The feasibility of mounting a small operation on the Moon to productively use lunar materials in support of programs such as the solar power satellite is addressed. A cost effective scenario of a small chemical process plant on the surface of the Moon and a small machine shop located in orbit is presented. The mass of the space installation is compared to the projected outputs in 90 days. It is indicated that the system would have the capability of replicating about 90% of its own components and would provide the metals, glasses, and silicon needed for the contruction of 90% to 96% of the mass of one solar power satellite per year

Oneill, G. K.

English

NASA Technical Reports Server

RECENT WORK ON USE OF LUNAR MATERIALS FOR SPS CONSTRUCTION
Gerard K. O'Neill (presented by David Criswell)
Princeton University, Princeton, New Jersey 08544
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22713
During 1978 and 1979 several workshops were held under the 6ponsorship of
the Space Studies Institute. Experts in spacecraft design, rocket mission opti-
mization, mass-driver design, chemical processing and industrial automation took
part in these workshops. An earlier version of the results will appear, in part,
in Astronautics and Aeronautics. The purpose of the workshops was to extend in
a logical way the concepts of scaling and bootstrapplng(1) studied earlier in
1976 and 1978 NASA studies on the use of nonterrestrlal materials. (2,3) In the
latest work, the group examined first the question of how small an operation
could be mounted that would make a productive use of the lunar materials. In
that operation, as far as possible only equipment being developed by NASA for
other purposes would be used (the Shuttle itself, without augmentation, small
crew workstations, spacesuits, a conventional chemlcally-powered orbital trans-
fer vehicle, and whatever minimal tele-operators are developed in the course of
the next few years).
The interim conclusion of the workshops was that the most cost-effectlve
scenario would be one in which a very small installation would be put on the
Moon: a mass-driver plus a small chemical process plant plus a small "machine-
shop" would be located in orbit, probably about 2/3 of the way from the Earth
to the Moon. By "machlne-shop" is meant a partially-automated, general purpose
production facillty akin to a small Job-shop, capable of making most (but not
a11) of the components of additional, identical mass-drivers, processing plants
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and machine-shops. On the basis of present-day commercial experience in indus- ' _-_
trial automation, the group concluded that it would be practical for the.machine- [i.i',_.i!"
shop to be about 90% automated. Many of the machines could be directed by human
operators on Earth through radio and TV links, with local microprocessors to
handle decisions only on a 3-second time scale, that being the round-trip time
lag for signals between Earth and Moon. The machlne-shop would produce only
relatively simple, repetitive, heavy components. All electronics and all high-
precision machine components would be brought from the Earth.
It was calculated that thesystem would have the capability of replicating
about 90% (by weight) of its own components. Its human crew would be malnly
for maintenance, especially for those unusual or unforeseeable failures that
could now be repaired by remotely-directed equipment. The lunar facility would
be installed by humans originally, but might only be revisited occasionally
thereafter. Its purpose would be to export (via mass-driver) material to the
space facility, and also to replicate locally additional mass-drivers, process
plants and machine-shops.
To establish a baseline for the "leverage" gained through the use of lunar
materials, an optimized electrical design was completed (3/80) for a small lunar
mass-drlver. The design took advantage _ the six years of design development
that have now gone into mass-drivers. _z,J) ,
Copyright 1980 by Gerard K. O'Neill, for the Space Studies Institute
223
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Earlier, detailed work by the Lunar and Planetary Institute under NASA.
sponsorship (D. Criswell, Principal Investigator) had established that a chemi-
cal process plant on the lunar surface would be able to process at least 40
times its own mass per year.(4) The group budgeted six tons for such a plant,
to yield in three months a total throughput of 60 tons, comprised mainly of
an aluminum output of 8 tons, iron output of 3 tons, silicon output of 12 tons,
and oxygen output of 24 tons.
Such a plant could provide sufficient feedstock for a machine-shop to
replicate in 90 days an additional mass-driver, process plant and machine-shop.
The total installation on the Moon would be 37 tons.
In the scenario of the workshop group, the lunar installation would be
called upon to produce 33 tons of finished products in three months. The author
had an opportunity to check the correspondence of that figure to the 6-ton mass
of the machine-shop, in the course of a recent visit to Japan, and found that
the 33 tons/6 tons rate of production assumed for the chemical process plant is
well within current industrial practice on Earth. During the 90-day replication
time, about four tons of specialized or labor-intensive components would have
