textfiles/ufo/moonbase.txt

                   STRATEGIES FOR A PERMANENT LUNAR BASE

        Michael B. Duke, Wendell W. Mendell, and Barney B. Roberts
               NASA-Johnson Space Center, Houston, TX 77058


                                 Abstract

    Planned activities at a manned lunar base can be categorized as 
supporting one or more of three possible objectives: scientific research, 
exploration of lunar resources for use in building a space infrastructure, 
or attainment of self-sufficiency in the lunar environment as a first step 
in planetary habitation. Scenarios constructed around each of the three 
goals have many common elements, particularly in the early phases. The 
cost and the complexity of the base, as well as the structure of the Space 
Transportation System, are functions of the chosen long-term strategy. A 
real lunar base will manifest some combination of characteristics from 
these idealized end members.


                        A MOON IN AMERICA'S FUTURE

    The Earth is unique in the solar system, not only for harboring life, 
but also for its relatively massive satellite. It is speculative that the 
two attributes are somehow related, but certainly the Earth's companion 
has left cultural and biological imprints on humanity. As cumulative 
application of the scientific method has increased our understanding and 
awareness of the physical universe, fascination with the habitability of 
the Moon has blossomed. As late as the late century, newspaper stories 
reported telescopic observations of the daily lives of lunar creatures. 
The manned lunar landings of the last decade have dispelled such 
romanticism forever but in turn have provided the technology and the 
information necessary to fulfill a greater dream - the transport of 
civilization beyond the confines of the Earth.

    Cultural expansion is a recurring theme in human affairs. Motivations 
for exploration or conquest vary from resource limitations (Mongol 
invasions) to religion (Turkish probings of medieval Europe) to commerce 
(global circumnavigations of the Sixteenth and Seventeenth Centuries). 
American history especially is permeated by the doctrine of manifest 
destiny. The concept of the frontier has come to symbolize for Americans 
the exercise of individual freedom, which in collective expression leads 
to social renewal. Contemporary popular writers cater to this mythos by 
describing for an overpopulated and confused world the "high frontier" of 
space. So far, the promise of space has been a reality for a few and only 
a vicarious experience for most. However, humanity, and the United States 
particularly, stands today at the threshold of a truly new world - the 
Moon.
    The promise of the Moon is not immediately evident from examination of 
the current American space program. However, the space shuttle and the 
proposed space station can be viewed as building blocks in a general 
purpose space transportation infrastructure (fig. 1). To service 
geosynchronous orbit, an upper stage is needed in addition to the shuttle. 
If that upper stage is provided in the form of a reusable orbit-to-orbit 
transfer vehicle docked at the space station, the transportation system 
can be multipurpose. In particular, a rudimentary lunar transportation 
system then will exist because the propulsion requirements for attaining 
geosynchronous orbit and lunar orbit are essentially identical. A lunar 
landing vehicle is required to place payloads on the lunar surface, but 
its design can be a straightforward adaptation of the orbital transfer 
vehicle (OTV). The space station and the reusable OTV constitute a natural 
evolutionary path that, when achieved, will make accessible all near-Earth 
space including the Moon. This "enabling technology" is a NASA target for 
the mid 1990's.

    When the requisite technology exists, the American political process 
inevitably will include lunar surface activities as a major space 
objective. In fact, some sort of declaration may well precede the actual 
establishment of the space station. It is therefore prudent to consider 
the nature of a permanent manned presence on the Moon and its potential 
impact on the evolution of the Space Transportation System (STS).

    Although the lunar base program is one in which the United States can 
assert its leadership in space, it is inherently international in scope 
and should involve as much participation as possible from other countries. 
Opportunities for international cooperation exist in the planning stages, 
in the science and technology development, and in operations at the lunar 
base. A legal framework will be needed to guarantee that potentially 
profit-making ventures adequately consider the concerns of the 
international community.


