Instead of planning to build a city on Mars, one SpaceX competitor is building cargo trucks to ferry supplies into orbit above Earth in a new space-based economy employing thousands of people.
The United Launch Alliance is building reusable rockets to ferry cargo into space where the supplies can be traded to companies mining valuable resources from the moon and passing asteroids.
The ULA reusable rocket is different from the one used by SpaceX, however. While SpaceX reuses the first stage of the rocket, ULA plans to reuse the second, the piece that normally carries the cargo to its final destination.
The company pictures a fleet of these space trucks permanently parked in orbit above the Earth.