"The Frontier Builder"

An Earth-Moon Hotel Cruise Ship


1992 Doug Armstrong and Peter Kokh, LRS Design Team


In this project, we aimed to define and then design a transit hotel to carry tourists, settlers, and business people between Low Earth Orbit shuttle (LEO-Shuttle) and Low Lunar Orbit shuttle (LLO-Shuttle) a) for their comfort and convenience, b) to support quickening lunar settlement and development, c) to win public support. Our starting points:

The cruise ship would maintain a 2:1 resonant orbit with the Moon, alternating 14 day circum- "lunar cruises" with 14 day space or "L3 cruises" (when the Moon is on the opposite side of its orbit).

Physically, the ship would be split into two roughly matched masses held together by a rigid boom and rotating around a common center of angular momentum in order to provide artificial gravity. Passengers would spend the bulk of their time aboard the cruise ship transitel, and only brief periods aboard the comparatively cramped and spartan LEO & LLO shuttles.


LUNAR LOOP CRUISE: This cruise would serve settlers going to the surface as well as settler trainee candidates and tourists making a shoestring swingby cruise. It would drop off more affluent tourists for expensive lunar surface excursions, picking them up after their surface stay on a subsequent run. It would also serve journalists and writers, scientists and businessmen, and official visitors.

L3 SPACE CRUISE: The alternating cruises would be devoted to maintenance work, training, scientific (and philosophical?) seminars, Mission to Planet Earth themes, and Mars gravity simulations.

ARTIFICIAL GRAVITY: Normally the cruise hotel would maintain 1/6 Earth-normal or full Moon-normal gravity. Possibly 3/8 standard or Mars level gravity would be offered on occasional Mars theme space cruises.

PASSENGER CLASSES: Here the model of the oceangoing cruise liner cannot be followed. On such ships there is normally one paid crew person to each 2 plus paying passengers, a ratio it would be prohibitive to duplicate in space if the "transitel" is not to price itself out of the market.

Accordingly, following the model of "Windjammer" cruises on Earth in which passengers pay to take crew positions, we propose only a Skeleton Permanent Staff, for management positions only. To supplement this, there would be a Crew Class for all subordinate crew positions to be filled by budget-fare passengers who would receive minimal accommodations. For many, not unlike those "working their way through college" this thrift option would provide their only real hope of ever making it into "deep" space and of ever seeing the Moon up close. For available Crew Class spots, priority would be given to settler candidates and trainees. For these there might be possible free trips to the lunar surface if combined with work-stays on Moon. Another precedent for paying for the right to work is the several archeological "digs" open to paying student-vacationers.

Crew class positions: a partial list of jobs to be filled would include: waiters, Maitre D', cooks and kitchen help, agri unit, composting and recycling attendants; domestic and housekeeping; room service, valet service, child supervision; activity room attendants. Specialty openings would include: masseur, barber, hairdresser, chaplain, lecturers, bartender, medic, nurse, doctor, communications people, etc.

To make such a "paying crew" work, without disaster, obviously several days of pre-departure "training" may be necessary for some positions where prior experience is not promising. Certainly there would need to be aptitude and attitude screening for those applying if the scheme is to work.

In contrast to modern cruise ships where the crew: passenger ration commonly lies between 2.3:1 and 2.9:1, in this scheme there would be far less paid persons aboard and far more paying ones, a profile absolutely essential to keeping fares as low as possible for all passenger classes. For those either unwilling, unable, or not needing to defray the costs of their passage, a traditional Tourist Class and a Luxury Class would round out the passenger list.

ACCOMMODATIONS: Among the available models we looked at are the Japanese Mini-hotel specs and the cabin suggestions of the Badger Space Society in their entry into the '91 Mars Cargo Run contest both suitable for the working Crew Class passengers. As suitable accommodations for general paying, non-working Tourists, we looked at Amtrak rail car cabins. Finally we looked at luxury staterooms aboard cruise ships and river boats for Luxury Class accommodations.

ACTIVITY SPACE: Hotels and cruise ships that are successful need to have well-designed and sufficiently ample common spaces designed to serve a variety of group activities. For our model, we considered activity space and activities common aboard cruise ships. Dining rooms; lounges for gaming, reading, and socializing; sports/gym/exercise/dance areas; chapel, seminar, and theater areas; grooming salons and gift shops; infirmary; purser office. We considered first three, then two shifts to use activity spaces more economically and efficiently. Shift assignment will attempt to honor preference and make use of around-the-world origin of passengers. It may be most efficient to put all children (and their parents or guardians) on the same shift.

