Saturn A-1, studied in 1959, was projected to be the first version of Saturn I

Saturn I

The Saturn I was the United States' first heavy-lift dedicated space launcher, a rocket designed specifically to launch large payloads into low Earth orbit. Most of the rocket's power came from a clustered lower stage consisting of tanks taken from older rocket designs and strapped together to make...

 and was to be used if necessary before the S-IV

S-IV

The S-IV was the second stage of the Saturn I, a rocket-powered launch vehicle used by NASA for early flights in the Apollo program.The S-IV was manufactured by the Douglas Aircraft Company and later modified by them to the S-IVB, a similar but distinct stage used on the Saturn IB and Saturn V...

 liquid hydrogen

Hydrogen

Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...

 second stage became available. The first stage, proposed for the Juno V

Juno V

The Juno V series of rockets were a design that was proposed in the late 1950s but cancelled. The rockets were multi-stage and, although they failed to reach production, their sections were used in other designs.- Juno V-A :...

 rocket, but finally used for the first Saturn rocket, would propel the Saturn A-1 into space, with the first stage of a Titan I

Titan I

The Martin Marietta SM-68A/HGM-25A Titan I was the United States' first multistage ICBM . Incorporating the latest design technology when designed and manufactured, the Titan I provided an additional nuclear deterrent to complement the U.S. Air Force's SM-65 Atlas missile...

 missile continuing the flight and finally, a Centaur

Centaur (rocket stage)

Centaur is a rocket stage designed for use as the upper stage of space launch vehicles. Centaur boosts its satellite payload to geosynchronous orbit or, in the case of an interplanetary space probe, to or near to escape velocity...

C high-energy double engine third stage could perform a small burn to send a payload into its final orbit, or it can perform a big burn to take a payload out of Earth orbit to other planets. Unfortunately, this rocket never flew, but all stages of the Saturn A-1 were used on different launch vehicles. Today, they are all retired.