A new company backed by two Google Inc. billionaires, film director James Cameron and other space exploration proponents is aiming high in the hunt for natural resources—with mining asteroids the possible target.

The venture, called Planetary Resources Inc., revealed little in a press release this week except to say that it would "overlay two critical sectors—space exploration and natural resources—to add trillions of dollars to the global GDP" and "help ensure humanity's prosperity." The company is formally unveiling its...