With crude oil now approaching $70 a barrel, and the environmental destruction of Earth-bound mining operations becoming more apparent by the day, asteroids are looking better and better.

Ground-based analyses indicate that asteroids and comets contain substantial amounts of valuable minerals, including semiconductor and platinum group metals as well as water and bituminous hydrocarbons (substances found petroleum sands). The water alone could serve as a fuel source for the vehicles' return trip.

Although most asteroids are beyond Mars, about 10% of them are easier to reach than Earth's moon in terms of time and energy required. According to Professor John Lewis, the resources of the Solar System - the most accessible being in near-Earth asteroids - could comfortably support as many as one quadrillion humans - about 150 times the current population. Since the growth of the human population shows no sign of slowing anytime soon, it is imperative that world governments start planning for this expansion by investing in technology that will allow our species to start moving off-planet.