Two identical spacecrafts know as Voyager 1 & 2 were designed to study Jupiter and Saturn. Voyager 2 was launched first on August 20, 1977 and its sister craft Voyager 1 went into space on September 5, 1977. Even though Voyager 1 left almost a month after its counterpart, it arrived at Jupiter on March 5, 1979 almost four months sooner than Voyager 2 which arrived on July 9, 1979. The spacecrafts continued to function long past their planned 5 year mission. Voyager 1 continued to orbit Saturn and further study the planet itself as well as its moons, while Voyager 2 went on to study Uranus, Neptune, their moons, and finally was sent on a path into interstellar space where it continues to transmit data. In their joint mission, Voyager 1 & 2 explored all the giant outer planets of the solar system, 48 of the planets' moons, and each of the planets' systems of rings and magnetic fields. Before its long journey in interstellar space, Voyager 2 captured a picture looking across our entire solar system. The information that scientists collected from the Voyager crafts would answer many key questions in astronomy while raising many more new questions which have yet to be answered.
Voyager was designed to withstand harsh conditions which include high levels of radiation that might be present in deep space. For this reason many of the 65,000 different components were radiation hardened and those that were more sensitive were shielded to withstand the radiation.
Because the spacecrafts were going to travel far from the Sun this mission was very different than the other exploratory missions. Scientists could not use solar panels to power and direct the spacecraft and instead devised a series of 16 thrusters that allowed very delicate maneuvers in the probes' trajectory. Voyager would rely mostly on the gravitational force of the planets it would visit in order to propel it toward its next destination.To power the scientific equipment on board Voyager uses radioisotope thermoelectric generators, which convert the heat given off by the natural radioactive decay of plutonium dioxide into electricity much like a mini nuclear generator.
The Voyager spacecrafts have the ability to perform ten different scientific experiments. To conduct these tests the crafts include television cameras, infrared and ultraviolet sensors, plasma detectors, magnetometers, and cosmic-ray and charged-particle sensors. In order to gather information about planetary atmospheres and ring systems, scientists used radios mounted on the probe. The spacecraft sends its data back to Earth and receives its controlling commands from the Earth using a global spacecraft-tracking system known as the Deep Space Network.
Voyager 1 & 2 provided so much new information about the outer planets that it is hard to do them justice in such a short article.
Jupiter's great red spot was discovered to be made up of a complex of swirling storms. Voyager found that below the atmosphere lies turbulent smaller storms and eddies throughout the banded clouds of the planet. A diffuse cloud of dusty material that formed a ring around the planet had been previously undetected. After studying the planet itself the Voyager probes went on to study the previously uncharted moons of Jupiter. Here they found the first active volcanoes in the solar system not on a planet. There were actually nine different active volcanoes on Jupiter's moon Io.
Saturn was found to have very similar features when compared to Jupiter but on a smaller scale. The rings that surround Saturn were made up of both very thin, concentrated rings and broad, diffuse rings. They also found unexpected structures in the rings like kinks and radial spokes. The most interesting finds were some features located on the different moons of Saturn. A crater on the moon Mimas is so large in magnitude that the impact that would have caused it, almost caused the moon to break apart. The larger Saturnian moon Enceladus had huge and unexpected faults and valleys.
The Uranus flyby revealed a strong magnetic field and a high layer of haze over the planet's sunlit pole. The greatest surprise when Voyager 2 visited Uranus was ten moons that had never been seen before from Earth. The inner most of the planet's largest moons, Miranda, seemed to indications of great geological activity. They included fault canyons as deep as 20 km (12 miles), terraced layers, and a mixture of old and new surfaces. The nine rings that surround Uranus were found to be composed of much larger particles and distinctly younger than those rings found surrounding Jupiter and Saturn.
Neptune was found to be very dynamic and contain several large dark spots of its own. Strong winds up to 2000 km/h (1240 mph), faster than on any other planet, circulate below the atmosphere of the planet. Triton, the largest of Neptune's moons, had guyserlike eruptions spewing nitrogen gas and dust particles far into its atmosphere.