During the first few decades of a permanent manned presence on the moon, bases and outposts will almost certainly take on a ‘modular’ approach. New components will have to be shipped from Earth as opposed to being manufactured on-site, and therefore habitats and such will be limited by what launch vehicles can carry. Like with the International Space Station, the most practical method of assembling the station will be with the use of pre-assembled modules that can be fitted onto an existing array of such structures.
Because of ongoing radiation hazards, much of a lunar base is likely to be constructed underground, or at least partially-buried to help reduce exposure risk. Construction rovers could excavate a hole for a new module, move it in via tractor or construct it inside, then cover the new module back over with lunar soil or sandbags filled with moondust. A number of visions for the moonbase also posits the use of large, lead-lined anti-radiation tarps stretched over the top of modules as an additional precaution.
Even though a moonbase is still at least over fifteen years away (putting it technically at Tech Level 12) most of the components needed to establish it can be constructed now, thanks to techniques pioneered for the ISS and earlier space stations.
A "module" here is defined as an enclosed, life-supporting modular structure that can be interconnected to other such structures to allow personnel easy access throughout their interiors. Moonbase surface structures, buildings exposed to vacuum and such, will be discussed in another section. Modules are also assumed to be constructed on Earth or in Earth orbit before being landed on the Moon. Structures built out of native lunar materials will be discussed in another section on Lunar Settlements.
A straight forward life-support module designed to house base personnel in relative comfort. Will most likely have self-contained life support and recycling systems with many redundancies, communication uplinks, workstations, sanitary facilities, and so on. The early habitat modules will probably be designed for three to about eight people, with later versions being able to handle more.
In the beginning, habitat modules will serve multiple purposes, as they will end up being the very first type of module deployed and will become the backbone of an early moonbase. They will not only have living facilities, but will have vacuum equipment lockers, EVA staging areas, science work stations, and so on, making arrangements very cramped. However, as the base expands and specialized modules are added, habitat module design would shift toward primarily providing comfortable living space for personnel.
Basically long, tube-like airlocks, designed to function both as convenient walk-through corridors between modules and as airlocks when connected at just one end. These would likely come in different configurations, the most common probably being the four-way connector. They would also serve to carry both power, data, communication, and life support between the various modules they connect.
The first mission-specific lunar base modules will probably be dedicated laboratory modules. Geologic (or, more properly on the moon, selenologic), chemical, and life science modules will probably be among those first prioritized, with lab modules exploring astronomy and industrial applications coming later.
A maintenance module would centralize many of the power, recycling, and life support functions of the base, allowing for much easier upgrading and maintenance as well as allowing for increased personnel capacity. Designed to supplement and perhaps eventually even replace the life support, recycling, and power distribution machinery in other modules. Will contain the relevant machinery designed to be easily accessed by base personnel without EVA, as well as perhaps a back-up generator and/or emergency high-capacity batteries to guard against a power failure.
Also called a logistics module. As a moonbase expands, centralized general operations will also be needed. The C & C Module will house the major processing and communication systems for the base, as well as act as a centralized "office" for handling personnel, logistics, resource control, and so on.
Basically a pressurized storage shed, to allow personnel to easily access long-term supplies without the need for EVA.
Basically a moonbase version of Bigelow Aerospace’s Transhab concept developed for the ISS. The shell of these inflatable modules would be a foot thick, composed of more than twenty different layers of foam, Nextel, Kevlar, Nomex, and other materials around a central core of collapsible interior walls and other hard-shell machinery. Would allow modules to have a greater interior volume than static-shell modules, whose volume would be determined by the interior of their launch vehicle.
As the moonbase expands, it will need more personnel, and as such will also need expanded facilities to provide ongoing care, take care of medical emergencies, and engage in long-term observation of their condition in the lunar environment.
A large module that would be used to grow and cultivate hydroponics plants for use by the base personnel as well as to help supplement air and water recycling. It would NOT be made transparent like true greenhouses on Earth because of the radiation hazard, but instead would use specialized interior lighting to promote plant growth. One of the biggest side benefits of a greenhouse module would be to give personnel a morale boost by giving them somewhere to retreat to on the base where they could be surrounded by living things.
One of the primary businesses of a moonbase will be processing lunar rocks and dust for valuable materials (in particular Helium-3), so a module that could house the primary processing machinery would prove very useful. Though an unpressurized surface structure may be desirable to handle greater volumes, a pressurized module would allow personnel to more easily access, upgrade, and maintain the machinery.
Small autonomous vehicles ("rovers") are assumed to make up a large part of the "workforce" of any future moonbase. So having a pressurized bay, complete with a small vehicle-shaped airlock, would be advantageous to allow moonbase personnel to maintain, repair, and upgrade them as needed without the need for EVA activities. The Motorpool Module would also be a very logical place for the teleoperation workstations that would control the rovers.
A radical proposal posited by NASA’s John Mankins, a human and robotic technology specialist, is to use a "Habot"--a lunar base module constructed on an ambulatory chassis, using legs or wheels to slowly move about on its own. Basically these would be module-sized, multi-ton, interconnectable rovers. This would greatly facilitate the quick construction or reconfiguration of a moonbase, but with foreseeable technology it would also be the most expensive and difficult type of basic habitat module to construct.
It would probably be more accurate to call a lunar hotel a series of interdependent modules that would be dedicated to one major purpose: lunar tourism. A lunar hotel would be a cluster of habitat modules designed to offer very comfortable accommodations to visiting guests and would put a heavier emphasis on providing a pleasant living experience than the more basic habitat modules. They would also be designed with a pleasing interior visual aesthetic, to better entice the upper-end tourists that a lunar hotel will likely attract in the first decade or two of operation. A Lunar Hotel may be the first privately-funded series of modules to be added to the moonbase.
An outgrowth of the inflatable module technology would be an inflatable habitat that could expand to a much greater size than earlier modules, and one that would not be constrained to follow the usual cylinder/half cylinder configuration. Advances in material technology could allow for thinner and much more flexible exterior membranes that would not have to sacrifice any structural strength. Spider silk, advanced composite materials, and even carbon nanotubes could provide the means to make these possible.
Unfortunately, such a large habitat would be that much harder to protect from the ongoing radiation hazards on the moon and would probably not be used overly much on the surface. The large "bubble cities" of lunar settlement so beloved of science fiction just isn’t practical, unless you want most of its inhabitants to suffer long-term health risks. Inflatable domes would most likely be used for either storage or to act as a temporary life-support environment for either excavation or the construction of surface structures.
The only other real practical application for an inflatable dome on a surface base is as a pressurized hangar. They would be the only module-type structures large enough to easily house translunar spacecraft and their support equipment. These might be equipped with large, vehicle-sized airlocks, but it is also just as likely the entire dome may have to be depressurized to bring the craft in, and then re-pressurized to allow personnel to perform extensive repairs, maintenance, and/or upgrades on the craft.
Even though derived from Inflatable Dome technology, of course the exact configuration need not be dome-like. Cylindrical or box-like hangers may prove more practical shapes.