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.
Due to the high launch and transportation costs of spaceflight, inaccurate identification of asteroids suitable for mining, and in-situ ore extraction challenges, terrestrial mining remains the only means of raw mineral acquisition today. If space program funding, either public or private, dramatically increases, 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 in general—are researched in greater detail.  : 47f However, it is yet uncertain whether asteroid mining will develop to attain the volume and composition needed in due time to fully compensate for dwindling terrestrial reserves.  
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 provide water. The process of in-situ resource utilization —using materials native to space for propellant, thermal management, tankage, radiation shielding, and other high-mass components of space infrastructure—could lead to radical reductions in its cost.  Although whether these cost reductions could be achieved, and if achieved would offset the enormous infrastructure investment required, is unknown.
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.    Why extraterrestrials would have resorted to asteroid mining in near proximity to earth, with its readily available resources, has not been explained.
|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 Δ v 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 reduction in transfer time comes at the cost of increased Δ v requirements.
Near-Earth asteroids are considered likely candidates for early mining activity. Their low Δ v 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 Δ v 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 Δ v 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:
- 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. 
- 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. 
- 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). 
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.  
There are three options for mining: 
- Bring raw asteroidal material to Earth for use.
- Process it on-site to bring back only processed materials, and perhaps produce propellant for the return trip.
- 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. The House of Representatives deleted a line item for the ARP budget from NASA's FY 2017 budget request.
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. In Situ mining will involve drilling boreholes and injecting hot fluid/gas and allow the useful material to react or melt with the solvent and the extract the solute. Due to the weak gravitational fields of asteroids, any drilling will cause large disturbances and form dust clouds.
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. However, no techniques for refining ore in zero gravity currently exist. Docking with an asteroid might be performed using a harpoon-like process, where a projectile would penetrate the surface to serve as an anchor; then an attached cable would be used to winch the vehicle to the surface, if the asteroid is both penetrable and 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 plans for three different types of satellites:
- 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. 
- Arkyd Series 200 (The Interceptor) Satellite that would actually land on the asteroid to get a closer analysis of the available resources. 
- 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:
- FireFlies are triplets of nearly identical spacecraft in CubeSat form launched to different asteroids to rendezvous and examine them. 
- 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. 
- 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's 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. While the cost of fuel is a relatively insignificant factor in the overall cost for low earth orbit manned space missions, storing it and the size of the craft become a much bigger factor for interplanetary missions. Typically 1 kg in orbit is equivalent to more than 10 kg on the ground ( for a Falcon9 1.0 it would need 250 tons of fuel to put 5 tons in GEO orbit or 10 tons in LEO ). This limitation is a major factor in the difficulty of interplanetary missions as fuel becomes payload.
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.
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.
For asteroids such as carbonaceous chondrites that contain hydrated minerals, water and other volatiles can be extracted simply by heating. A water extraction test in 2016  by Honeybee Robotics used asteroid regolith simulant  developed by Deep Space Industries and the University of Central Florida to match the bulk mineralogy of a particular carbonaceous meteorite. Although the simulant was physically dry (i.e., it contained no water molecules adsorbed in the matrix of the rocky material), heating to about 510 °C released hydroxyl, which came out as substantial amounts of water vapor from the molecular structure of phyllosilicate clays and sulphur compounds. The vapor was condensed into liquid water filling the collection containers, demonstrating the feasibility of mining water from certain classes of physically dry asteroids.
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 between 50 and 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. 
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 80% of a copy of itself, the other 20% being imported from Earth since those more complex parts (like computer chips) would require a vastly larger supply chain to produce.  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 it may be possible to achieve 100% "closure" with a reasonably small mass of hardware, although these technology advancements are themselves enabled on Earth by expansion of the supply chain so it needs further study. A NASA study in 2012 proposed a "bootstrapping" approach to establish an in-space supply chain with 100% closure, suggesting it could be achieved in only two to four decades with low annual cost.  A study in 2016 again claimed it is possible to complete in just a few decades because of ongoing advances in robotics, and it argued it will provide benefits back to the Earth including economic growth, environmental protection, and provision of clean energy while also providing humanity protection against existential threats. 
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, splitting it 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). Platinum and gold are raw materials traded on terrestrial markets, and it is impossible to predict what prices either will command at the point in the future when resources from asteroids become available. For example, platinum traditionally is very valuable due to its use in both industrial and jewelry applications, but should future technologies make the internal combustion engine obsolete, the demand for platinum's use as the catalyst in catalytic converters may well decline and decrease the metal's long term demand. The ongoing 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 split 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 ongoing ( OSIRIS-REx) mission.  This investment would have to be amortized through the sale of commodities, delaying any return to investors. There are also some indications that Planetary Resources expects government to fund infrastructure development, as was exemplified by its recent request for $700,000 from NASA to fund the first of the telescopes described above.
Another similar venture, called Deep Space Industries, was started by David Gump, who had founded other space companies.  The company hoped 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 mostly 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. 
