First Base

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.
• The "Long Endurance Rovers" article Thermal Management section gives a scheme for rejecting heat from a radiator on Luna away from the poles. The radiator is protected from sunlight and from infrared radiation of the landscape. Basically the radiator is set in a wall in an east west running ditch of parabolic cross section lined with shiny aluminum foil. The axis of the parabola coincides with the wall and is tilted away from the vertical toward the equator by an angle equal to the latitude. The top of the wall is below the focal point of the parabola so that all of the sunlight falling in the ditch is reflected back into space, missing the radiator and the wall. This sort of radiator could be used to reject the heat of a hydrogen and oxygen liquefaction plant. So these gasses could be conveniently stored for use in fuel cells during the two week and eighteen hour night. Cryogenic tank insulation is not much of a problem on Luna where vacuum is all around. Just pack the liquid hydrogen tank in a couple of feet of fines sifted from the regolith and that should suffice. Water from the fuel cells would build up during the night and need to be stored in a tank where it will not freeze. 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 it is all stuff people know how to do.
• 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.
• One possibility for the shelter which would be a major feature of a first base would be based on structural members that are cloth tubes stuffed with regolith. The tubes could have their seams laced up as they are filled with regolith, then more regolith piled on top. Only the cloth needs to be sent from Earth. 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.
• 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 a compression member 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 and 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.
• 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 a poll to be carried 10 meters above a rover 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 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.
• References