DECOR: We specify Moon Settlement Decor, using what has been achieved and simulating what is expected to be achieved in the settlements based on local resources and inspiration. The obvious purpose and opportunity here is to set an anticipatory mood for those descending to the Moon as well as to simulate the feel of life in a lunar town (including 1/6th G) for those unable to afford the luxury of a surface visit.

MENUS: Standard fare will be similar to settlement fare; other (Earth traditional) cuisines might be offered to those less game as an extra cost option.

INVOLVEMENT: The Earth-Moon Cruise Hotel would not be just a commercial venture (though it is necessary that it amortize its costs and earn a profit). In addition to investors, the Lunar Settlement/Mining Authority and the University of Luna (whether there is as yet a Luna campus or just an Earthside precursor) should be natural partners and interested parties. The U of L might determine decor, menus, and other mood-setters, organize artcraft demonstrations, educational seminars, and lectures (credit optional).


In approaching a design for our cruise hotel, we began with strong constraints and guidelines given by the above definition study. Among these:

Artificial gravity 1/6th Earth Normal = Simulated Lunar Gravity. This requires separation and distribution of the total mass of transitel away from a common center of rotation along with a comparatively low mass structure to hold it all together. We settled on the "dumbbell" paradigm with two masses to be joined by a boom structure that allowed passage of goods and personnel between the two sections with arrival & departure from a non-rotating hub.

Structural modularity using available technology, e.g. ET/Energiya sized tanks. Currently the capacity to build or launch hulls in excess of 27.5 ft (10.8m) in diameter does not exist. At the same time, it is not necessary to limit oneself to retrofitted shuttle external tank hydrogen tanks. Any "ET Compatible", pre-outfitted and dry, light enough to be strapped on to the standard fuel-carrying shuttle ET complex in lieu of the orbiter and carried to orbit, possibly with the help of a second pair of solid strap-ons, would work. A cluster of SSME engines would be affixed to the bottom of the fueled ET, clustered OMS motors and dedicated fuel tanks to the bottom of the ET compatible. Both mass concentrations of the transitel, "Hotel Wing" and "Service Wing" would be built with ET Compatibles.

Pressurized transit to the countermass component of the divided transitel structure. While hotel accommodations and function space will be concentrated at one end, some Crew Class positions may be open at the other end, e.g. working in the agricultural and recycling units. Further, pressurized travel must be available from the arrival/departure hub "down" to the "Hotel Level".

High passenger and activity density - compactness with the illusion of spaciousness. This is necessary to keep costs associated with total mass as low as possible i.e. original construction and course-correction fuel.

Need for ample change of scenery - many smaller diverse activity spaces, all with a "Lunar decor". This will work to prevent cabin fever in a relatively small construct on which passengers will spend one to two weeks.

A food production unit, with air/water/waste recycling for lunar menu items. This will accomplish several things: a) duplicate the conditions under which the actual settlers must live; b) keep down costs of resupply at LEO and LLO rendezvous points; c) provide additional Crew Class positions; d) serve as a training exercise for any settler trainee candidates who happen to be on board.

EVA options. This may be needed for emergency repairs or scheduled maintenance during mid-cruise. But it also offers the opportunity for supervised diversion for the passengers. One elegant possibility is a "lunar surface" platform to complete the settlement simulation experience for those who are not debarking at Lunar rendezvous.

Solar flare shielding beyond the Van Allen belts along with extra shielding for the quarters of the small permanent crew. This might be most economically provided at/around the arrival/departure hub.


Given that the passengers would be "hotel guests" for one week transits or two-week continuous round trips, a full spectrum of activities and the function space to support them need to be provided. We offer the following recommendations

A Diner: On cruise ships, restaurants are often sized to handle half the passenger load at a time in a 2-seating schedule. Since our passengers are already split into two shifts for economical use of the facilities we decided that the diner should be large enough to offer 1 sitting per shift. It might possibly be subdivided, e.g. via split level, decor, dividers etc., to serve the different fare Classes properly. When not in use for meals, this area could provide group meeting spaces, as well as host discussion groups, soapbox pulpits, and "Crew" meeting space.

