I have checked out the Wikipedia links you posted, and they seem accurate enough. I'm always a little waring about Wikipedia though. But, I fail to see how any of this proves that aliens have not visited earth? It proves, yes, that mankind is not capable of travel the distance needed to visit another inhabited planet, but it doesn't really prove anything about extraterrestrials.
I have read many accounts about aliens, and have done quite a bit of research on the phenomenon myself. What amazes me is that, what the aliens tell us is, most of the time, 100% consistent with what advanced beings from the afterlife tell us. Yes, I do know that there is legitimate proof concerning aliens being here on earth.
Moreover, why do you assume that any extraterrestrials visiting the earth are bound by the fairly-primitive space travel issues that we are?