Energy Minerals in the Solar System: Resources for the 21st Century
- 2008, American Association of Petroleum Geologists Annual Convention, April 21, 2008.
- William A. Ambrose,
Bureau of Economic Geology, John A. and Katherine G. Jackson School of Geosciences, The University of Texas at Austin, Austin, TX and
- Harrison H. Schmitt,
Engineering Physics, University of Wisconsin-Madison, Albuquerque, NM, USA
The Solar System contains a variety of energy mineral resources that could both sustain future human exploratory or settlement expeditions, as well as meet Earth’s energy challenges in the 21st century and beyond. These resources are inferred to be widely distributed, including metal-rich worlds in the inner Solar System, such as Mercury, Mars, and the Moon.
In contrast, many bodies in the outer Solar System, such as Titan, may be rich in hydrocarbons, ices, and volatiles. Metals and volatiles are also inferred to be abundant in asteroids and comets, respectively. The lunar regolith contains significant volumes of helium-3, a clean energy source for nuclear fusion. The undisturbed concentration of helium-3 in the sampled regolith at the Apollo 11 site is about 20 ppb, and ore grades in polar regions may be several times higher, given the values of measured hydrogen (some of which may be polar ice) from the Clementine and Lunar Prospector missions. Each 100 kg of helium-3 needed to annually fuel a 1000-MWe fusion power plant would require processing about 2 square kilometers of lunar regolith to a depth of 3 m each year.
Volatiles and ice are not only vital in sustaining human colonies, but the hydrogen and oxygen extracted from water produced by hydrogen-oxide reactions, can also be used for propellants. On the basis of radar reflectivity signatures, ice has been inferred to exist in polar regions on Mercury. In addition to significant volumes of ice at the Martian poles, large volumes of ice appear to lie in permafrost on Mars. Titan may be a source for cold-temperature extraction of hydrogen from hydrocarbons as well, where replenishment of methane in Titan’s atmosphere may be occurring via processes related to cryovolcanism.