Asteroid mining could become reality sooner than we think. Billionaire-backed Planetary Resources is launching technology demonstration missions this summer to showcase the asteroid-prospecting spacecraft they have developed. They say that within three years they will be launching their first customer-financed mission to explore targets for resource extraction.
The company has attracted some high profile investors, most notably Google executives Larry Page and Eric Schmidt. However, a recent set of studies from the Harvard-Smithsonian Center for Astrophysics highlighted just how little we know about the composition of space rocks. See
http://www.mining.com/is-space-mining-commercially-viable-22553/