Options for First Base
- A first base on Luna might be located at one of the Peaks of Eternal Light at the Lunar North Pole. Access to sunlight for solar power for the whole local summer and most of the winter would help maintain operating temperature for the machinery. The landscape might be too rugged to provide a convenient rocket landing area and base site the right distance apart.
- Another possibility is to put a base in the best flat place with a convenient area for rocket landings, and provide Nuclear Power. There have been some political difficulties with nuclear power in space in the past.
- It might be most economical to make a first base away from the polar region of Luna, a base for remotely controlled devices. The six month nights at the poles require some power source, such as people might get by establishing a power distribution grid of solar power stations ringing the pole at a distance of about fifty miles. Such power stations ought to have solar cells facing away from the pole on convenient hills. The trouble is that people would have difficulty establishing the grid during the five months that we can count on solar power at a lunar pole. A power station atop a 2000 foot tower could provide power through the lunar polar winter, but that would be no cinch either.
- A radiator will be required for most industrial processes on Luna. The low temperatures required for the radiators of oxygen and hydrogen liquefaction plants are more readily available on Luna than on Earth. It is a matter of managing the sunlight and the ambient infra red with properly shaped and deployed shields blackened and shiny in the correct places; and protecting the radiator from micrometeoroids. Storing the cryogenic liquids is not an insurmountable problem. The fines from lunar regolith make a very good insulation in the vacuum. Stored hydrogen and oxygen recombined in a fuel cell can provide the low power level needed to keep equipment from being damaged by cold during the lunar night. Water from the fuel cell would be kept in a tank maintained at the temperature for liquid water. Solar cells would power electrolysis during the day to recover the hydrogen and oxygen, and power the liquefaction process. There is considerable loss of power in storing it for reuse this way, but all involved processes are well understood.
- Add up the requirements. The tankage, the liquefaction plant, the protected radiator, the fuel cells, the supply of liquid hydrogen and oxygen, the thermally insulated building, the electrolysis unit. For a small base that could actually be shipped to Luna it is still less costly than the polar power tower or an entire power distribution grid. Start small and build up to the power distribution grid over a period of a few years. Meanwhile rovers could have some place to stay at night where they won't freeze to death. There would be no major activities at night, just enough power to stay alive. Naturally the elaborate pressure vessels with air locks and plumbing necessary for people ought to wait until there is more time to provide such out of mainly lunar materials.
- A shelter for machinery would be a major feature of a first base. One possibility is a tent whose rigid structural members are cloth tubes stuffed with regolith. The tubes would have seams designed to be laced up as the tubes are filled with regolith, then more regolith would be piled on top of the tent. Only the cloth needs to be sent from Earth. Eventually cloth can be woven from fiber glass on Luna. The advantage of this type of construction over inflated structures is less vulnerability to small leaks. A disadvantage is longer construction time. More substantial buildings (as described in Sintered Brick Construction) could be built from local materials when there is time to develop some industry. A covering of about 30 centimeters of regolith fines should be adequate for thermal insulation and micrometeoroid protection, but the precise thickness would be determined through an engineering design study.
- Another possibility for a shelter would be a tent made of triple or quadruple layers of metallized Mylar or similar material suitable for lunar use. In a vacuum such a shelter would provide good thermal protection. A zipper might work for the door or a door panel might be fitted with hooks to hang from a ledge included in the door frame of the tent. To minimize weight and maximize ease of setup, the tent could be of the dome tent variety with polyurethane foam filled tubes as compression members substituting for the familiar cord linked sections of fiberglass rod used on Earth. The foam filling the tubes when the tent is set up should be designed to provide the proper internal pressure relative to an ambient vacuum rather than the polyurethane foam designed to expand against one atmosphere on Earth. Just filling the compression members with a gas that initiates polymerization in a material in the wall of the compression members leaving rigid tubes might do the trick. Something has been published about a device for inflation in outer space which solidified after inflation to make it resistant to collapse after puncture with micrometeoroids.
- Heat for lasting the night could be stored in bricks in a specially insulated container within the tent. The bricks could be made by putting regolith into high temperature alloy foil loaf pans that would compactly nest in each other for shipment to Luna. These loaf pans would be heated during the lunar day in a solar furnace, forming one sintered brick per pan. They would be packed in their special container with every other brick in the stack rotated 90 degrees from the nesting position to produce stable stacks. During the night hot bricks could be removed from the container one at a time as needed. An insulated container can be made on Luna by digging a hole and placing a plain uninsulated box into the hole. Then the sides of the hole would be packed with regolith fines. The lid for the box would include compartments to hold regolith fines and be sturdy enough for a remote control device to walk over it while it lies on the container, its top surface level with the ground.
- The inflated tent and heat brick option might be lighter over all than the option of producing heat at night with fuel cell power. It might be light enough that the tent could be lifted off the ground and put atop polls to be carried 10 meters above rovers to the location at which it will spend the next night. It may be necessary to have a few rovers cooperate so that they can move camp every 709 hour lunar day taking along all necessary stuff.
- Remote controlled rovers and manipulators could set out from a base over a few years and establish a circumpolar power distribution grid within a possible time frame. From that point the requirements for Bootstrapping Industry should be clear.
- Peak of Eternal Light article at Wikipedia
- Rigidizable Inflatable Get-Away-Special Experiment (RIGEX). http://www.nasa.gov/mission_pages/station/science/experiments/RIGEX.html