Updated

Updated · spacedaily.com · Aug 8

Voyager 2 Completes 4-Planet Grand Tour, a 176-Year Opportunity Not Returning Until the 2150s

Updated

Updated · spacedaily.com · Aug 8

Voyager 2 Completes 4-Planet Grand Tour, a 176-Year Opportunity Not Returning Until the 2150s

Q: How did a once-in-176-years planetary lineup let Voyager 2 slash a 30-year journey and become the only probe to visit all four giant planets?

Voyager 2 pulled off the four-planet tour because the outer planets were in a rare, once-in-about-176-years arrangement that let one flyby set up the next. They were not lined up in a straight row. Instead, Jupiter, Saturn, Uranus and Neptune were positioned on the same broad side of the Sun so a spacecraft launched in the late 1970s could reach them in sequence and use each planet’s gravity to redirect and accelerate toward the next target. That is what cut the trip from an estimated 30 years to about 12. Rather than carrying the huge amount of fuel needed for a direct flight, Voyager 2 used gravity assists. In each encounter, the spacecraft passed through a planet’s gravitational field and exchanged a tiny amount of the planet’s orbital energy. Relative to the Sun, Voyager 2 gained speed and changed direction, while the planet lost an amount too small to matter. JPL researchers identified this “Grand Tour” opportunity in the 1960s, and NASA launched Voyager 2 on 20 August 1977 aboard a Titan IIIE-Centaur. It reached Jupiter on 9 July 1979, Saturn on 25 August 1981, Uranus on 24 January 1986 and Neptune on 25 August 1989, covering about 7.1 billion kilometers. The mission was originally funded for Jupiter and Saturn, but engineers preserved the option to continue if the spacecraft stayed healthy. It did, making Voyager 2 the only probe ever to visit all four giant planets. That exact Jupiter-Saturn-Uranus-Neptune opportunity will not return until the 2150s.

2 articles · Updated · spacedaily.com · Aug 8

Twelve years and five days after its 1977 launch, Voyager 2 reached Neptune on Aug. 25, 1989, becoming the only spacecraft to visit Jupiter, Saturn, Uranus and Neptune in one mission.
A rare outer-planet configuration let each flyby redirect and accelerate the 722-kilogram probe toward the next target, with NASA estimating Jupiter alone added about 35,700 mph in Sun-relative speed.
Mission planners chained the encounters tightly—Jupiter in 1979, Saturn in 1981, Uranus in 1986 and Neptune in 1989—after studying more than 10,000 trajectories, while Voyager 1 took a faster route that ended at Saturn.
The tour survived because NASA salvaged a cheaper two-spacecraft Voyager plan after canceling the near-$1 billion TOPS Grand Tour concept in 1972, then extended a mission initially designed for five years.
Comparable geometry for one spacecraft to repeat the full Jupiter-Saturn-Uranus-Neptune sequence will not return until the 2150s, though separate missions to Uranus or Neptune remain possible on other trajectories.

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spacedaily.com16h ago

Voyager 2 Completes Rare 176-Year Grand Tour of Outer Planets

sciencesprings.wordpress.com16h ago

From NASA Science Via LiveScience : 'NASA Engineers Help Prolong Voyager 2's Science Mission' – sciencesprings

How did a once-in-176-years planetary lineup let Voyager 2 slash a 30-year journey and become the only probe to visit all four giant planets?

Voyager 2 transformed our view of Uranus and Neptune—but what crucial mysteries about the ice giants still remain unsolved today?

With Voyager 2 still whispering from interstellar space, how much longer can NASA keep its aging instruments alive?

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2 total

spacedaily.com16h ago

Voyager 2 Completes Rare 176-Year Grand Tour of Outer Planets

sciencesprings.wordpress.com16h ago

From NASA Science Via LiveScience : 'NASA Engineers Help Prolong Voyager 2's Science Mission' – sciencesprings

Voyager 2 Completes 4-Planet Grand Tour, a 176-Year Opportunity Not Returning Until the 2150s

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