NEEP602 Course Notes (Fall 1997)
Resources from Space
Extraction of Solar Wind Volatiles
Professor G. L. Kulcinski
Oct. 15, 1997
The topics to be covered in this lecture are listed below:
- What are the Solar Wind Volatiles (SWV's)?
- What are the SWV's good for?
- What is the state of the SWV's on the Moon?
- At what temperature are the SWV's evolved from lunar regolith?
What are the Solar Wind Volatiles?
"The Solar Wind is a plasma of chemical elements, expelled
as ionized atoms from the atmosphere of the Sun"
The Solar Wind Volatiles fall into 2 general classes (Lunar Sourcebook,
The Solar Wind Volatiles (SWV's) have been "blowing"
on the planets (and Moons) of our solar system for some 4.5 billion years.
The Solar wind is ionized and therefore is deflected by the Earth's magnetic
Here's a more
detailed description of the solar wind.
A few facts about the Solar Wind are important to our understanding
with respect to SWV resources.
The measured concentration of the Solar Wind, and other, volatiles
ranges from mass parts per billion to a few tenths of a percent.
from Fegley and Swindle, 1993)
Even though these concentrations are small, the total amount
of SWV's can be very large, e.g., in the millions to billions of metric
from data in Fegley and Swindle, 1993)
1) Biogenic elements (H, C, and N)
2) Noble gases (He, Ne, Ar, Kr, and Xe)
What are the SWV's good for?
Lunar volatiles have many uses.
The growing of plants or the life support for humans has some
upper and lower limits with respect to gaseous elements or molecules.
The support of humans in space, with efficient recycle of critical
materials could require as little as 700-800 kg/y.
Bula et. al., 1988)
The current cost to bring even 700 kg/person-y to the Moon would
As an example of what one can obtain from the SWV's in 1 cubic
meter of regolith consider the following:
from J. Taylor and L Haskin)
In addition, the production of hydrogen and oxygen can be important
for future space travel in the Solar System as well as for life support
What is the state of the SWV's on the Moon?
In order to calculate the amount of SWV's available for use,
we need to know 5 important pieces of information.
As the Moon passes in and out of the Solar Wind, and as a consequence
of having one side always facing the Earth, the Solar Wind is distributed
preferentially on the "far side" of the Moon. The "near side"
collects only ~ 1/3 that of the "far side".
The location of some SWV's may be augmented by their association
with elements that can be detected optically. For example, high titanium
containing ilmenite may specifically trap helium isotopes. Therefore, if
one knows where Ti is, then it may be a good indication of where the Helium
is also. This association was made by Professor E. N. Cameron (1988, 1992,
1993) of the University of Wisconsin.
It is clear that the high Ti regions of the Moon are in the Mare
regions. The concentration of the He is much higher in those regions.
The regolith in those regions is made up of very fine grains
which has been gardened by meteorites over billions of years
Horz et. al., 1975
The depth of the regolith varies from site to site and may range
from 3 to 12 meters.
Because of the constant meteorite bombardment, the regolith has
been pulverized to a very small grain size, i. e., to between 40-130 microns
Carrier and Mitchell, 1989.
The solar wind, at 1 keV/amu, has a relatively short range in
the regolith. It has been calculated, by K. Kulhman (1996), that the range
of a 1 keV proton is ~ 140 Å in ilmenite while a 4 keV 4He
ion will penetrate to a depth of ~320 Å.
Since the Solar Wind does not penetrate very deep into the ilmenite
grains, the SWV's reside mainly in the near surface region. The "gardening"
process can result in SW implanted grains that exist far below the surface
of the regolith.
The efficiency of SWV evolution depends inversely on the size
of the regolith particle.
The concentration of the SWV, 3He, is relatively constant
with depth, at least down to 2.4 meters.
The concentration of the SWV, 3He, in lunar regolith
follows the 1/r law predicted earlier.
Data from Eberhart (1970), Kirsten (1970), and Hintenberger (1970)
Cameron (1988) has confirmed that most of the SWV, 3He,
is contained in particles smaller than 50 microns.
At what temperature are the SWV's evolved from
As lunar regolith is heated, a very complex SWV release pattern
Gibson and Johnson (1971)
from Gibson and Johnson (1971)
The release of the noble gases (He, Ne, Ar, Kr, and Xe) from
lunar regolith reveals that progressively higher temperatures are required.
