Three times more powerful than anything launched by America to that date, with a cluster of eight rocket motors for the first stage, the first Saturn I flew on October 27, 1961, and propelled America into the heavy-lift business. It was the Saturn I, and its successor the Saturn IB, with a more powerful second stage, that did all the preparatory work getting NASA ready to put men on the Moon.
Between 1961 and 1975, the 19 flights of the Saturn I and IB achieved several historic “firsts”, launching the world’s first high-energy liquid oxygen/liquid hydrogen upper stages into orbit in 1964, the first unmanned test of suborbital and orbital Apollo spacecraft in 1966, the first unmanned test of the Lunar Module in 1968, the first manned Apollo spacecraft Apollo 7 also in 1968, all three Skylab flights in 1973 and the last Apollo spacecraft flown in support of the Apollo-Soyuz Test Project in 1975.