Just to clarify for anyone unfamiliar with the US space program in the 50s-70s, or those just briefly confused by the discussion about planet sizes using planet names for things that aren't planets...

Mercury was a small space capsule containing 1 person designed to last a few hours in space. The Saturn V rocket was until recently the most powerful rocket ever launched, and took 3 crew, a crew module, a lander module, and payloads, to the moon.