Somewhere between "We choose to go to the moon" and "if you see something, say something" we traded all of our hope and optimism for fear and suspicion.
I'm just hoping for hope again.
The red scare continued through the late 1950s (and the cold war continued for decades -- there was no lack of fear and suspicion).
John Glen orbited the earth in 1962, in the middle of all this.
The nation doesn't wake up, flip and coin and decide it's either optimistic or fearful one day. You can be scared of some things and optimistic about others. Or both at the same time. Or some people are optimistic, and others have more fears.
It's complicated, but pithy quotes ("I'm just hoping for hope again") are stupid.
And almost entirely because of it; the U.S. space program didn't evolve independently of, or in tension with, the fear of Communism.
We chose to go to the moon because we were afraid (afraid of Communism, afraid of the Russians, afraid of the Cold War).
That doesn't mean great things can only come about as the result of fear and suspicion, but it's not like the Space Race was a great example of hope and optimism in contrast with fear and suspicion.
I wish we still lived in a science fiction world.