B Bruncherie: Instead of having all meals in one and the same large dining room, breakfast, lunch, and teas could be served in a smaller, more intimate room with 2 sittings per shift i.e. half-size). This room would offer, via its different decor, a change of scenery from the diner, adding to the illusion of spaciousness.

C Game Lounge for gaming, cards, lessons in "Lunar arts & crafts" and other compatible activities.

D Bar & Lounge, dancing (in a "glass-bottom" observation?). This area would offer further cozy spaces for relaxed one-on-one and small group socializing.

E Library. Books and personal audiovisual entertainment quiet space, possibly with a "Meditation corner".

F Univ. of Luna Campus Room for Lectures and Seminars, etc. Doubling as an Assembly Hall, Theater, Chapel Services, Lunar Music/Lessons and performances.

G Promenade walk around the periphery of the structure complete with view ports, a photo gallery of the Moon and/or memories of past cruises, murals of Lunar landscapes, museum display cases, etc. Many opportunities to be combined with the "constitutional" exercise function.

H Young People's activities room, and lockers with supervision by paying Crew Class members.

I Coriolis Room: An aerobics gym, a place to try 1/6 G acrobatics, and offering court sports, via some schedule.

J Sauna & Massage area, with workout equipment, a Jacuzzi, and scheduled barbering and hairdresser services.

K Hospital-infirmary: This would be a compact area with beds only for those who cannot be treated in their quarters.

L Elevator Lobby: access to the arrival/departure hub, and via the hub to the Service Wing counterplex. Positioned near M (see below) and A (see above), with ready access perhaps by a "grand staircase" to other function areas

M Purser's office: lunar excursion arrangements; supervised activity registrations etc.; Phone calls to Earth and Moon, plus a duty free shop: Made on Luna arts, craft, and clothing, and made-in-settler-training-camp items

In designing the transitel and placing function spaces within it, two things must be considered. Some parts of the structure will offer unobstructed views of space, others not. And if the axis of rotation of the complex can be kept on a Sunward-antisunward line, some areas will offer the opportunity for flooding with sunlight, others starlight. The Sunward caps (of the ET Compatibles) could have various forms of sunshine diffusers, stained glass inner paning, even welder's glass solar viewports. The Sunward Dome Caps of the cylindrical ET-compatible modules would be right for a Garden Lounge Bar, a Stained Glass Chapel. From these caps in-floor and in-ceiling light pipes could carry the sunlight to interior clerestories and skylights. There is nothing like abundant sunlight to cheer a space.

The starward caps could be more generously glassed but need contingency shuttering. These locations might be especially appropriate for a library and the Game Lounge.

Vertically, there are opportunities for rimward (lowest floor) and hubward (uppermost ceiling) views. This orientation via rotation provides a large number of ambiance-differentiable settings aboard the transitel - design opportunities to be taken.


While the amount of quarters space per passenger will differ according to fare class, we felt each space should be provided with some sort of personal infotainment centers.

CREW CLASS: We chose individual "berthettes" on the pattern of the BSS suggestion (illustration p.8 top left) with interior placing perhaps on the "promenade" deck. These berthettes would have fold-down desk and seat and under- or over-berth storage. For convenience, only individual night jars would be provided, and common bathroom & shower facilities.

TOURIST CLASS. Amtrak-type single, double, and joinable compartments, most(?) with portholes, seem to offer appropriate space. These might include daybed sofas, pull-down desks or daybed over kneehole desk/dresser. Individual toilet and basin would be provided, with common showers.

It may be advisable to have all children on the same shift and in the same accommodations module in specially designed "family" compartments

LUXURY CLASS. There will always be a few super-affluent who never need to question the price. In Luxury Class "suites" there would be space-hogging "full-time" beds, "full-time seating", fixed desk, and more generous floor space. Unstacked (not-bunked) same level full size beds would rest over storage space. For convenience there might be a microwave and a refrigerator and state of the art entertainment center. If placed in the sunward caps, such suites could be sun-flooded/sun-shielded - lighting by dial.

Luxury Suite Option$: room service, nanny service, valet service, escorted EVA at captain's discretion. etc.

