I am and have always been of the mind that WE are the aliens, discended from our ancestors who traveled here for some reason be it exploring or running from aggressors. there is a very good quote in a book where the analogy is made about technology advancement. It can only happen if there are enough people to support it. so if your space ship is damaged in some way and here is where you are you must survive based on what your group of people can provide in the way of food, shelter, manufacturing, and if you cannot keep up the current standard then you must fall back to something that you can sustain. and if you fall back far enough then you return to the hunter gatheror stage and advance forward from that point.....