Testimony of Dr. Paul D. Spudis to the Subcommittee on Space and Aeronautics of the House Committee on Science on “Lunar Science & Resources: Future Options”
Dr. Paul D. Spudis
Mr. Chairman and members of the committee, thank you for inviting me here today to testify on the subject of lunar science, resources, and the US space program.
Recently, President Bush articulated a new strategic direction for America in space, one that includes a return to the Moon and the development and use of off-planet resources. Although we conducted our initial visits to that body over 30 years ago, we have recently made several important discoveries that indicate a return to the Moon offers many advantages and benefits to the nation. In addition to being a scientifically rich object for study, the Moon offers abundant material and energy resources, the feedstock of an industrial space infrastructure. Once established, such an infrastructure will revolutionize space travel, assuring us of continuous, routine access to cislunar space (i.e., the space between and around Earth and Moon) and beyond. The value of the Moon as a space destination has not escaped the notice of other countries – at least four new robotic missions are currently being flown or prepared for flight by Europe, India, Japan, and China and advanced planning for human missions in many of these countries is already underway. Additionally, at least two of these future planned missions (India and China) have advanced their launch dates considerably within the last month, indicating that these nations recognize both the importance and value of the Moon and the urgency of establishing a presence there.
The points below elaborate on WHY the nation needs to return to the Moon and why that return should take place NOW rather than later.
(1) The Moon is close, accessible with existing systems, and has resources that we can use to create a true, economical space-faring infrastructure
The inclusion of the Moon as the first destination in the President’s new vision was no accident. The Moon is both a scientific bonanza and an economic treasure trove, easily reachable with existing systems and infrastructure that can revolutionize our national strategic and economic posture in space and at home. The dark areas near the poles of the Moon contain significant amounts (at least 10 billion tons) of hydrogen, most probably in the form of water ice. This ice can be mined to support human life on the Moon and in space and to make rocket propellant (liquid hydrogen and oxygen). Moreover, we can return to the Moon using existing infrastructure of evolved-expendable and Shuttle-derived launch systems for only a modest increase in the space budget within the next five years.
The Moon is also a testing ground, a small nearby planet where we can learn the techniques of the strategies and operations we need to explore the solar system. The “mission” of this program is to go to the Moon to learn how to use off-planet resources to make space flight easier and cheaper in the future. Rocket propellant made on the Moon will permit routine access to cislunar space by people and machines, vital to the servicing and protection of national strategic assets and for the repair and refurbishing of commercial satellites. The availability of refueling capability in low Earth orbit would completely change the way engineers design spacecraft and the way companies and the government think of investing in space assets. This capability will serve to dramatically reduce the cost of space infrastructure to both the government and to the private sector, thus spurring economic investment (and profit).
(2) The Moon is a unique scientific resource on which important research, ranging from planetary science to astronomy and high-energy physics, can be conducted.
Generally considered a simple, primitive body, the Moon is actually a small planet of surprising complexity. The period of its most active geological evolution, between 4 and 3 billion years ago, corresponds to a “missing chapter” of Earth history. The processes that work on the Moon – impact, volcanism, and tectonism (deformation of the crust) – are the same ones that affect all of the rocky bodies of the inner solar system, including the Earth. Because the Moon has no atmosphere or running water, its ancient surface is preserved in nearly pristine form and its geological story can be read with clarity and understanding. Because the Moon is Earth’s companion in space, it retains a record of the history of this corner of the Solar System – vital knowledge unavailable on any other planetary object.
Of all the scientific benefits of Apollo, appreciation of the importance of impact (the collision of solid bodies) in planetary evolution must rank highest. Before we went to the Moon, we had to understand the physical and chemical effects of these collisions, events completely beyond the scale of human experience. Of limited application at first, this new knowledge turned out to have profound consequences. We now believe that large-body collisions periodically wipe out species and families on Earth, most notably, the extinction of dinosaurs 65 million years ago. The telltale residue of such large body impacts in Earth’s past is recognized because of knowledge we acquired about impact from the Moon. Additional knowledge still resides there; while the Earth’s surface record has been largely erased by the dynamic processes of erosion and crustal recycling, the ancient lunar surface retains this impact history. Although other planets display craters, only the Moon resides in our vicinity of the solar system, records the same impact flux that has struck Earth over the geologic past and retains a unique record that cannot be read on any other body. When we return to the Moon, we will examine this record in detail and learn about its evolution as well as our own.
