The Mercury 1st Stage is a small first stage rocket part. This was used to deliver the Mercury capsule into space and is very useful in some missions of the game, such as mission 2. It shares a resemblance to the first stage of the Mercury-Redstone rocket, (original: Mercury-Redstone Launch Vehicle) which was used on 2 manned flights in 1961.
Like a select few parts: the Fairing Aero and the Solar Panel Small, this part is unlocked from the beginning of the game. It is very useful when you are still starting as this this is a stock part.
Mercury Launches