© 2016 by Paul D. Spudis
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Library of Congress Cataloging-in-Publication Data
Names: Spudis, Paul D., author.
Title: The value of the Moon : how to explore, live, and prosper in space using the Moon’s resources / Paul D. Spudis.
Identifiers: LCCN 2015033833| ISBN 9781588345035 | ISBN 1588345033
Subjects: LCSH: Moon–Exploration. | Outer space-Exploration. | Space flight. | Space industrialization.
Classification: LCC QB582.5 .S68 2016 | DDC 333.9/4-dc23 LC record available at http://lccn.loc.gov/2015033833
eBook ISBN: 9781588345042
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v3.1
CONTENTS
Cover
Title Page
Copyright
Preface
1 Luna: Earth’s Companion in Space
2 The Moon Conquered—and Abandoned
3 After Apollo: A Return to the Moon?
4 Another Run at the Moon
5 Implementing the Vision
6 Why? Three Reasons the Moon Is Important
7 How? Things We Should Have Been Doing
8 If Not Now, When? If Not Us, Who?
9 A Visit to the Future Moon
10 Where Do We Go From Here?
Notes
A Lunar Library
Illustration Credits
Index
PREFACE
Twenty years ago, I wrote The Once and Future Moon (Smithsonian Institution Press, 1996). That book described the field of lunar science for the interested nontechnical reader and explained what we had learned about the processes and history of the Moon from robotic and human missions. We were acquiring some tantalizing hints that the Moon was useful—that it contained the material and energy resources necessary for a sustained human presence there. In the decades since then, exploration by robotic spacecraft has shown us more about the nature of these resources, confirming that the Moon is a more compelling destination than we had previously thought.
Regrettably, strategic confusion currently abounds in the American civil space program. Despite the hype and disprovable propaganda that we are preparing to conduct human missions to Mars, such an effort is far away technically, politically, and especially fiscally. A program to extend human reach beyond low Earth orbit (LEO) was arbitrarily terminated in 2010, and no rational program was offered by the administration as a replacement. Into this leadership vacuum, Congress stepped forward with a makeshift program to build a heavy lift launch vehicle (the Space Launch System) along with a human spacecraft designed for missions beyond LEO. No mission for these two items has been articulated. We will soon have some nice hardware, but no place to go.
In part, this policy chaos resulted from a misguided attempt to re-create the Apollo program. Apollo, now almost a half-century in the past, was the national effort that sent humans to the Moon. Contrary to the belief of many, the Apollo program was not about space exploration—it was about beating the Soviet Union to the Moon by landing a man there first. The entire Apollo program was a Cold War battle, and the United States won. Afterward, we stopped going to the Moon. The wartime setting of Apollo dictated that it be conducted along the lines of a wartime program: with urgency, marshalling the best technology and industrial capacity we could muster, and with cost as a secondary consideration.
Since then, we have repeatedly failed to achieve sustainable space exploration beyond LEO by trying to shoehorn it into the Apollo template. After landing American astronauts on the Moon in a highly visible and successful manner, perhaps it was natural to assume that this approach should be the configuration for future space endeavors. But after continually trying to re-create the Apollo experience by focusing on a similar human mission to Mars, with all pieces launched entirely from the Earth, we are little closer to that goal today than we were fifty years ago. The Apollo template, applied to the even greater technical challenge of a Mars mission, is enormously difficult and thus, enormously expensive, requiring tens to hundreds of billions of dollars to conduct a single mission.
A slower but affordable approach to the problem of a human Mars mission would be to gradually and incrementally increase the range of spaceflight. To do this, we would need several technical developments, including reusable vehicles based in space, staging nodes at strategic space locations, and the ability to provision ourselves for the trip from non-Earth resources, especially with high-mass, low-information density items, such as life-support consumables and rocket propellant. To our great good fortune, nature has provided us with a readily available source for this materiel—the Moon.
We can use the Moon to create new spaceflight capability. Water ice, the most useful material in space, occurs in abundance at the poles of the Moon. We can access and extract these valuable deposits because the poles also possess areas where we can generate electrical power nearly continuously. The polar “oases” of the lunar desert allow us to live on the Moon and learn how to use off-Earth material and energy resources. This effort will create a new paradigm of spaceflight: to use what is available in space instead of launching it all from the deepest gravity well in the inner solar system, the Earth’s surface. Such a development will revolutionize space travel.
Of critical importance to achieving this revolution is working out how to affordably establish a presence on the Moon. We have limited time and money to spend on space. I believe that there is a path to the Moon, one that accommodates the needs of federal, international, and commercial interests, a visionary scheme that will open up the solar system to economic development.
Modern technical civilization depends on a variety of assets in space. These machines monitor our weather and environment, provide instant global communications, permit precision navigation anywhere in the world, and secure our nation and the world with strategic surveillance. Satellites are vulnerable, and a national presence in cislunar space—the space between Earth and the Moon—is essential to guarantee our continued and uninterrupted access to these assets. A robust presence by the United States in cislunar space is necessary to assure the future emergence of free markets and to promote the growth of a pluralistic, political system on the new frontier.
