Asteroid mining

Artist's concept of asteroid mining

433 Eros is a stony asteroid in a near-Earth orbit

Asteroid mining is the exploitation of raw materials from asteroids and other minor planets, including near-Earth objects. Minerals and volatiles could be mined from an asteroid or spent comet then used in space for in-situ utilization (e.g. construction materials and rocket propellant) or taken back to Earth. These include gold, iridium, silver, osmium, palladium, platinum, rhenium, rhodium, ruthenium and tungsten for transport back to Earth; iron, cobalt, manganese, molybdenum, nickel, aluminium, and titanium for construction; water and oxygen to sustain astronauts; as well as hydrogen, ammonia, and oxygen for use as rocket propellant.

Due to the high costs of current space transportation, extraction techniques still being developed and lingering uncertainties about target selection, terrestrial mining remains the primary means of raw mineral acquisition today. This situation is likely to change in the future as resources on Earth are becoming increasingly scarce and the full potentials of asteroid mining and space exploration are researched in greater detail. However, there is no guarantee asteroid mining will ever attain the volume needed to fully compensate for dwindling terrestrial reserves.

Purpose

Based on known terrestrial reserves, and growing consumption in both developed and developing countries, key elements needed for modern industry and food production could be exhausted on Earth within 50–60 years. These include phosphorus, antimony, zinc, tin, lead, indium, silver, gold and copper. In response, it has been suggested that platinum, cobalt and other valuable elements from asteroids may be mined and sent to Earth for profit, used to build solar-power satellites and space habitats, and water processed from ice to refuel orbiting propellant depots.

Although asteroids and Earth accreted from the same starting materials, Earth's relatively stronger gravity pulled all heavy siderophilic (iron-loving) elements into its core during its molten youth more than four billion years ago. This left the crust depleted of such valuable elements until a rain of asteroid impacts re-infused the depleted crust with metals like gold, cobalt, iron, manganese, molybdenum, nickel, osmium, palladium, platinum, rhenium, rhodium, ruthenium and tungsten (some flow from core to surface does occur, e.g. at the Bushveld Igneous Complex, a famously rich source of platinum-group metals). Today, these metals are mined from Earth's crust, and they are essential for economic and technological progress. Hence, the geologic history of Earth may very well set the stage for a future of asteroid mining.

In 2006, the Keck Observatory announced that the binary Jupiter trojan 617 Patroclus, and possibly large numbers of other Jupiter trojans, are likely extinct comets and consist largely of water ice. Similarly, Jupiter-family comets, and possibly near-Earth asteroids that are extinct comets, might also economically provide water. The process of in-situ resource utilization—using materials native to space for propellant, tankage, radiation shielding, and other high-mass components of space infrastructure—could lead to radical reductions in its cost.

Ice would satisfy one of two necessary conditions to enable "human expansion into the Solar System" (the ultimate goal for human space flight proposed by the 2009 "Augustine Commission" Review of United States Human Space Flight Plans Committee): physical sustainability and economic sustainability.

From the astrobiological perspective, asteroid prospecting could provide scientific data for the search for extraterrestrial intelligence (SETI). Some astrophysicists have suggested that if advanced extraterrestrial civilizations employed asteroid mining long ago, the hallmarks of these activities might be detectable.

Asteroid selection

Comparison of delta-v requirements for standard Hohmann transfers

Mission	Δv
Earth surface to LEO	8.0 km/s
LEO to near-Earth asteroid	5.5 km/s
LEO to lunar surface	6.3 km/s
LEO to moons of Mars	8.0 km/s

An important factor to consider in target selection is orbital economics, in particular the change in velocity (Δv) and travel time to and from the target. More of the extracted native material must be expended as propellant in higher Δv trajectories, thus less returned as payload. Direct Hohmann trajectories are faster than Hohmann trajectories assisted by planetary and/or lunar flybys, which in turn are faster than those of the Interplanetary Transport Network, but the latter have lower Δv than the former.

Near-Earth asteroids are considered likely candidates for early mining activity. Their low Δv makes them suitable for use in extracting construction materials for near-Earth space-based facilities, greatly reducing the economic cost of transporting supplies into Earth orbit.

The table above shows a comparison of Δv requirements for various missions. In terms of propulsion energy requirements, a mission to a near-Earth asteroid compares favorably to alternative mining missions.

