AAAS Pacific Region Meeting
Corvallis, Oregon
1988 June 19

Educational Simulations of
Lunar Bases Inside Lava Tubes
By Bryce Walden
President, Oregon L5 Society Chapter of National Space Society


F. Horz, in an article in Mendell (ed.), Lunar Bases and Space Activities of the 21st Century (1985), described the huge spaces and heavy shielding in lunar lava tube caverns. This makes them attractive shelter for lunar habitats. Oregon L-5 researchers demonstrated advantages and savings by conducting educational simulations of lunar bases in natural lava tubes. Young Astronauts, Students for the Exploration and Development of Space (SEDS), Oregon Museum of Science and Industry (OMSI), U.S. Forest Service, and the City of Bend, Oregon, cooperated in these missions. OMSI-L5 Young Astronauts and OMSI SEDS personnel were able to layout and construct basic functional modules and conduct scientific studies while inside a large terrestrial lava tube (Billings, Walden, and Dabrowski, 1988). The ubiquitous volcanic dust unique to Bend area caves appears to model 'lunar dust' remarkably well, making simulations all the more realistic. The unusual environment and immersion in the simulation make our facility a powerful educational tool. The City of Bend has offered the researchers a city-owned lava tube complex for education and research. We will conduct advanced educational simulations at this facility; it is also available as a lunar-like testbed for various lunar components and designs. Interested parties are invited to contact the author.


There is a real need for good, involving teaching tools to teach science. Researchers Bryce Walden, Thomas Billings, and Cheryl Singer with the Oregon L-5 Society chapter of the National Space Society, in cooperation with the Oregon Museum of Science and Industry (OMSI), developed a program of lunar base simulations housed in lava tube caves. The simulated lunar base serves as a vehicle for teaching science, planning, teamwork, and design. OMSI-L5 Young Astronauts (grades 4-9) and OMSI Students for the Exploration and Development of Space (SEDS) (high school) designed, constructed, and operated the simulated lunar base. Participants were enthusiastic about the mission simulations and found the unusual environment mysterious and exciting.

This paper includes a brief overview of lunar bases and the geologic setting of lunar lava tubes. Techniques and designs of educational lunar base simulations are described. The mission profile of a typical lunar base simulation exercise is followed, and a listing is given of specific science activities performed at the base. Results of these simulations suggest directions for future growth and development.

New Generation Lunar Bases

Lunar bases as envisioned by the scientists, writers, and artists of the 1950's and 1960's were cramped scientific outposts, housed in small cylinders and buried under several meters of lunar regolith (ultra-fine rock flour) to provide protection from the harsh exposure on the lunar surface. Following upon the Apollo findings, by the mid-70's researchers were suggesting ways in which the components of lunar rock could be refined to provide vital base elements and commercially exportable commodities (see for example Stine, 1975 and O'Neill, 1976). In 1988 at the Second Symposium on Lunar Bases and Space Activities of the 21st Century, lunar bases had expanded in scope from basic scientific outposts to include manufacturing, closed environmental life support systems, and an integration with orbiting facilities to create a spacefaring civilization (see for example Bova, 1987).

Friedrich Horz, in his overview article "Lava Tubes: Potential Shelters for Habitats" (1985), described gigantic cavernous spaces present in lunar lava tubes--nearly horizontal conduits for the lavas that poured out to form the lunar 'seas' or maria billions of years ago (Greeley & Spudis, 1986). These lava tubes are protected by at least 10m (and more likely around 50m) of hard basalt roof capped with regolith. These giant caverns may be hundreds of meters in diameter, offering hundreds of meters or even kilometers of shelter. In addition to natural protection from cosmic rays and solar storms (Angelo et al. 1988; Silberberg et al. 1985), the temperature is expected to be a constant -20C (-4F) (Mendell in Horz, 1985), compared to a range of roughly 300C (540F) on the lunar surface. These lunar lava tubes may provide the space necessary to house the expanded missions of the new generation lunar bases, as well as making additional development and expansion relatively easy.

In order to explore problems and opportunities of lava tube environments and to demonstrate the educational value of lunar base simulations, Oregon L-5 Society researchers conducted three lunar base mission simulations in real lava tubes near Bend, Oregon, during the winter of 1987-88. An overview of our work was described to researchers at the Second Lunar Bases and Space Activities of the 21st Century Symposium in Houston (Billings, Walden, and Dabrowski, 1988). The purpose of the present paper is to describe in detail the educational lunar base simulation design.