Because the Moon has no atmosphere and is a quiet, stable body, it is a premier place to observe the universe. Telescopes erected on the lunar surface will possess many advantages over both Earth-based and space-based instruments. The Moon’s level of seismic activity is orders of magnitude lower than that of Earth, permitting the construction of interferometers with multiple-kilometer baselines. Such an instrument can image the disks of terrestrial-sized planets orbiting nearby stars. The lack of an atmosphere permits clear viewing, with no spectrally opaque windows to contend with; the entire electromagnetic spectrum is visible from the Moon’s surface. Its slow rotation (one lunar day is 708 hours long, about 28 terrestrial days) means that there are long times of darkness for observation. Even during the lunar day, brighter sky objects are visible through the reflected surface glare. The far side of the Moon is permanently shielded from the din of electromagnetic noise produced by our industrial civilization. Unique electromagnetic windows on the sky, such as low-frequency shortwave radio (~10-100 m), can be mapped only from the lunar far side. There are areas of perpetual darkness and sunlight near the poles of the Moon. The dark regions are very cold, only a few tens of degrees above absolute zero and these natural “cold traps” can be used to passively cool infrared detectors. Thus, telescopes installed near the lunar poles can see both entire celestial hemispheres at once with infrared detectors, cooled courtesy of the cold traps.
Recent suggestions that lunar dust poses unsolvable problems and difficulties for telescopes on the Moon are incorrect; lunar dust does not “coat” surfaces if left undisturbed. The Apollo astronauts became covered in dust because in some cases, they fell, knelt, or had to literally wallow in dust to pick up the samples they wanted to return. The best evidence that lunar dust creates no long-term problems comes from the performance of the Laser Ranging Retroreflectors (LRRR), which were deployed by Apollo astronauts at four different sites. These passive arrays of glass cubes are used as mirrors to reflect laser pulses sent from Earth in order to precisely measure the Earth-Moon distance. After over 30 years of continuous use and exposure to the lunar dust environment, they show no degradation of photon return whatsoever.
(3) We already know the Moon possesses the resources needed to create a spacefaring transportation infrastructure in cislunar (Earth-Moon) space.
The return of the Apollo lunar samples taught us the fundamental chemical make-up of the Moon. The Moon is a very dry, chemically reduced object, rich in refractory elements but poor in volatile elements. The composition of the Moon is rather ordinary, made up of common Earth minerals such as plagioclase (an aluminum, calcium silicate), pyroxene (a magnesium, iron silicate), and ilmenite (an iron-titanium oxide). The Moon is approximately 40% oxygen by weight. Light elements, including hydrogen and carbon, are present, but in small amounts – in a typical lunar mare soil, hydrogen makes up between 50 and 90 parts per million by weight. Soils richer in titanium appear to be also richer in hydrogen, thus allowing us to infer the extent of hydrogen abundance from the global titanium concentration maps returned by both the Clementine and Lunar Prospector missions.
As usable commodities, lunar materials offer many possibilities. Because radiation is a serious problem for human spaceflight beyond low-Earth orbit, the simple expedient of covering surface habitats with soil can protect future lunar inhabitants from both galactic cosmic rays and even solar flares. Lunar soil can be sintered by microwave into very strong building materials, including bricks and anhydrous glasses that have strengths many times that of steel. When we return to the Moon, we will have no shortage of useful building materials.
Because of its high abundance in lunar materials, oxygen production is likely to be an important early lunar product. The production of oxygen from lunar materials is not magical, but simply involves breaking the very tight chemical bonds between oxygen and various metals in lunar minerals. Many different techniques to accomplish this task have been developed; all are based on common industrial processes easily adapted to use on the Moon. Besides human life support, the most important use of oxygen in its liquefied form is to make rocket fuel oxidizer. Coupled with the extraction of solar wind hydrogen from the soil, this processing can make rocket fuel the most important commodity of a new lunar economy.
