36 internautes sur 37 ont trouvé ce commentaire utile
- Publié sur Amazon.com
Harrison H. (Jack) Schmitt was the last of 12 Apollo Astronauts to set foot on the Moon in December 1972, a geologist whose professional background was indispensable for exploring the Valley of Taurus-Littrow, the landing site of Apollo 17. That skill was particularly evidenced by his on-the-spot field analysis of the origin of the house-sized broken boulder on the slopes of the North Massif, and by his discovery of orange-colored soil at Shorty Crater. The orange soil turned out to be pyroclastic glass, a chondritic volcanic material from a depth of around 500 km (300 miles), which had not changed in chemical composition since the origin of the Moon. This orange soil was not just localized to Shorty Crater. Jack's crewmates, Ron Evans and Gene Cernan, both spotted orange soil patterns around a number of other craters from orbit once they knew what to look for. Moreover, support geologists at Mission Control also later discovered more orange areas in some of the earlier Apollo 14 orbital photos while Apollo 17 was still circling the Moon. These observations have a profound impact on theories of the origin of the Moon because they indicate that the Moon's interior composition has changed little since it formed. Theories of formation that include complete re-melting of the interior, which would alter that chemical composition, can therefore be excluded.
Thus, drawing on his experiences as a field geologist, Jack found a clue confirmed at the time by others he instructed that is fundamental to our understanding of the Moon's origin. Now, 33 years after his mission, Jack has similarly drawn on that lunar geological experience, as well as his practical knowledge of NASA, industry, government, and teaching, to write a book astonishing in the breadth covered by its 14 chapters, each with references and endnotes for those wishing to pursue cited topics further. No one interested in the practical application of going back to the Moon and on to Mars can afford to miss reading this exposition.
The book is an outgrowth of course lectures that Jack gave at the University of Wisconsin-Madison (UWisc) over several years, the last series in the Spring of 2004, but since brought up to date and expanded considerably. His students must have really enjoyed attending those classes because he is a great lecturer! The basic premise is the establishment of a permanent lunar mining colony as a private commercial enterprise to process and ship Helium-3 (He-3), the light isotope of regular helium gas (He-4), back to the Earth to fuel fusion reactors for the production of electricity. He-3 is carried in the solar wind, which is deflected from the Earth by the geomagnetic field. However, it has been impinging on the lunar surface for the entire history of the Moon where it becomes embedded in the soil particles (regolith), constantly overturned by micrometeorite bombardment. Jack explains how these mostly pollution-free fusion reactions work in terms easy to understand, and their significance to the global economy. He devotes an entire chapter to the difficulties of He-3 fusion power production, describes successful fusion reactor experiments at UWisc (obtaining He-3 for research is only possible at present by purchasing it at $1000/gm from the U.S. or Russia as a by-product of tritium processing for nuclear weapons), projects the costs of building a 1000 MWe fusion power plant, and assesses the likelihood that such plants can be built.
He provides another chapter on determining the concentrations of He-3 in various areas of the Moon and estimates that there are about 2,500 metric tonnes derived from highest concentration soils in the first 3 meters of regolith from 84,000 sq. km of Mare Tranquillity alone, the lunar plain where Neil Armstrong first landed. Armstrong brought back particular soil samples that contributed to this determination. To this estimate can be added about the same quantity from soils of medium concentration over an area more than double that in the same Mare. The average regolith depth in Tranquillity, however, is 6 meters; thus, there is potentially about 10,000 metric tonnes of He-3 extractable from this one region of the moon. One metric tonne (2200 lbs) is worth about $1.4 billion in coal equivalent power estimated for the 2010-2020 time frame. That's 14 thousand billion (14 trillion) dollars worth of He-3 power available from one area of the Moon! The present U.S. electrical power consumption costs roughly $40 billion a year. Thus, there is not only a monetary incentive to bring this He-3 back to the Earth; but there is also enough of it to provide our energy needs for at least 350 years! Another way of looking at these figures is that 100 kg of He-3 would power a 1000-MWe fusion reactor for over a year. Ten such reactors would supply enough electricity for a city of 10 million for that period. That is 1/3 the population of California, or 1/6 the population of the U.K. The Mare Tranquillity output would thus supply that city with electrical power for 10,000 years!! Other areas of the Moon have lower, but not insignificant concentrations of He-3. However one slices the He-3 pie, can we as a nation, as a society, as a civilization really afford to ignore the potential global implications of vigorously investigating the economics of lunar He-3 mining? That is the core message contained in "Return to the Moon".
