Editing Gravity assist (section)

==Notable examples of use==
;''Luna 3''
The gravity assist maneuver was first attempted in 1959 for [[Luna 3]], to photograph the far side of the Moon.<ref>{{cite journal |last1=Negri |first1=Rodolfo Batista |last2=Prado |first2=Antônio Fernando Bertachini de Almeida |title=A historical review of the theory of gravity-assists in the pre-spaceflight era |journal=Journal of the Brazilian Society of Mechanical Sciences and Engineering |date=14 July 2020 |volume=42 |issue=8 |pages=406 |doi=10.1007/s40430-020-02489-x|s2cid=220510617 |url=http://urlib.net/8JMKD3MGP3W34R/42T4NAH }}</ref> The satellite did not gain speed, but its orbit was changed in a way that allowed successful transmission of the photos.<ref>{{cite report |last1=Santos |first1=Ignacio |title=Simulation and Study of Gravity Assist Maneuvers |date=2020 |url=http://www.diva-portal.org/smash/record.jsf?pid=diva2%3A1440099&dswid=4630}}</ref>

;''Pioneer 10''
NASA's ''[[Pioneer 10]]'' is a space probe launched in 1972 that completed the first mission to the planet [[Jupiter]].<ref name="PionOdys" /> Thereafter, ''Pioneer 10'' became the [[List of artificial objects leaving the Solar System|first of five artificial objects]] to achieve the [[escape velocity]] needed to [[Solar System#Farthest regions|leave the Solar System]]. In December 1973, ''Pioneer 10'' spacecraft was the first one to use the gravitational slingshot effect to reach escape velocity to leave Solar System.<ref>{{cite web |title=Let Gravity Assist You... |url=https://www.sciencedaily.com/releases/2003/10/031023071115.htm |website=ScienceDaily |access-date=5 December 2022 |language=en}}</ref><ref>{{cite book |author1=T. Franc |title=20th Annual Conference of Doctoral Students, WDS'11 "Week of Doctoral Students 2011", Charles University, Faculty of Mathematics and Physics, Prague, Czech Republic, May 31, 2011 to June 3, 2011 : [proceedings of contributed papers]. Pt. 3 Physics |date=2011 |publisher=Matfyzpress |location=Praha |isbn=978-80-7378-186-6 |edition=Vyd. 1 |url=https://www.mff.cuni.cz/veda/konference/wds/proc/pdf11/WDS11_309_f12_Franc.pdf |access-date=5 December 2022 |chapter=The Gravitational Assist}}</ref>

;''Pioneer 11''
[[Pioneer 11]] was launched by NASA in 1973, to study the [[asteroid belt]], the environment around [[Jupiter]] and [[Saturn]], [[solar wind]]s, and [[cosmic ray]]s.<ref name="PionOdys" /> It was the first probe to [[Exploration of Saturn|encounter Saturn]], the second to fly through the [[Asteroid belt#Exploration|asteroid belt]], and the second to fly [[Exploration of Jupiter|by Jupiter]]. To get to Saturn, the spacecraft got a gravity assist on Jupiter.<ref name="InDepth">{{cite web|title=Pioneer 11: In Depth|url=https://solarsystem.nasa.gov/missions/pioneer-11/in-depth/|access-date=December 10, 2017}}</ref><ref>{{cite web |last1=Mars |first1=Kelli |title=45 Years Ago, Pioneer 11 Explores Jupiter |url=https://www.nasa.gov/feature/45-years-ago-pioneer-11-explores-jupiter |website=NASA |access-date=5 December 2022 |date=2 December 2019}}</ref><ref>{{cite web |title=Pioneer 10 and 11, outer solar system explorers |url=https://www.planetary.org/space-missions/pioneer |website=The Planetary Society |access-date=5 December 2022 |language=en}}</ref>

;''Mariner 10''
The [[Mariner 10]] probe was the first spacecraft to use the gravitational slingshot effect to reach another planet, passing by Venus on 5 February 1974 on its way to becoming the first spacecraft to explore [[Mercury (planet)|Mercury]].<ref>{{cite web |title=In Depth {{!}} Mariner 10 |url=https://solarsystem.nasa.gov/missions/mariner-10/in-depth/ |website=NASA Solar System Exploration |date=20 December 2017 |access-date=5 December 2022}}</ref>

