NASA Technical Reports Server (NTRS) 19930007683: Alternative scenarios utilizing nonterrestrial resources

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by  NASA Technical Reports Server (NTRS)

N9 -16872
7o -" Alternative Scenarios Utilizing
Nonterrestrial Resources
Charles H. Eldred and Barney B. Roberts
This section of the report provides • Tangible materials
a collection of alternative scenarios • Lunar
that are enabled or substantially • Asteroidal
enhanced by the utilization of • Martian
nonterrestrial resources. Here we
• Vacuum
take a generalized approach to
• Energy
scenario building so that our report
• Low to negligible gravity
will have value in the context of
• Physical location/view
whatever goals are eventually
chosen.
The following paragraphs will
discuss, in varying detail, each of
One significant finding of this
these resources.
workshop is that to discuss only
tangible materials from asteroids or
the lunar surface is probably too Space Resources
limiting an assumption to permit
Tangible Materials
consideration of all viable
scenarios. Thus, although we Lunar materials: The foremost
decided to discuss the following lunar resource we identified was
space resources, we realize that lunar oxygen for rocket propulsion
this list is nonexhaustive. (see fig. 3). The Moon can also
Figure3
Lunar Materials Processing
Thisschematicdrawingshews threemain
classes of products(volatiles,metals, bulk
construction material) which can be made
from lunar raw material. Lunar regolith is
carried bya conveyor belt into areactor,
where itis heated byconcentrated solar
energy. Simple heating willcause itto
release trapped solar wind volatiles, Volatiles
including hydrogen andrare gases. Ifitis
heated inan atmosphere rich in hydrogen • I
or another reductant, chemical reduction
will takeplace, causing thelunar material
to release oxygen fromoxides and
silicates. When sufficientoxygen is
released, some of thereduced metals Lunar regolith
formed by theprocess can be refined
and formed into ingots orcast intouseful
shapes. Theremainingmaterial can be
withdrawn as slag, which can be used for
Refined
construction of buildings and roads or as
material
radiation shielding.
be a source of metals (iron, don't offer convenient staging
aluminum, magnesium, titanium) points.
and nonmetals (glass, ceramics,
concrete), which may find use as Martian materials: The utilization of
structural or shielding materials on martian resources, particularly to
and off the Moon. The Moon is produce propellants, is a probable
relatively deficient in some of the aspect of an intensive Mars
more volatile elements-hydrogen, exploration program. Propellants
carbon, and nitrogen. could be extracted from Mars'
atmosphere or from materials on
Asteroidal materials: Earth- the surface of Mars, Phobos, or
approaching asteroids are rocky Deimos (see fig. 5). These
bodies that can provide useful satellites have characteristics of
materials, including some elements carbonaceous asteroids and for
not found in abundance on the many purposes, including access,
Moon. Some asteroids contain may be considered as asteroids.
substantial quantities of water and
carbonaceous material; others have
Vacuum
abundant metal, including iron,
nickel, cobalt, and the platinum Vacuum, used in many scientific
group (see fig. 4). Some asteroids experiments and manufacturing
are energetically more accessible processes, is expensive to create
than the lunar surface; however, and limited in volume on Earth.
trip times are generally long and Workshop participants were not
low-energy opportunities limited. convinced t_at going into space to
For this reason, these asteroids utilize the vacuum would lead to
Figure 4
Mining anAsteroid
Mining asteroids willbe amajor
technological challenge. Here is one
concept inwhich arobot mining vehicle
withpaddle wheels moves around the
surface of theasteroid and throws out
material, which is caught in thecone-
shaped catcher attached tothe asteroid
withcables. Whenitis full, attached
thrusters willpropel thecatcher back to
near-Earth space, where the asteroidal
ore can be processed for water,
carbonaceous materials, and metals.
