Historical Entry—Saturday, August 25, 2012
The Voyager program is the United States space science program dedicated to the study of the outer planets. The program started originally as a concept known as the Grand Tour program. Initially conceived by Gary Flandro at the Jet Propulsion Laboratory in 1964, Grand Tour would have sent several pairs of probes to explore Jupiter, Saturn, Saturn’s moon Titan, Uranus, Neptune, and Pluto. The planning was based on the planetary alignment which occurs every 175 years, allowing the craft to reach all the planets using only gravitational assists.
Unfortunately in December 1971, the program was cancelled and its funds redirected to the Space Transportation System (Space Shuttle) program. NASA pivoted and suggested a smaller mission, using only two probes and only visiting four planets, Jupiter, Saturn, Uranus, and Neptune. The probes were based on the already existing Mariner series. These would have been numbers Mariner 11 and 12. Several design changes were added based on new technology and a significantly changed mission.
The program was christened Voyager in March 1977. Voyager 2 was set on the contingent JSX flight trajectory. This trajectory would allow for a Jupiter and Saturn flyby, but then deviate to perform flybys of Uranus and Neptune. Voyager 1, launched on 5 September 1977, was launched after Voyager 2. Its mission profile provided a faster route to Jupiter, and it passed Voyager 2’s progress on 19 December 1977.
Voyager 1’s mission was to fly by Jupiter, perform a gravitational assist to aim at Saturn, and fly by Saturn with an extended encounter with the moon Titan. This was the original planned end of the Voyager 1 mission. The mission was extended through the mid-1990s for further research into the trans-Jupiter portion of the solar system.
When Voyager 1 arrived at Jupiter, it began sending back massive amounts of new information. The discoveries credited to the Voyager 1 mission include the discovery of a thin ring around Jupiter, significantly more active storm systems on the planet than expected, two new moons (Thebe and Metis), the G-ring of Saturn, shepherd moons for the rings, and five new moons. It also photographed the moons Titan, Mimas, Enceladus, Tethys, Dione, and Rhea.
A decision was made to extend the mission into interstellar space. On Valentine’s Day 1990, scientists turned Voyager 1 and took a series of 60 images. These were the last photos taken by the probe before the cameras were shut off and the software deleted to conserve energy. This photo is known as the “Family Portrait” and shows Venus, Earth, Jupiter, Saturn, Uranus, and Neptune. Mercury was too close to the sun to be visible, Mars was obscured by the flare of the sun, and Pluto was out of position to be captured. Family Portrait also contains “The Pale Blue Dot” photo.
On February 17, 1998, Voyager 1 exceeded 69.4 AU from the Sun, overtaking the distance of Pioneer 10, becoming the most distant man-made object. The next big step was reaching the termination shock and entering the heliosheath. Voyager 1 reached this landmark on 16 December 2004.
Finally, on August 25, 2012, scientists concluded, based on instrumentation readings, that Voyager 1 had exited the heliosphere and entered interstellar space. This was the first time any man-made object was far enough away that the Sun was no longer shielding the area from cosmic radiation. It was followed by a sudden decrease and continuing decline in solar wind particle detection. Just over 43 years after mankind had stepped on a world other than Earth, mankind went interstellar.
Voyage 1 travels outside the solar system
Historical Event
2012
This Day in Science Fiction History examines notable events, real and fictional, concerning fantasy and science fiction in various media.
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