                             USES OF THE MOON

    A manned lunar base can be discussed in terms of three distinct 
functions. The first involves the scientific investigation of the Moon and 
its environment and the application of special properties of the Moon to 
research problems. The second produces the capability to utilize the 
materials of the Moon for beneficial purposes throughout the Earth-Moon 
system. The last, and perhaps the most intriguing, is to conduct research 
and development leading to a self-sufficient and self-supporting lunar 
base, the first extraterrestrial human colony. Although these activities 
take place on the Moon, the developed technology and the established 
capability will benefit society on Earth as well as the growing 
industrialization of near-Earth space.

Scientific Research
    A lunar base will create new opportunities for investigating the Moon 
and its environment and for using the Moon as a platform for scientific 
investigations. Analogous to the function of McMurdo Base in Antarctica, 
the lunar base will provide logistical and supporting laboratory 
capability to rapidly expand knowledge of lunar geology, geophysics, 
environmental science, and resource potential through wide-ranging field 
investigations, sampling, and placement of instrumentation. Access to 
large, free vacuum volumes may enable new experimental facilities such as 
macroparticle accelerators. The firm, fixed platform will enable new 
astronomical interferometric measurements to be obtained (fig. 2). The 
challenge of long-term, self-sufficient operations on the Moon can spur 
scientific and technological advances in materials science, bioprocessing, 
physics and chemistry based on lunar materials, and reprocessing systems. 
These concepts are explored by other papers in this volume.

Exploitation of Lunar Resources
    It has been argued that major industrialization of space cannot occur 
without access to the resources of the Moon. Studies of immense projects 
such as solar power satellites have demonstrated that at a sufficiently 
large scale, it is reasonable to develop the resource potential of the 
Moon to offset the high Earth-to-orbit transportation costs (Hearth, 
1976). The lower gravitational field of the Moon and the absence of an 
atmosphere that retards objects accelerated from the surface provides a 
potential 20 to 30-fold advantage for launching from the Moon instead of 
Earth. For example, at liftoff, about 1.5% of the space shuttle's mass is 
payload. Most of the mass is propellant. From the Moon, approximately 50% 
of the mass can be payload.

    The commodity currently envisioned to be most in demand in Earth-Moon 
space over the next three decades is liquid oxygen, which makes up 6/7 of 
the mass of propellant utilized by cryogenic (hydrogen-oxygen) rockets, 
such as the Centaur or postulated OTV's. Although it would appear unlikely 
than an atmosphereless body is a source for oxygen, it is actually an 
abundant element on the Moon (Arnold and Duke, 1978). It must be 
extracted, however, from silicate and oxide minerals into its liquid form 
for use as a propellant. Several processes have been suggested (Criswell, 
1980) for accomplishing this, including reduction of raw soil by fluorine 
(which is recovered) or reduction or iron-titanium oxide (ilmenite)  
hydrogen (also recovered). Preliminary laboratory studies have verified 
the concepts behind some of these processes.

    Systems studies (e.g., Carrol et al., 1983) show that oxygen 
production on the Moon could benefit STS in the early years of the next 
century, even if the hydrogen component of the propellant needed to be 
brought from Earth (fig. 3-5). Finding concentrations of water at the 
lunar poles (Arnold, 1979) or extracting the dispersed solar wind-derived 
hydrogen in the lunar regolith would greatly improve the economics of the 
transportation system.

    Other commodities also could be produced. Metals, such as iron or 
titanium, can be extracted from the lunar soil or from specific rocks or 
minerals with differing degrees of difficulty. For example, small 
quantities of metal (primarily iron) from meteorites can be concentrated 
with a magnetic device from large amounts of lunar soil, or, with much 
larger energy inputs, titanium can be obtained from ilmenite. These 
products could find applications in large space structures. Lunar titania 
or alumina might be used to produce aerobrakes (heat shields) used in 
OTV's. In the long term, at relatively high levels of development, 
production of components for solar electric power generation in space 
(e.g., solar power satellites) could be made feasible (Bock, 1979).