;''Voyager 1''
''[[Voyager 1]]'' was launched by NASA on September 5, 1977. It gained the energy to escape the Sun's gravity by performing slingshot maneuvers around Jupiter and Saturn.<ref name="auto"/> Having operated for {{time interval|5 September 1977 12:56:00|show=ymd}} as of {{Time|UTC|mdy|dateonly=yes}}, the spacecraft still communicates with the [[Deep Space Network]] to receive routine commands and to transmit data to Earth. Real-time distance and velocity data is provided<ref>{{Cite web|url=https://voyager.jpl.nasa.gov/mission/status/|title = Voyager - Mission Status}}</ref> by NASA and JPL. At a distance of {{Convert|152.2|AU|e9km e9mi|sigfig=3|abbr=unit|lk=on}} from Earth as of January 12, 2020,<ref name="voyager">{{cite web |url=https://voyager.jpl.nasa.gov/mission/status/ |title=Voyager – Mission Status |work=[[Jet Propulsion Laboratory]] |publisher=[[National Aeronautics and Space Administration]] |access-date=December 26, 2019}},</ref> it is the most distant human-made object from Earth.<ref>{{cite web |url=http://www.bbc.co.uk/science/space/solarsystem/space_missions/voyager_1 |title=Voyager 1 |work=[[BBC]] Solar System |access-date=September 4, 2018 |archive-url=https://web.archive.org/web/20180203195855/http://www.bbc.co.uk/science/space/solarsystem/space_missions/voyager_1 |archive-date=February 3, 2018 |url-status=dead}}</ref>

;''Voyager 2''
''[[Voyager 2]]'' was launched by NASA on August 20, 1977, to study the [[outer planets]]. Its trajectory took longer to reach [[Jupiter]] and [[Saturn]] than its twin spacecraft but enabled further encounters with [[Uranus]] and [[Neptune]].<ref name=ESBS>{{cite book |last1=Butrica |first1=Andrew |title=From Engineering Science to Big Science |page=267 |url=https://history.nasa.gov/SP-4219/Chapter11.html |access-date=September 4, 2015 |quote=Despite the name change, Voyager remained in many ways the Grand Tour concept, though certainly not the Grand Tour (TOPS) spacecraft. ''Voyager 2'' was launched on August 20, 1977, followed by ''Voyager 1'' on September 5, 1977. The decision to reverse the order of launch had to do with keeping open the possibility of carrying out the Grand Tour mission to Uranus, Neptune, and beyond. ''Voyager 2'', if boosted by the maximum performance from the Titan-Centaur, could just barely catch the old Grand Tour trajectory and encounter Uranus. Two weeks later, ''Voyager 1'' would leave on an easier and much faster trajectory, visiting Jupiter and Saturn only. ''Voyager 1'' would arrive at Jupiter four months ahead of Voyager 2, then arrive at Saturn nine months earlier. Hence, the second spacecraft launched was ''Voyager 1'', not ''Voyager 2''. The two Voyagers would arrive at Saturn nine months apart, so that if ''Voyager 1'' failed to achieve its Saturn objectives, for whatever reason, ''Voyager 2'' still could be retargeted to achieve them, though at the expense of any subsequent Uranus or Neptune encounter.}}</ref>

;''Galileo''
The ''[[Galileo (spacecraft)|Galileo]]'' spacecraft was launched by [[NASA]] in 1989 and on its route to [[Jupiter]] got three gravity assists, one from Venus (February 10, 1990), and two from Earth (December 8, 1990 and December 8, 1992). Spacecraft reached Jupiter in December 1995. Gravity assists also allowed ''Galileo'' to flyby two asteroids, [[243 Ida]] and [[951 Gaspra]].<ref>{{cite journal |last1=D'Amario |first1=Louis A. |last2=Bright |first2=Larry E. |last3=Wolf |first3=Aron A. |title=Galileo trajectory design |journal=Space Science Reviews |date=May 1992 |volume=60 |issue=1–4 |page=23 |doi=10.1007/BF00216849|bibcode=1992SSRv...60...23D |s2cid=122388506 }}</ref><ref>{{cite web |title=Galileo Heads Towards Second Gravity Assist |url=https://www.jpl.nasa.gov/news/galileo-heads-towards-second-gravity-assist |website=NASA Jet Propulsion Laboratory (JPL) |access-date=5 December 2022}}</ref>

