What I find the most unlikely about a NASA conspiracy is that the Soviets also have pictures of a round earth. If NASA would have discovered that the earth was flat, they would probably have proven that the Soviet images were fake by taking pictures of a flat earth and then publishing them. NASA would have punched a huge hole in the Soviet space programme and the cold war would have ended 40 years earlier.
NASA and the Soviet space programme likely came to the real conclusion around the same time as each other and decided to just keep perpetuating the Round Earth story for the sake of mutual profit.
"Mum's the word, comrade."
"Da! And ve share vealth!"
Actually if you have ever studied Economics, Money does not have nay intrinsic value. Money only reflects the value we place in what you can do with it. The current economic crisis is a good example of this. The value of the money is only what we place in it. If we, for some reason, loose that value we place in it (because we don't trust it), the value of that currency can fall fast.
So, you have to ask yourself, what is it that these conspirators value? It has been suggested that Money is what they value (that the conspiracy exists for the sake of making money), but as anybody who know even a little about economic knows, Money by itself is not really valuable.
What is important if you are going to ahve a conspiracy to make money on such a large (global) scale is that you need trust. But Trust is exactly what a conspiracy can not have. To trust them you first have to know them and then they have to be trustworthy and someone who constantly lies to you is not trust worthy.
So conspiracies on such global scale are self defeating (ie do not exist).
The other thing is it is absolutely
TRIVIAL to disprove the Earth is Round, if it is indeed Flat.
Remember, the time-scales that this conspiracy has gone on for would mean that the technological know-how that the conspirators used to p[rove the Earth was flat (to themselves) would be available in any high school textbook and probably available at the local hardware stores.
Basic geometry can be used to prove that the Earth is either Flat or Round. If a person could do this in a couple of weekends with only a small budget, then how could such a conspiracy last? Remember the only reason they they could make wealth out of this conspiracy is if they had enough trust. But as
ANYBODY could disprove the conspiracy so easily, then they could not retain that trust.
The only conclusions are that if a conspiracy was so easily broken, then either everybody (but you) is in on this, or that the conspiracy does not exist.
Given four clear nights, some simple tools and a car I (or anybody else) could blow this conspiracy wide open. The question is, why haven't they?
And, here it is:
At the first location, at a preset time, measure the angle of several stars from your position as compared to the horizontal. Repeat this at 3 other locations (4 in total) as far apart as you can get and measure the distances travelled over the ground to get there (work out the straight line distance).
You now have the data needed to map the changes of angle to the stars as a distance on the surface of the Earth.
This base line data (and an understanding of geometry that any high school student should know) can be used to confirm any map's accuracy. So if that any conspiracy exists that is falsifying the maps, then you can
go out and check the accuracy of them. Using this data you can confirm that at the same latitude/distance from the "Equator" (where the sun is over head at the equinoxes) has the same ground distances for a given longitude (angle around the north pole).
On a flat Earth this is impossible. On a round Earth this is expected.
No amount of bendy light, fiddled with GPS receivers, etc can explain this away. The further out from the north pole that you go on a flat earth the further the ground distance you have to travel for a given angle around the north pole. On a round earth, the distance increases the closer you get to the Equator and decreases towards either pole.
This conspiracy is bunk simply because it is so trivial to break it that any high school student could do it in a couple of weekends.
(oh, and to make ground distance measurements easier use one of these:
http://en.wikipedia.org/wiki/Trundle_wheel )