Lunar Tourism and Space Settlement
by David Dietzler
Requirements for Lunar Tourism
Vacationing on the Moon is a dream that will someday become reality, but making it so will not be easy. Transportation to the Moon is only part of the challenge. A substantial workforce in space consisting of stewards and stewardesses, pilots, technicians, engineers, construction workers, robot teleoperators, drivers, skilled craftsmen, artists, musicians, chefs, doctors, teachers and others needed for a viable civilization as well as large numbers of tourists and business travelers must be kept alive. Humans will require life support, comfort and entertainment. Some wealthier visitors may demand luxury as well. Early trips to the Moon might consist of a single loop around the Moon without landing and return to Earth via free return trajectory. That would be followed by trips that involve several lunar orbits and finally landings on the Moon. Rocketing to the Moon will be expensive so travelers deserve to see as much of the lunar surface as they can during their trip. There must be numerous places to stay in scenic locations and transportation systems on the Moon's surface. What else is required?
- Low cost access to LEO by reusable VTOL rocket or HOTOL space planes.
2. Reusable space ships for travel from LEO to EML1 or LLO space stations.
3. Reusable landers for travel between EML1 or LLO space stations and lunar surface.
4. Habitations on the lunar surface. Villages, towns and cities. Roads and railways.
5. LEO propellant depots and space cryogenic liquid transfer technology.
6. EML1 or LLO propellant depots with space cryogenic liquid transfer technology.
7. Mass driver base on lunar surface to launch regolith.
8. Mass catchers to receive lunar regolith and move it thru space.
9. Regolith smelting space stations for production of propellants including LOX and metals. Also oxygen production for life support.
10. Lunar surface propellant production for landers.
11. Space shipyards to build ships. Stations to service ships.
12. Factories and garages on the Moon to build and service landers.
13. Space stations in LEO to serve as ports for transferring passengers and cargo. Will require baggage handling systems and be combined with propellant depots.
14. Space stations at EML1 or in LLO to serve as ports for transferring passengers and cargo. Will require baggage handling systems and be combined with depots.
15. Food production in space. Requires large space stations and/or space settlements like Kalpana 2 These stations will also grow crops for fiber, biodegradable plastic, paper, etc. Food packaging and laundry facilities located at stations and settlements. Human waste from ships including CO2 could be processed by space station/settlement closed ecological life support systems and hydroponic farms. All food and water withdrawn from space settlements by ships must be returned as waste to the closed bio-system loop.
16. Water production from lunar oxygen, solar wind implanted hydrogen and polar ices.
17. Stations and/or settlements to house space workers and ship crews.
18. Shops and small factories in space stations and settlements for making and repairing necessary items for workers as well as travelers like tableware, containers, clothing, bedding, furniture, appliances, machinery parts, souvenirs, sundries, toiletries, medical and office supplies,etc.
19. Shops and factories on the Moon for making and repairing necessary items.
20. Lunar ground vehicles and sub-orbital vehicles. Vehicle manufacturing shops/factories and service garages on the Moon.
21. Telecommunication systems in space linking ships with space stations, lunar surface dwellings and Earth. Land lines and cell towers on the Moon.
22. Navigation satellite constellations in HEO and polar lunar orbit.
23. Computerized billing and banking systems. Ticket and reservation agents, etc.
24. Police forces, security cameras and alarm systems, government buildings, courts, brigs, etc.
25. Stores and kiosks in stations,settlements and lunar habitations where all sorts of products and services like hair cutting are available for sale to space workers and tourists.
26. Restaurants, bars, hotels, entertainment venues, offices on the Moon and in stations/settlements.
27. Medical and dental facilities.
28. Schools eventually, and libraries. Workers will live in space or the Moon with their families.
29. Chapels, churches, temples, mosques eventually.
30. Museums. Historical sites like Apollo landing sites.
32. Sports complexes and gyms/workout centers. Basketball, volleyball, tennis etc. on the Moon.
33. Dance halls/ballrooms, banquet rooms, theaters (live and movie),etc.
34. Spacesuits and life support backpacks for people of all shapes and sizes must be available on the Moon, in space and on Earth. Travelers might wear spacesuits during flight to LEO.