Lunar Autarky
    A self-sufficient lunar base is a possible long-term objective that 
creates new challenges in planning and development. In the near term, 
emplacement of a controlled environment capsule on the Moon involves known 
technology. The initial concept for a lunar habitat module is simply an 
extension of the design experience from Apollo, Skylab, the space shuttle, 
and space station (fig. 6). A different perspective is required to plan 
systems that can utilize the Moon's native materials and energy sources to 
produce a self-sufficient capability.

    Most of the generic technologies for an advanced system are similar to 
those employed in general space operations (life support, power, thermal 
control, communications, logistics, and transportation, etc.), but they 
must be modified to utilize lunar materials for growth and extension. 
Ultimately, the desire to minimize or to eliminate the resupply link from 
Earth required a host of applications, new to the space program, carried 
to new levels of system reliability. Exploration of technologies such as 
lunar metallurgy, ceramics, manufacturing processes, power systems, and 
others, will reveal whether autarky is a realistic objective and can 
prepare the way for achieving it an operational base. Perhaps this is the 
most compelling rationale for a lunar system, as it promises eventual 
self-sufficiency elsewhere in the solar system.


                     PHASED EVOLUTION OF A LUNAR BASE

    We loosely define three scenarios, each based on one of the long-term 
rationales described above: scientific research, production, and 
self-sufficiency (Tables 1-3). Each scenario passes through several  
phases, some of which are common to the other scenarios. The distinction 
among the three views lies with the culminating phase of each.

    Precursor Exploration. Because the scientific data base is incomplete, 
particularly in the polar regions, the first step in Phase I is global 
mapping of the Moon, both with relatively high resolution imagery and with 
remote-sensing measurements to determine the chemical variability. This 
task can be accomplished with an unmanned satellite, a Lunar Geochemical 
Orbiter or LGO (Minear et al., 1977), which is a proposed mission in 
NASA's planetary program and could be flown in the 1990-1992 time frame. 
The LGO is in the Planetary Observer mission class, a low-cost approach to 
planetary exploration recommended by the report of the Solar System 
Exploration Committee (1983). Secondly, Phase I should include research on 
technologies necessary to exploit lunar surfaces. Technology development 
in resource problems on Earth is typically a long lead time process. At 
the conclusion of Phase I, the initial site for a base will have been 
defined and planned activities understood in some detail. Concurrently 
with this preliminary phase in the lunar program, development of a space 
station and on OTV capable of supporting a lunar base would be carried out 
in NASA's STS program.

    Research Output. At Phase II, an initial surface facility would 
establish limited research capability for science, materials processing, 
or lunar surface operations. Depending on the long-term objectives of the 
lunar base program, the detailed studies and the experimental plans start 
to diverge at this phase for the different scenarios. A focus on lunar 
science and astronomy would result in local geological exploration, the 
establishment of a small astronomical laboratory, and emplacement of 
automated instruments. If production were to be the focus, a pilot plant 
for lunar oxygen extractions could be set up instead, and study of the 
fabrication of aerobrakes from lunar material could be initiated. If the 
program goal pointed to achieving self-sufficiency, the emphasis at this 
stage could be agricultural experiments utilizing lunar soil as substrate 
and recycling water, oxygen, and carbon dioxide.

    To accomplish Phase II in any of the scenarios, the STS must have the 
capability of landing and taking off from the Moon, transporting manned 
capsules (about 10,000 kg) to and from the lunar surface, and delivering 
payloads of about 20,000 kg to the lunar surface. This involves delivering 
approximately 40,000 kg into lunar orbit using OTV's. The requirement for 
storage of the return vehicle on the Moon for extended periods (14 days to 
3 months) may require new high-performance, storable propellent systems at 
this phase of development.