An example of a potential target for an early asteroid mining expedition is 4660 Nereus, expected to be mainly enstatite. This body has a very low Δv compared to lifting materials from the surface of the Moon. However it would require a much longer round-trip to return the material.

Multiple types of asteroids have been identified but the three main types would include the C-type, S-type, and M-type asteroids:

1. C-type asteroids have a high abundance of water which is not currently of use for mining but could be used in an exploration effort beyond the asteroid. Mission costs could be reduced by using the available water from the asteroid. C-type asteroids also have a lot of organic carbon, phosphorus, and other key ingredients for fertilizer which could be used to grow food.
2. S-type asteroids carry little water but look more attractive because they contain numerous metals including: nickel, cobalt and more valuable metals such as gold, platinum and rhodium. A small 10-meter S-type asteroid contains about 650,000 kg (1,433,000 lb) of metal with 50 kg (110 lb) in the form of rare metals like platinum and gold.
3. M-type asteroids are rare but contain up to 10 times more metal than S-types

A class of easily recoverable objects (EROs) was identified by a group of researchers in 2013. Twelve asteroids made up the initially identified group, all of which could be potentially mined with present-day rocket technology. Of 9,000 asteroids searched in the NEO database, these twelve could all be brought into an Earth-accessible orbit by changing their velocity by less than 500 meters per second (1,800 km/h; 1,100 mph). The dozen asteroids range in size from 2 to 20 meters (10 to 70 ft).

Asteroid cataloging

Main article: B612 Foundation

The B612 Foundation is a private nonprofit foundation with headquarters in the United States, dedicated to protecting Earth from asteroid strikes. As a non-governmental organization it has conducted two lines of related research to help detect asteroids that could one day strike Earth, and find the technological means to divert their path to avoid such collisions.

The foundation's current goal is to design and build a privately financed asteroid-finding space telescope, Sentinel, to be launched in 2017–2018. The Sentinel's infrared telescope, once parked in an orbit similar to that of Venus, will help identify threatening asteroids by cataloging 90% of those with diameters larger than 140 metres (460 ft), as well as surveying smaller Solar System objects.

Data gathered by Sentinel will be provided through an existing scientific data-sharing network that includes NASA and academic institutions such as the Minor Planet Center in Cambridge, Massachusetts. Given the satellite's telescopic accuracy, Sentinel's data may prove valuable for other possible future missions, such as asteroid mining.

Mining considerations

There are three options for mining:

1. Bring raw asteroidal material to Earth for use.
2. Process it on-site to bring back only processed materials, and perhaps produce propellant for the return trip.
3. Transport the asteroid to a safe orbit around the Moon, Earth or to the ISS. This can hypothetically allow for most materials to be used and not wasted. Along these lines, NASA has proposed a potential future space mission known as the Asteroid Redirect Mission, although the primary focus of this mission is on retrieval.

Processing in situ for the purpose of extracting high-value minerals will reduce the energy requirements for transporting the materials, although the processing facilities must first be transported to the mining site.

Mining operations require special equipment to handle the extraction and processing of ore in outer space. The machinery will need to be anchored to the body, but once in place, the ore can be moved about more readily due to the lack of gravity. Docking with an asteroid can be performed using a harpoon-like process, where a projectile penetrates the surface to serve as an anchor; then an attached cable is used to winch the vehicle to the surface, if the asteroid is rigid enough for a harpoon to be effective.

Due to the distance from Earth to an asteroid selected for mining, the round-trip time for communications will be several minutes or more, except during occasional close approaches to Earth by near-Earth asteroids. Thus any mining equipment will either need to be highly automated, or a human presence will be needed nearby. Humans would also be useful for troubleshooting problems and for maintaining the equipment. On the other hand, multi-minute communications delays have not prevented the success of robotic exploration of Mars, and automated systems would be much less expensive to build and deploy.

Technology being developed by Planetary Resources to locate and harvest these asteroids has resulted in the creation of three different types of satellites:

1. Arkyd Series 100 (The Leo Space telescope) is a less expensive instrument that will be used to find, analyze, and see what resources are available on nearby asteroids.
2. Arkyd Series 200 (The Interceptor) Satellite that would actually land on the asteroid to get a closer analysis of the available resources.
3. Arkyd Series 300 (Rendezvous Prospector) Satellite developed for research and finding resources deeper in space.

