The Voyager Spacecraft: The Grand Tour
The Twin Voyager spacecraft were sent to investigate the outer planets. Using a once in 173 year alignment, Voyager 2 was able to become the first, and only, spacecraft to visit all four of the outer planets.
You can build your own Voyager spacecraft out of LEGO here.
Voyager 1
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| Artist's concept of Voyager 1. Credit: NASA |
While Voyager 1 was launched after its sibling, it took a faster trajectory. On December 15, 1977, Voyger 1 surpassed Voyager 2 in the asteroid belt. Voyager 1 started to send images of Jupiter in april of 1978, at a distance of around 265 million kilometres.
Images showed that Jupiter was far more active than it was during the Pioneer flybys in the early 70s. On January 30, 1979, Voyager 1 continously imaged the planet every 96 seconds for 100 hours to create a timelapse of 10 Jupiter rotations (Jupiter's day is around 10 hours long).
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| Voyager 1's approach of Jupiter. Credit: NASA/JPL |
On February 10, Voyager 1 entered the realm of the Galilean moons. Voyager 1 discovered a faint ring system around the giant planet. Voyager 1 also observed eruptions on Io, Jupiter's innermost major moon. Voyager 1's closest approach with Jupiter was on March 5, 1979.
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| Montage of Voyager 1's Jovian system images (not to scale). Credit: NASA/JPL |
The earlier Pioneer images of Jupiter's moons were not of high quality, and little information could be gleaned from them. Voyager 1 showed that each of the Galilean moons was unique. Perhaps most suprising to mission scientists was the volcanic activity of Io. The moon appeared an unusual sulphur-brown, and yellow. This was literally sulphur, and this originated from the various volcanos that dot the surface. At least 8 active volcanos were seen during Voyager 1's flyby.
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| Eruption on Io captured by Voyager 1. Credit: NASA/JPL |
After the Jupiter flyby, Voyager 1 made a course correction on April 9, 1979, to flyby its next target: Saturn. What scientists were most interested in seeing besides the ringed giant itself, was its methan enshrouded moon Titan. Not much was known about Titan due to its hydrocarbon smog hiding the geology that lies beneath. Scientist were so interested in Titan, that if Voyager 1 failed to get good data on Titan, Voyager 2 would change its trajectory to fly by Titan, and lose the opportunity to visit Uranus and Neptune.
Fortunately, Voyager 1 performed its Saturn flyby admirably. On October 10, 1979, Voyager 1 made a correction maneuver so it would fly close to Titan, but not burn up in the atmosphere.
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| Voyager 1 image of Saturn's rings. Credit: NASA/JPL |
Voyager 1 discovered three new moons in the Saturn system, as well as new ring features. Along with additional rings, Voyager 1 discovered transient ring "spokes." Voyager imaged the major moons, including Mimas, Enceladus, Tethys, Dione, Iapetus, and Rhea. Perhaps however, most interesting was Titan.
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| Voyager 1 Image of Titan. Credit: NASA/JPL |
Voyager 1 flew past Titan on November 12, 1979, at a distance of around 4000 Kilometres. While the surface was still hidden from view, Voyager detected that the atmosphere was 90% Nitrogen. Voyager data was also used to correctly summize that Titan could have liquid on its surface. Due to the gravitational interactions with such a close flyb of Titan and Saturn, Voyager 1 was shot up at 35 degrees from the plane of the solar system.
On February 14, 1990, Voyager 1 looked back at the solar system, and imaged the planets as faint dots in the sky. Earlier on January 1, 1990, both Voyager spacecraft officially began their interstellar missions.
On December 16, 2004, Voyager 1 reached the termination shock, were the magnetic field was at a high intensity, as it deflected intersteller particles. The spacecraft spent the next 8 years in the heliosheath region, seperating the termination shock from intersteller space. On August 25, 2012, Voyager 1 officially entered interstellar space. Vorager 1 will operate until its antenna breaks, or its power runs out, which is expected to happen in this decade.
