Extraterrestrial resources

During the twenty-first century, new resources may well be required to build and energize civilization on other planets and in space, as well as to enhance accelerated change in a dynamic Earth-based society.

Classification of Resources

In the largest possible sense, there may be two broad categories of resources during the later decades of the twenty-first century: Earth-based resources and off-planet resources. The reason for the distinction is an economic one, based on where the materials will be used, and is driven by consideration of the gravitational field of Earth. Earth’s gravitational field is very strong in comparison with extraterrestrial space, where there is little gravitational influence. It is also strong in relation to Earth’s moon and to Mars, both of which have gravitational fields much weaker than Earth’s. Hence, materials required in space would be much more economical if mined from small bodies in space (such as asteroids or comets) or the moon, as the cost of shipping those same resources from Earth into space would be many times greater. This example is provided as an insight into the distinctive ways of looking at future resources in the developing economy of the twenty-first century. In a more systematic approach to categorization, one could fundamentally classify tomorrow’s most basic resources in the same broad classes used in recent times: agricultural products, chemicals (including petroleum and derivatives), metals, ceramics, energy, wood (and derivatives), and power.

Impact of Scientific Discovery

Though the same broad resource categories will be required in the future as are required today, many of their individual identities and uses will be much different. Scientists, particularly materials scientists, are researching new types of materials that will have a vital use and sometimes discovering new uses for old materials. In 1989, for example, scientists Martin Fleischmann and Stanley Pons announced that they thought they had discovered a revolutionary method of generating power via cold fusion. One major element in their design was the rare-earth metal palladium. Until their announcement, there had been few other uses for the metal; after their announcement, the price of palladium temporarily increased as a result of its presumed importance before falling again when the scientists' claims were debunked. New discoveries about both new and existing materials will cause the demand for the resources to change as availability dictates.

Scientific discovery and technological development are often the keys to the advancement and change of society and the resources that drive it. Examples from the past are abundant: tungsten presently used for light filaments had few uses before the invention of the incandescent light bulb; silicon, the key element of common beach sand, assumed vital importance with the discovery of microelectronics. Probably no other single resource has had a more far-reaching impact on humankind or planet Earth than petroleum and its derivatives. The science of superconductivity produces materials that conduct electrical current without resistance. Late in 1986, this branch of physics took a revolutionary turn when it was discovered that synthetically produced materials could become superconductive at temperatures much higher than had been thought possible. The synthetic materials were described as “artificial rocks” and were made by mixing together various metal oxides under very specific conditions. As the ultimate goal of room-temperature superconductivity is approached, the materials used in producing the superconductors are likely to become highly sought-after and, thus valuable resources.

Ceramics and Fiber-Reinforced Composites

The use of ceramic materials increased dramatically in the 1980s. Ceramic materials are nonmetal compounds produced by firing at high temperatures. Ceramics can be lightweight, resilient, and heat resistant. Materials used in the production of ceramics include clays, silicates, and calcium carbonates. Uses of ceramics include refractories (heat-shielding or heat-absorbing materials, such as those used to construct the space shuttle’s heat-shielding tiles) and electrical components. They have also been used in tests as automobile engine blocks. The resources that produce such ceramics are projected to have even broader applications in the future.

Another type of product that has become quite important and is expected to play a vital role in the future is fiber-reinforced composites. Such composites are made by drawing fibers through a material being cast. When the material hardens, the fibers cast inside it make even very light products, such as aircraft wings and space-vehicle fuselages, much stronger. The materials from which these composites are made (fiberglass, boron, tungsten, aluminum oxide, and carbon) will assume new importance with any increase in the use of fiber-reinforced composites.

Economics of Off-Planet Resources

Because the exploitation and possible settlement of space will probably be the most significant development of the twenty-first century, resources that drive that revolution will become highly valuable. The value of these space materials will be based on their origin. It will always be expensive to ship resources into space from Earth. A kilogram of aluminum mined and processed on the moon and shipped to Earth could one day cost a tenth of the amount of the same aluminum shipped to orbit from Earth because of launch-energy costs. Even under the best of circumstances, in a well-developed launch system, a liter of water launched from Earth into space will always cost thousands of times more than a liter of water on the surface.

One must always keep the gravitational interfaces in mind when considering the economics of space resources. Many studies have been conducted concerning the utilization of off-planet resources, their availability, and their applications. Some such studies concern the construction of bases and colonies on the moon and Mars or the construction of enormous space colonies.

Off-Planet Water and Power Resources

The most valuable resources in space will be water and energy. The use of one is dependent on the other. Water and energy yield two other vital resources: oxygen and hydrogen. Water is the most basic of all resources necessary for human survival. Aside from the obvious purposes of direct consumption and hygiene, water will be necessary for cleaning, cooling, and producing food. In addition, raw water can be broken down by a process called hydrolysis into elemental hydrogen and oxygen, whereupon the hydrogen may be used for energy production and oxygen for breathing.

The mass of water is great enough that the ability to launch enough water to meet the needs of space-based projects will play a significant role in determining the use of space. Much attention has been paid to the likely sources of water off-planet, especially in deposits that can be most easily exploited. In 2020, a Chinese lunar probe and NASA’s Stratospheric Observatory for Infrared Astronomy (SOFIA) both confirmed the existence of water on the Moon. Trace amounts of water had previously been discovered in volcanic glass beads retrieved by the Apollo 15 and Apollo 17 missions, in 1971 and 1972, respectively, suggesting that water was present in the moon's mantle and had been trapped in the beads as they formed. Using orbital satellite data, the researchers discovered that the Apollo samples were not unique; similar volcanic deposits were found to be widespread on the moon's surface, nearly all of which emitted spectroscopic signatures indicating the presence of water. The amount of water present in the deposits suggests that some, if not all, of the lunar mantle may contain as much water as Earth's.