Technology being developed by Deep Space Industries to examine, sample, and harvest asteroids is divided into three families of spacecrafts:

1. FireFlies are triplets of nearly identical spacecraft in CubeSat form launched to different asteroids to rendezvous and examine them.
2. DragonFlies also are launched in waves of three nearly identical spacecraft to gather small samples (5–10 kg) and return them to Earth for analysis.
3. Harvestors voyage out to asteroids to gather hundreds of tons of material for return to high Earth orbit for processing.

Asteroid mining could potentially revolutionize space exploration. The C-type asteroids high abundance of water could be used to produce fuel by splitting water into hydrogen and oxygen. This would make space travel a more feasible option by lowering cost of fuel.

Extraction techniques

Surface mining

On some types of asteroids, material may be scraped off the surface using a scoop or auger, or for larger pieces, an "active grab." There is strong evidence that many asteroids consist of rubble piles, making this approach possible.

Shaft mining

A mine can be dug into the asteroid, and the material extracted through the shaft. This requires precise knowledge to engineer accuracy of astro-location under the surface regolith and a transportation system to carry the desired ore to the processing facility.

Magnetic rakes

Asteroids with a high metal content may be covered in loose grains that can be gathered by means of a magnet.

Heating

For volatile materials in extinct comets, heat can be used to melt and vaporize the matrix.

Extraction using the Mond process

The nickel and iron of an iron rich asteroid could be extracted by the Mond process. This involves passing carbon monoxide over the asteroid at a temperature of 50 to 60 C, then nickel and iron can be removed from the gas again at higher temperatures, perhaps in an attached printer, and platinum, gold etc left as a residue.

Self-replicating machines

A 1980 NASA study entitled Advanced Automation for Space Missions proposed a complex automated factory on the Moon that would work over several years to build a copy of itself. Exponential growth of factories over many years could refine large amounts of lunar (or asteroidal) regolith. Since 1980 there has been major progress in miniaturization, nanotechnology, materials science, and additive manufacturing, so the self-replicating "factory" might be as small as a 3-D printer.

Proposed mining projects

On April 24, 2012 a plan was announced by billionaire entrepreneurs to mine asteroids for their resources. The company is called Planetary Resources and its founders include aerospace entrepreneurs Eric Anderson and Peter Diamandis. Advisers include film director and explorer James Cameron and investors include Google's chief executive Larry Page and its executive chairman Eric Schmidt. They also plan to create a fuel depot in space by 2020 by using water from asteroids, which could be broken down in space to liquid oxygen and liquid hydrogen for rocket fuel. From there, it could be shipped to Earth orbit for refueling commercial satellites or spacecraft. The plan has been met with skepticism by some scientists, who do not see it as cost-effective, even though platinum and gold are worth nearly £35 per gram (approximately $1,800 per troy ounce). The upcoming NASA mission OSIRIS-REx, which is planned to return just a minimum amount (60 g; two ounces) of material but could get up to 2 kg from an asteroid to Earth, will cost about US$1 billion.

Planetary Resources says that, in order to be successful, it will need to develop technologies that bring the cost of space flight down. Planetary Resources also expects that the construction of "space infrastructure" will help to reduce long-term running costs. For example, fuel costs can be reduced by extracting water from asteroids and converting it to hydrogen using solar energy. In theory, hydrogen fuel mined from asteroids costs significantly less than fuel from Earth due to high costs of escaping Earth's gravity. If successful, investment in "space infrastructure" and economies of scale could reduce operational costs to levels significantly below NASA's upcoming (OSIRIS-REx) mission.

Another similar venture, called Deep Space Industries, was started by David Gump, who had founded other space companies. The company hopes to begin prospecting for asteroids suitable for mining by 2015 and by 2016 return asteroid samples to Earth. By 2023 Deep Space Industries plans to begin mining asteroids.

At ISDC-San Diego 2013, Kepler Energy and Space Engineering (KESE,llc) also announced it was going to mine asteroids, using a simpler, more straightforward approach: KESE plans to use almost exclusively existing guidance, navigation and anchoring technologies from successful missions like the Rosetta/Philae, Dawn, and Hyabusa's Muses-C and current NASA Technology Transfer tooling to build and send a 4-module Automated Mining System (AMS) to a small asteroid with a simple digging tool to collect ~40 tons of asteroid regolith and bring each of the four return modules back to low Earth orbit (LEO) by the end of the decade. Small asteroids are expected to be loose piles of rubble, therefore providing for easy extraction.