The requirements for lunar tourism stand in stark contrast with Earth orbital tourism that can be experienced with just low cost access to LEO in the form of reusable space planes or rockets and re-entry vehicles. Space stations and space settlements could allow lengthy vacations and even permanent living in orbit.
Space Settlement Must Exist
Extensive industry in space and on the Moon must precede all this. Solar power satellite and helium 3 industries are most likely candidates for motivating space industrialization. Asteroid mining for precious metals is another potential profit making activity in space. Earth orbital tourism and pricey real estate in Earth orbiting settlements like Kalpana 2 could whet the appetites of entrepreneurs.
Lunar tourism cannot exist without an extensive amount of space settlement. Food must be produced in space. Launching food from Earth's surface would be ridiculously expensive. Food might be produced on the Moon and launched into space with mass drivers or rockets, but once it is in lunar orbit or at an EML1 (Earth-Moon Lagrange Point One) space station it must be hauled down to Earth orbit to be loaded on ships bound for the Moon. Solar electric tugs might take a year to do that and much of the food might spoil. Perhaps space ships that travel between LEO and EML1 space stations will load up on enough food from the Moon for an entire round trip. Food will become waste, including CO2, and this will have to be recycled given the dearth of organic materials on the Moon. Rockets would be needed to carry all the waste down into the Moon's gravity well. It should be far more efficient to produce the food and recycle wastes in space farms. Robots can do farm work, but humans will also be needed to tend the crops and tend the robots, so livable dwellings must be built for them. A trip to the Moon will take anywhere from about 30 to 80 hours. Unless the ships have centrifuges it is unlikely that there will be any cooking from scratch. People at the space farms can pre-cook the food and package it in foil and corn starch derived compostable plastic containers. Aluminum foil containers can be reheated aboard ships in ovens that use radiant heat since convection doesn't happen in weightlessness. Corn starch bioplastic, PLA, is not very heat resistant but it is easy to recycle or compost. Depending on the number of lunar travelers every year, it is easy to picture large space farm stations and thousands of people engaged in space farming.
It is not technically feasible to build a ship that can lift off from Earth's surface and travel directly to the Moon. Aerodynamic vehicles must be built specifically for traveling from Earth's surface to low Earth orbit and back. Ships that travel between LEO and EML1 have to be lightweight to reduce propellant consumption but large enough to keep travelers comfortable for a good deal of time. Landers can be much smaller because travelers will not spend too much time in them. Three different vehicles each designed for its specific role in transporting tourists to and from the Moon are needed. Space stations in LEO and EML1 where ships dock and passengers and their luggage are transferred from one space vehicle to the next must exist.
Pilots who fly space planes up to LEO can come home every day. Moon lander pilots would live on the Moon. Ship crews would spend long periods of time in space because landing them on Earth or the Moon and returning them to space after every flight would be too costly. There have to be accommodations for crews on lay-overs at the LEO and EML1 space stations. Workers who load and unload baggage, water and food at space dock stations, space ship service technicians and engineers, space station operating technicians and engineers and all other necessary personnel who can't go back to Earth or the Moon every day need nice homes to. There will have to be sizable rotating space stations to house and feed all these workers.
Spending astronomical sums of money to fly to the Moon won't be very popular if travelers don't have nice hotels, recreation facilities, opportunities to visit several scenic locations and the experience of walking on the Moon in a spacesuit. Lunar developers will probably be preceded by Moon mining companies that build manned bases where regolith is excavated and launched with mass drivers. Parts of the bases will be landed intact and other parts will be made on the Moon with on-site resources. An initial “seed” of machines, habitat, vehicles, supplies and replacement parts that has a mass of a few thousand tons could grow exponentially when all systems are working. The Moon mining companies would earn money by selling millions of tons of regolith to solar power satellite building companies. After decades of powersat construction the market will be saturated and Moon miners will need a new source of revenue. Lunar materials and equipment made from those materials could be sold to lunar hotel and resort developers. Hotels could be constructed with 10 to 20 meter wide cylindrical modules made of extruded fused regolith covered with 5 or 6 meters of regolith for protection from cosmic rays. The modules would be connected with metal tunnels and airlocks. Some modules would house visitors, others would house workers, many modules will contain stores and workshops and the majority of modules will be filled with hydroponic gardens. Small factories could build pressurized buses that drive across the Moon on dirt roads and sub-orbital spacecraft for rapid travel to distant locations. In the long run, high speed railroads will be built to connect the larger resorts and the towns and cities that grow up around them.