Similarly, there is considerable evidence to suggest that Mars may contain vast amounts of water locked up beneath its regolith as permafrost (water ice mixed with soil). Moreover, some asteroids may contain water ice, and comets are generally considered to be mostly water ice. These resources may be captured and relocated to an orbit suitable for mining. Finally, pure water is produced as a waste product of fuel cells that react with hydrogen and oxygen to produce power, but the hydrogen and oxygen of fuel cells were obtained by breaking down water in the first place.

Solar energy will be an abundant resource in space. Large reflectors can be used to concentrate heat to drive turbines and melt ores for smelting. Another source of energy is the direct conversion, by photovoltaic (solar) cells, of sunlight into electricity. Such cells may be produced off-planet using lunar materials such as silicon, a significant constituent of lunar soil. Future space colonists may want to locate reserves of radioisotopes for nuclear power; such reserves, if found, could be exploited with an excellent promise of safety, especially in high Earth, lunar, or solar orbit, as the isolation of the radioactive contaminants and power plant itself would be assured. Questions concerning other power sources, such as high-temperature fusion and unconventional fusion techniques, remain unresolved. Such power sources, if perfected, could overcome nearly every known deterrent, allowing the fullest exploitation of space.

Off-Planet Building Material Resources

Aside from the most basic resources of survival off-planet (water, power, hydrogen, and oxygen), space colonists will require massive building-material resources. Launching millions of tons of raw building materials into space is as impractical as hauling volumes of water. Princeton University physicist Gerard K. O’Neill addressed the question of producing such quantities of building materials for the construction of off-planet colonies. In the 1970s, O’Neill and his Princeton-based Space Studies Institute designed a mass driver, also known as an electromagnetic catapult, a device that could catapult “buckets” of lunar soil into lunar or Earth orbit to then be processed in automated space factories into sheets of aluminum, magnesium, titanium, glass, and other materials for use in the construction of lunar or orbiting colonies. Lunar soil has been found to be rich enough in the necessary materials to produce such materials in space.

Surveys of Off-Planet Resources

Space probes have been utilized to discover information on the locations and amounts of resources in space. The Apollo mission astronauts returned samples from the lunar surface that were analyzed extensively and used in subsequent engineering and economic studies to reveal how the lunar material might be processed as building materials. The resources of Mars were surveyed at two landing sites in 1976 by the US Viking landers. The Viking landers were not designed to return samples directly from Mars; instead, they were sent with a device called an X-ray fluorescence spectrometer, which would analyze the Martian soil for its inorganic materials.

The presence of water ice on asteroids and comets, once merely theoretical, was confirmed by a series of notable discoveries in the 2010s. Twice in 2010, first in April and then in October, scientists reported observing water ice on the surface of two different asteroids in the asteroid belt, 24 Themis and 65 Cybele; later, in 2014, a study published in the journal Nature announced that the dwarf planet Ceres, also in the asteroid belt, is emitting water vapor into space—the first conclusive evidence of water vapor in the asteroid belt—and may in fact contain more water than does Earth. These discoveries suggest that water may be more common on asteroids than was previously predicted. In addition, the European Space Agency (ESA) space probe Rosetta, which began orbiting the comet 67P/Churyumov–Gerasimenko in August 2014, observed the presence of ice on the comet's surface shortly after its arrival; in January 2016, analysis confirmed that the ice was, in fact, water ice.

Development of Energy Production

The survivability and quality of every human’s life is directly affected by the resources available to each individual. From water and power to food and building materials, humankind has been in a constant struggle to improve the availability and quality of resources while reducing the magnitude of the struggle to obtain them. The historical propensity of civilization, if not its fundamental purpose, is to ease that struggle and increase the availability of the resource base while constantly improving its superiority and basic usefulness.

The resources of the future will follow this trend, with momentous advances being made in the most elemental domain: energy. Energy production directly affects the acquisition of all other resources. Improved ways of generating power will directly influence food production for all people, but the most profound influence will affect those populations in regions fixed on the edge of continual famine. High-temperature superconductivity would change the basis of electronic devices, resulting in more efficient and cheaper electrical power production, storage, transmission, and use. The exploitation of this science would enable supercomputers that operate at unprecedented speed. Transportation on Earth and in space would be revolutionized.

Significance

As private transportation into space became a reality in the early 2020s, the mining and exploitation of space resources became a reality, though still in its infancy. NASA awarded commercial space mining contracts to four companies in 2020 to mine lunar resources. The efforts were to begin in 2024 as part of an effort to return humans to the Moon, but the project was delayed. With commercial resource exploitation in space comes a variety of political, legal, diplomatic, scientific, and environmental considerations. In 2020, the United States negotiated the Artemis Accords in an early attempt to guide resource development in outer space. In 2023, researchers published findings that the need for large amounts of metals in the coming decades to construct car batteries, wind turbines, and solar panels might be met, at least in part, by using extraterrestrial resources. The need for these metals will arise as the world continues to reduce carbon dioxide emissions.

Principal Terms

ceramics: nonmetal compounds, such as silicates and clays, produced by firing the materials at high temperatures

fiber-reinforced composites: materials produced by drawing fibers of various types through a material being cast to produce a high weight-to-strength ratio

hydrolysis: the breakdown of water by energy into its constituent elements of water and hydrogen

off-planet: pertaining to regions outside Earth in orbital or planetary space

permafrost: a layer of soil and water ice frozen together

photovoltaic cell: a device commonly made of layered silicon that produces electrical current in the presence of light; also, a solar cell

regolith: that layer of soil and rock fragments just above the planetary crust

superconductors: materials that pass electrical current without exhibiting any electrical resistance

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