The Moon has no atmosphere or global magnetic field, so the solar wind, the tenuous stream of gases emitted by the Sun (mostly hydrogen), are directly implanted onto the dust grains of the Moon. Although this solar wind hydrogen is present over most of the Moon in very small quantities, it too can be extracted from soil. Soil heated to about 700° C releases more than 90% of its adsorbed solar wind gases. Such heat can be obtained from collecting and concentrating solar energy using focusing mirrors on the lunar surface, a readily available form of energy on the Moon. Collected by robotic processing rovers, solar wind hydrogen can be harvested from virtually any location. Additionally, recent discoveries by space probes of the 1990’s suggest that special areas exist where this material is present in much greater abundance, making its collection and use much easier.
(4) Hydrogen, probably in the form of water ice, exists at the poles of the Moon in quantity and can be extracted and processed into rocket propellant and life-support consumables
The joint DoD-NASA Clementine mission was flown in 1994. Designed to test sensors developed for the Strategic Defense Initiative (SDI), Clementine was an amazing success story. This small spacecraft was designed, built, and flown within the short time span of 24 months for a total cost of about $150 M (FY 2003 dollars), including the launch vehicle. Clementine made global maps of the mineral and elemental content of the Moon, mapped the shape and topography of its surface with laser altimetry, and gave us our first good look at the intriguing and unique polar regions of the Moon. Clementine did not carry instruments specifically designed to look for lunar water, but encouraged by an interesting result from Arecibo radar data that suggested interesting deposits near the Moon’s south pole, an ingenious improvisation used the spacecraft communications antenna to beam radio waves into the polar regions; radio echoes were observed using the Deep Space Network dishes. Results indicated that material with reflection characteristics similar to ice are found in the permanently dark areas near the south pole. This major discovery was subsequently confirmed in 1998 by a different experiment flown on NASA’s Lunar Prospector spacecraft.
The Moon contains no internal water; all water is added to it over geological time by the impact of comets and water-bearing asteroids. Dark areas near the poles are very cold, only a few tens of degrees above absolute zero. Thus, any water that gets into these polar “cold traps” cannot get out so over time, significant quantities accumulate. Our current best estimate of the amount of water on the Moon comes from two orbital measurements. The Clementine bistatic experiment indicates that an area of about 135 km2 of pure ice exists within an observed area of about 45,000 km2, corresponding to a concentration level of about 0.3 %. This radar estimate is consistent with observations from Earth-based radio observatories, including Arecibo and Goldstone, which show small, scattered areas of high radar backscatter within the sun-dark regions of the lunar poles. The Lunar Prospector neutron spectrometer found a concentration level of about 1.5 % water over an area approximately 12,000 km2 in extent. It should be noted that because of the observing geometry between Earth and Moon, Clementine and Earth-based radar can only examine about a quarter to a third of the total dark area of the lunar south pole, whereas Lunar Prospector collected data from 100% of the dark region. This difference in part may explain the discrepancy. In all, we estimate that over 10 billion metric tons of water exist at the lunar poles, an amount equal to the volume of Utah’s Great Salt Lake – without the salt! Lunar polar water has the advantage of already being in a concentrated useful form, simplifying scenarios for lunar return and habitation. Water from the lunar cold traps advances our space-faring infrastructure by creating the first space “filling station” on the solar system highway.
The poles of the Moon are useful from yet another resource perspective – the areas of permanent darkness are in proximity to areas of near-permanent sunlight. Because the Moon’s axis of rotation is nearly perpendicular to the plane of the ecliptic, the sun always appears on or near the horizon at the poles. If you’re in a hole, you never see the Sun; if you’re on a peak, you always see it. We have identified several areas near both the north and south poles of the Moon that offer near-constant sun illumination. Thus, an outpost or establishment in these areas will have the advantage of being in sunlight for the generation of electrical power (via solar cells) and in a benign thermal environment (the sun is always at grazing incidence); such a location never experiences the temperature extremes (from 100° to –150° C) found on the lunar equator. These properties make the poles of the Moon an inviting oasis in near-Earth space.
(5) By allowing us to travel at will, with people, throughout the Earth-Moon system, a return to the Moon to use lunar resources gives the nation a challenging mission and creates capability for the future.