But the book covers much more than He-3 mining. It essentially spans the entire period of U.S. space exploration from Eisenhower's establishment of NASA in 1958 and his order to construct the Saturn V heavy booster through today's problems faced by Mike Griffin, the current NASA Administrator, who read a draft of the book prior to its publication. And Jack pulls no punches. Chapters 9 and 10 are a Tour de Force. Chapter 9 treats the lessons Apollo taught us, and where we went wrong in the post-Apollo period. Chapter 10 is an annotated collection of lengthy emails with the current White House's first Administration (primarily the OMB) on how NASA should be restructured and why. He points out that NASA and the U.S. public in general have become too risk adverse, which can lead to stagnation and ultimately to stopping human space exploration altogether. He also takes NASA to task for having ignored biomedical research proposals on humans in space as seriously funded endeavors with the National Institutes of Health and the Food and Drug Administration. He explains in detail the kinds of experiments that were done in the past and their significance, but that NASA basically took an "air sickness" approach to any problems that astronauts manifested (when they admitted to having problems). He also discusses what kinds of medical problems need further examination. Jack even advocates that he and his remaining fellow Moon walkers should be subject to thorough targeted autopsies because little is known of the effects of breathing in Moon dust laden with glass! Such effects need to be clearly defined before establishing a lunar settlement.
Jack also does not ignore other energy sources on how an expected worldwide 8-fold (conservative estimate) increase in energy demands by 2050 should be met. He provides detailed comparisons, relative costs, and the relative merits of the most significant of these, including nuclear fission vs. fusion power production. The latter discussions are most informative in showing how the U.S. lost its leadership role in the generation of nuclear fission power to France and Japan, and how the U.S. still erroneously considers all nuclear waste (spent nuclear reactor rods) as "waste" when at least 90% of it is recoverable.
People who run businesses at any level will enjoy the business acumen that Jack displays throughout the book. The core financial analyses are not just simple calculations, but rather detailed cost estimates of the various components needed to guarantee a successful return to the Moon with justifications for each choice. One of these is a new launch vehicle that Jack refers to as the "Saturn VI", which should have the capability of putting a 100 metric tonne payload on the Moon, twice that of the Saturn V booster. He suggested its specifications using the Saturn V as a benchmark. Interestingly because it is derived from the prior technology, Griffin himself has referred to the new launch system and CEV (crew exploration vehicle) that NASA plans to adopt for its projected return to the Moon as "Apollo on steroids"! In addition, Jack covers the legal issues of lunar mining, managerial problems, and how big projects should be organized. He also compares the cost-efficiency of 6 different models of achieving a self-reliant He-3 mining colony, ranging from an all-government approach to private enterprise. Once a commercially viable lunar colony has been established, the economic returns governed by the colony products and the worldwide distribution of power on Earth will serve to form a more stable civilization, one view of humankind's manifest destiny that ought not be overlooked.
There are a number of books on the market today advocating colonization of the Moon and travel to Mars, but Jack is one of only nine remaining authors who can truly say: "been there, done that". His book not only proves that, but by drawing on that experience it also justifies his privilege of having walked on the Moon. That may very well turn out to be the true legacy of Apollo!
26 internautes sur 28 ont trouvé ce commentaire utile
Arthur P. Smith
- Publié sur Amazon.com
A version of the following review appeared on the online site "slashdot".
No matter what the subject, one has to admire a book written by an astronaut and former US senator, illustrated with photos of the author at work on the Moon. When the subject is one as potentially important to the future of our civilization as the energy resources geologist Harrison ("Jack") Schmitt sees buried in the lunar surface, along with our future in space, it becomes all the more daunting to take issue with it. Unfortunately Schmitt's potentially inspiring commercial justification in this book rests on a shaky foundation.
With NASA now planning a lunar return and several other countries planning missions, the time is certainly ripe for a book with this title. Schmitt's book acknowledges the present context but sets out in his own direction, though one some other authors have touched on, arguing that the Moon will provide a critical contribution to our civilization's energy needs, and the lunar return discussed is primarily one of industry and commerce, rather than grand national programs.
The argument for industrial use of our celestial neighbor hinges on the utility of helium-3 fusion. However, that technology and the science behind it is dealt with in a perfunctory 4 pages in this book; Schmitt leaves the main argument to scientific papers from the University of Wisconsin Fusion technology Institute that has been promoting it.