economic benefits, considering the Energy
high cost of space transportation
today. However, the potential of the Energy from space has been of
limitless vacuum available in space practical use for many years. The
kept it on the list as a viable primary energy source is of course
resource. The unlimited vacuum the Sun. The most prominent
could enable new analytical or application is solar photovoltaic
testing procedures that depend on power for satellites now in orbit.
the surface properties of materials In the state-of-the-art process, solar
or the transmission of molecular cells directly convert incident solar
beams. The vacuum of space could energy into electrical energy. The
enable accelerators with no need, or advantages of collecting solar
a substantially reduced need, for energy in space rather than on
containment devices. Such vacuum Earth arise principally from two
might permit new uses of the metals facts: The first is that one can get
sodium and potassium, which are more solar energy by choosing an
difficult to handle in the Earth's orbit that has more "daylight"
atmosphere. And it could allow hours, and the second is that one
the high-temperature vacuum can avoid interference from the
processing of glasses, metals, and atmosphere.
cement.
Energy from space may be utilized
in space to power facilities
Figure5
(including those on the surfaces
Phobos of planetary bodies) or can be
Phobos, oneof thetwomoonsofMars, returned to Earth for conversion to
is alikely target for any futuremartian electrical energy. Alternatively, the
missions. Phobos is 27 by 19kmand has Sun's energy may be used directly.
arelativelylow density of 1.9gm/cm3.
The propulsive power of solar
Theescape velocity from Phobosis only
photons may be used to drive a
11m/sec. Theoptical properties of
solar sail. Direct use of thermal
Phobos are similar tothose of a typeof
asteroids thatare thoughtbymanyto be energy to provide process heat
of carbonaceous chondrite composition. may be important in space. The
Phobos has awell-developed groove
Sun's light could be reflected,
structure, which mayreflect major internal
selectively, to the Earth to light
fracturing originating fromlarge impacts.
Phobos isinside theRochelimit for Mars cities, agricultural areas, or arctic
andis being pulled evencloser by tidal night operations (see fig. 6).
forces. Withinabout50 million years,
Phobos willbe completely torn apart by Large space facilities, such as the
these tidal forces and willbecome a ring
around Mars. space station or a lunar base, will
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Figure 6
Reflected Sunlight Illuminates
the Earth
Ina simple example ofhow solar energy
from space might be useful, large-
diameter mirrors provide illumination
where needed on Earth. In this concept,
a mirror, 300 meters in diameter, made of
thinMylar film and supported bya ring
and girder structure, is being set up in
geosynchronous orbit. Such mirrors
would provide nighttime illumination
equivalent to full moonlight for any area
about 300 kmin diameter. Anumber of
mirrors could be pointed atthe same
area to provide much brighter
illumination. This illumination might be
useful for fighting cities, agricultural
areas, or arctic night operations. Other
potential uses are to fight up a disaster
area or an area undergoing a power
blackout.
Figure 7
Construction of a Large Solar
Power Station
In the future, large structures built in
space may include solar power stations
that wifl collect solar power using
photovolta_c arrays. This power could be
used in advanced space stations or
beamed to a lunar base by microwave. In
this view, a framework for such a station is
being constructed. The station includes a
service and equipment bay, in which
subcomponents can be assembled,
tested, and repaired.
Artist: John J. Olson
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require significant power (see fig. 7). not produce the high power levels
The power requirements for the needed for the primary supply
current space station configuration system.
are so large that the structural
design and control system Several NASA and privately funded
requirements will be driven by the efforts have been undertaken to
solar panels if photovoltaic devices define ways in which space-
are used. A competing design supplied energy might be used to
concept being considered is solar replace energy from nonrenewable
dynamic (see fig. 8). This approach Earth-based resources. One of
would use an energy-focusing mirror these was the solar power satellite
and a heat engine to drive a (SPS) system, which would ring the
generator. Another approach would Earth in geosynchronous orbit
use electrodynamic tethers to with 5- by 20-kilometer solar-
exchange orbital energy for powered satellites designed to
electrical energy. This very efficient microwave the energy to the Earth.
process may be useful in low Earth Another proposal for supplying
orbit for energy storage but could power from space to the Earth
Figure8
Solar Dynamic Power for the
Space Station
Inthis artist'sconception, asolardynamic
power generation systemuses
concentrated fight fromthe Sunto heat a
fluid, which turns agenerator toprovide
electrical power for thespace station.
