Editing Voyager program (section)

=== Mariner Jupiter-Saturn ===
{{also|Grand Tour program#Mariner Jupiter-Saturn}}
[[File:Voyager Path.svg|right|thumb|The trajectories that enabled the Voyager spacecraft to visit the outer planets and achieve velocity to escape the Solar System]]
[[File:Voyager 2 velocity vs distance from sun.svg|thumb|Plot of ''Voyager 2''{{'}}s heliocentric velocity against its distance from the Sun, illustrating the use of gravity assist to accelerate the spacecraft by Jupiter, Saturn and Uranus. To observe [[Triton (moon)|Triton]], ''Voyager 2'' passed over Neptune's north pole, resulting in an acceleration out of the plane of the ecliptic and reduced its velocity away from the Sun.<ref>{{cite web |author=Dave Doody |url=http://www2.jpl.nasa.gov/basics/bsf4-1.php |title=Basics of Space Flight Section I. The Environment of Space |publisher=.jpl.nasa.gov |date=15 September 2004 |access-date=29 December 2017 |archive-date=17 August 2015 |archive-url=https://web.archive.org/web/20150817051745/http://www2.jpl.nasa.gov/basics/bsf4-1.php |url-status=live }}</ref>]]

{{Blockquote
|text=Voyager did things no one predicted, found scenes no one expected, and promises to outlive its inventors. Like a great painting or an abiding institution, it has acquired an existence of its own, a destiny beyond the grasp of its handlers.
|author=[[Stephen J. Pyne]]<ref name="The Fantastic Voyage of Voyager"/>
}}
The two Voyager space probes were originally conceived as part of the [[Planetary Grand Tour]] planned during the late 1960s and early 70s that aimed to explore  [[Jupiter]], [[Saturn]], Saturn's moon [[Titan (moon)|Titan]], [[Uranus]], [[Neptune]], and [[Pluto]]. The mission originated from the [[Grand Tour program]], conceptualized by [[Gary Flandro]], an [[aerospace engineer]] at the Jet Propulsion Laboratory, in 1964, which leveraged a rare [[Syzygy (astronomy)|planetary alignment]] occurring once every 175 years.<ref>{{cite journal |last=Flandro |first=Gary |title=Fast Reconnaissance Missions to the Outer Solar System Using Energy Derived from the Gravitational Field of Jupiter |journal=Astronautica Acta |volume=12 |pages=329–337 |date=1966 |url=http://www.gravityassist.com/IAF3-2/Ref.%203-143.pdf |access-date=1 June 2024 |archive-date=30 March 2019 |archive-url=https://web.archive.org/web/20190330015134/http://www.gravityassist.com/IAF3-2/Ref.%203-143.pdf |url-status=live }}</ref><ref>{{cite web|url=http://voyager.jpl.nasa.gov/science/planetary.html|archive-url=https://web.archive.org/web/20131127192310/http://voyager.jpl.nasa.gov/science/planetary.html|archive-date=27 November 2013|url-status=dead|title=Planetary Voyage|date=30 October 2013|publisher=USA.gov|access-date=15 October 2013}}</ref> This alignment allowed a craft to reach all [[outer planets]] using [[gravitational assist]]s. The mission was to send several pairs of probes and gained momentum in 1966 when it was endorsed by [[NASA]]'s [[Jet Propulsion Laboratory]]. However, in December 1971, the Grand Tour mission was canceled when funding was redirected to the [[Space Shuttle program]].<ref name="GTN">{{cite book
 |last          = Butrica
 |first         = Andrew J.
 |title         = From Engineering Science to Big Science: The NACA and NASA Collier Trophy Research Project Winners
 |chapter       = Voyager: The Grand Tour of Big Science
 |editor1-last  = Mack
 |editor1-first = Pamela E.
 |url           = https://history.nasa.gov/SP-4219/Chapter11.html
 |access-date   = August 25, 2014
 |location      = Washington, D.C.
 |publisher     = NASA
 |date          = 1998
 |archive-url   = https://web.archive.org/web/20140823084758/http://history.nasa.gov/SP-4219/Chapter11.html
 |archive-date  = August 23, 2014
 |url-status    = live
 |isbn          = 978-1-4102-2531-3
}}</ref>

In 1972, a scaled-down (four planets, two identical spacecraft) mission was proposed, utilizing a spacecraft derived from the [[Mariner program|Mariner]] series, initially intended to be [[Mariner 11]] and [[Mariner 12]]. The [[gravity-assist]] technique, successfully demonstrated by [[Mariner 10]], would be used to achieve significant velocity changes by maneuvering through an intermediate planet's [[gravitational field]] to minimize time towards Saturn.<ref name="HMSmurmeier1974">{{cite web |last1=Smurmeier |first1=H. M. |title=The Mariner Jupiter/Saturn 1977 Mission" (1974) |url=https://commons.erau.edu/cgi/viewcontent.cgi?article=2830&context=space-congress-proceedings |website=[[Embry–Riddle Aeronautical University]] |access-date=May 16, 2024 |date=April 1, 1974 |archive-date=20 April 2023 |archive-url=https://web.archive.org/web/20230420101913/https://commons.erau.edu/cgi/viewcontent.cgi?article=2830&context=space-congress-proceedings |url-status=live }}</ref> The spacecrafts were then moved into a separate program named '''Mariner Jupiter-Saturn''' (also '''Mariner Jupiter-Saturn-Uranus''',<ref>{{cite web |title=The Voyagers: An unprecedented on-going mission of exploration |url=https://www.nasaspaceflight.com/2011/08/voyagers-unprecedented-on-going-mission-exploration/ |website=[[NASASpaceFlight.com]] |publisher=Jeff Goldader, Chris Gebhardt |access-date=May 17, 2024 |date=August 7, 2011 |archive-date=17 May 2024 |archive-url=https://web.archive.org/web/20240517013934/https://www.nasaspaceflight.com/2011/08/voyagers-unprecedented-on-going-mission-exploration/ |url-status=live }}</ref> '''MJS''', or '''MJSU'''), part of the [[Mariner program]], later renamed because it was thought that the design of the two space probes had progressed sufficiently beyond that of the Mariner family to merit a separate name.<ref>[https://history.nasa.gov/SP-4219/Chapter11.html '' Chapter 11 "Voyager: The Grand Tour of Big Science"''] {{Webarchive|url=https://web.archive.org/web/20200229064831/https://history.nasa.gov/SP-4219/Chapter11.html |date=29 February 2020 }} (sec. 268.), by Andrew,J. Butrica, found in ''From Engineering Science To Big Science'' {{ISBN|978-0-16-049640-0}} edited by Pamela E. Mack, NASA, 1998</ref>