The lunar regolith contains small quantities of solar wind implanted volatile compounds that have vital, basic uses for maintaining life support systems of lunar or space settlements. Recent proposals to utilize the helium-3 isotope (He-3) derived from the lunar regolith as a fuel for fusion reactors would result in the availability of large quantities of other lunar volatile compounds. The quantities obtained would provide the annual life support replacement requirements of 1150 to 23,000 inhabitants per ton of He-3 recovered, depending on the volatile compound. Utilization of the lunar volatile compounds for life support depends on the costs, in terms of materials and energy, associated with their extraction from the lunar regolith as compared to the delivery costs of these compounds from Earth resources. Considering today's conservative estimated transportation costs ($10,000 dollars per kilogram) and regolith mining costs ($5 dollars per ton), the life support replacement requirements could be more economically supplied by recovering the lunar volatile compounds than transporting these materials from Earth resources, even before He-3 will be utilized as a fusion fuel. In addition, availability of lunar volatile compounds could have a significant cost impact on maintaining the life support systems of the space station and a Mars base

Bula, R. J.

Kulcinski, G. L.

Tibbitts, T. W.

Wittenberg, L. J.

English

NASA Technical Reports Server

N 9 3 - 1 9 9 8
POTENTIAL OF DERIVED LUNAR VOI.ATILES
FOR LIFE SUPPORT
R.J. Bula, L.J. Wittenberg, T. W. Tibbitts, and G. L. Kulcinski
University of Wisconsin
Madison W! 53706
The lunar regotith contains small quantities of solar uqnd implanted t_glattie compounds that hats?
vital, basic uses for maintaim'ng ltfe _ systems of lunar or space settlements. Recent proposals
to utilize the hetium-3 isotope (He-3) den'ved from the lunar regotith as a fuel for fusion react¢rm u_guld
result in the availatn'tity of large quantities of other lunar volatile compounds. The quantities obtained
u_uld provide the annual life support replacement requirements of 1150 to 23,000 inhabitants per
tonne of He-3 recoverea[ depending on the volatile compound Utilization of the lunar t_latile
compounds for life _ depends on the costs, in terms of materk_ and energy, associated u$th
their extraction from the lunar regotith as compared to the delivery costs of these compounds from
Earth resources. Considoqng today's consert_tive estimated transpgwtaHon costs (810,000 per kaogram )
and regotith mining costs ($5 per tonne), the life supluwt replacement requirements could he more
economically supplied by recovering the lunar volatile confounds than tra_'ng these materials
from Earth resource_ even before He-3 ugti be utilized as a fusion fuel. In ada_'tion, at_ilabiti O, of
lunar volatile compounds could have a significant cost i_-t on maintaining the life sup_mt systems
of the space station and a Mars base.
INTRODUCTION
Efforts toward .settlements on the Moon and Mars will require
major technological developments in the area of life support. Two
recent reports concerning future U.S. space efforts (Paine et at.,
1986; R/de, 1987) point out that the key to living and working
in space is the development of reliable life support systems that
are not dependent on Earth resources. A bioregenerative life
support system that closes the food, water, and air loops has the
potential of providing the human requirements for survival in a
space environment independent of Earth resources.
The lunar regolith contains small quantities of volatile com-
pounds implanted from the solar winds. These volatile compounds
have vital, basic uses for establishing life support systems of lunar
or space bases by providing (1) raw materials for food produc-
tion and food processing and (2) an atmosphere in the space base
structures (Fig. 1). The available carbon, as carbon dioxide, hy-
drogen, nitrogen, and water of the lunar volatile compounds can
be combined with small amounts of other materials derived from
the lunar regolith to produce food through photosynthesis and
