trade route from earth to asteroid belt need some infrastructure

fleet of rockets transporting material between earth and asteroid belt 

in the asteroid belt there would be stations on asteroids that create fuel for rockets 

along the trade route there would be communications satellites enabling rockets to more easily communicate 

along the trade route there would be space based solar farms beaming energy to rockets 

along the trade route there would be a few autonomous rockets waiting to help rockets that have technical problems and too little fuel 

and there would be life boat rockets for evacuated passengers 

along the trade route there would be mobile space station hotels