“Voyager 1” was launched on September 5, 1977 at 12: 56 pm.
Three months and five days after the launch, “Voyager 1” entered the asteroid belt, the region of the Solar System located roughly between the orbits of the planets Mars and Jupiter. After nine days, “Voyager 1” overtakes the “Voyager 2” spacecraft, a 722-kilogram (1,592 lbs) space probe launched by NASA on August 20 to study the outer Solar System and eventually interstellar space. More than a year after, on September 8, 1978, “Voyager 1” exited the asteroid belt.
On the sixth of January 1979, the observation phase on Jupiter started. On March 5, the encounter with the Jovian system commenced. Jupiter, the fifth planet from the Sun and the largest planet within the Solar System, has 66 confirmed moons, giving it the largest retinue of moons with “reasonably secure” orbits of any planet in the Solar System. Amalthea, the third moon of Jupiter in order of distance from the planet flew by at 420,200 km (6:54 am). At 12:05:25 pm, “Voyager 1” had its closest approach with Jupiter at 348,890 km from the center of mass. On 3:14 pm, Io, the innermost of the four Galilean moons of Jupiter and, with a diameter of 3,642 km (2,263 mi), the fourth largest moon in the Solar System flew by at 20,570 km. Europa (“Jupiter II”), the sixth closest moon of Jupiter and the smallest of its four Galilean satellites, but still one of the largest bodies in the Solar System, also flew by at 733,760 km.
The next day, at 2:15 am, Ganymede (“Jupiter III”), a satellite of Jupiter and the largest moon in the Solar System flew by at 114,710 km. Callisto (“Jupiter IV”), another Jovian moon, flew by at 126,400 km (5:08 pm). Then there was a phase stop more than a month later, April 13.
On August 22, 1980, the Saturn observation started. The first encounter with the Saturnian system was on November 12 that year. The moons of Saturn, the sixth planet from the Sun and the second largest planet in the Solar System, after Jupiter, are numerous and diverse, ranging from tiny moonlets less than 1 km across, to the enormous Titan, which is larger than the planet Mercury. On that day, Titan (Saturn VI), the largest moon of Saturn, flew by at 6,490 km, 5:41:21 am. Tethys or “Saturn III,” a mid-sized moon of Saturn, about 1,060 km (660 mi) across, flew by at 415,670 km, 10:16:32 pm. More than an hour later, at 11:46:30 pm, “Voyager 1” had its closest approach to Saturn at 184,300 km from the center of mass.
The next day, at 1:43:12 am, Mimas, a moon of Saturn which was discovered in 1789 by William Herschel, flew by at 88,440 km. Seven minutes after, Enceladus, the sixth largest of the moons of Saturn, flew by at 202,040 km. At 6:21:53 am, Rhea, the second largest moon of Saturn and the ninth largest moon in the Solar System, flew by at 73,980 km. At 880,440 km, Hyperion, also known as “Saturn VII,” another moon of Saturn, discovered by William Cranch Bond, George Phillips Bond and William Lassell in 1848, flew by “Voyager 1,” 4:44:41 pm. The next day is another phase stop.
The Voyager Interstellar Mission began on December 14 that year.