Space resources

The vastness beyond Earth’s thin atmosphere is rich in extraterrestrial resources. Microgravity technologies have been developed to take advantage of those resources. Solar energy captured on Earth or in space is used to generate electrical power. Applications in communications, global monitoring, and the Global Positioning System have been developed to improve the quality of human life. Satellites document planetary biosphere changes that occur naturally or from human activity.

Background

With the launch of Sputnik 1 in 1957, the Soviet Union began a race to develop technology that would provide routine access to space. The region from low Earth orbit (LEO) outward to geostationary Earth orbit (GEO) is concentrated with satellites that peer regularly at Earth or look outward with telescopes. The region between LEO and GEO is the most utilized with regard to space resources. There, some resources have present commercial profitability. Space beyond GEO remains largely for scientific exploration and resource speculation.

Communication Satellites

An object in GEO revolves about Earth’s center in exactly one day. This means that as Earth rotates on its axis, a GEO object appears to hang directly overhead. Geostationary position is 35,800 kilometers above Earth’s surface.

Early communications satellites were only put in LEO. The next push was to install operational systems in GEO to relay television images, data, and telephone signals around the world. LEO satellites have regained a share of communications traffic. These cross an observer’s sky in ten to twenty minutes, so a constellation of satellites is required for continuous reception. Because LEO satellites are only 500 to 1,400 kilometers above Earth’s surface, they can be reached with a signal much less powerful than one required for a geostationary satellite. Consequently, ground stations that provide uplinks and downlinks for LEO satellites can be modest. Thus, LEO satellites can provide portable telephone service and data links to underdeveloped areas.

Weather and Climate Observing Satellites

Geostationary weather satellites provide images in visible and infrared light. Polar-orbiting weather satellites survey virtually the whole Earth. Satellite instruments monitor stratospheric ozone concentrations, atmospheric particulates, temperature profiles as a function of atmospheric altitude, and pollutant levels (such as chlorofluorocarbons). Some measure surface, lower atmospheric, and ocean temperature variations to monitor increases in global temperature. A great advantage of global weather systems has been advanced warning of hurricanes, tornadoes, and other destructive systems, resulting in tremendous savings of human life. The 2030 Agenda for Sustainable Development Goals received direct support from these satellites throughout the beginning of the twenty-first century through the accurate and timely observations available globally concerning weather, deforestation, and the melting of icecaps. Without the ability to measure these critical climate variables, it would be difficult to track changes and document long-term data.

Navigation Satellites

The Global Positioning System (GPS) is a network of thirty-one Navstar satellites, as of 2023, maintained by the US Department of Defense. The accuracy of these satellites depends on the quality of the receiver or device. At the inception of the technology, the US military was the only user, and accuracy was limited to around 300 meters, but in 2023, the average accuracy of basic GPS devices was approximately 7.0 meters 95 percent of the time. This is sufficient for civilians to drive to a location in a strange city, to hike on unmarked paths, or to navigate a ship. The military uses GPS not only for navigation but also to provide flight-path corrections to deployed smart weapons. GPS was incorporated into guidance and navigation systems aboard the space shuttle, and it has become a staple for search-and-rescue services and provides a means for detailed documentation of surface locations for commercial and scientific purposes.

In 2009, a GPS satellite launched by a Delta II booster lifted off from Cape Canaveral. At that point, the Delta II rocket had launched forty-seven GPS satellites in twenty years with only one failure. Since initial GPS deployment, various generations of GPS have been launched byDelta II, Atlas II, and Titan IV rockets. With this 2009 launch, there were thirty operational satellites, well beyond the minimum of twenty-four needed for the orbital constellation. By 2023, thirty-one operational satellites were in use.

Reconnaissance, Remote Sensing, and High-Resolution Imaging Satellites

In 1960, the Russians shot down an American U-2 spy plane flying over Soviet territory. This incident underscored the military’s desire to obtain high-resolution images in a less vulnerable manner. Soon, spy satellites, from the original Corona (cover name Discoverer) reconnaissance satellites that proved the utility of military intelligence gathering from orbit to modern classified electronic listening and imaging platforms took over from spy planes. Afterward, relying on assets from orbit became a major part of American military space programs. Resolution and other capabilities of military systems, naturally, remain secret.

The orbital vantage point not only is useful for reconnaissance and intelligence gathering but also provides a platform from which to perform Earth resources investigations. The story has been told of a Gulf of Mexico fisherman who, when shown an image taken from NASA’s Skylab Earth Resources Experiment Package (EREP), stated that he had learned more about where to find rich schools of fish and where currents and abundant nutrients flowed within his patrol area than he had during a lifetime of working on the sea. Multispectral imaging could be used to conduct environmental studies as well as uncover a wide range of natural resources. From early astronauts using simple cameras to the Skylab EREP package, the concept of remote sensing was proven quickly.

