodies. Admittedly, some of the geologic processes that have concentrated
ores on the earth don't exist on the moon, but this doesn't mean that concentrated
ore bodies will not be found. As stated, profit is not the only reason
to settle a new world. North America, for the most part, was not
settled by profitable corporations.
GETTING STARTED
To begin with a survey of the moon for available minerals, water, and sources of oxygen will need to take place. To a degree, this has already started in the forms of the Apollo moon landings, the Clementine, and Lunar Prospector probes. But eventually, someone will need to get more involved. At first this can be done with some kind of rover/telepresence technology.
There is an argument for sending people up to the moon to stay for a period of time. One reason being that there is a 3 second lag in any telepresence activities on the moon. This lag can be eliminated if people are on site. Additionally, it would be useful to analyze mineral samples as they became available, and to explore issues of physiology, botany, and power management at the same time.
The big challenge will be when the first people stay on the moon for
a full month. The structure and people inside will have to survive
both a lunar day -- two weeks at about 121° C (250° F), and a lunar
night -- two weeks at about -156° C (-250° F) with no solar power
to boot. Power may be the biggest challenge. Radio-isotope
batteries will probably be used in the first outpost. Some less controversial
approach might be developed as time goes by.
A LITTLE HOUSE ON THE MARE
The initial lunar habitats will undoubtedly be very modest. Below
is an example of a very modest design. I'm presenting the design
below not because I think it's the best implementation, but because it's
a forum to discuss some ideas about setting up a base on the moon.
My primary interest here is how to take advantage of the materials of the
lander to start a moonbase. So without further ado, Welcome to
Moonhab-1.
Moonhab-1. A nifty way to reuse fuel tanks.
The inspiration behind Moonhab-1 was to consider if it was reasonable to use the fuel tanks of my lander as a habitation area. Fuel tanks would be convenient because they are insulated pressure vessels by design, and would make adequate living space if properly setup -- and it would quickly become apparent to a lunar inhabitant that insulated, pressurized volumes of space are very difficult to come by once you start living on the moon. The fuel mix I had in mind for Moonhab-1 was either straight hydrogen peroxide, or hydrogen peroxide and alchohol. The reason to use hydrogen peroxide will become apparent later. One substantial disadvantage of this design is that Moonhab-1 is about 12 meters across when the tanks are in the vertical position, making it difficult to find a launcher to get it into earth orbit in one piece, so Moonhab-1 would be constructed in earth orbit. What follows is a scenario of Moonhab-1 establishing itself on the moon.
Moonhab-1 makes its journey from earth orbit to the moon, making use of the fuel stored in the four big fuel tanks. Moonhab-1 lands at the base site on four feet just like the Apollo LEM craft. Excess fuel is collected within compartments in each of the fuel tanks for later use. The fuel tanks are lowered from their vertical positions to horizontal positions. Sealant is pumped into the large circular joints that the tanks share with the lander base, so as to make an airtight seal. Inward opening panels/doors on the sides of the fuel tanks are either cut or opened to allow access to the insides of the tanks. The collected hydrogen peroxide is allowed to slowly decompose over time into water and oxygen, thus creating a breathable atmosphere and a supply of drinking water. Eventually, the whole station is covered with lunar soil to limit radiation exposure and to provide thermal insulation from the sun during the 2 week lunar day, and to limit heat dissipation during the 2 week lunar night. Power is provided by radio-isotope batteries.
In the design above, Moonhab-1 would travel to the moon by itself, then
the crew would meet up with it after it had deployed itself on the moon.
Of course a crew's cabin could be added above the engine (red), and thus
the crew and habitat could go to the moon as one unit. Moonhab-1
has the advantage that it can quickly set itself up on the moon.
It is a bit cramped, however. Moonhab-2 begins to answer that problem,
but requires more setup work.
Moonhab-2. Fun with balloons.
Moonhab-2 is an inflatable structure. After a long flat-bottomed trench is prepared by a solar powered tractor, a tough 'bag' is unrolled into it. The sides of the bag might consist of a tough outer and inner membrane with carbon fiber or fiberglass cloth impregnated with liquid plastic resin sandwiched in the middle. After the bag is inflated, the resin is allowed to cure. One method of curing involves exposure of the resin to the strong sunlight of the moon. Inflatable ribs could be built into the bag to provide increased structural support. Once the bag had cured, the dome would be covered with lunar soil to a depth of one or two meters for radiation protection and thermal insulation. NOTE: Although this may sound overly heavy, it's important to remember this construction is taking place in the moon's weak 1/6g gravity field. This weight would be equivalent to about 15 to 30 cm of soil on top of a similar structure on earth.
Both habitats are first attempts at relatively rapid habitat deployment.
Obviously Moonhab-1 would be able to deploy much faster, and would be easier
to automate. Moonhab-2 is basically a carbon fiber or fiberglass
tent, and a fair amount of set-up would be required, but still might be
deployable remotely.
POWER, WATER, and AIR
The biggest challenge to establishing a moon base will be the running of an air/wather/food recycling system and providing the energy necessary to run such a facility. Data from the Advanced Life Support and Gravitational Biology Group at the Kennedy Space Center indicate that approximately 226 cubic meters of greenhouse volume and 40 square meters of planted area per lunar resident3 would be needed to supply the moonbase's air and food.
Excess humidity in the air, brought about through the respiration of humans and plants alike, would be condensed into water for drinking, food preparation, and hygiene.
The per person planted area would require approximately 77 kilowatts4 of power to provide the necessary lighting (using mercury vapor lamps) to keep the plants healthy. Obviously, solar energy would provide the necessary lighting during the daylight hours on the moon and could be 'piped in' to the growing area using either optic fibers or some other alternative. Of course the biggest problem arises during the two weeks of lunar night that would follow. To provide the necesary power for a reasonable-sized lunar colony might require a nuclear reactor, or a Stirling heat engine power plant, or a solar power satellite at one of the lagrangian libration points, or perhaps just a really big orbitting solar reflector.
Massive Solar Reflector Array
The two arrays of reflectors are attached via a space tether, in order
to establish a "permanent" orientation in space relative to the earth and
consequently the moon. The reflectors are located at either the L4
or L5 lagrangian libration point. Although the reflectors pictured
here are quite large, in practice very small mirrors might be more practical.
Each mirror consists of a thin film supported by a stiff outer ring.
The mirrors position and focus might be controlled electrostatically.
The alighment and focus of each mirror could be monitored using a laser
and appropriate laser light receivers on the moon. The remainder
of the satellite structure is as "non-existent" as technically possible
in order to reduce launch costs. It is imagined that it should be
endevored to construct such a satellite using of a bunch of cellophane,
toothpicks, and a bit of well chewed gum, in other words using a minimalist
approach.
The other possiblility is to locate the moonbase near one of the lunar
poles. Here, there are craters forever shrouded in darkness, because
of the sun's low position on the horizon. At the same time, some
mountain peaks in this same area are almost always in sunlight, as the
sun is always seen skimming the lunar horizon during the lunar month, never
quite disappearing from sight. This is similar to the areas on earth
above the arctic circle and antarctica, which enjoy 24 hour days in the
summer and 24 hour nights in the winter.