autotrophic hydrogen and nitrogen bacteria.
The cost effectiveness for using these lunar volatile compounds
in a life support system has been greatly enhanced by the recent
proposal to use the helium-3 isotope (He-3) derived from the
lunar regolith as a fuel for fusion reactors (W/ttenberg et at.,
1986). Li and Wittenberg (1991) have developed a model of
He-3 mining using a relatively low heating temperature of 7OO°C
and have calculated the amounts of volatiles that would be
produced from the regolith at that temperature (Table 1 ). Thus,
large quantitites of other lunar volatile compounds would be
evolved during procurement of the He-3 (Fig. 2). The number
of inhabitants supported for a year by the nitrogen, water, and
carbon dioxide derived with each tonne of He-3 mined is shown
in Fig. 3.
Food, Atmosphere pressurization
Food, Atmosphere pressurization
Potable needs, Oxygen
Hydrocarbons, Microbiat synthesis
Water. Oxygen, Hydrocarbons
Atmosphere pressurization,
Food preservation
Fig. 1. Potential applications of solar wind dtTn)sited lunar volatile com-
I_)unds for life support.
NITROGEN REQUIREMENT
The nitrogen derived from the lunar volatile compounds can
be converted by appropriate bacteria to ammonia and then
incorlx)rated into proteins and other food materials. In addition,
nitrogen will serve a very necessary role by providing the principal
gas required for maintaining atmospheric pressures in the living
and working areas of the lunar base and for the plant growing
https://ntrs.nasa.gov/search.jsp?R=19930004810 2020-03-17T08:52:55+00:00Z
548 2rid Conference on Lunar Bases and Space Activities
TABLE 1. Estimated amounts of lunar volatile compounds released from lunar regolith heated to 700°C, volatile
compound replacement requirements, and amount of regolith processing required to provide the requirement_
Per Inhabitant
Amount Evolved' Volatile Required Regolith
Volatile from Regolith Requirements Processing
Compound (g per tonne) (g per day) (tonnes per day)
Nitrogen 4.0 960 240
Carbon dioxide 12.0 210 18
Water 23.0 390 17
Oxygen* 410
Methane: l l.O
Hydrogen_ 43.0
Helium ¶ 22.0
"From Hand Irdnenberg ( 1991 ).
twill be derived from electrolysis of water derived with the lunar volatiles or from reduction of lunar ilmenite.
ZCan be used as substrate for microbial synthesis of more complex carbon-containing compounds.
SCan be used to reduce ilmenite to produce water or oxygen.
qlNo life support need exists, but may be used to replace a portion of the nitrogen required to maintain atmospheric pressure.
1
H 61oo I
4oooll 3300 ==il / =
,9o ]1 31oo __ --,
1600 17002OOO
o
NITROGEN METHANE CARBON HELIUM WATER HYDROGEN
DIOXIDE
VOLATILE COMPOUND
Fig. 2. Tormes of lunar volatile compoun6s per tonne of He-3 rec(wered
from the lunar regolith.
100000
1oooo
1ooo
22000 23000
11000
1150
NITROGEN CARBON WATER WATER PLUS
DIOXIDE OXYGEN
VOLATILE COMPOUND
Fig. 3. Number of inhabitants supported tor a year by the nitrogen,
carbon dioxide, and water derived with each tonnc of He-3 mined.
facilities. The requirements for initially pressurizing the space base
volumes are not large, but the requirements for atmospheric pres-
sure maintenance of these volumes would be substantial because
of atmospheric leakage from the lunar structures and ingress and
egress activities. The amount of nitrogen required to maintain
atmospheric pressure represents o_er 99% of the annum nitrogen
replacement requirement because only a small amount would be
lost in the food production, food processing, and waste recycling
operations of the life support system, even ff a 10% annual loss
is assumed,
The annual replacement requirement of nitrogen is based on
providing a volume of 100 m 3 of living and working space per
person and the volume associated with a bioregenerative life sup-
port system. If a 1.0% per day leakage rate is assumed for this
volume, and an atmospheric pressure of lOl kPa is maintained,
the annual per person replacement requirement of nitrogen
would be 350 kg (0.96 kg per day × 365 days).
It is estimated that 400 tormes of nitrogen will be recovered
