1977 marked launch of two historic spacecraft, Voyager 1 and Voyager 2. These craft were part of the Voyager program, a mission series to explore the outer planets of the Solar System. 45 years on, the Voyager spacecraft remain active, sending data from the furthest edges of our Solar System and beyond back to Earth.
Voyager 1 was launched on the 5th of September 1977, with a mission objective of flying past both Jupiter and Saturn. Voyager 1 reached Jupiter 18 months later in March of 1979, performing fly-bys of the Jovian moons – Io, Europa, Ganymede and Callisto – as well as the gas giant planet itself. By November 1980, Voyager 1 had encountered Saturn, again taking detailed images and scientific observation of many moons, the dynamic ring system and the swirling cloud tops of the second largest planet in our Solar System.
Despite being launched after its sister spacecraft, Voyager 1’s trajectory placed it on an accelerated path to Jupiter, quickly overtaking Voyager 2. Harnessing the power of Jupiter’s gravity for a boost to Saturn, the probe performed another gravity assist at Saturn to fling itself away from the Sun and towards the edge of the Solar System. After completing its scientific objectives, an extended mission plan to explore the distant Solar System was enacted by NASA to continue using the active probe.
Voyager 2 launched 18 days before it’s companion craft, on the 20th of August 1977. Voyager 2 made a close approach to Jupiter in July of 1979, and then an approach with Saturn in August 1981, taking detailed observations of both planets while doing so. After the launch of the craft, a decision to send Voyager 2 out to Uranus and Neptune was made, due to the chance alignment of the outer planets that occurs once every 175 years.
Voyager 2 made its close approach with Uranus in January 1986, becoming the first and only spacecraft at the time of writing to visit the planet. The planetary system was observed in greater detail than ever before, with many new discoveries being made as a result of the fly-by. Just three years later, Voyager 2 made history again by becoming the first and only spacecraft to visit Neptune and it’s moons, completing the spacecraft’s grand tour of the outer Solar System.
Similarly to Voyager 1, Voyager 2 was shifted to an extended mission profile to explore the edges of the Solar System, a mission that the spacecraft is still working on today.
In the decades since the completion of their primary mission objectives, both Voyager spacecraft have been hurtling towards the edge of the Solar System, still riding on the energy harnessed from gravity assists with giant planets. Voyager 1 crossed heliopause, the barrier between Solar System space and interstellar space in August of 2012, making it the first spacecraft to do so. Voyager 1 is expected to continue functioning until 2025, when its radioisotope generator will be unable to power the craft. Voyager 2 crossed heliopause in November 2018. Voyager 2 remains in contact with ground stations here on Earth, namely NASA’s DSS 43 communication antenna near Canberra. The craft is expected to continue to remain in communication with NASA until the mid to late 2020s.
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