Simulations as Teaching Tools

Simulations are vital at the highest levels of training in the space program and in aeronautics (Hughes and Holkan, 1988). Simulations in aeronautics have reached the stage where commercial air transport pilots can be rated to fly a new jumbo jet without ever actually stepping foot in a real cockpit. NASA uses simulations to train astronauts and mission specialists in routine and exotic space maneuvers. These businessmen, engineers, and researchers know the educational value of simulations. Simulations attempt to create as closely as possible the conditions they are designed to simulate: in this way parts and personnel are tested in integrated operation over a range of responses and complex relationships are revealed. Because of the holistic nature of simulations it is possible to simplify the elements in order to study the general structures and relationships between people, parts, and problems. This reaches its most notable extension in computer simulations, where all elements are represented by simple mathematical statements and relationships and which sometimes can be set up to run themselves (Bilby and Nozette, 1988; Boles and Ashley, 1988; Evanich and Modell, 1988; Fairchild, Bell, and Trotti, 1988; Hughes and Holkan, 1988).

One reason that simulations make excellent teaching tools is that the learner is immersed in the educational environment, not just reading a book or conducting a carefully delineated experiment. Environmental and interpersonal factors mix in and the learners are participants as well as observers. The multiplicity and dimensionality of associations in a physical simulation makes correct recall of target data more probable--that is, simulations enrich the learner and improve retention and integration of learned material. These factors influenced the researchers, who are OMSI-L5 Young Astronaut leaders, to choose lunar base educational simulations in real lava tubes as a project of the 1987-88 school year.

Mission Definition and Site Location

Lunar bases may be characterized by the following domains:
  1. Location: (1/6 gravity, vacuum, lunar dust/regolith, solar winds, cosmic radiation, temperature extremes, fortnightly day/night cycle, etc.).
  2. Architecture: (Buildings, Machines, Roads, Industries, Laboratories, Equipment, etc.)
  3. Personnel: (Quantity; Rotation; Mix; Ages; Biomedical; Psychological; etc.)
  4. Activities: (Life Support, Astronomy, Lunar Science, Manufacturing, etc.)
  5. Governance: (Governments, Managements, Capitalization, etc.)
Of these domains, Personnel and Governance can be simulated almost without "penalty" (points where simulations fail to mirror expected conditions) and Architecture can be scaled relatively easily to any degree of desired accuracy. Some Activities, such as life cycle systems, can be well-tested here on Earth; other Activities that depend on special qualities of the Moon will have to make-do without wholly accurate simulants. It is Item I, the high-vacuum, low-gravity, irradiated and pummelled lunar surface location that is hardest to simulate. To test lunar landers and rovers, NASA created costly "simulated lunar soil" at a government test station in Vicksburg, Mississippi (Morea, 1988). If lunar lava tubes are chosen as base sites, their structure of solid basalt walls and ceiling should be well-modelled by the smaller but similarly-formed lava tubes of Earth. Nature has provided us with an excellent laboratory that does, in this instance, mirror lunar conditions.

Our first steps were to survey a variety of large lava tube caves in Oregon and S.W. Washington for their match to lava tube forms expected on the Moon and for their suitability from a practical standpoint for lunar base simulations. A small list of demonstration caves resulted from this survey--this list is available from the author and includes brief notes on the selected caves, all of which are open to the public (Walden, 1988b). These large lava tubes on Earth are 12m-40m in diameter and would easily house full-size models of the first lunar habitats. For our initial mission simulations we acquired U.S. Forest Service permission to use Skeleton Cave, 12m in diameter, which is easily negotiated and readily accessible from Bend, Oregon. We are not the first to notice the similarity of the volcanic features common around Bend to those seen on the Moon: NASA brought astronauts here in the 1960's to train them for their lunar activities (Peterson and Groh, 1965; Greeley, 1971).