with each tonne of He-3 recovered from the regolith. This amount
of nitrogen would provide the annual nitrogen replacement re-
quirement of 1150 people. The quantities of helium recovered
from the lunar regolith could be used ms a partial substitution for
the nitrogen in the atmosphere. This would extend the supply
of nitrogen in proportion to the percentage of helium substitution
possible. Research is needed to determine what percentage of
nitrogen in the atmosphere can be replaced with helium.
Bula et al.: Derived lunar volatiles for life support 549
OXYGEN REQUIREMENT
Oxygen is a critically important requirement of a life support
.system. Gaseous oxygen has not been found among the lunar
volatile compounds; however, heating the lunar regolith to 700°C,
ms proposed for the extraction of He-3, does result in a portion
of the hydrogen reducing the iron-oxide-bearing regolith materials
to form water. The oxygen required for life support could be
derived by electrolysis of the water obtained in this manner. An
alternative method of obtaining the needed oxygen is by hydrogen
reduction of lunar-surface ilmenite and electrolysis of the water
as proposed by Gibson and Knudsen (1985). The primary use
of oxygen produced by this or similar meth(_Ls would be as a
propellant. Thus, the amount involved for life support purposes
would be relatively inconsequential by comparison.
Replacement requirements of oxygen are associated with at-
mospheric leakage and logs in the food production, fo(xl proc-
essing, and waste recycling operatkms. If the partial pressure of
oxygen in the atmosphere is maintained at a level equiwalent to
the Earth's atmosphere (20.2 kPa) for the volumes described for
the nitrogen requirements, the annual oxygen replacement would
be 95 kg per person per year (0.26 kg per day × 365 days).
The amount of oxygen lost in the other aspects of the life
support system can be estimated from data quantifying the amount
of oxygen given off by plants. It is estimated that a 20-m 2 area
of plants would provide the daily caloric requirements of one
person (Wheeler and _lbbitts, 1987). A plant area of this size
would give off approximately 1500g of oxygen per day. If a 10%
Io_s of this oxygen is assumed in the food production, f(x)d
processing, and waste recycling operations, then 150 g of oxygen
per person per day would need to be replaced. This amounts to
an annual replacement requirement of 55 kg per person (0.15 kg
per day × 365 days). Thus, considering the losses associated with
atmospheric leakage and with the food and waste recycling
processes, the total oxygen replacement requirement per person
per year would amount to 150 kg.
CARBON DIOXIDE REQUIREMENT
Analysis of the annum carbon dioxide requirement is based on
a 10% loss in the f(x)d production, food proce_ing, and v_,_stc
recycling operations because the carbon dioxide loss associated
with atmospheric leakage is negligible. A 20-m 2 plant area
produces approximately 2100g of carbon dioxide per day
(Wheeler and Tibbitts, 1987). If a 10% loss of carbon dioxide in
the food production, food processing, and waste recycling
operations is assumed, then 2 IO g per person per day would need
to be replaced. This would amount to an annual carbon dioxide
replacement requirement of 77kg per person (0.21 kg per
day× 365 days). It is estimated that approximately 1700 tonncs
(ff carlx)n dioxide will be recovered with each tonne of He-3,
thereby providing the annual estimated carbon dioxide rcTflace-
ment requirement of 22,000 people.
WATER REQUIREMENT
Water replacement requirements are based on estimates that
a person requires approximately 3900 g of l_)table w-ater per day
(NA._A, 1985). _llais does not represent the total water require-
ment, but rather only the amount of l_)table water for drinking,
f()(_l preparation, and in unprepared f(x)d, if 10% of this water
amount is lost during the recycling prc)ce._s, then 390 g of water
per person per day would need to be replaced. This indicates an
annual water requirement of 142kg per person (0.39kg per
day × 365 days).
The total annual replacement amount of water can be
