6 April 1973

Launch of Pioneer 11 spacecraft.

Pioneer 11 was a NASA spacecraft launched on April 6, 1973, with the primary mission of studying the gas giant planets Jupiter and Saturn. It was the second spacecraft to visit Jupiter, after Pioneer 10, and the first to flyby Saturn.

The spacecraft was designed and built by NASA’s Ames Research Center, and it weighed about 260 kilograms (570 pounds). It was powered by four radioisotope thermoelectric generators (RTGs), which provided electrical power for its scientific instruments and communication systems.

During its journey, Pioneer 11 made important scientific discoveries, including confirming the existence of a radiation belt around Jupiter, identifying new moons around both Jupiter and Saturn, and discovering the complex structure of Saturn’s rings.

The spacecraft continued to transmit data back to Earth until its last contact on September 30, 1995, when it was about 6.5 billion miles from Earth. Pioneer 11 is currently drifting through space and is expected to continue to do so indefinitely, as it is not on an intercept course with any known objects.

Pioneer 11 was a groundbreaking mission, paving the way for future exploration of the outer solar system. Its legacy lives on as an important milestone in the history of space exploration.