Parameterizing the Energy Cost of Establishing Mining Outposts on Asteroids

Extraction of resources will be a critical step in powering up a Space Economy. Space mining is, however, a still-emerging field that is exceedingly difficult to achieve with our existing space infrastructure. Therefore, it has become important to pick mining targets carefully. Currently, the spotlight has shone on the Moon and Mars, close to Earth in proximity and gravity. Asteroids provide a fundamentally different but equally lucrative mining environment-their higher concentrations of resources of interest mean less mining equipment needs to be hauled and maintained to achieve the same output and their lower gravity equalizes ΔV costs despite their increased distance from Earth. The objective of this study is to provide a method to quantitatively compare the difficulty of establishing mining operations on various asteroid targets and to draw comparisons with the Moon and Mars using the same controls. Difficulty is measured by the sum of the electrical and kinetic energy costs accrued by space mining infrastructure over their operational lifecycle-energy costs will be presented as equations parameterized in terms of variables representing the mining conditions and the equipment properties. The mining operations in question are envisioned as a surface outpost exporting refined materials while supplied by mobile robotic miners. The output of various outposts (measured in mass) is held constant, so energy costs correlate better with difficulty. Each possible outpost picks mining equipment out of a standardized set relevant to its site characteristics: distance from Earth, hydration, metal concentration, surface cohesion, and size. Outpost energy consumption is divided into three broad categories: transportation, excavation, and refining. Among small bodies, near-Earth asteroids outperformed main belt asteroids for ease of transportation and the corresponding lower fuel requirements. Size had a marked, though complex effect on export costs, as landers would be necessary to ferry products from the surface to an orbital depot. Mining energy costs favor low cohesion or differentiated bodies, as scooping materials requires less force than drilling them. This benefits both rubble pile asteroids and large bodies like the Moon. Refining costs vary strongly with hydration but minimally with metal concentration. Metals separation is complicated by low gravity and cohesion, suggesting the use of an orbital centrifuge which, in turn, increases transportation energy costs. Overall, hydrated NEAs rise to the top of energy accessibility among the asteroids. These asteroids, however, are rare. When these asteroids are not an option, hydrated main belt asteroids and anhydrous NEAs are promising options too. The Moon and Mars are generally matched in import and export costs due to their large gravity, but this same gravity allows their outposts to neglect low TRL anchoring equipment. Selectively placed outposts on these bodies could refine both water and metals, albeit at lower concentrations than prime asteroid targets. The Moon and Mars have notable characteristics not covered by this study, such as Mars’ atmospheric drag or the possibility of crewed lunar outposts due to the Moon’s proximity. Going forward, hard data from each selected technology will be required to generate the desired outcome-holistically condensing the difficulty of developing asteroid targets into a single number. Studies examining difficulties. that cannot be encapsulated by an energy number can be used to corroborate these results and help determine the best “first step” mining target for humanity.