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Planetary bodies such as the Moon, Mars, asteroids and comets contain substantial deposits of valuable resources. This has captured the attention of both researchers and industry who hope that they will be mined to support a space economy.
Establishing any kind of off-Earth mining industry will be a difficult task. Here are some of the challenges that we are facing.
Considering off-Earth mining, the first thing that may come to mind is extracting materials from bodies in space and bringing them back to Earth. However, this is unlikely to be the first commercially viable system. If we want to establish a permanent base on the Moon as proposed by NASA, we would need to resupply astronauts living there. Consumable resources such as water can only be recycled to an extent. Resources are extremely expensive to launch from Earth. Today it cost roughly two thousand five hundred dollars to launch one pound into Earth orbit. It costs more to boost a payload out of Earth orbit to the Moon or beyond. It is likely that materials that have been mined in space will be used in space to help save on launch costs.
Harvesting materials that will be utilized on-site is called “in-situ resource utilization”. It can involve anything from collecting materials to construct buildings on the Moon to mining ice for water.
Mining in space could also be transformative for satellite management. The current practice is to de-orbit satellites after ten to twenty years when they run out of fuel. One major goal of space companies such as Orbit Fab is to design a type of satellite that can be refueled using propellant collected in space. Even for low-Earth orbiting satellites, the energy required to reach them from the Moon is less than that needed to reach them from Earth.
With respect to off-Earth mining opportunities, there are a few resources that are both abundant and valuable. Some asteroids are known to contain vast amounts of iron, nickel, gold and platinum group metals. These can be used for construction and electronics manufacture.
Lunar regolith (rock and soil) contains large amounts of helium-3. This may become a valuable resource in the future if nuclear fusion can be achieved on Earth. British company Metalysis has developed a process that could be used to extract oxygen from lunar regolith.
Ice is expected to exist on the surface of the Moon in permanently shadowed craters near the lunar poles. It is also believed that there is ice beneath the surface of Mars, asteroids and comets. This could be used to support life or it could be broken down into oxygen and hydrogen to use for rocket propellant.
Some proposals for off-Earth mining are similar to mining techniques on Earth. For example, lunar explorers could mine lunar regolith with a bucket-wheel excavator. Asteroids could be mined with a tunnel boring machine. Other proposals are less well known. A vacuum-like machine could pull regolith up a tube. This system has been used on some excavations on Earth.
Researchers from the University of New South Wales Sydney and the Australian National University propose the use of biomining. This system introduces bacteria into an asteroid that would then consume minerals and produce a gas. The gas could then be harvested and collected by a probe.
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