At least two companies, Planetary Resources and more recently, Deep Space Industries, have announced plans to take advantage of these massive rock clumps, which are in seemingly endless supply and believed to be the source of great mineral wealth.

The asteroid making a record-close approach to Earth this week could be worth up to $195 billion in fuel and metal, according to Deep Space Industries.

Unfortunately, asteroid 2012 DA14 is not a good target because its orbit is tilted relative to Earth, requiring too much energy to chase down.