I feel that we, as a species, may well colonise other planets as our population expands and we wear out the resources on this planet, unless we find a superior, cleaner energy source. If we don't, we'll just become a scavenger species, moving from planet to planet and destroying it as we use up its resources. It's a sad thing to imagine, but unless we become more environmentally aware and willing to co-operate? It's a bleak future.