    Permanent Occupancy. At Phase III, permanent occupancy is the 
objective. The surface infrastructure would include greater access to 
power, better mobility in and away from the base, and more diversified 
research capability. Still, depending on the long-term objectives, the 
nature of the base can vary. A science base might emphasize long-range 
traverses for planetological studies or extension of observational 
capability with larger telescopes. A production base will incorporate 
highly automated systems to produce and transfer liquid oxygen for use in 
the transportation system. Advanced research for a self-sufficient base 
would be making first extensions of the base utilizing indigenous 
materials. The production and the self-sufficiency scenarios require a 
small cousin to the Earth-orbit space station in lunar space (lunar orbit 
or an Earth-Moon libration point) to provide for transfer, refueling and 
maintenance of the lunar lander and the OTV's.

    Advanced Base. The advanced base, Phase IV, is even more specialized. 
Depending on the long-term plan, it produces more types or a greater range 
of scientific investigations, adds products to the growing lunar 
industrial base, or enters a phase of significant expansion of 
capabilities using lunar materials as the majority of the feedstock. This 
is the terminal phase for the science and production scenarios. Future 
growth may occur by enlarging the number of experiments or products 
produced on the Moon, but a self-sustaining capability is not included. 
The production base might even develop toward a highly automated state 
where permanent occupancy was unnecessary. For the production and 
independence scenarios, the base should begin paying its own operational 
costs. In the self-sufficiency scenario, research and development of pilot 
plants aimed at a broad range of indigenous ;lunar technologies would be 
pursued. The final phase of the self-sufficiency scenario is a truly 
autarkic settlement, a lunar colony, in which the link to Earth can be 
discretionary.

                         EVOLUTION OF THE PROGRAM

    Figure 7 ties the possible development of a lunar base to the growth 
of lunar resource support of the transportation system. Initially, the 
base is totally dependent on terrestrial supply where 7 kg in low-Earth 
orbit is required to place 1 kg on the lunar surface. With the 
introduction of lunar oxygen first into near-Moon operations and then into 
the return leg of the transportation system, the slope of the curve 
changes from 7:1 to 3.5:1. As the lunar manufacturing capability increases 
to the point where aerobrakes can be manufactured, the slope decreases to 
somewhat slightly greater than 1:1. Further growth of lunar capability 
allows expansion of base mass to be more or less independent of the 
quantity of imported terrestrial mass. At the point of self-sufficiency, 
only trace minerals and crew changeout are chargeable weight to lunar 
operations; the slope of the curve in fig. 7 is essentially flat.

    Another consideration in the growth of lunar activities is the 
economic "balance of trade" between Earth orbit and the lunar surface. The 
value of lunar products may support lunar operations before a true mass 
balance is achieved. It is difficult to calculate the economic value of 
lunar oxygen and other products in low-Earth orbit. However these "lunar 
credits" are shown qualitatively in fig. 7 at the point where a closed 
ecological life support system (CELSS) and a significant manufacturing 
capability are available. The slope of the "credits" line will be a 
function of many things, such as the amount of oxygen required to support 
non-lunar activities, the value of science and research enabled by the 
lunar base. Finally, the dashed line of constant slope indicates the 
continued total dependency that would exist if these technologies are not 
pursued on the Moon, that is, if a self-sufficiency element is not 
included in the lunar base program.

    The real lunar base will evolve as some combination of the above 
scenarios. Determination of the right mix requires research, development, 
and debate. Even if a program is started now, several years should be 
devoted to study of the detailed lunar base scenario. The time is 
available because the development of the space transportation 
infrastructure and the completion of the orbital science survey will take 
7-10 years. Proper preparation will make it possible to decide on a 
specific lunar base design in the early 1990's. That time frame is 
consistent with the development of the infrastructure that will enable the 
lunar base program to be carried out to its full potential. The first 
manned landings could occur early in the first decade of the next century; 
permanent occupancy could be achieved by the year 2007, the fiftieth 
anniversary of the Space Age.