One factor important to all lunar base and equipment designs is powdery lunar dust (Morea, 1988). Astronauts reported it was abrasive and pervasive, clinging to everything possible. Lava tubes in the Bend area have preserved a fine volcanic dust deposited 6,800 years ago by the giant eruption that created Crater Lake (Chitwood, 1982). A precursor feasibility study by the researchers identified this cave dust as a major problem. The tiny silicic shards cling by the hundreds to every grain of sand in samples collected deep within the cave, as revealed by microscopic examination back at OMSI. This dust is stirred up by any activity, just by putting a foot down, and it is electrostatically attracted to most surfaces, including moving or tight-fit parts of components. It is very abrasive and can contaminate lubricants. In sufficiently disturbed areas it becomes a suspended haze in the atmosphere and irritates respiratory passages, eyes, etc. This analog to lunar dust is relatively unique to Bend area lava tubes, and adds to the realism of lunar base simulations conducted at these sites.

Simulations in dust-polluted lava tube caves therefore model at least four special lunar conditions: large shielded cubic volume; hard basalt roof and walls; floors varying from rough rockpiles to relatively smooth lava; and fine abrasive dust. A fifth lunar feature revealed during the actual mission simulations was sensory deprivation in the plain lava tube environment. Although initially interesting for its size and its formational history, the interior of a lava tube is essentially dull and dark (black rock), presenting a low visual relief, constant temperature, and muffled sound environment. This introduces personnel requirements of entertainment, variety, and for being left alone or socializing at will.

Lunar Base Design

While the lava tube site survey was in progress, OMSI-L5 Young Astronauts were engaged in mission definition and design of functional modules to be erected and used at the lava tube lunar base. "Building blocks" for these modules were the large-scale plastic-tube-and-connector "QUADROS" developed in W. Germany. A minimal lunar base design was fixed with four functional modules: a communications/power console, a galley, a sanitation station, and a sleeping/work platform to raise personnel above the cold and dusty cave floor. Construction of these modules was practiced and their designs were refined in the OMSI labs during the weeks before the mission. The module parts were then stowed in bags and prepared for transport to the mission site. Many square feet of tarpaulin were included in the supplies to cover the cave floor and act as a partial control for the fine sand-borne dust.

Free-standing battery-powered lights would provide ambient illumination for construction and activities at the base (all participants had at least two sources of light with them at all times as well, per cave safety procedures). Some of these electric lanterns could be plugged into the base power system once it was operational. Because of the extensive use of plastics in these simulations and the necessity not to pollute the enclosed air space of the cavern, combustion for heat or light was not allowed at the base.

Design for all elements was kept as simple as possible. The sleeping/work platform was a straightforward 2.5m by 7.5m flat surface raised about half a meter from the floor. Sleeping bags and padding were added to the surface by the participants, and at other times the platform was cleared for a relatively dust-free general work surface.

The galley was a structure about 0.5m deep by 2m wide by 1.5m high with many shelves for food storage, a work surface for food preparation while standing, and a raised platform for a light. Campstoves are not permitted in the galley, due to the ban on combustion. Instead, foods are either eaten cold or are warmed in a 12v cooler/warmer unit based on a NASA thermal module.

The sanitation facility consisted of a closet-sized enclosure for a camp toilet (using enzymatic digesters rather than chemicals) and an attached privacy enclosure for washing and changing clothes. Soap and water are vital components in the dusty cave environment, but water at cave equilibrium temperature (+4C/39F) is just like water taken from the typical refrigerator. Hot water is not a luxury but a necessity for simulations as well as for the lunar base. Solar energy or another of the NASA thermal modules will answer to this need in future simulations.

The power console was designed and built by the Commander (grades 7-9) Young Astronaut chapter with the help of chapter leaders, and unveiled in the third mission simulation. For simulations involving Young Astronauts a 12-volt power system that uses off-the-shelf components was selected for safety reasons. The power console switches and fuses main power lines, meters power usage, has its own lighting system, and provides a mount for the independently-powered communications system. The control panels and power socket panels can be collapsed to a compact package for storage and transportation. The deployed panels are housed in a QUADROS framework 0.5m deep, 0.5m wide and 1.5m tall. Initially, power has been provided by deep-cycle 12v marine batteries for weekend-long simulations. A full 120v generator will be required for more elaborate or lengthy simulations.

