I don't know anything about anybody aside from Von Daniken, who wrote "Chariot of the Gods" and a couple of other such books, and has been completely discredited. The others are unknown to me, but the basic premise "Ancient Aliens researchers contend that Aliens landed on the earth thousands of years ago.......Let us suppose it is true" and then they go about building a whole show based on this being true. The point is, it has not been proven to be true, confirmed fact. It is not. A lot of what they show in trying to make people believe that there were Aliens on the planet are quite explainable, and have been explained. Things like why the column sections in the Acropolis fit together so tightly (sand was placed between the sections, and the sections were rotated against one another , so the sand acted like an abrasive), how the giant blocks that the Pyramids were made of were put into place (inclined plane with tree trunks as rollers), how they got the stones to Stonehenge (boats, tree trunk rollers, block and tackle, and stone tipping). A lot of evidence is shown of painting/carvings of supposed ancient astronauts, yet they neglect to acknowledge that the drawings are not realistic, but stylized, as many of the other elements in the same drawings are.