Goals: Pioneer 11 was the first mission to explore Saturn and the second spacecraft in humanity's early reconnaissance of the outer solar system. The spacecraft carried instruments to study magnetic fields, the solar wind and the atmospheres, moons and other aspects of Jupiter and Saturn.
Accomplishments: Among Pioneer 11's many discoveries are Saturn's F ring and a new moon. It recorded the planet's overall temperature at -180°C, indicating that it emits 2.5 times as much heat as it receives from the Sun. Photographs revealed a more featureless atmosphere than that of Jupiter, and calculations based on data from Pioneer 11 suggested that Saturn is primarily liquid hydrogen with a core of about 10 Earth masses.
The dormant spacecraft is now headed out of our solar system in the general direction of Sagittarius, toward the center of the galaxy. Both Pioneers 10 and 11 carry a plaque with a message for any intelligent beings that might find them.