;''Ulysses''
In 1990, NASA launched the [[European Space Agency|ESA]] spacecraft ''[[Ulysses (spacecraft)|Ulysses]]'' to study the [[geographical pole|polar]] regions of the Sun. All the planets orbit approximately in a plane aligned with the equator of the Sun. Thus, to enter an orbit passing over the poles of the Sun, the spacecraft would have to eliminate the speed it inherited from the Earth's orbit around the Sun and gain the speed needed to orbit the Sun in the pole-to-pole plane. It was achieved by a gravity assist from Jupiter on  February 8, 1992.<ref>{{cite web |title=ESA Science & Technology - Orbit of Ulysses |url=https://sci.esa.int/web/ulysses/-/42904-orbit-of-ulysses |website=sci.esa.int |access-date=5 December 2022}}</ref><ref>{{cite web |title=ESA Science & Technology - Gravity Assist |url=https://sci.esa.int/web/ulysses/-/33640-gravity-assist |website=sci.esa.int |access-date=5 December 2022}}</ref>

;''MESSENGER''
The [[MESSENGER]] mission (launched in August 2004) made extensive use of gravity assists to slow its speed before orbiting Mercury. The MESSENGER mission included one flyby of Earth, two flybys of Venus, and three flybys of Mercury before finally arriving at Mercury in March 2011 with a velocity low enough to permit orbit insertion with available fuel. Although the flybys were primarily orbital maneuvers, each provided an opportunity for significant scientific observations.<ref>{{cite web |title=MESSENGER – Unlocking the Mysteries of Planet Mercury |url=https://messenger.jhuapl.edu/About/Mission-Design.html#gravity-assists |website=messenger.jhuapl.edu |access-date=5 December 2022}}</ref><ref>{{cite web |title=Resources / News Archives FLYBY INFORMATION |url=https://messenger.jhuapl.edu/Resources/Flyby-Information.html |website=messenger.jhuapl.edu |access-date=5 December 2022}}</ref>

;''Cassini''
The [[Cassini–Huygens|''Cassini–Huygens'' spacecraft]] was launched from Earth on 15 October 1997, followed by gravity assist flybys of Venus (26 April 1998 and 21 June 1999), Earth (18 August 1999), and Jupiter (30 December 2000). Transit to Saturn took 6.7 years, the spacecraft arrived at 1 July 2004.<ref>{{cite web |title=Cassini Trajectory |url=https://solarsystem.nasa.gov/resources/11776/cassini-trajectory/ |website=NASA Solar System Exploration |date=15 October 1997 |access-date=5 December 2022}} {{PD-notice}}</ref><ref>{{cite web |title=ESA Science & Technology – Getting to Saturn |url=https://sci.esa.int/web/cassini-huygens/-/31240-getting-to-saturn |website=sci.esa.int |access-date=5 December 2022}}</ref> Its trajectory was called "the Most Complex Gravity-Assist Trajectory Flown to Date" in 2019.<ref>{{cite book |last1=Bellerose |first1=Julie |last2=Roth |first2=Duane |last3=Tarzi |first3=Zahi |last4=Wagner |first4=Sean |title=Space Operations: Inspiring Humankind's Future |chapter=The Cassini Mission: Reconstructing Thirteen Years of the Most Complex Gravity-Assist Trajectory Flown to Date |date=2019 |pages=575–588 |doi=10.1007/978-3-030-11536-4_22 |chapter-url=https://link.springer.com/chapter/10.1007/978-3-030-11536-4_22 |access-date=5 December 2022 |publisher=Springer International Publishing |isbn=978-3-030-11535-7 |s2cid=197554425 |language=en}}</ref>