Solardynamicpower generation mayhave
some advantages over solar photovoltaic:
potentially higher efficiency per unit area
of reflector and possibly lower cost for
largepower capacity. Asolar dynamic
systemmayalso be easier tomaintain.
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uses large areas on the Moon for electrophoresis process for
relatively low-efficiency photovoltaic separating cells having small
devices utilizing indigenous lunar differential charges is being
material, such as silicon. The lunar developed by private industry. In
power station would also transmit the absence of gravity, an electrical
energy to Earth by microwave. field can cause the desired cells to
migrate toward a collector. The
The Sun's energy is a perpetual great selectivity of this process and
source of clean, nonpolluting the purity of its products may lead
power, and major technological to drugs effective in the treatment
advances in photoconversion and of cancer, diabetes, and other
energy transmission could diseases (see fig. 9). Other
substantially alter any space processes may produce new alloys,
scenario. high strength glasses, and more
efficient semiconductors. The
Low to Negligible Gravity more space transportation costs
are reduced, the wider the range of
Many manufacturing processes economical microgravity processing
may be enabled or improved will be. This is an area of
by the utilization of the low to potentially significant commercial
negligible gravity of space. An investment.
Figure 9
Electrophoresis In Space
Manufacturing or materials processing in
the microgravity of space may prove to be
a major activity. Here, astronaut Jack
Lousma is handling an electrophoresis
column used for human ceil separation on
the STS-3 flight. Space manufacturing
and processing of biological and
pharmaceutical materials may prove cost-
effective because of the potentially very
high value of these substances per unit
mass.
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AND WHITE ,'-:;.-,'OTORr_.,_-:-,
Physical Location/View technology developments are
under way to further utilize this
Physical location in space and the unique space resource for
view from off the Earth have shown communication, navigation, search
themselves to be a resource of and rescue, and other purposes.
great benefit to the public (see The location of astronomical
figs. 10 and 11). The particular facilities in space has been
characteristics of the demonstrated to be of fundamental
geosynchronous orbit, both from scientific importance (see fig. 12).
the standpoint of view (weather Another potential utilization of
satellites) and from the standpoint location/view would be for
of stability (communication recreation in low Earth orbit.
satellites), have been heavily Studies have shown that a market
exploited and have provided does exist for the public to use
substantial benefits in revenue and space as a recreational area, if
in public safety. Significant public transportation costs can be made
and private (as well as joint venture) affordable.
Figure 10
The "Big Blue Marble"
Location inspace mustbe considereda
resource in thesense thatitenables
some veryvaluableactivities. Inthis whole
Earthviewtakenbythecrewof Apollo T7,
itis apparent thatlarge-scale weather
patterns can be photographed, thatthe
geology and vegetation of large land
masses can be observed by remote
sensing,and thatmanypoints on the
Earthcanbe reached byasingle
data transponder forenhanced
communication. Mostof the economic
payback from spaceactivities has so far
been in these three areas, allof which
takeadvantage oflocation inspace.
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Figure 11
. . . , , . _
: ...._.!_?_:-'_i_!!_i_i_':_:_ Space Shuttle and Horizon as Seen
From the Shuttle Pallet Satellite (SPAS)
This is a satellite view of the Orbiter taken
on the STS-7 mission. The Orbiter had
previously launched two communication
satellites (Telesat Anik C2 and Palapa D),
and the protective cradles for these
satellites can still be seen in the cargo
bay. The Space Shuttle has been used
heavily as a launching vehicle for
communication satellites. Much of
Ii this task may now be taken over by
expendable launch vehicles. Thelocation
in space of communication satellites gives
them such high value that the enormous
expense of building and launching them
can be paid back by revenues in a
reasonable length of time.
