S-IV
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![](http://upload.wikimedia.org/wikipedia/commons/thumb/0/08/S-IV_rocket_stage.jpg/220px-S-IV_rocket_stage.jpg)
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. It was first used on the Saturn-Apollo 5 mission, which was launched January 29, 1964. It's last use was for the Saturn-Apollo 10 mission, launched July 30, 1965.
The S-IV is similar to, but distinct from, the S-IVB stage used on the Saturn IB rocket.