The Voyager mission began in the 1960s, as a "grand tour" of the planets. Once every 175 years, Jupiter, Saturn, Uranus, and Neptune aligned so that a single spacecraft could visit all of them. Each planet's gravitational field could be used to "sling" the spacecraft toward the next planet.
Construction of the Voyagers
When the time came to build the spacecraft, it was decided to build two of them for insurance: Voyager 1 and Voyager 2. Both of these were Mariner-class spacecraft, which meant that they could travel through space without spinning or tumbling. Not only does it allow the spacecraft to take pictures more accurately, but it also looks better.
Putting jokes aside, one of the major obstacles of building the spacecraft was the weight. Scientist determined that the weight had to be under 1,800 pounds. While that may seem like a lot, the Voyager would require communications equipment, power supplies, altitude-control engines, data storage, and a computer control system. This only left 1/6th of the weight left for scientific instruments, and without scientific instruments the mission would be meaningless.
With weight as the controlling factor, scientist prioritized and selected. By far the most important instrument was a camera [no pictures, no fun]. In fact, the voyagers each carried 2 television cameras. One was for a wide shots, and the other was for narrow and detailed shots.
Another challenge when building the Voyager was providing power for the spacecraft to keep its instruments and equipment running. Since the Voyager was going to travel billions of miles away from the sun, solar energy was about as practical as burning wood [no oxygen]. To solve this problem, NASA chose to use radioisotope thermal generators, which converts the heat released from plutonium (a radioactive element), into electricity.
The Planetary Voyage
By 1977, two identical Voyager spacecraft were ready to be launched. Although they were identical Voyager 2 was going to travel slower and it was launched first. Voyager 1 followed two weeks later. When the two Voyagers passed Jupiter, scientists were eager to find out more about the Great Red Spot. Located in the middle of Jupiter's southern hemisphere, the Great Red Spot could be seen on Earth by anyone with a small telescope. When we did not understand until then was what caused the GRS. From the pictures that the Voyagers took, the Great Red Spot was revealed to be a swirling, oval-shaped storm that was kept alive by 2 parallel bands of winds that flowed in different directions just north and south of the spot.
Voyager's cameras investigated more that the Great Red Spot though. Another major duty was to study Jupiter's moons. The moon Io (eye-oh) in particular, astounded scientist. Io was full of active volcanoes. In fact, as least 9 of them were erupting right before Voyager's cameras!
As there were any surprises at Jupiter Voyager also discovered many new things at Saturn. What was originally thought to be 6 rings that Saturn had, turned out to be thousands of very thing rings called ringlets. The Voyagers also found 7 new moons at Saturn. Most of the smaller ones are very irregular in shape, which suggests that they are probably fragments of smashed larger moons.
When the Voyagers arrived at Uranus on January 24, 1986, it was the first time that an Earth spacecraft visited the mysterious 7th planet. An interesting feature of Uranus is that its axis points left and right instead of up and down like the other planets do. The Voyagers discovered 10 rings total around Uranus as well as 10 new moons.
The end of Voyager's planetary journey was nearing when it arrived at Neptune, the furthest planet in the solar system (Pluto was closer to the sun at that time and we don't really consider Pluto to be a planet anyway). Since Neptune was the furthest planet from the Sun and received the least amount of heat, scientists expected Neptune to have the least active atmosphere [Boy were they in for a surprise]. It turned out that Neptune's clouds were moving at very high speeds. Neptune contained atmospheric spots similar to Jupiter. The largest spot, named the Great Dark Spot by scientists was similar to the Great Red Spot on Jupiter. In the region around the Great Dark Spot, wind speeds reached at much as 1,400 miles per hour! [Compare that to 200mph tornadoes on Earth] Like the previous planets, Voyager also discovered new moons and rings around Neptune.
Voyager Interstellar Mission
Having finished their planetary mission, the Voyagers have a new mission to begin. Both Voyagers are heading for the stars at a rate of 37,000 miles per hour. Unless they collide with a comet or are captured by he gravity of a star, the Voyagers will continue on their journey through space for millions or even billions of years.
Attached to the outside of each of the Voyagers is a copper phonograph record. The records are encased in aluminum jackets and will last billions of years. The record contains photographs as well as sounds including: picture of the Earth, sound of animals, airplanes, rockets lifting-off and greetings in 60 languages. A message from President Jimmy Carter was also included:
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"This I a present from a small distant world, a token of our sounds, our science, our images, our thoughts, and our feelings. We are attempting to survive our time so we may live in yours. We hope someday, having solved the problems we face, to join a community of galactic civilizations. This record represents our hope and our determination, and our goodwill in a vast and awesome universe."
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