{{multiple image
| align             = center
| caption_align     = center
| total_width       = 1000
| image1            = Cassini interplanet trajectory.svg
| caption1          = ''Cassini'' interplanetary trajectory
| image2            = Animation of Cassini trajectory.gif
| caption2          = Animation of ''Cassini''{{'s}} trajectory from 15 October 1997 to 4 May 2008 <br /> {{legend2|magenta|''Cassini–Huygens''}}{{·}}{{legend2|Gold|[[Jupiter]]}}{{·}}{{legend2|lime|[[Saturn]]}}{{·}}{{legend2|Royalblue|[[Earth]]}}{{·}}{{legend2|Cyan|[[Venus]]}}{{·}}{{legend2| OrangeRed| [[Mars]]}}
| image3            = Cassini's speed related to Sun.png
| caption3          = ''Cassini''{{'s}} speed relative to the Sun. Gravity assists form peaks to the left, while periodic variations on the right are caused by the spacecraft's orbit around Saturn.
}}

After entering orbit around Saturn, the ''Cassini'' spacecraft used multiple [[Titan (moon)|Titan]] gravity assists to achieve significant changes in the inclination of its orbit as well so that instead of staying nearly in the equatorial plane, the spacecraft's flight path was inclined well out of the plane of the rings.<ref>{{cite web |title=Gravity Assists {{!}} Mission |url=https://solarsystem.nasa.gov/missions/cassini/mission/gravity-assists/ |website=NASA Solar System Exploration |date=25 September 2018 |access-date=5 December 2022}} {{PD-notice}}</ref> A typical Titan encounter changed the spacecraft's velocity by 0.75&nbsp;km/s, and the spacecraft made 127 Titan encounters. These encounters enabled an orbital tour with a wide range of periapsis and apoapsis distances, various alignments of the orbit with respect to the Sun, and orbital inclinations from 0° to 74°. The multiple flybys of Titan also allowed Cassini to flyby other moons, such as [[Rhea (moon)|Rhea]] and [[Enceladus (moon)|Enceladus]].{{fact|date=May 2022}}

;''Rosetta''
[[File:Animation of Rosetta trajectory.gif|thumb|Animation of ''Rosetta''{{'s}} trajectory from 2 March 2004 to 9 September 2016 <br /> {{legend2|magenta|''Rosetta''}}{{·}}{{legend2|lime|[[67P/Churyumov–Gerasimenko|67P/C-G]]}}{{·}}{{legend2|Royalblue|[[Earth]]}}{{·}}{{legend2|maroon|[[Mars]]}}{{·}}{{legend2|Cyan|[[21 Lutetia]] }}{{·}}{{legend2|Gold|[[2867 Šteins]]}}]]
The ''[[Rosetta (spacecraft)|Rosetta]]'' probe, launched in March 2004, used four gravity assist maneuvers (including one just 250&nbsp;km from the surface of Mars, and three assists from Earth) to accelerate throughout the inner Solar System. That enabled it to flyby the asteroids [[21 Lutetia]] and [[2867 Šteins]] as well as eventually match the velocity of the [[67P/Churyumov–Gerasimenko]] comet at the rendezvous point in August 2014.<ref>{{cite web |title=ESA Science & Technology – Rosetta Second Earth Swing-by |url=https://sci.esa.int/web/rosetta/-/41758-rosetta-second-earth-swing-by |website=sci.esa.int |access-date=5 December 2022}}</ref><ref>{{cite book |last1=Alexander |first1=C. |last2=Holmes |first2=D. |last3=Goldstein |first3=R. |last4=Parker |first4=J. |title=2008 IEEE Aerospace Conference |chapter=The U.S. Rosetta Project: Mars Gravity Assist |date=2 March 2008 |pages=1–9 |doi=10.1109/AERO.2008.4526265 |isbn=978-1-4244-1487-1 |s2cid=29248228 |chapter-url=https://trs.jpl.nasa.gov/handle/2014/41429}}</ref>

;''New Horizons''
''[[New Horizons (spacecraft)|New Horizons]]'' was launched by NASA in 2006, and reached [[Pluto]] in 2015. In 2007 it performed a gravity assist on Jupiter.<ref>{{cite web |last1=Boen |first1=Brooke |title=NASA – Grand Theft Pluto: New Horizons Gets a Boost From Jupiter Flyby |url=https://www.nasa.gov/mission_pages/newhorizons/news/jupiter_flyby.html |website=www.nasa.gov |access-date=5 December 2022 |language=en |archive-date=8 March 2016 |archive-url=https://web.archive.org/web/20160308061923/http://www.nasa.gov/mission_pages/newhorizons/news/jupiter_flyby.html |url-status=dead }}</ref><ref>{{cite web |title=New Horizons Jupiter Flyby |url=https://pds-atmospheres.nmsu.edu/data_and_services/atmospheres_data/Horizons/newhorizons.html |website=pds-atmospheres.nmsu.edu |access-date=5 December 2022 |language=en}}</ref>