Lava Tube Cities
There are lava tubes on the Moon large enough to contain towns and small cities. Entrances could be sealed with dams built of boulders and molten regolith that hardens to seal the tubes. Abundant oxygen from regolith could pressurize the caves. A “shirtsleeve” environment would be created inside where workers could lay bricks, pour concrete and weld metals just as they do on Earth. Underground cities connected by surface railways and subways could someday emerge on the Moon. There could even be sub-selene fish ponds, swimming pools, homes to rent, parks with trees, golf courses and outdoor barbecues inside the lava tube towns. Microbreweries, gambling casinos and adult entertainment could be found in some of these communities while others will be more family oriented and feature musical productions, amusement parks and museums. Many workers and permanent residents of the Moon will bring their families. Schools, libraries, hospitals, drug stores and shopping centers will be needed. University towns might evolve in the sub-surface worlds of the Moon.
Lunar development will require an enormous financial investment and business leaders may rely on the “if we build it they will come” philosophy. However, without space transportation and support systems
that cost billions of dollars this will not be possible. At the same time, without anyplace to visit on the Moon there will be no reason to go there. Business leaders will have to collaborate and agree upon standards rather than engage in cut throat competition for the sake of humanity's future in space.
Earth Orbit First
Innovative technologies will be needed to realize low cost access to space. This might be achieved by the Skylon space plane or the SpaceX ITS (Interplanetary Transport System) also known as the BFR (Big Falcon Rocket). The ITS consists of a large booster with a winged rocket second stage. This author proposes the development of a rocket based on a modified Shuttle external tank, reusable aerospike main engine module and chemically propelled booster; perhaps the first stage of the ITS or a variant of it. The booster would land on a barge at sea and the main engine module would travel once around the Earth, re-enter and parachute down to Earth near the launch site. The external tank would ride to orbit along with the cargo. It would be used in space along with the cargo module and any packaging. The external tank could supply roughly 30 tons of aluminum alloy, titanium and some polyurethane to space construction enterprises. The cargo module and packaging could supply composites, polyurethane foam and even cardboard. The polyurethane might be broken down into carbon and hydrogen. Nothing would go to waste; therefore this system might be economical especially when assembly line production of external tanks, cargo modules, boosters and main engines is applied. Hulls for lunar ships could be based on external tanks. These would be strong and lightweight. If tourists are launched with this rocket in a large capsule that sits atop the external tank a large number of tanks would be orbited. Hundreds, thousands, even tens of thousands and more tons of aluminum and titanium for building space stations and settlements in orbit 500-600 kilometers up could be delivered in the form of external tanks in addition to actual cargo that might have a mass of 100 tons or more with each flight. Finished modules, hard and inflatable, for space stations that house human and robot crews could be launched. Workers would use various machines to dismantle external tanks and process the metals along with actual cargo into space structures.
Orbital hotels, condominiums and time shares could appear in Earth orbit. These celestial pieces of real estate would be self supporting with hydroponic farms and bioreactors to recycle all oxygen, water, food and waste. Crops like cotton and hemp could be grown for fiber to make cloth and paper. Corn could be cultivated to produce PLA, a biodegradable plastic, from corn starch. Algae and yeast along with the inedible stems and leaves from crops could provide livestock feed for real meat, dairy and eggs. Some people will eat liver, sweetbreads, tongues and brains. Undesirable entrails could be turned into pet food. Cats and dogs will join humanity in the settlement of outer space.
