Table of Contents
Recommendations and Conclusions
8. Recommendations and Conclusions
In the course of the 10-week study, it became apparent that there are
many aspects of the design of a space colonization project for which the
necessary data are not available. Many are critical to the design so
that, in the absence of firm data, conservative assumptions had to be
made. This forced the overall design in a conservative direction with
considerable weight, size and cost penalties compared with what might be
an optimum design.
Before a detailed practical design of a space colony can be undertaken,
the following subjects must be researched to fill in the gaps in current
- Acceptable Radiation Dose. The 0.5 rem per yr radiation dose is
achieved in this design study by accepting a considerable penalty in
weight and system complexity. This dosage rate is the upper limit allowed
for the general population in the United States and is chosen arbitrarily
as a conservative measure. Extensive biological testing should be
undertaken to establish a realistic dose limit taking into consideration
the colony's population distribution and the scenarios for habitation of
the colony. The effect of radiation on agricultural specimens also needs
study to assure stable food supplies.
- Acceptable g Levels. The physiological effects of zero-g are serious
for long-duration exposure in space. For this reason and since little is
known about exposure at intermediate g levels, 1 g was chosen as the
design standard. The 1-g choice has significant influence on the design
and may be unnecessarily high. An examination of physiology under partial
g is required in the Spacelab and subsequent space station missions to
determine the minimum g value for which there are no serious long-term
physiological effects upon humans.
- Maximum Acceptable Rate of Habitat Rotation. The rate of rotation
required to achieve the desired pseudogravity has substantial impact on
the design. Since the g-level and rate of rotation determine colony
dimensions to a large extent (and thus the weight) determination of an
acceptable rate of rotation is important. While it is difficult to test
human vestibular functions in a realistic way on Earth, it is critical that a better understanding of
the subject be obtained by studies both on Earth and in space.
- Closure of the Life Support System. The critical role of agriculture
in providing food and regenerating the atmosphere in the colony requires
that it be undertaken with utmost confidence and understanding. The
components of the agricultural system require study to determine their
detailed characteristics and their suitability. While possible in theory,
large living systems have never been operated in a closed loop. First on
a small scale, and finally on a large scale, complete closure of a
demonstration life support system should be accomplished before
colonization begins. The requirements for microbial ecology need to be
- Intensive Agriculture. The support of the colony's inhabitants on the
agricultural output from 150 acres is based on highly intensive
photosynthetic production, beyond that realized to date. The exact
enhancement of yields from lighting, increased carbon dioxide, and
regular irrigation needs to be determined, and actual prototype farming
needs to be conducted prior to closed life support system tests.
- Methods of Radiation Shielding. The requirement for 10 million tonnes
of passive shielding resulted from uncertainty in the effectiveness and
the complications of active shielding techniques. In particular, it is
recommended that studies be undertaken with the plasma shield to achieve
the acceptable dose with a workable system.
- Productivity in Space. The size, cost, and schedule for colony (and
SSPS) construction are critically dependent upon the number of workers
and their productivity. Terrestrial examples of worker productivity may
be unrealistic for colony construction. Significantly greater definition
of worker productivity is required for the colony design and should be
accompanied by actual experimentation in space to derive realistic
- Processing of Lunar Surface Material. The aluminum and titanium
extraction and refining processes suggested by this study are novel and
largely unstudied because of the unusual nature of the lunar ores
compared to terrestrial ores. The need to develop these processes in the
laboratory, the terrestrial pilot plant, and eventually the space pilot plant
is critical to the success of the program. Efficient production of glass from
lunar rock is also required under the limitation of minimal additives. Physical
and optical properties of the resulting glass need to be determined.
- Lunar Mass Launcher. The efficient transfer of lunar ore to a space
processing facility is essential to the success of the space colonization
concept. Alternative methods (such as the gas gun) need further study so
that a careful design analysis can be made of the entire subsystem. A
scaled prototype should be tested. More detailed engineering analysis of
the baseline system is required.