Public access to satellite images began in 1972 with the Landsat satellite series. A similar program to observe the oceans, called Seasat, was developed with less success than Landsat. Early Landsat images had a resolution of eighty meters. During the Jimmy Carter administration, NASA transferred Landsat operations to the National Oceanographic and Atmospheric Administration (NOAA). NOAA funding ran low during the first George Bush administration, and NASA again entered the picture. By 1995, images with high resolution were available for commercial uses ranging from land management to insurance claims adjustment. Landsat 7 was launched in 1999. Commercial satellites followed. The IKONOS and the French Système Pour l’Observation de la Terre (SPOT) systems have resolutions closer to claimed American military capabilities. Google Earth uses satellite images to provide incredibly detailed views of Earth’s human infrastructure.

As for US assets, after the turn of the century, only Landsat 5 and 7 remained available. In August 2007, Landsat 5 unexpectedly tumbled out of its working orbit. Several days later, that satellite was recertified for continued operations; some believed Landsat 5 had been hit by debris from the Perseid meteor shower. This anomalous orbit incident, however, illustrated another aspect of using the resources of space: the expanding danger of micrometeoroid and orbital debris (MMOD). Both LEO and GEO have become filled with operational satellites, space junk, spent booster parts, and other debris. Quite often, the International Space Station (ISS) has to execute collision-avoidance maneuvers to miss orbital debris.

In 2009, an investigation of joint management NASA and the Department of the Interior US Geological Survey indicated that Landsat was not meeting requirements of the 1992 Land Remote Sensing Policy Act. This investigation called for greater thermal imaging capability and urged an expanded Landsat Data Continuity Mission to maintain Landsat legacy data.

Astronomical Satellites

Atmospheric density fluctuations cause starlight to twinkle. Without adaptive optics built into land-based telescope facilities, optical images smear out and obscure detail. Placing the Hubble Space Telescope above the in LEO in 1990 enabled astronomers to begin resolving individual stars and distant galaxies much farther away than ever before. This provided a better measurement of the size of the observable universe and a more accurate value for the rate at which the universe is expanding, the so-called Hubble constant. Other astronomical satellites have detected radiation that is partially or completely blocked by Earth’s atmosphere, including infrared, ultraviolet, x-ray, and gamma-ray radiation. The Cosmic Background Explorer (COBE) measured diffuse infrared and microwave radiation thought to be remnants of the big bang and revealed tiny fluctuations that may have led to galaxy formation.

Vela satellites, launched in 1969 to monitor the Nuclear Test Ban Treaty, discovered unexpected celestial gamma-ray emissions. The use of Earth-orbiting and solar-orbiting positions for astrophysical studies of the cosmos at wavelengths not available to Earth-based observatories was quickly realized by such early spacecraft as the Orbiting Astronomical Observatory, Orbiting Solar Observatory, and High Energy Astronomy Observatory satellites. The aforementioned Hubble Space Telescope became but one of a collection of Great Observatories that NASA launched into space. Others were the Compton Gamma Ray Observatory, the Chandra X-Ray Observatory, and the Spitzer Space Telescope, the latter of which was an infrared observatory. These Great Observatories permitted coordinated studies in several ranges of the electromagnetic spectrum, greatly expanding the understanding of high-energy astrophysics and cosmological issues.

NASA and other international space agencies also developed smaller space-based observatories designed for more specific investigations. The Fermi Gamma-Ray Space Telescope and the Swift Gamma-Ray Burst Mission extended gamma-ray studies by Compton and some Russian spacecraft. The French launched the Convection Rotation and Planetary Transits (COROT) telescope to look for transits of extrasolar planets across their star. NASA’s Kepler spacecraft greatly exceeded COROT in capability and began looking for Earth-class planets in extrasolar systems in 2009. In 2015, NASA confirmed that the Kepler spacecraft discovered the one-thousandth exoplanet, By 2023, the Kepler and follow-up observations had discovered more than 2,600 explanets. NASA retired the Kepler spacecraft in 2018.

Manufacturing in Microgravity

Any object in a circular orbit about Earth is in a state of free fall, having just enough speed (hence the right total mechanical energy) to fall around Earth instead of getting radially closer to its surface. This condition is weightlessness, a state wherein gravitational influence is balanced by centripetal motion. This description applies equally to elliptical orbits in which the orbiting object’s speed varies as it undergoes periodic orbital motion. Effects such as the gravitational attraction of other bodies on an object may give that object a weight many orders of magnitude smaller than its normal “Earth” weight, a situation referred to as “microgravity.”

When crystals are formed out of solution on Earth, they often develop imperfections because of convective flow within the solution. More nearly perfect crystals can be formed in microgravity because there are no gravitationally induced convection currents. Microgravity materials processing has proven to be useful, but it has yet to become cost-effective. As of 2009, it cost roughly $22,000 per kilogram to deliver a payload to orbit. In 2022, Rocket Lab, a company that launches small satellites into orbit, charged around $5 million per flight or $10,000 per pound of payload. Space X, a similar but competitively priced company, offered rides aboard their Falcon 9 rocket for $1,200 per pound of payload or $62 million per launch.