In September 2012, the NASA Institute for Advanced Concepts (NIAC) announced the Robotic Asteroid Prospector project, which will examine and evaluate the feasibility of asteroid mining in terms of means, methods, and systems.

Economics and safety

Currently, the quality of the ore and the consequent cost and mass of equipment required to extract it are unknown and can only be speculated. Some economic analyses indicate that the cost of returning asteroidal materials to Earth far outweighs their market value, and that asteroid mining will not attract private investment at current commodity prices and space transportation costs. Other studies suggest large profit by using solar power. Potential markets for materials can be identified and profit generated if extraction cost is brought down. For example, the delivery of multiple tonnes of water to low Earth orbit for rocket fuel preparation for space tourism could generate a significant profit.

In 1997 it was speculated that a relatively small metallic asteroid with a diameter of 1.6 km (1 mi) contains more than US$20 trillion worth of industrial and precious metals. A comparatively small M-type asteroid with a mean diameter of 1 km (0.62 mi) could contain more than two billion metric tons of iron–nickel ore, or two to three times the world production of 2004. The asteroid 16 Psyche is believed to contain 1.7×10¹⁹ kg of nickel–iron, which could supply the world production requirement for several million years. A small portion of the extracted material would also be precious metals.

Not all mined materials from asteroids would be cost-effective, especially for the potential return of economic amounts of material to Earth. For potential return to Earth, platinum is considered very rare in terrestrial geologic formations and therefore is potentially worth bringing some quantity for terrestrial use. Nickel, on the other hand, is quite abundant and being mined in many terrestrial locations, so the high cost of asteroid mining may not be cost effective.

Although Planetary Resources says platinum from a 30 m (98 ft)-long asteroid is worth US$25–50 billion, an economist remarked any outside source of precious metals could lower prices sufficiently to possibly doom the venture by rapidly increasing the available supply of such metals.

Development of an infrastructure for altering asteroid orbits could offer a large return on investment. However, astrophysicists Carl Sagan and Steven J. Ostro raised the concern altering the trajectories of asteroids near Earth may pose a collision hazard. They concluded orbit engineering has both opportunities and dangers: If controls instituted on orbit-manipulation technology were too tight, future spacefaring could be hampered, but if they were too loose, human civilization would be at risk.

Scarcity

Main article: Natural resource § Classification

Scarcity is a fundamental economic problem of humans having seemingly unlimited wants in a world of limited resources. Since Earth's resources are not infinite, the relative abundance of asteroidal ore gives asteroid mining the potential to provide nearly unlimited resources, which could practically eliminate scarcity for those materials.

The idea of exhausting resources is not new. In 1798, Thomas Malthus wrote, because resources are ultimately limited, the exponential growth in a population would result in falls in income per capita until poverty and starvation would result as a constricting factor on population.

• Proven reserves are deposits of mineral resources that are already discovered and known to be economically extractable under present or similar demand, price and other economic and technological conditions.
• Conditional reserves are discovered deposits that are not yet economically viable.
• Indicated reserves are less intensively measured deposits whose data is derived from surveys and geological projections. Hypothetical reserves and speculative resources make up this group of reserves. Inferred reserves are deposits that have been located but not yet exploited.

Continued development in asteroid mining techniques and technology will help to increase mineral discoveries. As the cost of extracting mineral resources, especially platinum group metals, on Earth rises, the cost of extracting the same resources from celestial bodies declines due to technological innovations around space exploration.

Financial feasibility

Space ventures are high-risk, with long lead times and heavy capital investment, and that is no different for asteroid-mining projects. These types of ventures could be funded through private investment or through government investment. For a commercial venture it can be highly profitable as long as the revenue earned is greater than total costs (costs for extraction and costs for marketing). The costs involving an asteroid-mining venture have been estimated to be around $100 billion US.

There are six categories of cost considered for an asteroid mining venture:

1. Research and development costs
2. Exploration and prospecting costs
3. Construction and infrastructure development costs
4. Operational and engineering costs
5. Environmental costs
6. Time cost

Determining financial feasibility is best represented through net present value. One requirement needed for financial feasibility is a high return on investments estimating around 30%. Example calculation assumes for simplicity that the only valuable material on asteroids is platinum. On September 5, 2008 platinum was valued at US$1,340 per ounce, or US$43,000 per kilogram. For a 10% return on investment, 173,400 kg (5,575,000 ozt) of platinum would have to be extracted for every 1,155,000 tons of asteroid ore. For a 50% return on investment 1,703,000 kg (54,750,000 ozt) of platinum would have to be extracted for every 11,350,000 tons of asteroid ore.