    There are potential technological problems that may slow the 
development of the lunar base, and at each phase there will be serious 
questions as to whether to proceed and how and when to proceed. A 
commitment need not be made now to the whole plan. Nevertheless, the 
long-term objective is one of immense significance in human history and 
should not be casually discarded. It is inevitable that humankind will 
settle the Moon and other bodies in the Solar System. We live in a 
generation that has already taken very significant steps along that path. 
With careful planning, we can nuture the capability to move from the 
planet, to provide benefits to Earth, and to satisfy humanity's spirit of 
adventure.

                                REFERENCES

    Arnold, James R. (1979) Ice in the lunar polar regions, J. Geophys. 
    Res., 84, 5659-5668.

    Arnold, James R. and Duke, Michael B. (1978) Summer Workshop On 
    Near-Earth Resources, NASA CP-2031, NASA, Washington, DC, 1-7 pp.

    Bock, Edward H. (1979) Lunar Resources Utilization for Space 
    Construction, Final Report for Contract NAS9-15560, General Dynamics 
    Convair Div., Advanced Space Programs, San Diego, CA.

    Carroll, W. F., Steurer, W. H., Frisbee, R. H., and Jones, R. M. 
    (1983) Extraterrestrial materials - Their role in future space 
    operations, Astronaut, Aeronaut, 21, 80-85.

    Criswell, David R. (1980) Extraterrestrial materials processing and 
    construction, Final Report Contr. NSR 09-051-001, Lunar and Planetary 
    Institute, Houston, TX.

Hearth, Donald P. (1976) Outlook for Space, NASA SP-386, NASA, Wash., DC,
237 pp.

Minear, J. W., Hubbard, N., Johnson, T.V., and Clarke, V. C., Jr. (1977) 
Mission Summary for Lunar Polar Orbiter, JPL Document 660-41, Rev. A., Jet 
Propulsion Laboratory, Pasadena, CA.,36 pp

Solar System Exploration Committee (1983) Planetary Exploration Through 
Year 2000: A Core Program, U.S. Government Printing Office, Washington, 
DC, 167 pp.

                               Figure Titles

Figure 1. The Space Transportation System of the future may service a 
station in geosynchronous orbit as well as a lunar base via a station in 
lunar space. The lift capacity of the Shuttle fleet may be augmented by an 
unmanned heavy lift vehicle, designed to ship fuel and consumables to 
space.

Figure 2. A radio telescope located on the farside of the Moon would be 
shielded from background noises generated by terrestrial sources. Although 
depicted here with a parabolic dish in a convenient crater, an initial 
lunar instrument may well be a phased array of dipole antennas.

Figure 3. Liquid oxygen fuel (LOX), manufactured on the Moon and delivered 
to low-Earth orbit may become a profitable export for a lunar base. A 
critical parameter in analyses of the system is the mass payback ratio, 
defined as the ratio of the excess lunar LOX in LEO to the liquid hydrogen 
fuel delivered from Earth to LEO.

Figure 4. The mass payback ratio for lunar LOX delivered to LEO is 
sensitive to the design characteristics of the OTV used as a lunar 
freighter. The fractional mass of the OTV aerobrake and the oxidizer to 
fuel ratio are key parameters. Manufacture of aerobrakes on the Moon would 
enhance system performance.

Figure 5. A simple cost-benefit analysis assumes that a lunar oxygen 
production facility has its capital costs amortized solely by "profits" on 
delivery of LOX to LEO. While lunar oxygen is competitive with shuttle 
delivery in all cases, introduction of a cost-efficient heavy lift vehicle 
reduces the advantage under more conservative cost estimates for the lunar 
operation. If costs of lunar LOX are shared with other activities, the 
advantage is restored.

