Rocket Ship Galileo.
I was really young when I read this. I was maybe 13 years old. It was funny reading it again when I am 56.
This was written in 1947 and was filled with the post WWII optimism regarding space travel. It was one of his books written for the young adult science fiction market.
I love how naive it is. It also shows that he completely missed the fall of the educational system in the US.
It also still had Nazi's as the villains!
I have also been working this week on my collection of short stories and read a couple of other collections:
Philip K. Dick