Recent discoveries of near-Earth asteroids (NEAs) and chemical analyses of fragments of asteroids (meteorites) suggest that there may be a gold mine, literally, in near-Earth space. Judged from meteorite analyses, two types of asteroids offer particularly bright prospects for recovery of large quantities of precious metals (defined as Au, Pt, Ir, Os, Pd, Rh, and Ru), the oridinary LL chondrites, which contain 1.2--5.3% Fe--Ni metal containing 50--220 ppm of precious metals, and metallic asteroids, which consist almost wholly of Fe--Ni phases and contain variable amounts of precious metals up to several hundred ppm. The pulverized regolith of LL chondrite asteroids could be electromagnetically raked to separate the metallic grains. Suitable metallic asteroids could be processed in their entirety. Statistically, there should be approximately six metallic NEAs larger than 1 km in diameter that contain over 100 ppm of precious metals. Successful recovery of 400,000 tons of more of precious metals contained in the smallest and least rich of these metallic NEAs could yield products worth $5.1 trillon (US) at recent market prices. If marketed over 20 years, this would represent a 10-fold increase over the recent global production rate of all precious metals combined. The market response to the hypothetical introduction of such large quantities of precious metals is difficult to predict, because these metals historically have not obeyed normal economic laws of the market.

An empirical model suggests that the effects on market prices of a hypothetical increase in production of a given metal can be predicted given existing knowledge of the metals's present market value and production rate. This model suggests that the total value of 400,000 metric tons of precious metals, if over 20 years, would decline to about $320 billion ($16 billion per year). Except for Au, for which production and prices would be marginally affected, the market prices of precious metals may decline by 1 to 2 ordes of magnitude if one of the six asteroids were to be mined to depletion over 20 years. Less conservatively, there is a 50% chance that the richest metallic NEA contains at least 1.9 million metric tons of precious metals; this quantity, if marketed over 40 years, may be worth approximately $900 billion at collapsed market prices ($22.5 billion per year). The actual economic and technological impact of asteroidal metals may be considerably greater due to the increased availability and reduced prices of these resources. Despite this great potential, first-order technological, scientific, and economic uncertainties remain before the feasibility of exploitation of asteroids for precious metals can be ascertained. ¿ American Geophysical Union 1994