> Even though their destinations were closer and more habitable I actually (genuinely) wonder about that those two. Distance isn't the right metric - it's dif

> Even though their destinations were closer and more habitable I actually (genuinely) wonder about that those two. Distance isn't the right metric - it's difficulty of making the journey. Ocean travel is taken for granted these days. In the past it was a lot more difficult and dangerous. How did those difficulties then compare to interplanetary travel today? (I'm genuinely asking). And similar applies to how habitable the destination was. I remember reading about the initial English colonies in America, and all difficulties they had with things like trying to grow crops. How do those difficulties compare to the difficulties we'd face for Mars? (again, I don't know the answer, but I'm curious as to what it might be).