Water and Hydrogen Resources on the Moon, Mercury, and Mars
Water ice and other volatiles are vital in sustaining human settlement in space. Hydrogen and oxygen extracted from water by hydrogen-oxide reactions can be used as propellants on short-range interplanetary missions in the inner Solar System prior to developing more advanced propulsion systems for long-range interplanetary missions to follow. Water ice and other volatiles occur in polar areas on Mercury and the Moon, the two major airless bodies in the inner Solar System. As a consequence of their low obliquity, polar areas on Mercury and the Moon contain a large number of permanently shadowed, topographically low areas in crater floors. These permanently shadowed areas are cold traps for volatiles that accumulated over the past one to two billion years (1 to 2 Ga) from impacts from volatile-rich comets and asteroids. Evidence for water ice at the Moon's poles is based on (1) polarized radar signatures, first detected by the Clementine probe in 1994 and later measured in refined detail by the Mini-SAR synthetic aperture radar on the Chandrayaan-1 probe in 2009, (2) neutron scattering signatures that indicate hydrogen, detected by the Lunar Prospector Mission in 1999 and confirmed by subsequent missions, (3) spectral reflectance data, imaged by the Moon Mineralogy Mapper, and (4) detection of hydroxyl ions from ultraviolet emission spectra in a dust- and ice-plume generated from impact of the upper stage of the LRO Centaur rocket. Approximately 600 million metric tons of ice exists in the region of the Moon's North Pole. This amount of ice could yield sufficient hydrogen and oxygen for daily launches of a space shuttle for 2,200 years. Martian water-ice resources far exceed those on the Moon and Mercury. Water ice occurs in abundance on Mars in polar ice caps, shallow permafrost, and in layered terrain adjacent to the poles. Martian permafrost, which holds more water ice than the poles, occurs as tropical mountain glaciers and in polygonal terrain with morphologies similar to those of terrestrial periglacial features. Subsurface ice on Mars has an areal distribution exceeding 20 million square kilometers, whereas the polar caps, although 2.7 and 3.1 km thick at the North and South Poles, respectively, each encompass an area >1 million square kilometers.
AAPG Datapages/Search and Discovery Article #90189 © 2014 AAPG Annual Convention and Exhibition, Houston, Texas, USA, April 6–9, 2014