Research opportunities on the ISS in 2009 began to expand greatly under a plan to operate ISS as a national laboratory with international partners. As a result of ISS research, a salmonella vaccine developed in space was put into clinical trials on Earth. Other pharmaceutical projects on ISS held the potential for billions of dollars in profits in addition to lessening human suffering. By 2022, the ISS and the research surrounding it improved medical scanning technology, aided in the creation of a new muscular dystrophy medication, and began the development of synthetic animal blood.

Solar Satellite Power Stations

Some have proposed using solar satellite power stations (SSPSs) to generate electrical energy. Ideas such as these go back as far as the late 1960s. A large SSPS in geostationary orbit might require fifty square kilometers or more of solar collectors. Electricity from those solar collectors could be converted into microwaves and be beamed down to a ground-based antenna array, where it could be converted into normal alternating electric current. To maintain a safe microwave beam intensity, the antenna array would need to cover many square kilometers. Some have suggested that one or two hundred of these stations could supply all electrical needs of the United States.

The idea has certain attractions, especially if the receiving arrays could be situated in unpopulated regions. Solar power would generate no carbon dioxide emissions to aggravate global warming. On the other hand, there would be huge amounts of mining and manufacturing wastes associated with acquiring materials for constructing the receiving arrays and satellites. Lifting the satellite materials into orbit might require between thirty thousand and sixty thousand space-shuttle-class launches, which, beyond the idea’s impracticality, would be an environmental disaster in and of itself. This idea remains popular among certain commercial space and public space advocacy groups but has generated little government support.

Mining the Moon and Mars

In 1969, Gerard K. O’Neill of Princeton University set up his freshman physics course as a seminar geared toward exploring whether a planetary surface was really the right place for an expanding technological civilization; the students returned a negative answer. However, consensus grew that colonies in space were feasible and could provide access to abundant energy, raw materials, freedom, and frontiers beyond Earth. O’Neill’s disciples and successors have a remarkable idealism and a zeal about humankind’s place in space. They organized as the Space Studies Institute (SSI) and the Space Frontier Foundation. Other advocacy groups arose, such as the 15 Society, named after a concept to place a huge human space colony at a specific Lagrange point in the Earth-moon system.

Using solar energy and appropriate industrial chemical processes, extracting oxygen, silicon, iron, calcium, aluminum, magnesium, and titanium from lunar rocks and soil should be possible. Oxygen and powdered aluminum could be used as rocket fuel. Mass drivers, devices designed with tracks and sequentially activated magnetic coils to propel buckets of material to launch speeds, could launch supplies from the lunar surface. Space tugs could catch these supplies and transport them to a space colony. It would cost much less energy to bring material from the moon to build an SSPS than it would to provide it from Earth. Even so, it is doubtful that the SSPS would pay for itself unless the space colony were already in place.

The Martian surface, or perhaps Phobos, one of Mars’s two small irregular moons, could become a spacecraft fueling station. Water could be mined from polar ice or from permafrost and be converted into high-grade rocket fuel based on hydrogen and oxygen. Carbon dioxide from the Martian atmosphere could be processed into a rocket-fuel combination of oxygen and carbon monoxide. The ability to refuel would make access to Mars and the asteroid belt easier. Aggressive exploration and exploitation of Mars have been advocated by Robert Zubrin and the Mars Society. Mars remains a long-range, albeit unfunded, goal of NASA manned spaceflight.

In the aftermath of the Columbia accident in 2003, the second Bush administration advanced the Vision for Space Exploration with the motto “The Moon, Mars, and Beyond.” The primary charge to NASA was to return to the moon to stay, with initial lunar operations to begin by 2020. A goal of steadily building up a lunar base at the moon’s south pole, using as many in situ resources as possible, became NASA’s Project Constellation. Other nations, including China, Russia, India, and Japan, developed interests in exploring lunar space as well. An implied Chinese manned spaceflight goal was to reach the moon before NASA’s return. Apollo 17 moonwalker Harrison Schmitt developed an economically sustainable plan to mine lunar soil for helium 3 to be used on Earth in fusion-based power generation systems. As of 2022, NASA announced a $93 billion plan to return to the moon in 2026, beginning with the launch of a test rocket as part of the Artemis program.

Mining Asteroids

Some asteroids are excellent sources of nickel and iron. Others contain a great deal of carbon and water. There are an estimated two thousand asteroids 1 kilometer in diameter or larger that cross Earth’s orbit. These asteroids are more accessible than those within the main asteroid belt. It is at least theoretically possible to adjust the orbits of smaller asteroids using mass drivers or gravity tractors, but it might take years or decades to achieve the desired orbit. It is believed that a single nickel-iron asteroid 1 kilometer in diameter would contain nearly seven times the estimated earthly nickel reserves.

In 2009, British scientists presented a design for a gravity tractor that would fly close to an asteroid surface and, through gravitational influence alone, over perhaps fifteen years, make changes in the orbital path of such a body. If a near-Earth object or small asteroid were on a collision course with Earth, such a spacecraft placed close to its surface could avert a deadly global catastrophe. As of 2021, a 9-metric-ton gravity tractor, however, could not be used to bring a resource-laden asteroid into Earth proximity for convenient mining operations, nor could it be used to divert the path of asteroids with a size over 500 meters in diameter.

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