"Regency Suites" at a super-luxury fare premium might offer end cap verandahs, private "partytainment" space, catering/butler $ervice, and boast crew tended garden plants in the verandah space. In short, whatever people will pay for.


One of the hard lessons to learn from the Biosphere II experiment still in progress is that it is not possible to devise a fully bio-regenerative closed loop life support system for spacecraft or space settlements unless we are prepared to provide an as yet unknown number of acres of vegetation for each human to be supported. If our habitat space is to be more urban-dense than rural, then we will have to settle for bio-assisted systems in which plants "assist" mechanical-chemical primary systems in keeping the air and water fresh, as well as providing aesthetic appeal and an illusion of nature-cradling.

Aboard our "Frontier Builder" transitel, there will be opportunities for passageway planters, nook & cranny gardens, hanging plants, and other greenery and flowers. A "Suncap Garden Lounge" is a possibility, and perhaps a section of the promenade might feature a wall-mounted bonsai forest strip in eye- and waist-level tiers. Perhaps these little touches will in fact contribute not much more than a fresh smell and fragrance to the air, but that bit will be important.

At the opposite end in the Service Wing, more extensive fruit and vegetable gardening will help provision the kitchens and aid in recycling the water reserves. Visiting this Farm Unit could be a popular activity, and some passengers (besides the Crew Class personnel working there) might even take to frequenting the facility. In it, high yield trays with LED-grown vegetables and salad stuffs would be featured with fish tanks for Talapia, as well as mushroom beds in the composting area. As a key part of the air & water recycling apparatus, at least a portion of human wastes and all waste biomass composting would be handled here.


The Frontier Builder would be famed for its Lunar decor: settlement-made or -makable furniture, furnishings, surfaces, and accessories. Board games too could be those made and played on the surface. All these items would be distinctive because they would have to be made of elements economically available on the lunar surface and manufacturable by processes and equipment available to the small communities there. Lunar dance demonstrations and lessons - free style, ballroom, ballet, and "square" could add to the atmosphere.


Seminars, both free noncredit and fee for credit instruction with correspondence follow-up where necessary could be offered in Solar System Astronomy, Stellar Astronomy, Solar System Economic, Biospheric and Lunar Agriculture, Settlement Industry, Space History, Settlement History, Tourism and Entrepreneurial Opportunities in Space and on the Moon, and tips for Moon Shopping Excursions.

Frontier-Pioneer Craftsmanship past, present, & future might be an attractive offering along with a "Spin-up" Earthside Enterprise Opportunities Seminar. Science Fiction of the Pssst! variety (Plausible Solar System Settlement Tales!) and a Sci-Fi writer's workshop could be offered for a fee. In depth observing of the "Earth from Space" would be popular. As the transitel gets closer to the Moon and skirts the farside, porthole "Selenography" sessions would be well attended.

For business people, networking sessions and individual settlement and enterprise counseling would be in order. In the "extracurricular" field, "sixthweight" sports such as All-Wall Handball with color-cue walls (cf. Jai Alai), Lunar Style Badminton and Ping Pong could be taught.


Given a pre-trained Crew Class that changes with each cruise, and assuming a total transitel crew-passenger list in the 200-300 range (our design goal), how few permanent staff positions could we get by with? If their work day was staggered to coincide with the last half of one passenger/crew shift and the first half of the other shift, we might get by with a permanent staff of only seven!:

(1) Captain, (2) First Mate, (3) Hotel Purser, (4, 5, 6, 7) Staff foremen in these areas: (4) Agricultural & Recycling (A&R), (5) Kitchen & Dining (K&D), (6) Domestic & Housekeeping (D&H), (7) Education & Entertainment (E&E). We feel all subordinate and assistant positions, including medical, could be adequately filled by paying Crew Class personnel.

Note: The Hotel Purser and Crew Foremen have 12am-12pm duty shifts that overlap passengers' 6am-6pm and 6pm-6am shifts to allow staff time with each shift thus avoiding the need to duplicate personnel. The Captain might choose the same hours. Most operations would be automatic and require only occasional oversight. The First Mate would alternate shift duty with the Captain.