Helium-3 fusion, while having the advantage of lower radiation levels, is considerably harder than deuterium-tritium (D-T) fusion: the extra proton in helium means the ideal fusion temperature for He3-D mixtures is over four times as large. An alternative hydrogen-boron reaction would require almost 10 times the D-T temperature. That makes the traditional approaches to fusion reactors, creating very hot and dense plasmas, essentially impractical for He3 fusion. Non-traditional inertial electrostatic confinement (for example, "Farnsworth fusor") technology gets around the high temperature problem by essentially shooting the nuclei directly at one another in a steady-state fashion. In principle any kind of fusion is possible with such a design. However, in practice the maximum power output obtained so far is 1 Watt - you would need a hundred of them just to power a light bulb!
So that leaves a huge and unknown technology gap in scaling things a factor of 1 billion or so to power plant size. Schmitt lightly skips over this problem with the note that "much engineering research lies ahead" and then bases an economic analysis on the assumption that such a plant would have to compete with fossil-fuel plants; we know roughly the numbers there. This does provide real constraints on the costs of retrieval of He3 from the Moon, so it's a useful analysis. But there's still the fundamental question of whether He3 fusion could ever be economically practical.
Schmitt doesn't let those questions slow him down; cost estimates for the "much engineering research" piece are folded into capital cost estimates for building up to 15 fusion plants, building and launching (and staffing) 15 lunar mining settlements, and operational costs for the whole system to reach the conclusion that it could, after the 15th set of facilities was completed, be close to competitive with electric energy from coal. That's not a bad accomplishment, but it rests on a lot of assumptions of unstated but likely very high uncertainty.
Ironically, the best reason for replacing coal, the threat of global warming from atmospheric CO2 release, is given short shrift as an "international political issue" in Schmitt's introductory chapter on our energy future. In this and in a bias toward non-governmental solutions, Schmitt's text unfortunately betrays the caution of an incompletely recovered politician.
Organizational approaches are covered in detail in chapter 8, where Schmitt compares models ranging from all-government to various public/private partnerships, to an all-private approach, analyzing each model according to over two dozen financial, managerial, and external criteria. After giving each a 1 to 10 rating, he multiplies by another subjective weighting factor and adds them all up. Somehow, the all-private model wins every time. The text surrounding these numbers suggests that, despite what the numbers say, several of the public-private partnership approaches make a great deal of sense. This ranges from the Intelsat multilateral model to simply encouraging government funding of the necessary research, development, and testing, and passing technology on to private industry to earn a profit.
Schmitt's discussion of lessons from Apollo is almost reverential, including a proposal for a "Saturn VI" heavy-lift rocket, to lower launch costs. It seems unlikely that the Apollo conditions can be duplicated, but he does have an interesting argument in favor of in-house engineering talent and having a large pool of young engineers. This and the letters of chapter 10 are perhaps too bluntly put to have an impact on NASA directly, but could certainly help inspire organizational virtues in a private venture, so NASA's more recent mistakes aren't repeated.
There is much that is good here. The book covers some ideas in detail, including the lunar geology issues for helium-3 recovery. Designs for mining equipment, the idea of finding markets first in space, and only later on Earth, and the proposal to make the miners permanent settlers, rather than just temporary visitors are all interesting concepts developed here. The author has included copious citations for more in-depth reading.
Much of the infrastructure Schmitt calls for could be applied to any other commercial utilization of the Moon, for example to help develop solar power satellites or lunar solar power facilities, to provide lunar oxygen (or hydrogen) for in-space use, for lunar tourism, and so forth. Schmitt believes the He3 approach provides easier access to capital markets due to lower start-up costs, so less government involvement may be needed than for those other commercial justifications for a lunar return. However, the status of He3 fusion itself seems sufficiently uncertain that relying on private equity to make it happen could still be a very slow process, at least once development reaches the point of billion-dollar space missions.
This vision for a new day in lunar exploration is very different from what we have been hearing from NASA, even in recent years when a human lunar return has been on the table. There is considerable evidence we have an urgent need for new energy sources. The possibility of exploitation of the Moon for human benefit has hardly crossed public consciousness yet, but it's something that we will increasingly be turning to as humanity reaches limits here on Earth. We should all be grateful Dr. Schmitt has helped here to get that ball rolling.