The race to space was no joke for the former Soviet Union, and support from the populace–while not exactly necessary— was important. The propaganda posters from the late-fifties and early-sixties are nothing short of spectacular. From Russia Travel Blog, some examples:
“For the Peace.”
Alternately: “In Soviet Russia, space conquers you!”
“Gagarin, Titov, Nikolaev, Popovich – the mighty knights of our days”
For more of these (complete with traslations), check out this post.