Implementation of this objective for our national space program would have the result of establishing a robust transportation infrastructure, one capable of delivering people and machines throughout cislunar space. Make no mistake – learning to use the resources of the Moon or any other planetary object is a challenging technical task. We must learn to use machines in remote, hostile environments, working with ore bodies of small concentration under difficult conditions. The unique polar environment of the Moon, with its zones of near-permanent illumination and permanent darkness, provides its own challenges. But for humanity to have a foothold beyond low-Earth orbit, we must learn to use the materials available off-planet. We are fortunate that the Moon offers a nearby, “safe” laboratory for our first steps in using space resources. Initial blunders in mining tactics or feedstock processing are better practiced three days from Earth than from Mars, located many months of space travel away.
A mission learning to use these lunar resources is scalable in both level of effort and the types of commodities to be produced. We begin by using the resources that are the easiest to extract. Thus, a logical first product is water derived from the lunar polar deposits. Water is producible there regardless of the nature of the polar volatiles – ice of cometary origin is easily collected and purified while molecular hydrogen on lunar dust from the solar wind can be combined with oxygen extracted from rocks and soil (through a variety of processes) to make water. Water is easily stored for use as a life-sustaining substance for people or broken down into its constituent hydrogen and oxygen for use as rocket propellant.
Although we currently possess the minimal information to plan a lunar return, investment in a few robotic precursor missions would be greatly beneficial. We should map the polar deposits of the Moon from orbit using imaging radar to determine the extent, purity, and thickness of the ice in these dark regions. A camera and associated instrument to make a high resolution global topographic map (e.g., radar or laser altimetry) is also needed on this orbital mission to make high quality maps for future explorers and miners. The next step will be to land small robotic probes to conduct chemical analyses of the polar deposits and radio results to Earth. Although we expect water ice to dominate the deposit, impact deposits from cometary cores are made up of many different substances, including methane, ammonia, and organic molecules, all potentially useful resources. We need to inventory these species, determine their chemical and isotopic properties, and their physical nature and environment. Just as the way for Apollo was paved by such missions as Ranger and Surveyor, a set of robotic precursor missions, conducted in parallel with the planning of manned expeditions, can make subsequent human missions safer and more productive.
After these robotic missions have documented the nature of the deposits, focused engineering research efforts should be undertaken to develop the techniques and machinery needed to be transported to the lunar base as part of future human expeditions. There, the processes and principles of resource extraction will be established and validated, thus paving the way to automation and commercialization of the mining, extraction and production of lunar hydrogen and oxygen.
(6) This new mission will create routine access to cislunar space for people and machines, which directly relates to important national economic and strategic goals.
By learning space survival skills close to home, we create new opportunities for exploration, utilization, and wealth creation. Space will no longer be a hostile place that we tentatively visit for short periods; it becomes instead a permanent part of our world. Achieving routine freedom of cislunar space makes America more secure (by enabling larger, cheaper, and routinely maintainable assets in orbit) and more prosperous (by opening an economically limitless new frontier.)
As a nation, we rely on a variety of government assets in cislunar space, from weather satellites to GPS systems to a wide variety of reconnaissance satellites. In addition, commercial spacecraft continue to make up a multi-billion dollar market, providing telephone, Internet, radio and video services. America has invested billions of dollars in this infrastructure. Yet at the moment, we have no way to service, repair, refurbish or protect any of these spacecraft. They are vulnerable with no bulwark against severe damage or permanent loss. It is an extraordinary investment in design and fabrication to make these assets as reliable as possible. When we lose a satellite, it must be replaced and this process takes years.
We cannot now access these spacecraft because it is not feasible to maintain a human-tended servicing capability in Earth orbit – the costs of launching orbital transfer vehicles and propellant would be excessive (it costs around $10,000 to launch one pound to low Earth orbit). By creating the ability to refuel in orbit, using propellant derived from the Moon, we would revolutionize our national space infrastructure. Satellites would be repaired, rather than written off. Assets would be protected rather than abandoned. Very large satellite complexes could be built and serviced over long periods, creating new capabilities and expanding bandwidth (the new commodity of the information society) for a wide variety of purposes. And along the way, we will create new opportunities and make ever greater discoveries.
