Polaris

A Polaris missile. This is a Navy solid-fueled submarine-launched ballistic missile.

It's interesting that the Polaris is displayed near the Jupiter missile. The Jupiter was originally going to be a joint project between the Army and the Navy. The Jupiter is short and squat (as compared to the Redstone) so that it could be handled more easily within the confines of a ship. However, the Navy was never keen on liquid-fueled missiles and eventually backed out the Jupiter program and developed the Polaris. (I thought I remembered reading about some Navy brass witnessing an explosion shortly after launch and the resulting fireball a the fuel fell from the air, but I can't seem to find any trace of this story. Drop me an email if you have any recollection of this story.)