calculated to include the loss associated with providing the
potable water and the oxygen. It is estimated that approximately
3300 tonnes of water will be recovered with each tonne of He-
3 recovered. If only the replacement requirement as,sociated with
the drinking water loss is considered, the 3300 tonnes of water
would provide the annual estimated water replacement require-
ment of 23,000 people. If the water is used to provide the re-
placement for both the water and oxygen loss, the 3300 tonnes
of water would provide the annual replacement requirement of
approximately 11,000 people.
COSTS OF LUNAR-DERIVED VOLATILE
COMPOUNDS COMPARED WITH
DELIVERY COSTS OF RESUPPLIES
FROM EARTH RESOURCES
Utilization of the lunar volatile comlxmnds for life support will
depend on costs, in terms of materials and energy, associated with
their extraction from the lunar regolith as compared to the
delivery costs of these compounds from Earth resources. The
value of He-3 as a fusion fuel is estimated to be at least $1,000,000
per kilogram (Kulcinsk_ 1988). Obviously, if the lunar volatile
compounds used for life support are obtained as a part of the
He-3 extraction process, the costs of obtaining the non-He-3
volatile compounds on the Moon would be much less than the
delivery costs from Earth resources.
Today's transportation costs (ff Earth resources to a lunar base
are optimistically estimated to be $10,000 per kilogram (Koelle,
1991). Considering that the annual total life support material re-
placement (nitrogen, carbon dioxide, oxygen, and water) is es-
timated at 719 kg per person, the present-day transportation costs
of them life support materials would approximate $7,190,000 per
per.,_m per }'ear. The number of lunar h,se inhabitants has been
projected to be 30 by 2010 (Ride, 1987). Annual tran_rtation
costs, on the basis of today's cost estimates, for replacement of
life support materials for a lunar b_se of that size would anlount
to $21 _,700,000. It is anticipated that future trans'lx)rtation costs
may be reduced by an order (ff magnitude, or to $1000 per kilo-
gram of payload transported from the Earth to the Moon.
By comparison, the costs of recovering the lunar w)latile
comlx)unds from the lunar regolith can be estimated on the basis
of the amount of regolith that would have to be mined to provide
the life support replacement requirements. Large-male regolith
mining costs, such as would be involved in recovering large quan-
tities of He-3, arc estimated at $5 per tonne of regolith handled
(SIqatoslavsky andJacobs, 1988). Mining the regolith for the _)le
purlx)se of life suplx)rt replacement materials would not be con-
sidered as large-_ale mining and, therefore, the per tonnc mining
costs could be higher than $_. Comparisons cff the break-even
costs of lunar regolith mining compared to transt_)rtation costs
from Earth to a lunar base are shown in Fig. 4. The relationships
shown in Fig. 4 are based on the assumption that 240 tonnes of
regolith per inhabitant per day must be mined and pr(x:essed to
supply the nitrogen replacement requirement (Table l ). Mining
this amount of rcgolith will he sufficient to supply the
replacement requirements of all the other volatile comlx)unds. At
550 2nd Conference on Lunar Bases and Space Activities
1 O0
za.
m ....... m • • • .... • .......
1000 10000 100000
TRANSPORTATION COSTS, $ PER PAYLOAD KG DELIVERED
Fig. 4. Comparison of costs for supplying the life support replacement
requirements from lunar regolith volatile compounds vs. transportation
costs for resupply from Earth resources. The dotted lines correspond to
twice the costs estimated by Koelle ( 1991 ).
transportation costs of $20,000 [twice the current costs estimated
by Koelle (1991)], it would be more economical to obtain the
life support replacement materials from the lunar regolith if
mining costs were less than $200 per tonne. Likewise, ff mining
costs are less than $5 per tonne [as currently estimated by
Stqatoslavsky andJa_'obs (1988)], then transportation costs to
the Moon would need to be less than $400 per kilogram to be
