In order to colonize other worlds, it’s more economically viable to not go there in the first place. Even if you wanted to send just machines to another planet, it would take decades or even centuries to get there.

Unless you have a massive energy source, it’s going to take our current speeds over 100,000 years to make it to Alpha Centauri. If you harvested all the fossil fuels on earth, you could probably get a space shuttle near 98% light speed. You’d need to harvest the energy of a supernova to get to 100%. At 100% lightspeed, it takes four years to travel to our nearest neighbor. .

In other words, you’re using up all the energy on one planet to travel to another planet so you can harvest all the energy on that one to send an empty shuttle back to earth. The only way it’s going to be economically viable to travel to another star system is if we figure out something where our current understanding of physics is limited. Otherwise, our sole purpose for going to other systems should be for scientific exploration and research. It will be a money sink regardless of what we do.