Pioneer 11 (originally designated Pioneer G) is a NASA space probe launched in 1973 that completed the first mission to the planet Saturn. It was the first spacecraft to encounter Saturn, the second to fly through the asteroid belt, and the second to fly past Jupiter. It later became the fourth human-made object to pass beyond the orbits of the planets and the second of five artificial objects to reach the escape velocity needed to leave the Solar System. NASA Ames Research Center in California managed the mission, and TRW Inc. built the spacecraft. The spacecraft was built around a hexagonal satellite bus and used four radioisotope thermoelectric generators (RTGs) to supply electrical power, producing a combined 155 watts at launch.

Wikipedia: https://en.wikipedia.org/wiki/Pioneer_11. Related NASA reference: https://science.nasa.gov/mission/pioneer-11/. Description adapted from Wikipedia contributors (CC BY-SA 4.0; https://creativecommons.org/licenses/by-sa/4.0/).