Figure 12
The Hubble Space Telescope
Another priceless advantage of a location
in space is illustrated by this artist's
concept of the Hubble Space Telescope.
This telescope will be above the Earth's
atmosphere, which greatly interferes with
the optical clarity of an Earth-based
telescope and which also absorbs
important parts of the light spectrum. The
Hubble telescope can be serviced in
space and can even be returned to Earth
by a Space Shuttle mission for extensive
maintenance or overhaul, if needed.
Eventually, telescopes on the Moon may
also be feasible and desirable. Radio
telescopes located on the far side of the
Moon will avoid the ever-increasing
electromagnetic noise from the Earth.
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Other potential developments in the potential for a much changed
the cultural and societal arena are mix of space users, with increased
certain to appear but difficult to levels of commercial, international,
quantify. Historical evidence and military space activities. The
suggests that humankind always objective of this section of the
modifies its culture and societal report is to view the broad range
norms to adapt to major alterations of mission alternatives that may
of its sphere of influence. It is use space resources and to select
conceivable that artistic and a few examples that illustrate a mix
sporting activities could find a role of mission characteristics.
in space and may be marketable.
Mission Characteristics and
By way of concluding this section Options
on space resources, we, the
Table 1 illustrates the variety of
members of the workshop, want
options that are possible for future
to stress that the list of space
resources is not limited to those we missions. Most missions can be
have mentioned. Other usable described by one or more of the
options related to each item.
resources might be isolation (for
Therefore, a specific mission can
nuclear waste disposal or very
be characterized by a total set of
hazardous research projects) and
extreme temperature gradients (for option choices.
heat engines).
Mission goals: Four broad goal
options are shown. The
Generic Scenarios for identification of relevant goals is
Utilization of Nonterrestrlal imperative to advocacy of the
Resources overall program and its technology
requirements. Each of the goals
]n order to suitably characterize the represents a valid component of
future utilization of nonterrestrial the total space program. Although
resources, we should assess some goal from the leadership/
scenarios broad enough to bring to human spirit class may be the only
the surface all or most of the key goal of a specific mission, most
technology issues. The exploitation space missions have been
of nonterrestrial resources dominated by a strong set of
encompasses a very broad range scientific or applications goals.
of potential products, benefits, Such human goals can often be
resources, supporting systems, and attained with only marginal costs
technology requirements. The when added to more concrete
eyolution of space activities goals.
into the 21st century also holds
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TABLE 1. Options for Aspects of Mission Development
Item [ Options "
1. Goals: Leadership Public applications Commercial Security
Exploration Military
Human spirit
2. Participants:
Type: Government Government/commercial Commercial
Countries: National International
3. Purpose: Science/research Enhanced mission Valuable product Prestige/power
4. Space resource: Materials Vacuum Energy Gravity Location/view
5. Resource location: LEO GEO LEO/cislunar Lunar Asteroidal Planetary
(debris/expendables) (Mars & moons)
6. Product: Materials Information/data Energy Pleasure
Volatiles
Low value solids
High value solids
7. Processing:
Location: In situ LEO Other
Type: None Automated Manned
8. Transportation:
Processing site Same In situ processing/ Intermediate site At use site
RUesesousrcitee site I used elsewhere
Mode: Chemical rocket Aerobrake Other
9. Infrastructure: Earth-to-orbit LEO space station Observation instruments Planetary bases or
transportation outposts
Orbital transfer
vehicles
*The columns in this table do not represent related categories but are used simply to enumerate options for each item.
Participants: The mix of States, military funding of space
participants in space activities activities now exceeds that of
is rapidly changing from the NASA. The U.S. program
historical dominance of the is encouraging commercial
U.S.A.'s civilian space agency participation. And most of the
and the more military space effort advanced countries and many
of the U.S.S.R. In the United developing countries are pursuing
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