Being the largest body in the asteroid belt, Ceres could become the main base and transport hub for future asteroid mining infrastructure,  allowing mineral resources to be transported to Mars, the Moon, and Earth. Because of its small escape velocity combined with large amounts of water ice, it also could serve as a source of water, fuel, and oxygen for ships going through and beyond the asteroid belt.  Transportation from Mars or the Moon to Ceres would be even more energy-efficient than transportation from Earth to the Moon. 
Companies and organisations
Organisations which are working on asteroid mining include the following:
|Deep Space Industries||Private company|
|Planetary Resources||Private company|
|Moon Express||Private company|
|Asteroid Mining Corporation Ltd. UK ||Private company|
According to the Asterank database, the following asteroids are considered the best targets for mining if maximum cost-effectiveness is to be achieved: 
|Asteroid||Est. Value (US$)||Est. Profit (US$)||Δv (km/s)||Composition|
|Ryugu||95 billion||35 billion||4.663||Nickel, iron, cobalt, water, nitrogen, hydrogen, ammonia|
|1989 ML||14 billion||4 billion||4.888||Nickel, iron, cobalt|
|Nereus||5 billion||1 billion||4.986||Nickel, iron, cobalt|
|Didymos||84 billion||22 billion||5.162||Nickel, iron, cobalt|
|2011 UW158||8 billion||2 billion||5.187||Platinum, nickel, iron, cobalt|
|Anteros||5570 billion||1250 billion||5.439||Magnesium silicate, aluminum, iron silicate|
|2001 CC21||147 billion||30 billion||5.636||Magnesium silicate, aluminum, iron silicate|
|1992 TC||84 billion||17 billion||5.647||Nickel, iron, cobalt|
|2001 SG10||4 billion||0.6 billion||5.880||Nickel, iron, cobalt|
|2002 DO3||0.3 billion||0.06 billion||5.894||Nickel, iron, cobalt|
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 if space tourism itself proves profitable, which has not been proven. 
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 × 10 19 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. 1.7
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 make it economically viable. 
Although Planetary Resources indicated in 2012 that the platinum from a 30-meter-long (98 ft) asteroid could be 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. 
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 would essentially 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. It should be noted that Malthus posited this 219 years ago, and no sign has yet emerged of the Malthus effect regarding raw materials.
- 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. However, it should be noted that the "substitution effect", i.e. the use of other materials for the functions now performed by platinum, would increase in strength as the cost of platinum increased. New supplies would also come to market in the form of jewelry and recycled electronic equipment from itinerant "we buy platinum" businesses like the "we buy gold" businesses that exist now.
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 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 US$100 billion.
There are six categories of cost considered for an asteroid mining venture:
- Research and development costs
- Exploration and prospecting costs
- Construction and infrastructure development costs
- Operational and engineering costs
- Environmental costs
- 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. On August 16, 2016 the value had decreased to $1157 per ounce or $37,000 per kilogram. At the $1,340. price, 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. This analysis assumes that doubling the supply of platinum to the market (5.13 million ounces in 2014) would have no effect on the price of platinum. A more realistic assumption is that increasing the supply by this amount would reduce the price 30–50%.
Regulation and safety
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 that space law authorities consider 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.
Asteroid mining in particular is regulated, among others, by the Outer Space Treaty and the Moon Agreement.
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. 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.
Astrophysicists Carl Sagan and Steven J. Ostro raised the concern altering the trajectories of asteroids near Earth might pose a collision hazard threat. They concluded that 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.   
The Outer Space Treaty
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 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).
Hobe (2006) explains that the Outer Space Treaty “explicitly and implicitly prohibits only the acquisition of territorial property rights” – public or private, but extracting space resources is allowable.
The Moon Agreement
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 Moon Agreement allows space mining, specifically the extraction of natural resources. The treaty 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.
The objection to the treaty by the spacefaring nations is held to be the requirement that extracted resources (and the technology used to that end) must be shared with other nations. The similar regime in the United Nations Convention on the Law of the Sea is believed to impede the development of such industries on the seabed. 
Legal regimes of some countries
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.  The law recognizes the right of U.S. citizens to own space resources they obtain and encourages the commercial exploration and utilization of resources from asteroids. According to the article § 51303 of the law: 
A United States citizen engaged in commercial recovery of an asteroid resource or a space resource under this chapter shall be entitled to any asteroid resource or space resource obtained, including to possess, own, transport, use, and sell the asteroid resource or space resource obtained in accordance with applicable law, including the international obligations of the United States
In February 2016, the Government of Luxembourg announced that it would attempt to "jump-start an industrial sector to mine asteroid resources in space" by, among other things, creating a "legal framework" and regulatory incentives for companies involved in the industry.   By June 2016, announced that it would "invest more than US$200 million in research, technology demonstration, and in the direct purchase of equity in companies relocating to Luxembourg." 
Ongoing and planned
- OSIRIS-REx – planned NASA asteroid sample return mission (launched in September 2016)
- Hayabusa 2 – ongoing JAXA asteroid sample return mission (arriving at the target in 2018)
- Asteroid Redirect Mission – potential future space mission proposed by NASA (if funded, the mission would be launched in December 2020)
- Fobos-Grunt 2 – planned Roskosmos sample return mission to Phobos (launch in 2024)
First successful missions by country:
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.   
- 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
- This is the average amount; asteroids with much lower delta-v exist.