The 1962 Mercury mission that made pilot John Glenn the first American to reach Earth orbit, with three orbits before re-entry.
The mission that performed the first orbital maneuvers by a crewed spacecraft, and which was the first crewed flight of the Gemini spacecraft.
The first human space flight to leave earth orbit, and the first to enter the gravitational field of another celestial body — the Moon.
All Missions (in chronological order)
The first human space flight
First American crewed mission
Second American crewed mission
First American to reach earth orbit
Second American orbital mission
First Gemini mission
The first people to leave earth orbit
First person to walk on the moon
A mission with a problem