Due to budget constraints, NASA canceled an earlier concept that would send a dedicated spacecraft to each outer planet. However, the Voyagers mission team proposed that Voyager 2 could still visit Uranus and Neptune if Voyager 1 did a good enough job at Jupiter, Saturn, and Titan.
As mentioned previously, Voyager 2 launched before Voyager 1, but was overtaken in the asteroid belt. On April 24, 1979, Voyager 2 transmitted its first images of Jupter. Voyager 2 approached Jupiter's moons much closer than Voyager 1 did. Voyager 2 spent 10 hours watching the volcanos on Io alone!
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| Voyager 2 image of Callisto. Credit: NASA/JPL |
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| Mosaic of Europa from Voyager 2. Credit: NASA/JPL |
Voyager 2 also detected lots of atmospheric activity in Jupiter's atmosphere, which went unnoticed in the earlier Pioneer flybys. Voyager 2 was at closest approach with Jupiter on July 9, 1979. Two hours later, Voyager 2 made a course correction to set it on a trajectory towards Saturn.
Two years after reaching Jupiter, Voyager 2 approached Saturn on August 22, 1981. After closest approach, which occured on August 26, Voyager 2 passed through the plane of the rings at 13 kilometres per a second. The spacecraft was pummeled by tiny ring particles, and was constantly firing its thrusters to keep itself stable.
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| Montage of Voyager 2's images of some of Saturn's minor moons. Credit: NASA/JPL |
Four-and-a-half years after Voyager 2 flew by Saturn, it approached Uranus, the only spacecraft to do so to this day. Careful trajectory planning accured throughout Voyager 2's mission in order to get it this far. Closest approach with the aquamarine planet took place on January 24, 1986.
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| Image of Uranus from Voyager 2. Credit: NASA/JPL-Caltech |
Voyager 2 discovered 10 new moons, and imaged the 6 largest in a decently high resolution. Uranus looked surprisingly plane in the images, with hardly any clouds. In recent years, we've seen Uranus warm up, and images from the Keck telescope have shown that it is now more active as it progresses through its seasons.
Perhaps the most unusual of Uranus's moons was Miranda. Miranda was the moon that Voyager 2 was able to approach the closest, at a distance of only 28,260 kilometres. Miranda possessed a sort of "Frankenstein" terrain. This unusual mishmash of terrain features has several theories to explain its formation, some of which your can read about in this article.
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| Voyager 2 mosaic of Miranda. Credit: NASA/JPL-Caltech |
After the flyby, on February 14, 1986, Voyager made a course correction to set it on its way to its final destination: Neptune. Voyager 2 discovered five new moons around Neptune, and was at closest approach with the planet on August 25, 1989. This was Voyager 2's closest planetary flyby, and it got to within 4800 kilometres above Neptune's cloud tops.
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| Montage of Neptune and Triton from Voyager 2 images. Credit: NASA/JPL/USGS |
Neptune was found to be surprisingly active during the flyby. In fact, Neptune was measured to have the fastest winds in the solar system. Voyager 2 was also able to image a decent portion of Neptune's largest moon: Triton. Triton is believed to be a captured dwarf planet, because it orbits in a retrograde (backwards) fashion.
- You can see Voyager 2's view of its Triton flyby in this video: PIA18669-320.mp4
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| The Golden Record. Credit: NASA |
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| Voyager 2's Journey. Credit: NASA/JPL-Caltech |
The Targets
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| Cassini image of Jupiter, with Europa's shadow. Credit: NASA/JPL/University of Arizona |
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| Image of Saturn taken from Cassini on January 2, 2010. Credit: NASA/JPL-Caltech/Space Science Institute |
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| Image of Uranus from Voyager 2. Credit: NASA/JPL-Caltech |
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| Voyager 2 image of Neptune. Credit: NASA/JPL |
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