Mission Profile

Three mission simulations were conducted in the 1987-88 school year: two at Skeleton Cave and one at Young's Cave. All missions followed the same general mission profile, as follows:

Transportation arrangements modelled the flight profiles for lunar-bound craft. Friday after school, Young Astronauts, Students for the Exploration and Development of Space (SEDS), chapter leaders and adult volunteers rendezvoused at the Oregon Museum of Science and Industry in Portland, which served as an Earth launch site. There the cargo vehicle (OMSI van) was loaded and "launched" and personnel boarded the passenger shuttles for the four-hour "space" trip to the Bend, Oregon "Moon Country." The first arrivals secured the site, installed signs directing the public to other caves in the area, and erected a "surface base" using camping tents. In some mission simulations a "space station" simulant was provided courtesy of Sunriver Preparatory School near Bend, which served as a staging area.

The second wave of personnel and cargo arrived Saturday morning. First order was to explore the cave to find a good base site and conduct trash patrol to clean up the litter left by years of public abuse. All mission personnel wear safety hardhats and follow cave safety and conservation procedures recommended by the National Speleological Society. A site deep within the cave (470m) was chosen for its spacious size, 13m wide by 15m high by 60m long, featuring high parallel walls, an arched ceiling, and an essentially flat floor made of washed-in sands from the surface. A typical lunar lava tube would be 15 or 20 times bigger than this. Nonetheless, with no sign of the outside world, encased in basaltic rock, it was easy to imagine we were on the Moon.

Crews first spread out the tarpaulins to control the dust and construction lamps were set out--one result of our energy use studies was our complete conversion to efficient fluorescent lights. The construction parts were distributed to the sites selected for each component. Environmental measurement stations (thermometers, hygrometers, wind measurement) were deployed in the cave and on the surface, and the intercom wire was strung from the base to the surface encampment. This intercom, incidentally, was a very valuable part of the mission and was worth the cost of emplacement in saved time and energy.

There is an order to construction and emplacement of facilities. First order of business is the sanitation station. It is placed in the lowest region of the site in case of spills or leaks. After constructing the open framework of QUADROS, wash station and toilet facilities are emplaced and filled with water, then the framework is covered with an opaque tarpaulin to provide privacy from the outside and between compartments.

While the sanitation station is being built, the power team connects the base-to-surface intercom and unpacks the power control panels. The console is located nearest the entrance to minimize intercom and external power cable lengths. The battery is sealed inside the base of the console and the main power feed is plugged into the control panel. Additional lights become available when the power console is energized and power accessories such as air pumps and thermal modules can be used. The intercom is pressed into service to coordinate surface and interior activities.

With the first two modules in place, construction/emplacement proceeds on the sleeping/work platform and the galley. The galley is placed near the power console in order to minimize cable lengths and associated electrical losses. When these jobs are finished, the galley is immediately pressed into service and the participants prepare and eat their meals deep in the cave at the now-operational lunar base.

After the meal there is time for a unit of science study. When skies are clear, this is usually astronomy. OMSI's Pacific Rim Space Education Center supplied a portable 8-inch telescope for use on the missions. In addition to learning constellations, there were opportunities to observe nebulae and clusters, moons of Jupiter and rings of Saturn. After about 60-90 minutes free time there is a call for "lights out". Participants bed down in sleeping bags on the sleep/work platform, safely above the ground-hugging layer of chilled air, and darkness returns to the ancient cave. The night security watchman reports temperatures dipping to 28F (-2C) outside, but the cave temperature dips only a degree to 42F (5.5C) in the lava tube.

The next morning after breakfast there is time to conduct another science project or, with enough personnel, projects (see below). Science teams range from the lunar base and return there with their data. The sleeping/work platform is cleared of bedding, which can be stowed inside the structure, and converted to a work surface to spread out notes, samples, etc.

After lunch is prepared and eaten at the galley, base teardown begins. Reverse order is followed, starting with the sleep/work platform. Cargo is loaded into the cargo shuttle and passengers board their shuttles for the long "space" trip back to OMSI "Earthport". A mission "debriefing" serves as a review session for the participants and gives the research team feedback on the simulation.