- Mass Catcher. The location and operational principle of the mass
catcher are critical to space colonization and weakly substantiated in
this study. The entire subsystem needs much greater study and eventually
testing in space.
- Minimum Acceptable Partial Pressure of Nitrogen and Oxygen in the
Space Colony Atmosphere. To minimize the quantity of nitrogen brought
from Earth, the problems resulting from oxygen-rich atmospheres need
detailed study to determine the minimum amount of nitrogen required in
- Satellite Solar Power Station Design. This study did not focus on
the details of the SSPS design. The method of energy conversion
(photoelectric vs. thermalmechanical) needs to be selected on the basis
of detailed comparative study and perhaps on the basis of fly-off testing
on small-scale prototypes. The methods of construction need careful
examination from the viewpoint of efficient material and manpower
- Transportation System. In addition to the main transportation
elements (the HLLV, the mass launcher, and mass catcher), the rotary
pellet launcher and the ferrying ion engines require research and
development. While the HLLV is proposed within the current baseline, even
more advanced vehicles with larger payloads and lower launch costs would
be of enormous benefit to the space colonization program at any time in
- Environmental Impacts. The frequency of launches needed and the
products from rocket combustion need to be studied to determine the
impact upon the Earth. The high power microwave beam from the SSPS may
have effects on certain biota in or near the beam, and rf interference
with communications, terrestrial navigation and guidance systems, and
radio astronomy should be examined.
- Human Physical, Psychological, Social, and Cultural Requirements for
Space Community Design. The diversity of options and the uncertainty of
absolute requirements for various human factors require considerable study, elaboration, and agreement. Factors governing design include
habitat configuration, efficient utilization of area, methods and
diversity of construction, visual sensations, and colonist activities.
All need to be thoroughly evaluated.
- Political, Institutional, Legal, and Financial Aspects of Space
Colonization. The space colonization effort is of such magnitude that it
requires careful analysis with respect to organization and financing. For
this analysis competent, realistic, and thorough study is needed.
National versus international, and governmental versus private or
quasi-governmental organization, requires study and evaluation. The
operational organization for space colony implementation is of sufficient
magnitude to merit this study being made very early in consideration of a
program to establish human habitats in space.
- Economic Analysis of Space Colonization Benefits. A more
sophisticated analysis is needed to determine whether the benefits of
space colonization do or even should justify the costs. In particular,
studies are needed which compare space colonization and SSPS production
with alternate methods of producing electricity.
- Additional Topics for Later Study. Space colonization in general
covers such a wide spectrum of diverse topics as to allow many fruitful
studies with varying depths of analysis. Examples of subjects that need
to be investigated are:
a. Method of immigrant selection.
b. Effect of "deterrestrialization" of colonists.
c. Effects of large-scale operations on the lunar, cislunar, and
terrestrial environment, and effects on the solar wind.
d. Disposal of nuclear waste on the lunar surface.
e. Alternate colony locations (such as lunar orbit, L2, LEO inside Van
Allen belt, free orbit, near asteroids, Jupiter orbit).
f. Detailed metabolic requirements (input and output data) for plants
g. Suitability of condensed humidity for human consumption, for fish,
and for crop irrigation.
h. Recycling of minerals from waste processing.
i. Production of useful products from plant and animal processing
j. Characterization of trajectories from lunar surface to the various
loci of potential activity.
k. Analysis of the potential foreign market for electric power.
l. Quantitative analysis of nonelectrical space benefits, for example,
benefits from production of communication satellites in space.
m. Development of alternative mission profiles which increase emphasis
on SSPS production or on colony production.
n. Effect of an established space colony on future space missions, their
feasibility and cost.
o. Application of learning curves to space colonization.
p. Ecological balance within the colony, microbial and insect ecologies
(including role of nitrogen fixation).
q. Chemical processing with nonaqueous or even gaseous techniques.
r. Determination of the proper safety margins for various systems.
s. Detailed design of windows and their optical properties.
t. Dynamics of atmospheres in rotating structures.
