NASA Canceled the Grand Tour. Voyager Flew It Anyway

In 1965, a student at the Jet Propulsion Laboratory found that Jupiter, Saturn, Uranus and Neptune would line up in a way that comes around about once every 175 years. NASA planned a Grand Tour of all four planets, then canceled it in 1971. What flew instead was a cheaper mission, approved to visit only Jupiter and Saturn, and one of its two spacecraft, Voyager 2, went on to visit all four. Part 1 of 5 of Voyager: The Road to One Light-Day, a series leading up to November 18, 2026, when Voyager 1 will be a full light-day from Earth. Chapters 0:00 The once-in-175-years line-up 1:02 The problem of distance 1:50 Borrowing a planet's speed 2:57 The line-up 4:25 A spacecraft built to last 5:36 Christmas, 1971 6:21 Something less grandiose 7:42 Testing the trick 8:31 A name for the journey 9:07 What the line-up gave us Sources Andrew J. Butrica, "Voyager: The Grand Tour of Big Science" (NASA SP-4219, 1998): https://www.nasa.gov/history/SP-4219/... Douglas Smith, "The Other Side", Caltech Engineering & Science, Winter 2013: https://calteches.library.caltech.edu... NASA Science, Voyager: https://science.nasa.gov/mission/voya... Planet and spacecraft positions in the diagrams: JPL Horizons, https://ssd.jpl.nasa.gov/horizons/ Image credits (from the NASA Image and Video Library unless noted) Neptune's crescent, Voyager 2, 1989 (NASA/JPL): https://images.nasa.gov/details/PIA01539 Neptune, Voyager 2, 1989 (NASA/JPL): https://images.nasa.gov/details/PIA01492 Voyager 1 launch, September 5, 1977 (NASA/JPL-Caltech/KSC): https://images.nasa.gov/details/PIA21747 Saturn, Voyager 2, 1981 (NASA/JPL): https://images.nasa.gov/details/PIA01364 The planets, a montage of mission images (NASA/JPL): https://images.nasa.gov/details/PIA00545 A model of the Mariner 4 spacecraft, 1964 (NASA Glenn): https://images.nasa.gov/details/GRC-1... Mariner 4's first picture of Mars, 1965 (NASA/JPL-Caltech/Dan Goods): https://images.nasa.gov/details/PIA14032 Jupiter, Voyager 1, 1979 (NASA/JPL/USGS): https://images.nasa.gov/details/PIA00343 Jupiter's Great Red Spot, Voyager 1, 1979 (NASA/JPL): https://images.nasa.gov/details/PIA01384 Uranus, Voyager 2, 1986 (NASA/JPL-Caltech): https://images.nasa.gov/details/PIA18182 Thomas Jefferson, painted by Rembrandt Peale in 1800 (public domain; White House Historical Association): https://commons.wikimedia.org/wiki/Fi... Gary Flandro at the Voyager 40th anniversary, 2017 (NASA/Aubrey Gemignani): https://images.nasa.gov/details/NHQ20... Jupiter with Io and Europa, Voyager 1, 1979 (NASA/JPL): https://images.nasa.gov/details/PIA00144 Crescent Uranus, Voyager 2, 1986 (NASA/JPL/USGS): https://images.nasa.gov/details/PIA00346 Apollo 17, the last Moon landing, December 1972 (NASA): https://images.nasa.gov/details/as17-... James Fletcher (right) at the Apollo 15 launch, July 1971 (NASA): https://images.nasa.gov/details/0302335 Crescent Earth over the Moon, Apollo 17, 1972 (NASA): https://images.nasa.gov/details/as17-... The Voyager proof test model in the space simulator, 1976 (NASA/JPL-Caltech): https://images.nasa.gov/details/PIA21734 The first Mariner Jupiter-Saturn science meeting, December 1972 (NASA/JPL-Caltech): https://images.nasa.gov/details/PIA21122 Voyager in system test, 1976 (NASA/JPL-Caltech): https://images.nasa.gov/details/PIA21729 William Pickering, James Van Allen and Wernher von Braun with Explorer 1, 1958 (NASA): https://images.nasa.gov/details/5663627 Pioneer 10 being readied at Cape Kennedy, 1972 (NASA Ames): https://images.nasa.gov/details/ARC-1... Pioneer 10 approaching Jupiter, 1973 (NASA Ames): https://images.nasa.gov/details/ARC-1... Venus, Mariner 10, 1974 (NASA/JPL-Caltech): https://images.nasa.gov/details/PIA23791 Voyager 1's Titan-Centaur rocket, January 1977 (NASA/JPL-Caltech/KSC): https://images.nasa.gov/details/PIA21739 Voyager 2 launch, August 20, 1977 (NASA/JPL-Caltech): https://images.nasa.gov/details/PIA21744 Voyager 1 launch, September 5, 1977 (NASA/JPL-Caltech/KSC): https://images.nasa.gov/details/PIA21746 Voyager 1 launch, September 5, 1977 (NASA/KSC): https://images.nasa.gov/details/PIA17464 Script, diagrams, editing and music are original. This channel is not affiliated with or endorsed by NASA.