Figure 6. The first lunar base habitats and laboratories could be space 
station modules, buried in the lunar regolith for protection from solar 
flare radiation. Interface modules not only interconnect the buries 
structures but also can be stacked to create exits to the surface.

Figure 7. Initially, almost 7 kg must be lifted into LEO for every kg 
landed on the Moon. As lunar oxygen is introduced into the transportation 
system, the ratio improves as a unit mass goes from Earth to Moon with 
only little overhead in the system. In a Phase IV advanced base, the 
growth of lunar surface infrastructure becomes only weakly dependent on 
imports from Earth. A favorable balance of trade is ultimately 
conceivable.

         Table 1. Lunar Base Growth Phases: Sciences Base Scenario

A growing capability to do lunar science and to use the Moon as a research 
base for other disciplines, using lunar resources to a limited extent to 
support operations.
Phase I: Preparatory exploration
    . Lunar orbiter explorer and mapper
    . Instrument and experiment definition
    . Site selection
    . Automated site preparation

Phase II: Research Outpost
    . Minimum base, temporarily occupied, totally resupplied from Earth
    . Small telescope/Geoscience module
    . Short range science sorties
    . Instrument package emplacement

Phase III: Operational Base
    . Permanently occupied facility
    . Consumable production/Recycling pilot plant
    . Longer range science sorties
    . Geoscience/Biomedical laboratory
    . Experimental lunar telescope
    . Extended surface science experimental packages

Phase IV: Advanced Base
    . Advanced consumable production
    . Satellite outposts
    . Advanced geoscience laboratory
    . Plant research laboratory
    . Advanced astronomical observatory
    . Long-range surface exploration


        Table 2. Lunar Base Growth Phases Production Base Scenario

A lunar base that is intended to develop one or more products for 
commercial use. Manned activity may be continuous, but a high degree of 
automation is expected.

Phase I: Preparatory exploration
    . Lunar orbiter explorer and mapper
    . Lunar pilot plant definition
    . Site selection
    . Automated site preparation

Phase II: Research outpost
    . Minimum base, temporarily occupied, totally resupplied from Earth
    . Surface mining pilot operation
    . Lunar oxygen pilot plant
    . Lunar materials utilization research module

Phase III: Operational base
    . Permanently occupied base
    . Expanded mining facility
    . Consumables supplied locally
    . Oxygen production plant
    . Lunar materials processing pilot plant(s)

Phase IV: Advanced base
    . Large scale oxygen production
    . Ceramics/Metals production facility
    . Locally derived consumables for industrial use
    . Industrial research facility


    Table 3. Lunar Growth Phases: Lunar Self-Sufficiency Research Base 
                                 Scenario

A lunar base that grows in its capacity to support itself and expand its 
capabilities utilizing the indigenous resources of the Moon, with the 
ultimate objective of becoming independent of Earth.

Phase I: Preparatory exploration
    . Lunar orbiter explorer and mapper
    . Process definition
    . Site selection
    . Automated site preparation

Phase II: Research Outpost
    . Minimum base, temporarily occupied, totally resupplied from Earth
    . Surface mining, pilot operation
    . Lunar oxygen production pilot plant
    . Closed systems research module

Phase III: Operational base
    . Permanently occupied facility
    . Expanded mining facility
    . Lunar agriculture research laboratory
    . Lunar materials processing pilot plant(s)

Phase IV: Advanced base
    . Lunar ecology research laboratory
    . Lunar power station-90% lunar materials-derived
    . Agriculture production pilot plant
    . Lunar manufacturing facility
    . Oxygen production plant
    . Lunar volatile extraction pilot plant

Phase V: Self-sufficient colony
    . Full-scale production of exportable oxygen
    . Volatile production for agriculture, Moon-orbit transportation
    . Closed ecological life support system
    . Lunar manufacturing facility: tools, containment systems, fabricated 
    assemblies. etc.
    . Lunar power station - 100% lunar materials - derived
. Expanding population base