;''Juno''
The [[Juno (spacecraft)|Juno spacecraft]] was launched on August 5, 2011 (UTC). The trajectory used a gravity assist speed boost from Earth, accomplished by an Earth flyby in October 2013, two years after its launch on August 5, 2011.<ref>{{cite web |url=http://www.nasa.gov/missions/highlights/schedule.html |title=NASA's Shuttle and Rocket Launch Schedule |publisher=NASA |access-date=February 17, 2011}}</ref> In that way ''Juno'' changed its orbit (and speed) toward its final goal, [[Jupiter]], after only five years.

;Parker Solar Probe
{{wide image|Velocity of Parker Solar Probe wide.svg|900px|The speed of the probe and distance from the Sun, from launch until 2026|center|alt=}}

[[File:Animation of Parker Solar Probe trajectory.gif|thumb|right|An animation of the Parker Solar Probe{{'s}} trajectory from August 7, 2018, to August 29, 2025:<br />{{legend2|magenta|Parker Solar Probe}}{{·}}{{legend2|Yellow|[[Sun]]}}{{·}}{{legend2|Lime|[[Mercury (planet)|Mercury]]}}{{·}}{{legend2|Cyan|[[Venus]]}}{{·}}{{legend2|RoyalBlue|[[Earth]]}}]]

The [[Parker Solar Probe]], launched by NASA in 2018, has seven planned Venus gravity assists. Each gravity assist brings the Parker Solar Probe progressively closer to the Sun. As of 2022, the spacecraft has performed five of its seven assists. The Parker Solar Probe's mission will make the closest approach to the Sun by any space mission.<ref>{{cite web |title=Parker Solar Probe Completes Its Fifth Venus Flyby – Parker Solar Probe |url=https://blogs.nasa.gov/parkersolarprobe/2021/10/19/parker-solar-probe-completes-its-fifth-venus-flyby/ |website=blogs.nasa.gov |date=19 October 2021 |access-date=5 December 2022}} {{PD-notice}}</ref><ref>{{cite web |last1=Garner |first1=Rob |title=Parker Solar Probe Changed the Game Before It Even Launched |url=https://www.nasa.gov/feature/goddard/2018/parker-solar-probe-changed-the-game-before-it-even-launched |publisher=NASA |access-date=5 December 2022 |date=4 October 2018}}</ref><ref>{{cite journal |last1=Guo |first1=Yanping |last2=Thompson |first2=Paul |last3=Wirzburger |first3=John |last4=Pinkine |first4=Nick |last5=Bushman |first5=Stewart |last6=Goodson |first6=Troy |last7=Haw |first7=Rob |last8=Hudson |first8=James |last9=Jones |first9=Drew |last10=Kijewski |first10=Seth |last11=Lathrop |first11=Brian |last12=Lau |first12=Eunice |last13=Mottinger |first13=Neil |last14=Ryne |first14=Mark |last15=Shyong |first15=Wen-Jong |last16=Valerino |first16=Powtawche |last17=Whittenburg |first17=Karl |title=Execution of Parker Solar Probe's unprecedented flight to the Sun and early results |journal=Acta Astronautica |date=1 February 2021 |volume=179 |pages=425–438 |doi=10.1016/j.actaastro.2020.11.007 |bibcode=2021AcAau.179..425G |s2cid=228944139 |language=en |issn=0094-5765|doi-access=free }}</ref> The mission's final planned gravity assist maneuver, completed on November 6, 2024, prepared it for three final solar flybys reaching just 3.8 million miles of the surface of the sun on December 24, 2024 (see figure).<ref name="parker-2024-flyby">{{Cite web |title=NASA's Sun-Bound Parker Solar Probe Swings Through Final Venus Flyby {{!}} Johns Hopkins University Applied Physics Laboratory |url=https://www.jhuapl.edu/news/news-releases/241108-venus-gravity-assist-7 |access-date=2024-12-19 |website=www.jhuapl.edu |language=en}}</ref>