To make our artificial G cruise ship idea work, we need to separate enough of the tasks, facilities, and equipment in an opposing countermass to balance the teeter-totter. We feel that all hotel space, accommodations and function areas, should be contiguous and together in the Hotel Wing. This leaves the following items for the Service Wing Complex:

Fuel Tankage (for trajectory corrections)

Surplus Volatile Tankage (oxygen, nitrogen, water)

Main Electrical Generation and Solar Arrays

Water & Air Recycling Systems

Agricultural and Composting Unit

Main Pantry Stores

Tool Crib and Maintenance Shop


The "Bridge" may be in the Hotel Wing, in the Hub, or in the Service Wing. Wherever located, A and B Auxiliary "Caboose" Helms could be located in the alternate sites.


The concept of a non-rotating hub of a rotating structure (e.g. the Wheel Station in "2001") seems familiar and straightforward enough. In truth, however, it actually presents formidable engineering challenges that have never, to our knowledge, been adequately addressed. The central problem is fairly simple to state. Because the rotating complex is an inhabited functioning thing, the shifting of movable masses (people, consumables, sundry items) means that the center of net structural mass is not necessarily the gross center of gravity i.e. the center of angular momentum at the moment. How do you keep your Hub Docking Structure from oscillating around an actual ever shifting center of gravity and rotation? If you can't, actual docking may prove to be a pretty hairy affair.

We felt that in the greatly simplified special case of a dumbbell arrangement in which masses shift, for all practical purposes, along only one axis, a special case solution might be devised. This solution would not, however, give comfort to architects of full wheel or cylinder rotating craft or stations. Our suggestions will be illustrated below.


As the structure through which all arrivals and departures of both personnel and supplies are funneled, the Hub is the natural place for some other Transitel facilities.

Through Baggage would be more efficiently stored in Hub Vestibule lockers.

Actual "parking spaces" for detachable Shuttle Passenger Cabins to be alternately mated to quite differently designed LEO-shuttle and LLO-shuttle chases would be a good idea. First the fuel cost to match trajectory and momentum with the Transitel has already been paid, and during the cruise they would then be available as lifeboats. For this purpose no real propulsion system would be needed, only a means of "shoving clear" if necessary, for they would follow the transitel trajectory to the next LEO of LLO rendezvous (and rescue) point. Even during "space" ("L3") cruises. it might make sense for a LEO-Transitel shuttle to stay parked for the duration especially if it came outfitted to support a special science and R&D agenda for the cruise, as well as serving as lifeboat.

Multiple docking port: In the above eventuality, at least two docking ports will be needed. One for the loaded arriving shuttle cabin being dropped off, the other for the loaded departing shuttle cabin being picked up. If only half the passengers can be accommodated aboard such a cabin, however sardine-packed, then four ports may be needed.

Course correction engines (at tetrahedral points?: 1 sunward, 3 angled antisunward?).

Hub-skirting paired shaft elevators would allow for gradual up-down reorientation thus avoiding flip-flop point ambiguity by not routing traffic between the Hotel and Service Wings directly through the center of rotation of the complex. Thus a double boom structure is called for and this will provide our opportunity to solve the central hub problem alluded to above.

Flywheel for spin-up and spin-down when necessary after construction and during maintenance or retrofitting. This is an option (instead of rockets) that may offer an elegant way to provide a Flare Shield for Solar Flare Storm Shelter, plus extra shielding for Permanent Staff Cabins, and K-ration storage.

Observatory Telescope for Passenger viewing of the stars and planets will be a natural for a no-rpm hub.

Micro-Gravity Trans Van Allen Belt Research platforms & stations or L3 cruise hookup science module can be located at the hub.


The capacity of the original Earth-Moon Cruise Hotel can be either expanded by addition of extra modules or duplicated by adding similar craft to the Earth-Moon run. The latter is the more logical avenue for expansion as it would eventually allow around-the-month departure dates.

But inter-line rivalry may spark actual addition to existing transitels. These could be added during spin-down on L3 maintenance trips. Existing modules will be periodically updated as the diversifying lunar economy offers more sophisticated, fresher "Lunar Decor" choices. Replaced items might be kept in hubside storage lockers to be auctioned to passengers or traders on subsequent cruises.

Function spaces will not only be "redone". They may be reapportioned as experience and shifting demands dictate.

One add-on frill not included in our original design workup would be a Simulated Moonscape Platform for EVA access by all passenger classes. (See illustration below)


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