Thus, a return to the Moon with the purpose of learning to mine and use its resources creates a new paradigm for space operations. Space becomes a part of America’s industrial world, not an exotic environment for arcane studies. Such a mission ties our space program to its original roots in making us more secure and more prosperous. But it also enables a broader series of scientific and exploratory opportunities. If we can create a spacefaring infrastructure that can routinely access cislunar space, we have a system that can take us to the planets.
(7) Timing is everything: It is important for America to undertake this mission NOW, rather than later.
Many nations have recently indicated an interest in the Moon. The possible collection and use of lunar resources raises some interesting political and economic issues. Currently, the 1967 United Nations Treaty on the Peaceful Uses of Outer Space prohibits claims of national sovereignty on the Moon or any other object. However, it is not clear that private claims are likewise prohibited under this treaty. The 1984 United Nations Moon treaty specifically prohibits private ownership of lunar assets, but the United States, Russia, and China are not signatories to that treaty, ratification of which was specifically rejected by the United States Senate.
Our initial return to the Moon would be an engineering and scientific research and development project. We undertake our studies of the extraction of lunar resources to ascertain the best methods to harvest and use these materials. Our presence on the Moon does not give us title to it. However, a strong and continuing American presence on the Moon can help establish de facto the broad legal framework and economic paradigm of democratic, free-market capitalism off the Earth. It is not clear that other nations would be similarly inclined. In short, regardless of impressions, we are indeed in a race to the Moon – not a race comparable to the 1960’s Cold War race to the Moon between America and the Soviet Union, but a race no less important in establishing future socio-economic stability. History has shown that our economic-political system produces the most wealth and freedom and highest quality of life for the most people in the shortest time. America needs to continue to lead in space, ensuring an open economic and self-determining, democratic framework is established off-Earth.
(8) The infrastructure created by a return to the Moon will allow us to travel to the planets in the future more safely and cost effectively.
This benefit comes in two forms. First, developing and using lunar resources can enable movement throughout the Solar System by permitting the fueling of interplanetary craft with materiel already in orbit, thereby saving the enormous costs of launch from Earth’s surface. Second, the processes and procedures that we learn on the Moon will be applied to all future space operations. To successfully mine the Moon, we must learn how to use machines and people in tandem, each taking advantage of the other’s strengths. The issue isn’t “people or robots?” in space, it’s “how can we best use the combination of people and robots in space?” People bring the unique abilities of cognition and experience to exploration and discovery; robots possess extraordinary stamina, strength, and sensory abilities. We can learn on the Moon how to best combine these two complementary skill mixes to maximize our exploratory and exploitation abilities.
A return to the Moon will give us operational experience on another world. Activities on the Moon will make future planetary missions less risky as we gain valuable experience in an environment close to Earth, yet on a distinct and unique alien world. Systems and procedures can be tested, vetted, revised and re-checked. By learning to live and work on the Moon, we gain both experience and confidence in planetary exploration and surface operations.
The Moon provides a nearby laboratory and industrial test-bed where we can hone our exploratory skills and lay the foundations for a future space-based economy. Human expansion to the Moon will provide new opportunities and horizons for the American entrepreneur, our businesses, and our workforce. Developing new technologies has always led to new markets and increased our general prosperity. Expansion of the economy is vital to our national health and security. Who will capitalize on this opportunity and become the next Rockefeller, Carnigie, Ford, Getty, or Gates?
America needs a challenging, vigorous space program. It must present a mission that inspires, educates, and enriches. It must relate to important national needs yet push the boundaries of the possible. It must serve larger national concerns beyond scientific endeavors. The President’s program fulfills these goals. It is a technical challenge to the nation. It creates security for America by assuring access and control of our assets in cislunar space. It creates wealth and new markets by producing commodities of great commercial value. It stimulates and inspires the next generation by example. A return to the Moon is a giant step into the Solar System.
Thank you for your attention.
Spudis Lunar Resources was created by renowned planetary geologist Paul D. Spudis (1952-2018) and is archived by the National Space Society with the kind permission of the Spudis family.