At space stations in Earth orbit space ship components finished on the ground and launched into space could be assembled with large tele-robotic arms. Large structures envisioned for outer space like solar power satellites and the hulls of space settlements will consist of simple components that are repeated and assembled. Space ships might eventually be built in space with materials from the Moon and asteroids, but the first ships would be built on the ground due to their complexity. Propellant depots could be made of external tanks with aluminum foil solar shields. Compressors, refrigeration devices, pumps, corrugated metal hoses, solar panels, electric motors and other elaborate parts for propellant depots would be made on the ground and rocketed into space.
Propulsion to Luna and Beyond
Launching propellant for inter-lunar ships from Earth would be too expensive, although some kind of mountainside mass driver might launch tanks of liquid hydrogen or canisters of metal hydrides. Solar power satellite construction in GEO would involve transforming lunar regolith into silicon solar panels, magnesium reflectors and aluminum frames. A substantial amount of by-product oxygen would result. There would also be a lot of iron and calcium of little use for powersat building. There might also be more than enough silicon. Liquid oxygen, iron, calcium and excess silicon from regolith smelting could be transported from GEO to LEO with solar electric robotic tugs that use ion drives or ablation propulsion in addition to electrodynamic tethers. Substantial quantities of residual hydrogen might be available in LEO. Vehicles that can orbit 30 tons are reasonable developments. One hundred passengers would have a mass of about 10 tons. An extra 20 tons of liquid hydrogen could be piggybacked in the vehicles' fuel tanks. When combined with silicon that's enough to make 160 tons of combustible liquid silane. Silane could be used as a carrier liquid for bio-propellant rockets that burn iron and calcium powders with liquid oxygen. These metals would not yield a very high specific impulse; however, a delta velocity of only about 3.4 kilometers per second over Earth orbital speed is needed to send a ship to the Moon in about 30 hours. Aluminum powder has been found to be a reasonable rocket fuel. In time, there could be hundreds of powersats supplying a substantial amount of Earth's energy demands. When no more powersats are needed except for new ones to replace aging satellites, aluminum could be sold for rocket fuel. Eventually there would be asteroid mining and large amounts of oxygen, metals, hydrogen and carbon from Near Earth Objects could be supplied. With high thrust chemical rockets and propellant in Earth orbit it becomes possible to accelerate ships with electric drives to escape velocity in a matter of minutes instead of days or weeks. Electric drives can deliver low thrust for days or weeks and propel ships to Mars at high velocities. One form of electric propulsion, VASIMR (Variable Specific Impulse Magnetoplasmic Rocket), could get a ship to Mars in only 45 days.
Moon mining, solar power satellite construction, lunar helium 3 mining perhaps, orbital tourism, lunar tourism, free space settlement and the settling of Mars can be viewed as parts of an interdependent inter-related system of commercial enterprises. The goal is not merely the creation of high priced travel and real estate for the privileged few, but the creation of a space faring civilization. Employment and mercantile opportunities for small businesses as well as giant corporations will be plentiful in space. Ultimately, populations larger than the carrying capacity of planet Earth will thrive in free space settlements and other worlds of the solar system like Mars and Titan. Given the vast resources of outer space, the return on investment approaches infinity and the galaxy, not merely the sky, is the limit.
