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Mining extra-terrestrial bodies for their natural resources will be driven by two main factors. Firstly, as metal resources on Earth dwindle and high-grade deposits become rarer metal-rich bodies such as asteroids will appear more attractive.
Secondly, as humans advance outwards from Earth, or their machinery advances to explore and expand the forefront of civilization in our stead, it would require less energy and capital investment to exploit and extract off-world resources and construct vessels for deep-space applications, including further mining operations, in space.
Use of Remote and Autonomous Systems in Space
Prospecting and exploration, including initial sampling, will most likely be carried out by drones. Remote and Autonomous systems for exploration are being developed by ispace, Kleos Space, and Offworld. Detection of potential targets can also be carried out satellites. Planetary Resources’ Arkyd-6 orbiter uses infrared sensors to detect water and hydrated minerals on asteroids.
Such technology represents only the first, tentative step towards actually exploiting extra-terrestrial bodies and ideally any exploration activity would be confined to space without the need to bring the material back to Earth for analysis.
Asteroid Mining Program
Students from the University of Washington’s Department of Aeronautics and Astronautics’ Senior Space Design Class, led by their instructor, Dr. Dana Andrews constructed a hypothetical commercial asteroid mining program in 2013 with their architecture plans subsequently published in 2015. Their aim was to put mining equipment on near-Earth asteroids for the lowest Life Cycle Cost possible. Utilized in their planning procedure were costs based on results from NASA-funded studies, including space vehicle concept and near-Earth asteroid mining studies, in addition to commercial costing tools.
Both prospecting and exploitation steps would, at least initially, require Earth to orbit (ETO) launch systems. Both re-usable and low-cost expendable systems could be used with reusable systems currently typified by the Falcon Heavy system, developed by Space-X. Multiple Space Operations Centers (SOC) were included in the program architecture and represent hubs for storage and transfer of materials, such as propellant and harvested ores. Transfer of any material coming up from or heading back to Earth would have to be done by an Orbital Maneuvering Vehicle that would be based at the SOC and would move propellant from and, potentially, harvested ores to ETO vessels.
Reusable Nuclear-Powered Tug
Additionally, a Reusable Nuclear-Powered Tug would be used to bring multiple payload capsules from asteroids to the SOC between missions. Powered by a fission reactor and bearing payload mounting ports this would rendezvous between the mining modules and the SOC.
Once deployed to asteroids several approaches could be taken to recover materials with many technologies used on Earth applicable to recovery of economically viable materials from extra-terrestrial bodies.
Using a lander with a scoop to harvest non-magnetic regolith or a magnetic rake for iron-nickel-platinum group metal alloys would effectively recover loose material at the asteroid’s surface. M-type asteroids, i.e. those with high metal content, could also be mined using carbonyl reactions whereby the metals are turned into Fe- or Ni-carbonyl gases and collected into inflatable containers. Bucket chain excavators, similar to those used to strip-mine coal on Earth could also play a part in hard-rock mining on asteroids or moons.
One technology currently under development by TransAstra Corp. for the harvesting of water and volatiles is optical mining. A vessel would capture and despin an asteroid. The sun’s rays would then be focused into the icy body using reflectors, with a telescopic penetrator driving its way through the icy body to fracture it into smaller pieces for recovery.
Autonomous Systems for Space Mining
Autonomous systems requiring limited human oversight would be instrumental for advancing space mining. Ideally, a point of self-sustainability would be reached whereby any products harvested in space could be used to further develop the industry without the need for further materials to be delivered from Earth. The Solar System is abundant with the chemical components needed for such machinery however with dwindling resources on Earth we may require more metals and ores to be sent back before we are ready to push forward into space.
Sources and Further Reading