In the most recent episode of Mad Men, a few characters asked why money was being spent on the Space Program when "there are people starving here on Earth." Was this a common sentiment or was it rare?
I don't know how widespread the criticism would have been, but it did exist with some visibility in the American left. One of the more popular and influential protest singers of the 1960s and '70s, Phil Ochs, referenced the space program in two of his songs.
From the song "Spaceman" [song] [lyrics]
Way high, so high:
Travelin' fast and free.
Spaceman, look down:
Tell me what you see.
Can you see the hunger there
Strike without a sound?
Can you see the food you burn
As you circle round?
From the song "Tape from California" [song] [lyrics]
Half the world is crazy and the other half is scared
Maddonas do the minuet for the naked millionaires
The anarchists are rising while we're racing for the moon
It doesn't take a seer to see that the scene is coming soon
Ochs was best known for his songs against the Vietnam War, including "I Ain't Marching Anymore," "Draft Dodger Rag," and "The War is Over." He had professional and personal relationships with other famous singers such as Bob Dylan, Pete Seeger, John Lennon, and Victor Jara (the latter's torture and murder in Chile would contribute to Phil's spiraling depression that eventually ended his life).