;Solar Orbiter
[[Solar Orbiter]] was launched by ESA in 2020. In its initial cruise phase, which lasts until November 2021, Solar Orbiter performed two gravity-assist manoeuvres around Venus and one around Earth to alter the spacecraft's trajectory, guiding it towards the innermost regions of the Solar System. The first close solar pass will take place on 26 March 2022 at around a third of Earth's distance from the Sun.<ref name="NASA">{{cite web |title=GMS: Solar Orbiter's Orbit |url=https://svs.gsfc.nasa.gov/13532 |website=svs.gsfc.nasa.gov |access-date=14 February 2020 |date=27 January 2020}} {{PD-notice}}</ref>

;''BepiColombo''
[[BepiColombo]] is a joint mission of the [[European Space Agency]] (ESA) and the [[JAXA|Japan Aerospace Exploration Agency]] (JAXA) to the planet [[Mercury (planet)|Mercury]]. It was launched on 20 October 2018. It will use the gravity assist technique with [[Earth]] once, with [[Venus]] twice, and six times with [[Mercury (planet)|Mercury]]. It will arrive in 2026. BepiColombo is named after [[Giuseppe Colombo|Giuseppe (Bepi) Colombo]] who was a pioneer thinker with this way of maneuvers.<ref>{{Cite web|url= https://sci.esa.int/web/bepicolombo/-/47346-fact-sheet|title = ESA Science & Technology BepiColombo|date = 28 June 2022}}</ref>

;''Lucy''
''[[Lucy (spacecraft)|Lucy]]'' was launched by NASA on 16 October 2021. It gained one gravity assist from Earth on the 16th of October, 2022,<ref>{{cite web|title=Lucy completes its first Earth gravity assist after a year in space|url=https://www.nasaspaceflight.com/2022/10/lucy-first-earth-flyby|website=www.nasaspaceflight.com|publisher=NASA Spaceflight.com|date=16 October 2022|access-date=24 October 2022|author=Lee Kanayama}}</ref> and after a flyby of the main-belt asteroid [[152830 Dinkinesh]] it will gain another in 2024.<ref>{{cite web|title=NASA Awards Launch Services Contract for Lucy Mission|url=https://www.nasa.gov/press-release/nasa-awards-launch-services-contract-for-lucy-mission|website=nasa.gov|publisher=NASA|date=31 January 2019|access-date=29 March 2021}} {{PD-notice}}</ref> In 2025, it will fly by the inner main-belt asteroid [[52246 Donaldjohanson]].<ref name="round 1">{{cite news |url=http://www.planetary.org/blogs/casey-dreier/2015/09301336-discovery-downselect.html|title=NASA announces five Discovery proposals selected for further study|publisher=The Planetary Society|last1=Dreier |first1=Casey|last2=Lakdawalla|first2=Emily|date=30 September 2015}}</ref> In 2027, it will arrive at the {{L4}} Trojan cloud (the [[Greek camp]] of asteroids that orbits about 60° ahead of Jupiter), where it will fly by four Trojans, [[3548 Eurybates]] (with its satellite), [[15094 Polymele]], [[11351 Leucus]], and [[21900 Orus]].<ref name="NYT-20170106">{{cite news|url=https://www.nytimes.com/2017/01/06/science/nasa-psyche-asteroid.html|title=A Metal Ball the Size of Massachusetts That NASA Wants to Explore|last=Chang|first=Kenneth|newspaper=The New York Times|date=6 January 2017}}</ref> After these flybys, ''Lucy'' will return to Earth in 2031 for another gravity assist toward the {{L5}} Trojan cloud (the [[Trojan camp]] which trails about 60° behind Jupiter), where it will visit the [[Binary asteroid|binary]] Trojan [[617 Patroclus]] with its [[minor-planet moon|satellite]] [[617 Patroclus|Menoetius]] in 2033.

'''''In fiction'''''

In the 1968 novel ''[[2001: A Space Odyssey (novel)|2001: A Space Odyssey]]'' – but not [[2001: A Space Odyssey|the movie]] – the spaceship ''Discovery'' performs such a manoeuvre to gain speed as it goes around Jupiter. As Arthur C. Clarke made clear at various times, the location of TMA-2 was switched from near Saturn (in the novel) to near Jupiter (in the movie).