Pioneer 10 was the first spacecraft to fly past Jupiter, reaching the planet in December 1973.
NASA launched Pioneer 10 on March 3, 1972, and it crossed the asteroid belt before making its closest approach to Jupiter on December 4, 1973. The probe returned the first close-up images of the planet and studied its intense radiation environment and magnetic field.
Its passage demonstrated that a spacecraft could safely travel through the asteroid belt and survive Jupiter’s hazardous radiation. Pioneer 10 also carried a plaque depicting a human couple and a diagram intended to identify the spacecraft’s origin.
Pioneer 11 followed Jupiter in 1974 and then became the first spacecraft to fly past Saturn. Voyager 1 later made a much closer Jupiter encounter in 1979, so it was not the first Jupiter flyby.