to be brought from the Earth to complete the replication of the facility. The
liquid oxygen to bring that four tons from Shuttle altitude to the Moon is within
the 24 tons of oxygen-output that the initial lunar facility would produce in
that period.
On commissioning of the replica of the original installation, the through-
put of material into space from the Moon would be doubled, to 4,700 tons/year.
Six more doublings, over a period of less than two years, would bring the total
throughput to 300,000 tons per year, with operation only during the lunar days.
That 300,000 tons of lunar material in space would be more than sufficient to
provide the metals, glasses and silicon needed for the construction of 90% to
96% of the mass of one Solar Power Satellite per year. (5) The process plant
and machine-shop located originally in orbit, and itsreplicas, would operate
in full-time sunlight. The table below shows the figures for the process plant.
Installation in space, to process initial
throuzhput of 2340 tons/year
Process plant mass
Machine-shop mass
Habitat mass
29 tons
29 tons
12 tons
Total mass 70 tons
Outputs in 90 days:
Aluminum
Iron
Silicon
Oxygen
82 tons
30 tons
.i17 tons
230 tons
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The initial installation in space is therefore more than capable of pro-
ducing in 90 days the 63 tons of finished products that would constitute 90%
of its mass, the remaining 10% for a replica being brought from the Earth. The
oxygen produced by the original plant would be far more than required for supply
of propellant to bring the necessary 7 tons of Earth-built components for the
replica. With the 90-day replication time, the orbital facility, like the lunar
facility, would be capable of growth to a value of 300,000 tons/year of through-
put in seven doublings, or about two years.
The workshop group has not yet studied the optimization of the mix of prod-
ucts in space between replicas of the primary system and machinery designed for
the production of SPS components. Presumably, in the simplest scenario, on
reaching the 300,000 ton/year figure the entire output of the facility would be
turned to the production of those machines. On the basis of the NASA-funded
study _5_ directed by R. Miller and D. Smith of M.I.T., the orbital facility
could produce in one to two years most of the machines that would be needed for
a steady production thereafter of one 10-GW SPS per year.
For the installations that would be replicated, the total amount of unique
equipment for which R & D would have to be carried out would be approximately
15 tons. Using cost figures based on Shuttle experience (approximately $60
million per ton) the total investment required for establishment of the initial
installations on the Moon and in space, for verification of the overall plan
and initiation of the replication process, would therefore include one billion
dollars for R & D and $0.4 billion for 16 Shuttle flights, needed to lift 107
tons of equipment and 340 tons of propellant to low Earth orbit. Total program
investment to the point of first replication appears therefore to be well under
five billion dollars.
The interim conclusion of the workshop group is that the concepts of scal-
ing, bootstrapping, and replication appear certain to provide major cost savings
in any program, such as that of the SPS, which requires the emplacement of large
payloads in high Earth orbit. It is also clear that there is great value in an
approach of that kind, which can achieve high return on a modest investment
without exceeding the llft capabilities of the unaugmented Shuttle system. The
workshop studies will continue, turning to a detailed examination of optimized
growth scenarios and the details of equipment design.
At present (1980) mass-driver development is adequately funded at a level
of $250,000 through the NASA Office of Propulsion and Power. Other than the
mass-driver, the only item of equipment in the scaling and replication method
that is without industrial precedent is the chemical processing plant. There-
fore the Space Studies Institute will initiate a grant, approximately in Septem-
ber 1980, of approximately $i00,000 (first year) for research and development
on a bench-chemlstry level system for the separation of simulated lunar soils
into pure elements.
The research reported in this article was supported by the Space Studies
Institute, Box 82, Princeton. NJ 08540.
225
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REFERENCES
O'Neill, Gerard K., "The Low (Profile) Road to Space Manufacturlng,"
March 1978 Astronautics and Aeronautics (A/A), Vol. 16, No. 3, pp. 18-32.
O'Neill, Gerard K., and O'Leary, Brian, eds., Space-Based Manufacturing
from Nonterrestrial Materials, AIAA, New York, 1977.
3. Billingham, John, Gilbreath, William and O'Leary, Brian, eds., Space
Resources and Space Settlements, NASA SP-428, NASA, Washington, DC, 1979.
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4. Criswell, David, Extraterrestrial Materials Processlm 8 and Construction,
NASA Johnson Space Center, Houston, Texas, 1978.
1 Miller, Rene H., and Smith, David, Extraterrestrial Processlng and
Manufacturing of Larse Space Systems, CR-161293, NASA Marshall Space
Flight Center, Huntsville, Alabama, 1979.
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226


Recent work on use of lunar materials for SPS construction

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