Science Activities at the Lunar Base

Basic science is one of the primary functions of the first lunar bases, and the lunar base simulation offers educators an opportunity to demonstrate science techniques and data analysis in the field. Once the base is operational, various scientific studies and experiments can commence. The following science projects have been conducted during lunar base mission simulations:

Environmental Science: Even before the base is fully operational, Young Astronauts have set out environmental monitoring instruments both inside and outside the lava tube and allowed them to stabilize. Data sheets are kept near each station and as participants pass the station they record the time, read the instruments, and record the environmental data. This is an ongoing study through the whole mission. In the first missions the data consisted of temperature, humidity, and wind direction and speed. Barometer readings were also included when available. Back in the lab, data can be displayed as graphs showing changes and relationships between the parameters. Typical values in Skeleton Cave were temperature +6C (43F) and relative humidity 80%. A very slight breeze seemed to change direction on a scale of several hours.

Astronomy: During the winter months in which the simulations were conducted, the skies were dark by the time the base became operational. OMSI provided an 8-inch reflecting telescope which was set up near the cave entrance to examine star clusters, planets, and nebulae. Young Astronauts were aided by chapter leaders in identifying planets, stars, and constellations.

Cartography: Maps are important for planning and many activities. Young Astronauts learned to use compass, tape, and inclinometer measurement to map the interior of the cave. Then they returned to the entrance and repeated their readings on the surface in order to find the surface projection of the underground lunar base.

Sand/Dust Analysis: Samples of the troublesome cave sands were collected from the vicinity of the base. Back at OMSI they were examined by microscope and other analytical techniques (flotation; magnets; spectral analysis). Magnetically susceptible particles were rare. Magnification revealed exceptionally tiny glassy particles coating every grain of sand, like dirt on a boulder. The surface area represented by these particles is huge, which helps explain their suspension in atmosphere, their dryness, and their electrostatic affinity. To counter the dust contamination, it was decided a dry, anti-static lubricant was needed. One of the researchers (Walden) suggested an aerospace lubricant developed by Ball Corporation and marketed as a vinyl phonograph record preserver called "Sound Guard." This lubricant appeared to alleviate some of the problems caused by the dust.

Geology: OMSI volunteer Henry Maisler brought some simple geological analysis tools to the base site. Young Astronauts collected samples of rocks, sand, and cave-wall mineralization which were then subjected to oxidizing and reducing thermal reactions. Some elements could be analyzed by examining the spectral characteristics of the samples. All samples tested were metal-poor.

Sample Collection: Geological and biological samples were collected, collection sites and contexts were described, and the samples were identified by reference to books or experts. Collections could be organized according to criteria selected by the collectors.

Time-Motion-Design Studies: In the process of constructing the lunar base and using the components for housekeeping, science studies, etc., design and procedural changes would be suggested by experience. This is a simplified version of time-and-motion efficiency studies and human-engineered design work. Thanks to the modular QUADRO construction system, designs could be changed easily; since the QUADROS are so lightweight, system components could be physically rearranged even after construction in order to improve efficiency or answer to other needs. Other problems were best addressed by modifying the work procedures or reassigning personnel.

Summary and Future Plans

Lunar bases will be a vital and continuing part of humanity's expansion into near-Earth space and beyond. Researchers and industrialists are finding more and more activities appropriate to lunar bases, and lunar base designs have expanded accordingly. Gigantic lunar lava tube caverns will provide ready-made and cost-effective shelter for all sizes of lunar bases. We have found it possible to simulate lunar bases in terrestrial lava tubes, thereby demonstrating the many benefits offered by the lava tube environment. Young Astronaut and SEDS participants found the lunar base simulations to be exciting adventures in science. The mission activities provided practical experience in data collection and analysis. An appreciation was gained for the many interlocking factors of lunar bases and of scientific research.

The enthusiasm generated by these simulations has encouraged the Oregon L-5 researchers to continue and expand these activities. The City of Bend has offered Oregon L-5 use of a city-owned lava tube complex for long-term educational and research activities. Plans are underway to continue and expand development of lunar base educational simulations, and to make the lava tube facility available for students and researchers seeking a test-bed for lunar designs and procedures. Educators and researchers interested in this facility or the educational mission simulations are encouraged to contact the author.


Angelo, Joseph A. Jr., Madonna, Richard G., and Quam, William (1988), Radiation Protection Issues and Techniques in Support of Lunar Base Operations, in Abstracts of the Second Lunar Bases and Space Activities of the 21st Century Conference, Lunar and Planetary Institute, Houston.

