Extraterrestrial mining – A novel method for extracting minerals and metals from asteroids

Extra-terrestrial mining is vital for access to strategic metals for space exploration and to feed an increasing terrestrial need for metals in sustainable energy generation and storage. This study demonstrates for the first time the catalytic dissolution of metals from meteorite proxies of metal-rich asteroids using a deep eutectic solvent (DES). DESs are of particular interest for extra-terrestrial mining as they can be designed to have relatively low vapour pressures and could potentially be made from waste products created in extra-terrestrial settlements. Three types of meteorites were investigated: 2 chondrites (H3, H5) and one iron (IAB-MG) meteorite. Chondrites samples were composed of silicates (olivine, pyroxene) with metallic phases occurring as native metal alloys and sulphides. Metallic Fe-Ni and troilite (FeS) are the most abundant metal-bearing phases in all three samples, particularly in the iron-rich meteorite. The samples were subjected to chemical micro-etching experiments with iodine and iron(III) chloride as oxidising agents in a DES formed from the mixture of choline chloride (ChCl) and ethylene glycol (EG). Micro-etching experiments demonstrated that Fe-Ni phases are effectively leached out in this system, while other mineral phases remain unreactive.