economically competitive. These cost comparisons do not take
into consideration the possibility of using helium for replacing a
portion of the nitrogen used for maintaining atmospheric
pressure. By using some of the available helium, the mining costs
would be reduced because less regolith would need to be mined
to obtain the replacement life support materials since consider-
ably more helium than nitrogen is recovered per tonne of regolith
(Table 1 ).
A_ailability of lunar volatile compounds would provide addi-
tional, distinct advantages related to life support for inhabitants
of space bases. The quantities of replacement supplies available
on the lunar surface would allow some relaxation of the othervdse
stringent re,-Tcling requirements being projected for a space-based
life support sTstem. Some of the waste materials and other carbon-
containing volatile compounds, such as methane, could be utilized
by plants and microorganisms to produce complex carbon com-
pounds. 11aese complex carbonaceous compounds could serve ;is
raw materials for the synthesis of other products required at a
space station, such as plastics. Also, the lunar volatile compounds,
or the synthesized products (food), could be exported to other
space bases, such as the space station and Mars, more cconom-
icaliy than from Earth resources. The value of the lunar volatile
compounds in this context is not possible to estimate at this time;
however, it is likely to be significant, particularly as the number
of inhabitants at space bases increases.
It appears reasonable to conclude that the life support replace-
ment requirements of a lunar base could be more economically
supplied by recovering the lunar volatile compounds than
transporting these materials from Earth resources even bt-fore He-
3 will be utilized as a fusion fuel. Therefore, development of
technology to recover lunar volatile compounds could be started
in the next decade without waiting for the D-He-3 fusion reactors
to be built on Earth. The early use of the lunar volatile compound
recovery technology could reduce significantly the costs of
maintaining the life support ,systems (ff the space station and of
,settlements on the Moon and Mars.
REFERENCES
Gibson M.A. and Knudsen C.W. (1985) Lunar oxygen production from
ilmenite. In Lunar Bases and Space Activities of the 21st Century
(W. XX( Mendell, ed.), pp. 543 550. Lunar and Planetar3, Irkstitute,
Houston.
Koelle H. H. (1992) The influence of lunar propellant production on the
cost-effectiveness of cislunar transportation systems. In The Second
Conference on Lurwrr Bases and Space Activities of the 21st Century,
this volume.
Kulcinski G.L. (1988) Commercial Attractiveness of D-He j Fusion
Reactors. UWFDM-755, Univ. of Wisconsin, Madison. 49 pp.
Li Y.T and Wittenberg LJ. (1992) Lunar surface mining for automated
acquisition of helium 3: Methods, processes, and equipment. In The
Second Conference on Lunar Bases and Space Activities of the 21st
Century, this volume.
NASA (1985) Engineering and Configuration of Space Stations and
Platforms, pp. 468-473. Noyes Publications, Park Ridge, NJ.
Paine T O. et al. (1986) Pioneenng the Space Prontier. The Report of the
National Commission on Space. Bantam, New York.
Ride S.K. (1987) Leademkdp and Ame_'s Future in Space: A Report
to theAdminiMrator. U.S. Govt. Printing Office, Washington, DC. 63 pp.
Sviatoslavsky 1. N. and Jacobs M (1988) Mobile helitml-3 mining system
and its benefits toward lunar base self-sufl_ciency. In Space Engineering,
Construction, and Operation in Space (S. _ Johnson and J. !_ Wetzel,
eds. ), pp. 310-321. American Society of Civil Engineers, New York.
Wheeler R.M. and Tibbitts T X_ (1987) Utilization of potatoes for life
support systems in space. Ill. Productivity of successive harvest dates
under 12-hour and 24-hour photoperiods. Am. PotatoJ., 64, 311 320.
wittenberg LJ., Santarius J. E, and Kulcinsld G. L (1986) Lunar source
of SHe for commercial fusion power. Fus/on Teehnol., 10, 167 178.


Potential of derived lunar volatiles for life support

Abstract

Similar works

Full text

Available Versions

NASA Technical Reports Server