This book tells the story of how we once went to the Moon, what we found as a result, our various efforts to return there, and especially why and how we should go back. We go to the Moon to create new capabilities. It is the next logical step in space beyond LEO.
I thank my colleagues who critically read and reviewed all or parts of the manuscript: Sam Lawrence (Arizona State University), John Greuner (NASA–Johnson Space Center), Jack Frassanito (Frassanito and Associates, Inc.), Tony Lavoie (NASA–Marshall Space Flight Center), and Ben Bussey (Johns Hopkins University Applied Physics Labo
ratory, currently detailed to NASA Headquarters). Some figures were provided by Dennis Wingo (Skycorp, Inc.), Mark Robinson (Arizona State University), and Jack Frassanito. As always, my wonderful wife, Anne, is my most insightful critic, merciless editor, and best friend; I especially thank her for editing multiple versions of this manuscript and for general inspiration.
1
Luna: Earth’s Companion in Space
Humans dreamed of touching the Moon for millennia. It was only within living memory that we actually left our planet and stepped upon the strange new world that lies on our celestial doorstep. Recently, an international flotilla of robotic probes mapped the properties and determined the processes of this lunar world. Amazingly, it found that the Moon contains the material and energy resources needed to establish a permanent, sustained human presence there. Water ice was found near the poles of the Moon—billions of tons of ice, trapped in its cold, dark regions. Areas close to these ice deposits are bathed in sunlight for most of the lunar year. Water and light are two resources that permit us to use the Moon to create new capabilities for spaceflight. Thus, the Moon is an object of great utility that offers us strategic and operational possibilities that other destinations in space do not.
Because the Moon is close, we can access it easily and continuously, unlike virtually any other deep space destination. The Moon’s nearness means that much of the initial work of producing water and preparing the surface for habitation can be done remotely with robots under the control of human operators on Earth. Unique among space destinations, the proximity of the Moon allows us to begin its development before sending people, making the lunar surface the most inexpensive space goal beyond low Earth orbit, where significant progress can be attained early. The low gravity of the Moon (one-sixth that of Earth) enables us to use its resources to provision ourselves with the air, water, and propellant needed for the interplanetary journeys that humanity will undertake in the future.
The Moon is a small, complex satellite with a protracted and fascinating history and evolution. The early history of the solar system, a distant age when planets collided, globes melted, and crusts were formed and bombarded by impacts of leftover debris, are recorded in the rocks and soil of the Moon. The Moon has a core, a mantle, and a crust. Giant impact craters and basins have excavated thousands of cubic kilometers of rock and then crushed, melted, and reassembled it into complex forms. Internal melting generated magmas, which were released onto the surface as massive outpourings of lava, flooding large regions of the lunar surface. Following this period of violent geological events, near quiet has presided over the last billion years. The fossilized world of the Moon intrigues us, challenging our understanding of how the universe works.
All of these attributes place the Moon in the high-value column when selecting future strategic directions for humans in space. We went there half a century ago largely because a human lunar landing was a dramatic space goal achievable within a reasonable amount of time. Now, this same proximity, coupled with the Moon’s intrinsic interest and resources, again makes it an attractive destination. As we consider this, it is important to know how we went before, what we learned and why the Moon is the logical next strategic goal for the American space program. I will relate the history of our efforts to return to the Moon and the multiple starts and stops of that effort. Like Sisyphus and his stone, each time we thought we were on the road back to the Moon, we seemingly rolled back to the beginning. But unlike Sisyphus, each failed attempt to restart lunar spaceflight resulted in the acquisition of new data and information that has shown us that the Moon is an even more useful and inviting destination than we had thought. It is a wandering and complex (but fascinating) story involving geopolitics, government spending, big science and technology, and national greatness.
The Moon as an Object of Wonder, Mystery, and Worship
As the largest object in our night sky, the Moon has always been an object of interest and awe. From our first gaze overhead, we have wondered about and studied it, charting its path across the heavens. Because the Moon’s shape and appearance changed with regularity, it suggested to early humans that there was order in the otherwise capricious and potentially dangerous unknown world around them. The Moon allowed the earliest life on Earth to measure the passage of time, predict the seasons, and plan ahead—survival skills important to all species. Early religious speculation involved the worship of nature. The Moon’s changing appearance over the course of a month, along with the passing of days and seasons, became the natural timepiece whose rhythms and cycles helped humans regulate their lives. The coincidence of the duration of the lunar cycle to human menses suggested a female presence in the heavens. In the pantheon of deities, Moon goddesses Artemis, Diana, and Selene oversaw the natural world.
