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
Planetary Scientist
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.