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Journal of the Southern African Institute of Mining and Metallurgy

On-line version ISSN 2411-9717
Print version ISSN 2225-6253

J. S. Afr. Inst. Min. Metall. vol.114 n.12 Johannesburg Dec. 2014




Mining off-Earth minerals: a long-term play?



G. A. CraigI; S. SaydamI; A.G. DempsterII

ISchool of Mining Engineering, The University of New South Wales, Australia
IIThe Australian Centre for Space Engineering Research, The University of New South Wales, Australia




The Moon, asteroids, and planets of the solar system represent the most distant caches of wealth that humanity has ever considered recovering. Yet, in addition to the potentially recoverable values represented there, harvesting off-Earth resources has a second, almost incalculable sustainable benefit in that they can be retrieved with absolutely no damage to Earth.
Previous research mostly assessed the potential of asteroids and the Moon for mining purposes from a theoretical and scientific point of view. These studies investigated drawbacks that could be experienced in this type of operation, but no detailed economic evaluation that is meaningful for mining project management has been conducted and the parameters that are most likely to make an operation feasible are unknown. This paper provides a preliminary economic and sensitivity analysis of a possible off-Earth mining business extracting minerals from an existing asteroid.

Keywords: off-Earth mining, space mining, in situ resource utilization, future mining.




As history has repeatedly shown, where there are valuable minerals to be mined, adventurous humans will arrive in droves -even if it means battling extreme conditions and excessive risks. The motivation for off-Earth mining is clear: an abundance of valuable resources that can feed our technologically-driven society, the necessity of discovering new places that our society can colonise, and the development of new technologies and processes to enable these missions, which will generate spin-off technologies that can be used in fully-automated terrestrial mining endeavours.

By widening the scope of mining engineering to incorporate off-Earth opportunities, the mining industry can be sustained from an economic standpoint. In a similar way, the increased costs of mining and diminishing natural resources available close to the surface of the Earth may soon support the idea that off-Earth resources are more profitable.

Limited research has been conducted in this area. O'Leary (1988) initiated one of the first off-Earth mining studies and identified that the surfaces of the Earth's Moon, Mars's two moons, and an asteroid named 1982 DB have the potential for developing missions for space mining. However, he focused on a manned mission, which entails high operational and safety risks. Duke et al. (1997) designed three operational scenarios to extract water ice at the lunar poles, using microwave energy for heating the ice, thermal processing and steam pipe transportation, and using a dragline with thermal processing. Their designs were conceptual and did not consider the economic feasibility of the operations.

Sonter (1997) investigated the design process for feasibility studies of off-Earth mining operations and developed a net present value (NPV) analysis including variables based on orbital mechanics, rocket fuel requirements, mining and processing methods, product mass returned, and duration of the return trip. A new analysis concept was also utilized by Sonter (1997; 2001), the 'mass payback ratio', which illustrates the need to expend mass in the form of propellants, rocket bodies, and mining consumables in order to return product mass to the market. Moreover, Sonter (2001) applied a scenario where resources obtained from asteroids are brought into low Earth orbit (LEO) and sold as construction material for LEO infrastructure. These materials include water to make propellant, nickel and iron for construction, and semiconductors to make solar cells. Sonter's studies (1997; 2001) were the first that considered the economic viability of such missions.

Ross (2001) published a report on the important factors in determining the feasibility of an asteroid mine. This report considers the extraction of several commodities from asteroid orebodies, including water and volatiles, precious metals, rare earth metals, refractory material, and iron and nickel. Ross's study, like Sonter's, used NPV analysis as the primary tool. Ross also outlines the market demand, which is subject to continual iteration due to its size and nature. Notably, geological characteristics were not mentioned and the actual analysis stage was not undertaken. This limits the credibility of the study, in that it suggests principles without testing. However, Blair et al. (2002) from the National Aeronautics and Space Administration (NASA) Jet Propulsion Laboratory (JPL) investigated the feasibility of off-Earth mining for water extraction. A simple NPV analysis was found to be insufficient to make an investment decision, due to the high capital and research investment required for a start-up operation, creating unpredictable risks and uncertainties in the business model.

Erickson (2006) studied asteroid mining with a particular focus on optimal return on investment (ROI) from near-Earth asteroids (NEAs), and stressed the cost efficiency and risks of a possible operation. He further recommended that the mining equipment to be used at such an operation should be flexible, adaptable, and re-usable to handle a variety of NEA conditions. He particularly pointed out that robotics with artificial intelligence is essential to stage such a mission.

Zacharias et al. (2011) compared feasibility studies of potential mining projects on asteroids, the Moon, and Mars based on each of their dynamic locations. They conducted an NPV analysis of possible 10-year mining operations for an arbitrary mineral and found that the Moon returned the most favourable NPV compared to Mars and two selected asteroids. Based on their assumptions, both the Moon and Mars provided positive NPVs, but the asteroids had negative NPVs. However, a possible asteroid-mining operation would be expected have a much longer lifespan than a typical Earth-based operation, so the economic analysis could be quite different considering all the variables and risks associated with the operation.

Pelech (2013) studied an economic evaluation of mining comets and the Moon for an off-Earth water market. He developed four water-mining scenarios to supply a H2/LOx propellant market in LEO and established a ratio, named 'propellant payback ratio', inspired from Sonter's studies (1997; 2001), which indicates the economic return on the forgone opportunity to launch the propellant directly from the Earth. He used the opportunity cost concept considering infrastructure and equipment launched from Earth. In this study, for every kilogram of mining equipment and infrastructure launched into LEO, the opportunity to launch a kilogram of propellant has been forgone.

Gertsch and Gertsch (2003) applied terrestrial surface mine design and planning techniques to the production of lunar regolith for extracting gases for life-support for 100 people at a lunar base. They discussed various hypothetical scenarios with basic assumptions for mining regolith from five large cold trap craters near south lunar pole. Muff et al. (2004) conducted a study at NASA that includes a prototype design of a bucket wheel excavator to be used on the surface of the Moon and Mars to extract surface regolith. Both studies focused on using similar excavation techniques and equipment to those that are used in terrestrial mining operations.

Schmitt et al. (2008) summarized the vision for space exploration, determining that the first stage would incorporate the development of mining initiatives on the Moon to extract life-sustaining elements such as H, He, C, N, and O. These elements are all available in various concentrations in the lunar regolith or surface rock. They proposed that a base would be needed on the Moon to provide an extensive refuelling and life-support system.

Yoshikawa et al. (2007) and Raymond et al. (2012) studied asteroid characteristics providing valuable information. Subsequent spacecraft missions reduced the geological uncertainty surrounding this analysis.

Karr et al. (2012) from NASA studied the potential of using ionic liquids (ILs) to dissolve metal-bearing regolith in order to exploit the water and metal present within it. Acidic IL was used to dissolve small samples of a nickel/iron meteorite (named Campo del Cielo) and the metals were recovered by electrowinning. When the voltage was slowly raised from an initially low level, it was possible to recover the different metals separately at the anode. The water was removed using a micro-distillation apparatus. This represents the first extraction of oxygen, in the form of water, from an extraterrestrial source, as well as a possible method of processing metals in space. The authors also mentioned that this dissolution technique i