On September 1, 1979, NASA’s robotic space probe Pioneer 11 became the first spacecraft to fly by Saturn. Launched in 1973, Pioneer 11 was part of a mission to explore the asteroid belt, Jupiter, and Saturn. After launching directly toward Jupiter, it used the planet’s gravity to slingshot around it, altering its course toward Saturn. Four years and nine months later, it reached Saturn, coming within about 13,000 miles (2,100 kilometers) of the planet’s cloud tops. During its flyby, Pioneer 11 passed through Saturn’s rings to test if the Voyager probes, then en route to Saturn, could do the same safely. The mission discovered several new moons, a previously unknown ring, and the first evidence of a magnetic field around Saturn. Pioneer 11 was the twin of Pioneer 10, which had launched earlier in 1972 to explore Jupiter. NASA needed to confirm that spacecraft could survive the asteroid belt and Jupiter’s intense radiation before sending the Voyager probes on a grand tour of the outer planets. This tour was possible due to a rare planetary alignment that occurs once every 175 years. Pioneer 10 successfully passed through the asteroid belt and flew by Jupiter in 1974, paving the way for Pioneer 11’s more ambitious mission. Launched in April 1973, Pioneer 11 followed a similar path to Jupiter, using its gravity to redirect its journey toward Saturn. After passing Jupiter in December 1974, Pioneer 11 continued its journey to Saturn, capturing detailed images of the planet’s atmosphere and its famous Great Red Spot. The spacecraft was equipped with 12 scientific instruments and took 440 images of Saturn during its encounter. It discovered two new moons and a previously unseen ring, while also revealing that Saturn’s atmosphere is primarily composed of liquid hydrogen and that the planet has a magnetic field. Pioneer 11 also captured images of Titan, Saturn’s largest moon, which appeared as an orange sphere with an average temperature of minus 315 degrees Fahrenheit (minus 192 degrees Celsius). Pioneer 11 flew by Saturn at an incredible speed of 71,000 mph, but continued to study the planet even after its closest approach, sending back data until October 1979. Originally expected to last only 21 months, the probe operated for over 22 years, eventually passing beyond the outer planets in 1990 on its way to interstellar space. NASA lost contact with Pioneer 11 on November 24, 1995, by which time it was 4 billion miles from Earth and still traveling outward. The probe carried a plaque designed by scientists Carl Sagan and others, intended to communicate information about humanity to any potential alien civilizations—an early version of the golden records carried by the Voyager probes. Today, models of Pioneer 11 and Pioneer 10 are on display at the Smithsonian National Air and Space Museum in Washington, D.C.