On this date twenty years ago, September 1, 1979, the robotic probe Pioneer 11 made the first flyby of the planet Saturn, thanks to an impressive gravity boost from its encounter with Jupiter in late 1974.
Though its images would not match in quality with the ones taken by Voyager 1 and 2 in the next two years, Pioneer 11 was a true pathfinder for those more sophisticated explorers and all other space vessels to follow.
To quote from the main Pioneer Web site:
"Pioneer 11 flew within 13,000 miles of Saturn and took the first close-up pictures of the planet. Instruments located two previously undiscovered small moons and an additional ring, charted Saturn's magnetosphere and magnetic field, and found its planet-size moon, Titan, to be too cold for life. Hurtling underneath the ring plane, Pioneer 11 sent back amazing pictures of Saturn's rings. The rings, which normally seem bright when observed from Earth, appeared dark in the Pioneer pictures, and the dark gaps in the rings seen from Earth appeared as bright rings."
To add to this, in order to show just how exciting and dangerous the Pioneer 11 Saturn mission was, the probe came within a celestial hairsbreadth of one of those previously unknown moons.
Mission planners also considered sending Pioneer 11 through the Cassini Division in Saturn's rings, as they thought it was an actual empty area in the ring field. Thankfully they decided not to do this to Pioneer 11, as the Cassini Division is full of material like the rest of the rings, only darker.
The last communication from Pioneer 11 was received in November 1995, shortly before Earth's motion carried it out of view of the spacecraft antenna.
The spacecraft is headed toward the constellation of Aquila (The Eagle), Northwest of the constellation of Sagittarius. Pioneer 11 may pass near one of the stars in the constellation in about 4 million years.
Like Pioneer 10, it carries the famous Pioneer Plaque with basic information on the human race that built these first interstellar explorers from Earth.
For more information on Pioneer 11 see the following URLs: