The Rising Influence of Rising Affluence

[OakesCS]

avg platinum concentrations in siderophillic asteroids are only about 1E2 to 1E4 higher than Earth's crust so space mining of PGEs is an extremely dicey proposition. Much easier to identify geologic bodies on earth that result from the differentiation processes that form ores (metal >> avg concentrations). No guarantee that any particular asteroid will have undergone differentiation beyond gross iron separation and i doubt separating 0.5 to 50 ppm Pt from something that is 90+ wt% Fe & Ni would be more economic than old-fashioned mother Earth.

As for water as a fuel: these folks have a much more practical approach and may actually become investable within few years.
http://www.accion-systems.com/