I have an 11 yr old son who wonders the same thing. What I tell him as a scientist is that we have no evidence of alien life on other planets, but that the possibility of life on other planets exists. As a father, I tell him I'm sure there is life on other planets and I hope we find it some day. As for your project, there is no scientific basis for it except to propose that the conditions for life on other planets are possible, particularly since we are finding other solar systems which may have terrestrial planets like Earth, Mars and Venus. The study of the conditions for life on other planets is exobiology, so you should google it and see what you find.
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