Steps to Space Industry
1. Cheap access to LEO with SpaceX or Blue Origin rockets
2. Solar electric tugs for LEO to EML1 transfer and landers to the lunar surface. Also some kind of system for moving work crews to the lunar surface
3. At least 1000 metric tons of lunar industrial “seed” equipment too 33.1 deg. E on the Moon's equator and bootstrapping of a mining and mass driver launch base
4. Mass catchers to LEO then to EML2 with solar electric tugs
5. Establishment of space stations in GEO. Robots teleoperated from ground stations. Workers to GEO stations by system used to move workers to the Moon
6. In GEO, loads of regolith are smelted with a device similar to a huge mass spectrometer. Iron is extracted and converted to steel by combining it with carbon from Earth using the ancient crucible steel or cementation process. The steel is poured into sodium silicate bonded sand molds on rotating platforms in the vacuum to cast heavy parts for rolling mills. Aluminum and magnesium are rolled into sheet and foil reflectors to concentrate solar energy on to gallium based photovoltaic modules launched up from Earth. See: Jones, Royce. “The Space Grid Sun-synchronous orbiting SBSP Satellites with Equatorial orbiting Reflector Satellites for Earth and Space Energy.” NSS Space Settlement Journal. Issue #1 December 2011. Available:
7. SPS frame members cast from simple fused regolith or cast basalt. Aluminum wires and aluminum coated calcium wires, titanium parts, iron for magnetrons, glass,, etc,
8. Smelting in GEO results in large quantities of oxygen, silicon, iron and calcium in excess for use in SPS construction. These could be moved down to LEO with solar electric tugs.
9. Silicon could be combined with hydrogen sent up from Earth to make silane, SiH4, to serve as carrier fluid for powdered silicon, iron and calcium fuel to be burned with LOX in bipropellant rockets. Magnesium and hydrochloric acid needed to make silane, but Mg and Cl can be recycled.
10. Establishment of assembly stations, propellant processing and propellant depots in LEO
11. Using hulls based on space shuttle external tanks or some other standard component for hulls and propellant tanks, ships are assembled and fueled in LEO
12. A station where passenger vehicles from Earth and inter-lunar ships can dock is assembled in LEO.
13. Passengers travel to LEO station via space planes or reusable two stage rockets and take trips around the Moon in inter-lunar ships.
14. Mining and mass driver base continues to “bootstrap” or expand to build hotels, rockets that can ferry passengers between EML1 and lunar surface, ground vehicles, sub-orbital vehicles, etc.
15. Passengers/tourists start visiting the Moon. There should be a way station at EML1.
- abundance of glass, iron and fused regolith in GEO sent down to LEO for building space stations of various sizes including Kalpana Two style space settlements in addition to other elements and cargoes launched up to LEO from Earth happens at the same time all this does. Since regolith is 40% oxygen there is no shortage of that vital element.
Lunar Resource Notes
by David Dietzler
There is not a lot of carbon on the Moon. There is plenty of carbon in asteroids, comets, ices of several moons, the atmospheres of Venus, Titan (and in its methane lakes) and the Gas Giant Outer Planets. In the early years of lunar development we will have to save carbon for atmospheres, but that only requires a few hundred parts per million. Even so, we might want to increase CO2 content over typical Earth atmosphere levels in farm chambers to stimulate plant growth and as crops lock up carbon in their tissues we will have to add CO2 to maintain its partial pressure. It would seem that steel is not lunar appropriate but the fact is only a tiny amount of carbon makes a large amount of steel. One ton of carbon can make 300 tons of 0.33% mild steel, 200 tons of 0.5% medium carbon steel and 50 to 100 tons of 1% to 2% high carbon steel. Huge quantities of carbon (coke) for blast furnaces are not needed. Iron can be extracted electrically and magnetically from regolith that contains up to 14% iron. Iron bars or plates can be packed in carbon and brought up to red heat (1000-1200 C.) for several days or a week or more in an insulated electric furnace. Iron will absorb carbon and form steel. This steel can then be melted to homogenize the steel. So steel is not really carbon intensive. This may require lots of energy but plenty of energy is available on the Moon in the form of reliable solar energy never obscured by clouds.