u. Tools and techniques for working in zero g.
v. Rendezvous with asteroids.
w. Remote assembly of large structures.
x. Halo orbits.
y. Description of everyday phenomena in a rotating environment.
z. Fire protection.
aa. Synthetic soils.
bb. Space manufacturing.
cc. Extension of economic geography to space.
dd. Adaptable and evolutionary aspects of habitat design.
ee. Atmospheric leakage rates and gaskets.
ff. A zero-g colony.
gg. Studies of work organization in remote locations.
hh. Studies of social and economic interdependence among communities in
remote locations with respect to transportation.
ii. Studies of functional division of labor within human communities.
jj. Study of methods for transporting and storing gaseous materials such
as hydrogen and nitrogen in various chemical forms such as ammonia,
ammonium salts, or other compounds.
kk. Space viticulture and enological techniques.
ll. Heterogeneity as a desired or required characteristic.
mm. Rotation of habitat within the shield.
nn. Colony governance.
oo. Requirements for interior illumination. Is sunlight really needed in
living and even agricultural areas?
pp. A detailed list of colonist activities and the land area usage
dictated by analysis of interior illumination needs.
qq. Composite material fabrication techniques in space.
rr. Construction of lunar mass launcher from lunar materials using
bootstrapped pilot plants.
ss. Detailed study and list of materials to be imported from Earth to
support the everyday needs of the colony.
tt. Extrusion techniques for space.
uu. Alternative diet components.
vv. An acceptable name for the first colony.
A principal recommendation of this summer study is that a major systems
study be made of space industrialization and space colonization. In
addition, it is recommended that the following space ventures be
undertaken as necessary preludes to space colonies.
Space colonization is desirable because of the hope it offers humanity.
A sense of the limits of Earth has been heightened in recent years by
growing awareness of the delicate ecological balance of the planet, its
finite resources and its burgeoning human population. The sense of
closure, of limits, is oppressive to many people. In America, growth has
been the vehicle of rapid and often progressive change; it has been the
source of opportunity for millions of people and has played an important
role in fostering American democracy and political freedoms. To have
opportunities restricted and to be forced to devise political
institutions to allocate equitably, resources insufficient to meet
demand, are unpleasant prospects. Space offers a way out, with new
possibilities of growth and new resources. Space offers a new frontier, a
new challenge, and a hope to humanity, much as the New World offered a
frontier, a challenge, and a hope to Europe for more than 4 centuries.
- Continue development of the space transportation system (shuttle) and
- Start development of the shuttle-derived Heavy-Lift Launch Vehicle.
- Construct a large space laboratory for placement in low-Earth orbit
in which experiments necessary to space colonization can be carried out.
- Establish a lunar base to explore and to test for the availability of
- Send an unmanned probe to the asteroids to determine their chemical
Space also offers riches: great resources of matter and energy. Their
full extent and how they might be used are not altogether clear today. It is likely that solar energy collected
in space, converted to electricity, and beamed to Earth would be of great value. The manufacture of the satellite power
stations to bring this energy to Earth and of other commercial activities
that use the abundant solar energy, the high vacuum, and the
weightlessness available in space, might bring substantial returns to
investors. It seems possible that the historic industrialization of Earth
might expand and go forward in space without the unpleasant impacts on
the Earth's environment that increasingly trouble mankind. On the other
hand, the potential of space must not detract from efforts to conserve
terrestrial resources and improve the quality of life on Earth.
On the basis of this 10-week study of the colonization of space there
seems to be no insurmountable problems to prevent humans from living in
space. However, there are problems, both many and large, but they can be
solved with technology available now or through future technical
advances. The people of Earth have both the knowledge and resources to
It is the principal conclusion of the study group that the United
States, possibly in cooperation with other nations, should take specific
steps toward that goal of space colonization.
Units and Conversion Factors
Table of Contents
NASA Responsible Official:
Dr. Ruth Globus
Last Updated: July 10, 2002
If you find any errors on this page contact Al Globus.