BOOK REVIEW
Mining the Moon
Paul Spudis
Return to the Moon: Exploration, Enterprise, and Energy in the
Human Settlement of Space. Harrison H. Schmitt. xvi + 335
pp. Praxis Publishing, 2006. $25.
Of the 12 men who have walked on the moon, the last to set foot
there, Harrison (Jack) Schmitt, is the only one with scientific
training (he has a Ph.D. in geology). He has seen and done things
most scientists only dream of. Schmitt's work on the Moon in 1972
ranks as one of the most exciting and productive episodes in the
history of exploration. His memories of the three days he spent in
the Valley of Taurus-Littrow are a priceless treasure trove of
scientific and aesthetic insights. Unfortunately, those experiences
are not the subject of his new book, Return to the Moon.
Instead, the volume is structured as a legal brief, in which Schmitt
makes the case for returning to the Moon to mine the isotope
helium-3. He claims that because fossil fuels are limited in supply
and because their extraction and use harm the environment, our
rapidly industrializing world requires new sources of energy. The
ultimate solution, he suggests, is the generation of power by
nuclear fusion—not of deuterium and tritium, as is usually
proposed, but of deuterium and helium-3.
This reaction, which does not produce any fast neutrons, is clean
and nonpolluting. There are, however, two drawbacks to its
industrial use. First, the fusion of deuterium and helium-3 is very
difficult to start and sustain, requiring roughly an order of
magnitude more energy than the fusion of deuterium and tritium.
Second, there are no plentiful stocks of helium-3 on Earth. Although
the isotope is found naturally as a trace component in reservoirs of
natural gas and also as a decay product of tritium (making our
stockpile of nuclear weapons the best current terrestrial source),
there is not enough helium-3 on our planet to support commercial
power generation through fusion.
Enter the Moon. Because the Moon has been bombarded for billions of
years by solar wind, which consists largely of ionized hydrogen and
ionized helium, helium-3 is available in the dust of the lunar
surface. Even there, however, helium-3 is present only in
concentrations between 10 and 20 parts per billion. Hundreds of
millions of tons of lunar soil (more properly called regolith) must
be mined and handled to extract a ton of helium-3. Schmitt has
looked at this problem in some detail, and he outlines a plan for
mining helium-3 on the Moon to feed a commercial industry for
generating power here on Earth.
After a brief introduction and a short discussion of the legacy of
Apollo, Schmitt considers the future of energy production on Earth,
concluding that all of the various proposed alternatives to fossil
fuels have drawbacks. However, he maintains that mining the Moon for
helium-3 is a viable solution to our energy problems.
Next Schmitt surveys the economics of rocket launches, the economics
of fusion power and the geology of lunar helium, covering the
composition and state of the rocks and soils of the Moon in some
detail. He then describes possible strategies for the mining and
production of helium-3 and suggests how to organize the effort.
Because helium-3 is such a minor constituent of the regolith, mining
it produces valuable by-products in abundance, particularly
solar-wind hydrogen, which could be used to fuel an Earth-Moon
transportation infrastructure and to support human life at the lunar outpost.
Schmitt then devotes two chapters to his idiosyncratic take on how
NASA should be reorganized to regain the management prowess lost
since the end of the Apollo program. The material on restructuring
NASA consists largely of the text of e-mails that Schmitt sent to
various members of the Bush administration in 2001—before the
loss of the space shuttle Columbia precipitated a detailed
examination of the goals of America's space program, resulting in
the new Presidential Vision for Space Exploration in 2004.
Next Schmitt outlines his recommendations for lining up investors in
a commercial operation for mining helium-3 on the Moon. Schmitt
believes that for his plan to be successful, it must attract
considerable private-sector investment. Would such an endeavor be
legal? Space law regarding lunar resources is unclear. Nonetheless,
Schmitt is convinced that existing treaties permit lunar economic
development, particularly if it is carried out not by national
governments, but by a user-based international consortium like those
developed to manage communication satellites.
The next-to-last chapter touches on the value of humans in space.
The book then concludes with the thought that a private effort to
mine the Moon for helium-3 could not only solve our energy problems
but also open the door to human settlement of the solar system.
Exactly how one takes all of this depends very much on one's
personal predilections and how one views the track record and
credibility of people promising commercial fusion power. The
traditional comment on this field is that commercial fusion power is
10 years away—and has been since the middle of the past
century. And as noted above, the simplest fusion reaction,
deuterium-tritium fusion, has yet to come close to breakeven (to
producing as much energy as is needed to start the reaction),
despite being an order of magnitude easier to achieve than the
fusion of deuterium and helium-3.
Some other criticisms are that Schmitt is not clear as to what role
NASA should play in his scenario. Any involvement on NASA's part
would appear to be only tangentially related to the new Vision for
Space Exploration, which has been adopted as national policy by both
the executive and legislative branches. Also, Schmitt discusses and
interprets the geology of the Moon, the organization of the U.S.
government's space program, space law and private-sector involvement
in space through his own lens. Many of these issues are subjects of
active debate, and those who wish to understand the wide scope of
arguments being made should consult other books for different perspectives.
The concept of a book as a legal brief has a long and distinguished
pedigree in science. In Schmitt's own field, Charles Lyell's
Principles of Geology (1830) comes closest to such
status, being primarily an extended brief supporting the gradualist,
Huttonian model of the evolution of the Earth. Darwin took a copy of
Lyell's Principles with him on the voyage of the H.M.S.
Beagle. Will astronauts returning to the Moon carry a copy
of Schmitt's book?