Even after ancient nature worship had been largely abandoned in western culture, the Moon remained a timekeeper and an object of intrigue. Both Judaic and Muslim religious calendars are lunar-based, not solar-based. Because the lunar and solar cycles are not coincident, holidays such as Passover and Ramadan fall on different dates every year. Aside from its early, practical use as a timekeeper, the Moon also influenced culture. A full moon permitted considerable outdoor activity during preindustrial history, spawning tales and legends of werewolves and “lunacy”—the idea that a full moon (Luna) could induce unnatural and abnormal behavior and activity.1
We now know that Earth’s Moon has been, and will remain, intimately tied to human origins, history, and development. The Moon’s twenty-eight-day orbit around Earth acts as a stabilizing influence on the obliquity of Earth’s spin axis, causing it to be stable for extended geological periods. Without this stabilization, rapid and chaotic changes in the orientation of its spin axis would make Earth oscillate wildly between climatic extremes, as happened on Mars. The Moon’s rotation around Earth causes tides on its oceans and land, resulting in the development of periodically inundated coastal areas, sometimes below water and sometimes above it. Such terrain fluctuation is believed to have facilitated the development of land creatures, as marine species began to tolerate brief periods on dry land. Thus, because of its gravitational influence, the Moon was a major driving force in the evolution of life on Earth.
Anaxagoras (500–428 BCE) was among the first of the early Greeks philosophers to examine the Moon scientifically. He believed that the Moon did not shine from its own light, but merely reflected the light of the Sun. He also developed the first correct explanation of solar eclipses. Aristotle (384–322 BCE) believed that the Moon was a sphere, always showing the same hemisphere (the near side) to us. Aristarchus of Samos (310–230 BCE) calculated the distance between Earth and Moon at 60 Earth radii, an astonishingly good estimate (in its elliptical orbit, the Moon actually varies in distance between 57 to 64 Earth radii, or between 363,000 to 406,000 km).2
During the Middle Ages, leading up to the Renaissance, or roughly the fifth to the sixteenth centuries, the Moon was simply another object to astronomers, but it did play a key role in the development and evolution of modern physical science. Galileo (1564–1642), an Italian philosopher, physicist, and astronomer, not only observed the Moon with a primitive telescope but also conducted experiments on the laws of motion and was an early convert to the Copernican system of a heliocentric solar system. The recorded motions of the Moon and planets against a background of fixed stars by careful observers, such as the Danish court astronomer Tycho Brahe (1546–1601), led German scientist Johannes Kepler (1571–1630) to formulate his three laws of planetary motion. A key insight is that planets and moons orbit their primaries in elliptical paths, not circular ones, as Copernicus (1437–1543) had suggested. As the Renaissance gave way to the Age of Enlightenment, English physicist Isaac Newton (1643–1727) synthesized the observations of Tycho, and the laws of planetary motion by Kepler, into a unified theory of gravitation. Once again, the Moon played a critical role. As Newton observed an apple fall from a tree in his garden, he wondered if the force acting upo
n the apple was the same force that kept the Moon in its orbit around Earth. From this simple musing, he developed the laws of motion and universal gravitation, a mathematical system that explained the physical world in exquisite, clockwork detail.
Although the naked eye cannot resolve individual landforms on the Moon, patches of light and dark areas on its visible disc have been discussed since antiquity, leading to fanciful Rorschach-like interpretations, ranging from the famous “Man in the Moon” to rabbits, dogs, dragons, and a wide variety of other creatures or objects. The dark and light areas are caused by the Moon’s two principal terrains: the dark, smooth maria (Latin for “seas”) and the brighter, rougher terra (“land” or highlands). The association of the dark terrain with seas has a muddled history. Galileo is often credited with it, but he didn’t actually equate the dark areas with water; he only suggested that some “might” be so. Using the newly invented telescope, Galileo made drawings and wrote detailed descriptions of the complex landforms that make up the lunar surface.3 By observing the Moon during different phases and surface illuminations, he saw that its surface was not smooth, as some of the classical philosophers had surmised, but rough and jagged, consisting of towering mountains and most significantly, circular depressions in a wide variety of sizes. Even though the Moon’s near side had been thoroughly mapped and remapped by astronomers over the previous two hundred years, the use of the word “crater” (from the Greek word meaning cup or bowl) to describe these holes was not used until the late eighteenth century.
With the advent of increasingly more powerful telescopes, the landscape of the lunar near side became known in much greater detail (figure 1.1). Astronomers now moved past the Moon to the more interesting stars, nebulas, and galaxies beyond. Lunar studies were left to a few diehards, mostly amateur astronomers and rogue geologists. The vast bulk of work on the Moon in the nineteenth and early twentieth centuries dealt with descriptions and studies of its surface features and history—most pressingly, the problem of the origin of craters. There were two opposing camps regarding craters. One group held that volcanic explosions and eruptions formed craters, while the other group believed that craters were made by the impact of small bodies, such as asteroids and comets.4 This debate grew to near religious intensity, often with more heat than light being shed on the problem. The two proposed mechanisms had very different implications. The volcanic hypothesis suggested that the Moon was an active body, with internal heat and ongoing volcanism. The impact idea suggested instead that the Moon was cold and dead and might never have had any internal activity. To support their arguments, each side marshaled the best examples they could; few analogues from the study of Earth’s landforms were of any help. Although Earth has many volcanoes that have been studied for years, at the beginning of the twentieth century, no recognized terrestrial impact feature had as yet been described.
The Value of the Moon Page 1