Bilby, Curt, and Nozette, Stewart (1988), Modeling a Lunar Base Program, in Abstracts of the Second Lunar Bases and Space Activities of the 21st Century Symposium, Lunar and Planetary Institute, Houston.

Billings, Walden, & Dabrowski (1988), Evolving Lunar Lava Tube Base Simulations with Integral Instructional Capabilities, Second Lunar Bases and Space Activities of the 21st Century Symposium, Paper No. LBS-88-044, Lunar and Planetary Institute, Houston.

Boles, Walter, and Ashley, David (1988), Modeling Construction Requirments for a Manned Lunar Base, in Abstracts of the Second Lunar Bases and Space Activities of the 21st Century Symposium, Lunar and Planetary Institute, Houston.

Bova, Ben (1987), Welcome to Moonbase, Ballantine.

Chitwood, Lawrence A. (1982), Geology of Central Oregon, in Larson (1982). Evanich, Peggy, and Modell, Michael (1988), The Role of Computerized Modeling and Simulation in the Development of Life Support System Technologies, in Abstracts of the Second Lunar Bases and Space Activities of the 21st Century Symposium, Lunar and Planetary Institute, Houston.

Fairchild, Bell, and Trotti (1988), Earth-Based Analogs of Lunar and Planetary Facilities, in Abstracts of the Second Lunar Bases and Space Activities of the 21st Century Symposium, Lunar and Planetary Institute, Houston.

Greeley, Ronald (1971), Geology of Selected Lava Tubes in the Bend Area, Oregon, Bulletin 71, State of Oregon, Department of Geology and Mineral Industries, 1069 State Office Bldg, Portland, Oregon 97201.

Greeley & Spudis (1986), Hadley Rille, Lava Tubes and Mare Volcanism at the Apollo 15 Site. In Workshop on the Geology and Petrology of the Apollo 15 Landing Site (Spudis and Ryder, eds.) pp.58-61. LPI Tech. Rpt. 86-03. Lunar and Planetary Institute, Houston.

Horz, F. (1985), Lava Tubes: Potential Shelters for Habitats. In Mendell, pp405-412.

Hughes, Frank E., and Holkan, Robert K. (1988), Training for 21st Century Space Missions, Second Lunar Bases and Space Activities of the 21st Century Symposium, Paper No. LBS-88-097, Lunar and Planetary Institute, Houston.

Larson, Charles V., ed. (1982), An Introduction to Caves of the Bend Area: Guidebook of the 1982 NSS Convention, National Speleological Society.

Mendell, W.W., ed. (1985), Lunar Bases and Space Activities of the 21st Century. Lunar and Planetary Institute, Houston.

Morea, Saverio F. (1988) "The Lunar Roving Vehicle" A Historical Perspective, Second Lunar Bases and Space Activities of the 21st Century Symposium, Paper No. LBS-88-203, Lunar and Planetary Institute, Houston.

O'Neill, Gerard K. (1976), The High Frontier, Bantam.

Peterson, N.V., and Groh, E.A. (1965), State of Oregon Lunar Geological Field Conference Guidebook, Ore. Dept. Geol. and Min. Ind., Bull. 57.

Silberberg, Tsao, Adams Jr., & Letaw (1985), Radiation Transport of Cosmic Ray Nuclei in Lunar Material and Radiation Doses. In Mendell, pp663-670.

Spudis, Paul D., and Ryder, Graham (1986), Workshop on the Geology and Petrology of the Apollo 15 Landing Site. LPI Tech. Rpt. 86-03. Lunar and Planetary Institute, Houston. 126 pp.

Stine, G. Harry (1975), The Third Industrial Revolution, Ace.

Walden, Bryce (1988b), Lunar Base Simulations in Lava Tubes of the Pacific Northwest, Atmospheric and Earth Sciences Section, AAAS Pacific Region Annual Meeting, Corvallis, Oregon 1988 June 20.

Bryce Walden, President
(503) 655-6189
Oregon L-5 Society, Inc., Chapter of National Space Society
P.O. Box 86
Oregon City, OR 97045-0007

The Planetary Society National Space Society

Home | Intro | Join | LBRT | MIST | Contacts | New Info | Links