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Astronaut Buzz Aldrin poses next to the U.S. flag on July 20, 1969 on the moon during the Apollo 11 mission. - 

Looking back, sending a man to the moon seems like an easy sell. But in the 1960s, NASA had to convince the American public that the space program was a good idea.

"In the 1960s, it was just a radical idea," says David Meerman Scott, co-author of "Marketing the Moon: The Selling of the Apollo Lunar Program." "Can you imagine deciding that we’re going to send 12 people to the surface of the moon and it's going to cost 4 percent of the national budget and 2 percent of the national workforce for a decade? So we had to sell it."

And unlike their Soviet counterparts, NASA allowed their success and failures to be public.

"They were selling it not only to the American people, but to the world," says Richardz Jurek, co-author of the book. "It was really the vanguard of real time communication happening with the whole world watching."

To keep Americans interested, NASA hired former journalists to run their publicity campaign. And NASA's publicity department had help from outside marketers, too. As Americans became more interested in the Apollo program's success, they became more interested in buying items associated with the astronauts.

Any company making something for the astronauts – from Stouffer's to Tang to Omega Watches, used the space program in ads to sell their product.

"The brilliance of what NASA did at the beginning is they focused on what we would call today 'brand journalism' in marketing speak," says Jurek.

Coke and Pepsi cans flown aboard STS-51-F in 1985  on display at the National Air and Space Museum.

Follow Kai Ryssdal at @kairyssdal