Aluminum and Steel
There is plenty of aluminum on the Moon but aluminum threads strip and rip out easily. Aluminum is too soft for ball bearings and roller bearings. Steel is needed for threaded pipes, fittings, nuts, bolts and screws. Fortunately, the required mass of these will not be too large. Steel is needed in moderate quantities for threaded parts, nuts, bolts, ball bearings, roller bearings, hand tools, power tools, cutting tools (cemented carbides might also be used) drill bits (cobalt steel), machines like lathes, grinders, milling machines, extruders (for chambers and rams), gears, drive shafts, axles (titanium might suffice for that), razors and good knives. Strong maraging steel contains almost no carbon but does require cobalt (from meteoric iron-nickel fines) and molybdenum and can be used for things like rocket motor casings but it won't take a good edge for blades and knives. Nickel, chromium and manganese exist on the Moon for steel alloys like stainless steel. Steel can be customized for almost any desired application by altering carbon content, heat treating and alloying. Steel metallurgy, like chemistry, is a very mature science. Steel's only major weakness is that it rusts. That will not be a problem in the lunar vacuum. So, yes, steel is biodegradable and can be easily recycled by melting and re-casting. Pure iron which is abundant in lunar regolith has strength properties similar to wrought iron and can be used for ornate works, nails (in aerated auto-claved concrete), hinges, pins, pots, pans, rails, handles, rods, furniture, etc. Wrought iron was used for steam train rails before the now obsolete Bessemer Process made large amounts of cheap steel available in the 19th century. In the low gravity and rust free vacuum of the Moon pure iron might be sufficient for railway tracks.
Compressed and cryogenic gas cylinders could be made of aluminum or titanium. Ground and space vehicles could be made of aluminum, magnesium, aluminum-magnesium alloys, aluminum-magnesium-silicon alloys, aluminum-manganese alloys and titanium. Commercially pure titanium is strong and light weight but vanadium for the workhorse alloy Ti-6Al-4V is lacking on the Moon. It does exist in traces. Vanadium might be imported if significant amounts cannot be extracted from regolith. It might also be possible to use titanium aluminides and alloys with a beta stabilizer other then vanadium even if it is not as light as Ti-6Al-4V.
Plastics, Paper and Nitrogen
Polymers are a problem in the low C,H,N environment of the Moon. Sulfur polymers have been suggested. Silicones made of silicon, carbon, oxygen and hydrogen can also be used to extend the supply of light elements. Fortunately, oxygen is abundant in rocks and regolith and so is silicon. Small amounts of polymers will be needed for gaskets and pipe seals. Lubricants, the life's blood of machinery, are also needed. Silicone oils and elastomers could be used. We might use PLA plastic from corn and cultivate oil crops (jojoba? castor beans? soy? linseed?). This should be simpler than complex chemical factories. It all depends on how much C, H and N we get from solar wind implanted volatiles mining and lunar polar ices. Eventually, we will get C, H and N from Mars, NEOs and other bodies of the solar system. The challenge of developing the Moon without plastic fantastic and lots of cheap oil has a certain romance to it. Returnable glass bottles and cast basalt bottles can replace vast amounts of plastic. What little plastic there is that is used on the Moon will not be cheap as it is on Earth and it will absolutely have to be recycled. Many people have cried,”We will trash outer space the way we have trashed the Earth.” I doubt it. Space is such an austere environment that we cannot afford to be wasteful and survive.
There won't be much wood on the Moon, but paper can be made from hemp, rice, peanut shells and almost any other vegetable fiber. That paper will not be cheap and it will have to be recycled. If someone manages to produce cheap paper the local governments may put a hefty deposit on it to force recycling.
Nitrates for explosives will be in short supply. It will be possible to make explosives with magnesium or basalt tanks containing a slurry of aluminum or magnesium powder in LOX ignited by an electric spark. These explosives exist today and are called oxyliquits. Hard rock mining will require explosives. A square kilometer of lunar surface mined to a depth of three meters, or about 4.5 million tons of regolith, can yield about 200 tons of hydrogen, 82 tons of carbon in the form of CO, CO2 and CH4 and 16 tons of nitrogen according to scientists at the University of Wisconsin. They have designed a machine that would shovel up regolith, heat it to about 700 C. to drive out the solar wind implanted gases, and compress them. Nitrogen which is necessary for atmospheres and fertilizer is the element in shortest supply, not carbon and hydrogen. Many bodies of the solar system contain ammonia (NH3) ices and the atmosphere of Mars is a few percent nitrogen.
See: Lunar Chemistry and Biomaterials