This looks like a Mercury capsule to me, or maybe a Gemini spacecraft. Either way, it's something of a time capsule... the park found some money back then and this was their idea of something fun and useful.
The good news is that they were right then. Although I'm a bit taller now, I can still climb through and slide down that slide. I wonder how many thousands of children enjoy this without knowing what it was modelled after?
I always wanted to be an astronaut...