Legal regimes

Space law involves a specific set of international treaties, along with national commercialization laws. The system and framework for international and domestic laws were established through the United Nations Office for Outer Space Affairs. The rules, terms and agreements considered by space law authorities to be part of the active body of international space law are the five international space treaties and five UN declarations. Approximately 100 nations and institutions were involved in negotiations. The space treaties cover many major issues such as arms control, non-appropriation of space, freedom of exploration, liability for damages, safety and rescue of astronauts and spacecraft, prevention of harmful interference with space activities and the environment, notification and registration of space activities, and the settlement of disputes. In exchange for assurances from the space power, the nonspacefaring nations acquiesced to U.S. and Soviet proposals to treat outer space as a commons (res communis) territory which belonged to no one state.

After ten years of negotiations between nearly 100 nations, the Outer Space Treaty opened for signature on January 27, 1966. It entered into force as the constitution for outer space on October 10, 1967. The Outer Space Treaty was well received; it was ratified by ninety-six nations and signed by an additional twenty-seven states. The outcome has been that the basic foundation of international space law consists of five (arguably four) international space treaties, along with various written resolutions and declarations. The main international treaty is the Outer Space Treaty of 1967; it is generally viewed as the “Constitution" for outer space. By ratifying the Outer Space Treaty of 1967, ninety-eight nations agreed that outer space would belong to the “province of mankind”, that all nations would have the freedom to “use” and “explore” outer space, and that both these provisions must be done in a way to “benefit all mankind.” The province of mankind principle and the other key terms have not yet been specifically defined (Jasentuliyana, 1992). Critics have complained that the Outer Space Treaty is vague. Yet, international space law has worked well and has served space commercial industries and interests for many decades. The taking away and extraction of Moon rocks, for example, has been treated as being legally permissible.

The Moon Agreement (1979-1984) is often treated as though it is not a part of the body of international space law, and there has been extensive debate on whether or not the Moon Agreement is a valid part of international law. It entered into force in 1984, because of a five state ratification consensus procedure, agreed upon by the members of the United Nations Committee on Peaceful Uses of Outer Space (COPUOS). Still today very few nations have signed and/or ratified the Moon Agreement. In recent years this figure has crept up to a few more than a dozen nations who have signed and ratified the treaty. The other three outer space treaties experienced a high level of international cooperation in terms of signage and ratification, but the Moon Treaty went further than them, by defining the Common Heritage concept in more detail and by imposing specific obligations on the parties engaged in the exploration and/or exploitation of outer space. The Moon Treaty explicitly designates the Moon and its natural resources as part of the Common Heritage of Mankind. The framers of Outer Space Treaty initially focused on solidifying broad terms first, with the intent to create more specific legal provisions later (Griffin, 1981: 733-734). This is why the members of the COPUOS later expanded the Outer Space Treaty norms by articulating more specific understandings which are found in the “three supplemental agreements” – The Rescue and Return Agreement of 1968, the Liability Convention of 1973, and the Registration Convention of 1976 (734). After these treaties were enacted, key actors involved in space law negotiations, set out to establish and confirm a few more legal norms which were to be embodied in the Moon Agreement, since important issues such as the environment, public health and sharing to benefit all mankind were left open. Many of the terms written into the Moon Treaty were sticking points during early negotiations.

Varying degrees of criticism exist regarding international space law. Some critics accept the Outer Space Treaty, but reject the Moon Agreement. Therefore, it is important to note that even the Moon Agreement with its common heritage of mankind clause, allows space mining, extraction, private property rights and exclusive ownership rights over natural outer space resources, if removed from their natural place. The Outer Space Treaty and the Moon Agreement allow private property rights for outer space natural resources once removed from the surface, subsurface or subsoil of the moon and other celestial bodies in outer space. Thus, international space law is capable of managing newly emerging space mining activities, private space transportation, commercial spaceports and commercial space stations/habitats/settlements. Space mining involving the extraction and removal of natural resources from their natural location is without question allowable under the Outer Space Treaty and the Moon Agreement. Once removed, those natural resources can be reduced to possession, sold, traded and explored or used for scientific purposes. International space law allows space mining, specifically the extraction of natural resources. The Moon Agreement specifically provides in Article 11, paragraph 3 that:

Neither the surface nor the subsurface of the Moon, nor any part thereof or natural resources in place [emphasis added], shall become property of any State, international intergovernmental or non-governmental organization, national organization or non-governmental entity or of any natural person. The placement of personnel, space vehicles, equipment, facilities, stations and installations on or below the surface of the Moon, including structures connected with its surface or subsurface, shall not create a right of ownership over the surface or the subsurface of the Moon or any areas thereof.

