Hello, the Flat Earth model does not work (Southern star trails, required size of Southern 'hemisphere', etc). However Flat Earth theory does point out problems with the official cosmology (you can see too far over water, way too far). This is why the Flat Earth operation has had some success. People make the logic fail of seeing problems with one model as proof for the other. Both models do not work and the trick is framing it as a choice between the two of them.

GPS - http://www.bbc.com/news/science-environment-29758872 In WW2 they had a system that had these capabilities, before satellites were claimed to be launched(http://support.radioshack.com/support_tutorials/gps/gps_tmline.htm). In this article they suggest it as a backup should GPS system go down. So satellites appear to not be required in order to provide GPS service, it could all be ground based. Have you ever seen an image of a satellite in space? All the ones I see look like CGI.

every astronaut and scientist that has been into space

Did you know that this number is somewhere in the neighborhood of 300? NASA is part of the US military which makes extensive use of compartmentalization, many people just staring at screens. Contrast this with the Manhattan project which managed secrecy for years with hundreds of thousands of people involved.