Original data from Pepin (1970) modified by Kuhlman (1996)
The peak release temperature for He from Apollo-11 regolith occurs
at 500 oC.
Original data from Pepin (1970) modified by Kuhlman (1996)
The conclusion of the data presented is that there are many trade-offs
to be considered before one picks a temperature at which the SWV of choice
is recovered. For the case of He, the maximum should be below 700-800 oC
because of the release of S compounds which may compromise the integrity
of the mining equipment.
Bula, R. J., Wittenberg, L. J., Tibbets, T. W., and Kulcinski, G. L.,
1988, "Potential of Derived Lunar Volatiles for Life Support",
p. 547 in The Second Conference on Lunar Bases and Space Activities of
the 21st Century, W. W. Mendell ed., NASA Conference Publication 3166,
Cameron, E. N., 1988, "Helium Mining on the Moon: Site Selection
and Evaluation", University of Wisconsin Technical Report, WCSAR-TR-AR3-8810-6.
Cameron, E. N., 1992, "Helium Resources of Mare Tranqillitatis",
University of Wisconsin Technical Report, WCSAR-TR-AR3-9207-1.
Cameron, E. N., 1993, "Evaluation of the Regolith of Mare Tranqillitatis
as a Source of Volatile Elements," University of Wisconsin Technical
Carrier, W. D. III, Mitchell, J. K., 1989
Eberhardt, P., et. al., 1970, "Trapped Solar Wind Noble Gases, Exposure
Age and K/Ar-age in Apollo-11 Lunar Fine Material", Proc. Apollo-11
Lunar Conf. 2:1037-1070.
Fegley, B., Jr., and Swindle, T. D., 1993, "Lunar Volatiles: Implications
for Lunar Resource Utilization", in Lewis, J., Matthews, M.S., and
Guerrieri, M. L., 1993, Editors, Resources of Near-Earth Space, University
of Arizona Press.
Gibson, E. K. Jr., and Johnson, F. S., 1971, Proceedings 2nd Lunar
Sci. Conf., Vol. 2, p. 1351.
Haskin, L., 1988, "Water and Cheese From the Lunar Desert: Abundances
and Accessibility of H, C, and N on the Moon", P. 393 in The Second
Conference on Lunar Bases and Space Activities of the 21st Century,
W. W. Mendell ed., NASA Conference Publication 3166, Vol. 1
Heiken, G., et al, 1991, Lunar Source Book, Cambridge University
Press, Cambridge, 736p.
Hintenberger, H., et. al., 1970, "Concentrations and Isotopic Abundances
of the Rare Gases, Hydrogen and Nitrogen in Apollo-11 Lunar Matter",
Proc. Apollo-11 Lunar Conf. 2:1607-1625.
Horz, F., Gibbons, R. V., Gault, D. E., Hartung, J. B., and Brownlee,
D. E., 1975, "Some Correlation of Rock Exposure Ages and Regolith Dynamics",
Proc. 6th Lunar Sci. Conf., p. 3495-3508.
Kirsten, T., Muller, O., Steinbruhnn, F., and Zahringer, J., 1970, "Study
of Distribution and Variations of Rare Gases in Lunar Material by a Microprobe
Technique", Proc. Apollo-11 Lunar Conf. 2:1331-1343.
Kuhlman, K., 1996, unpublished data.
Pepin, R. O., Nyquist, L. E., Phinney, D., and Black, D. C., 1970, "Rare
Gases in Apollo 11 Lunar Material", Proc. Apollo 11 Lunar Sci. Conf.,
Swindle, T. D., Glass, C. E., and Poulton, M. M., 1990, "Mining
Lunar Soils for 3He", UA/NASA Space Engineering Research
Center TM-90/1 (Tucson: UA/NASA SERC).
Taylor, G. J., 1995, Univ. of Hawaii, artwork on the food and soft drinks
1.) Compare the energy required to extract 1 kg of 3He from
lunar regolith at 700 oC to that required at 900 oC.
Use the data presented in class for the evolution as a function of temperature
and be clear about your assumptions on the thermal properties of lunar regolith
2.) Reproduce L. Haskin's calculation on the amount of food one could
produce from the Solar Wind Volatiles in 1 m3 of lunar regolith.
3.) Discuss the engineering considerations that you would have to consider
if you wanted to gather the maximum amount of nitrogen from lunar regolith.