This provision was negotiated into the Moon Agreement by the United States in order to make sure that natural resources extracted from the Moon were legally permissible to take. Taking natural resources out of their location, from the surface or subsurface, has been interpreted by space law authorities as meaning that those resources are no longer tied to the “in place” restrictions against ownership.

Christol (1980) in The Moon Treaty: Fact and Fiction explains this legal distinction. He states that the Moon Treaty “ … does allow for the removal from the Moon and other celestial bodies of their natural resources”. It is generally understood within the space law authorities that extracting space resources is allowable, even by private companies for profit. However, international space law prohibits property rights over territories and outer space land. Hobe (2006) explains that the Outer Space Treaty “explicitly and implicitly prohibits only the acquisition of territorial property rights” – public or private.

Some nations are beginning to promulgate legal regimes for extraterrestrial resource extraction. For example, the United States "SPACE Act of 2015"—facilitating private development of space resources consistent with US international treaty obligations—passed the US House of Representatives in July 2015. In November 2015 it passed the United States Senate. On 25 November US-President Barack Obama signed the H.R.2262 - U.S. Commercial Space Launch Competitiveness Act into law.

In fiction

See also: Asteroids in fiction § Mineral extraction, and Category:Asteroid mining in fiction

The first mention of asteroid mining in science fiction is apparently Garrett P. Serviss' story Edison's Conquest of Mars, New York Evening Journal, 1898.

The 1979 film Alien, directed by Ridley Scott, is about the crew of the Nostromo, a commercially operated spaceship on a return trip to Earth hauling a refinery and 20 million tons of mineral ore mined from an asteroid. C. J. Cherryh's novel, Heavy Time focuses on the plight of asteroid miners in the Alliance-Union universe, while Moon is a 2009 British science fiction drama film depicting a lunar facility that mines the alternative fuel helium-3 needed to provide energy on Earth. It was notable for its realism and drama, winning several awards internationally.

In several science fiction video games, asteroid mining is a possibility. For example, in the space-MMO, EVE Online, asteroid mining is a very popular career, owing to its simplicity.

In Star Citizen, the mining occupation supports a variety of dedicated specialists, each of which has a critical role to play in the effort.

Gallery

• 

  Artist's concept from the 1970s of asteroid mining

• 

  Artist's concept of an asteroid mining vehicle as seen in 1984

• 

  Artist's concept of an asteroid moved by a space tether

• 

  A future space telescope designed by Planetary Resources company to find asteroids

See also

• Asteroid capture
• Asteroid Redirect Mission
• In-situ resource utilization
• Human mission to an asteroid
• Mining the Sky: Untold Riches from the Asteroids, Comets, and Planets
• Near Earth Asteroid Prospector
• Planetary Resources Inc.
• Sample return mission
• Space manufacturing
• Space-based industry
• SpaceDev

References

Publications

• Space Enterprise: Beyond NASA / David Gump (1990) ISBN 0-275-93314-8.
• Mining the Sky: Untold Riches from the Asteroids, Comets, and Planets / John S. Lewis (1998) ISBN 0-201-47959-1
• Ricky Lee: Law and Regulation of Commercial Mining of Minerals in Outer Space. Springer, Dordrecht 2012, ISBN 978-94-007-2038-1
• Viorel Badescu: Asteroids - prospective energy and material resources. Springer, Berlin 2013, ISBN 978-3-642-39243-6.

External links

Text

• The Technical and Economic Feasibility of Mining the Near-Earth Asteroids, M. J. Sonter.
• The Future of Space Mining
• The Plan to Bring an Asteroid to Earth
• How Asteroids can save mankind

Video

• Video Beyond Earth - NEO Destinations NewSpace Conference of the Space Frontier Foundation, Aug 7, 2011
• Video Moon, Mars, Asteroids - Where to Go First for Resources? Space manufacturing Conference of the Space Studies Institute, October 2010
• Video Moving An Asteroid California Institute of Technology, Workshop Public Lecture Panel, September 2011
• Video Asteroid Mining - The Market Problem and Radical Solution, November 2013