View source for Exploration of Saturn

{{short description|Overview of the exploration of Saturn}}
[[File:Cassini Saturn Orbit Insertion.jpg|thumb|Artist's concept of ''Cassini''{{'s}} [[orbit insertion]] around Saturn]]

The '''exploration of Saturn''' has been performed solely by crewless probes. Three missions were flybys, which formed an extended foundation of knowledge about the system. The ''[[Cassini–Huygens]]'' spacecraft, launched in 1997, was in orbit from 2004 to 2017.<ref name="NASA-20170915">{{cite news |last1=Brown |first1=Dwayne |last2=Cantillo |first2=Laurie |last3=Dyches |first3=Preston |title=NASA's Cassini Spacecraft Ends Its Historic Exploration of Saturn |url=https://www.jpl.nasa.gov/news/news.php?feature=6948 |date=September 15, 2017 |work=[[NASA]] |access-date=September 15, 2017 }}</ref><ref name="NYT-20170914">{{cite news |last=Chang |first=Kenneth |title=Cassini Vanishes Into Saturn, Its Mission Celebrated and Mourned |url=https://www.nytimes.com/2017/09/14/science/cassini-grand-finale-saturn.html |date=September 14, 2017 |work=[[The New York Times]] |access-date=September 15, 2017 }}</ref>

==Missions==
A list of previous and upcoming missions to the outer Solar System (including [[Saturn]]) can be found at the [[List of missions to the outer planets]] article.

==Flybys==

===''Pioneer 11'' flyby===
[[Image:P11F81.jpg|thumb|''Pioneer 11'' image of Saturn.]]
Saturn was first visited by ''[[Pioneer 11]]'' in September 1979. It flew within {{convert|20,000|km}} of the top of the planet's cloud layer. Low-resolution images were acquired of the planet and a few of its moons; the resolution of the images was not good enough to discern surface features. The spacecraft also studied the rings; among the discoveries were the thin F-ring and the fact that dark gaps in the rings are bright when viewed towards the Sun, or in other words, they are not empty of material. ''Pioneer 11'' also measured the temperature of Titan at 250 [[Kelvin|K]].<ref>{{Cite web|url=http://spaceprojects.arc.nasa.gov/space_projects/pioneer/PN10&11.html|title=Pioneer Mission Description Page|date=December 6, 1998|website=spaceprojects.arc.nasa.gov|archive-url=https://web.archive.org/web/19981206131339/http://spaceprojects.arc.nasa.gov/space_projects/pioneer/PN10&11.html|archive-date=1998-12-06}}</ref>

===Voyagers===
{{Main|Voyager program}}
In November 1980, the ''[[Voyager 1]]'' probe visited the Saturn system. It sent back the first high-resolution images of the planet, rings, and satellites. Surface features of various moons were seen for the first time. Because of the earlier discovery of a thick atmosphere on Titan, the Voyager controllers at the Jet Propulsion Laboratory elected for ''Voyager 1'' to make a close approach of Titan. This greatly increased knowledge of the atmosphere of the moon, but also proved that Titan's atmosphere is impenetrable in visible wavelengths, so no surface details were seen. The flyby also changed the spacecraft's trajectory out from the plane of the Solar System which prevented ''Voyager 1'' from completing the [[Planetary Grand Tour]] of Uranus, Neptune and Pluto.

Almost a year later, in August 1981, ''[[Voyager 2]]'' continued the study of the Saturn system. More close-up images of Saturn's moons were acquired, as well as evidence of changes in the rings. ''Voyager 2'' probed Saturn's upper atmosphere with its radar, to measure temperature and density profiles. ''Voyager 2'' found that at the highest levels (7 kilopascals pressure) Saturn's temperature was 70 [[Kelvin|K]] (−203&nbsp;°C) (i.e. 70 degrees above absolute zero), while at the deepest levels measured (120 kilopascals) the temperature increased to 143 [[Kelvin|K]] (−130&nbsp;°C). The north pole was found to be 10 [[Kelvin|K]] cooler, although this may be seasonal. Unfortunately, during the flyby, the probe's turnable camera platform stuck for a couple of days and some planned imaging was lost. Saturn's gravity was used to direct the spacecraft's trajectory towards Uranus.

The probes discovered and confirmed several new satellites orbiting near or within the planet's rings. They also discovered the small Maxwell and Keeler gaps in the rings.

==''Cassini'' orbiter==
[[Image:Saturn eclipse.jpg|thumb|Saturn eclipses the Sun, as seen from ''Cassini''.]]
[[File:Animation of Cassini trajectory around Saturn.gif|thumb|right|Animation of '' Cassini''{{'s}} trajectory around Saturn from 1 May 2004 to 15 September 2017<br>{{legend2|magenta| '' Cassini''}}{{·}}{{legend2| Lime |[[Saturn]]}}{{·}}{{legend2|OrangeRed|[[Enceladus]]}}{{·}}{{legend2| Gold |[[Titan (moon)|Titan]]}}{{·}}{{legend2|Cyan|[[Iapetus (moon)|Iapetus]]}}]]
On July 1, 2004, the ''[[Cassini–Huygens]]'' spacecraft performed the SOI (Saturn Orbit Insertion) maneuver and entered into orbit around Saturn. Before the SOI, ''Cassini'' had already studied the system extensively. In June 2004, it had conducted a close flyby of [[Phoebe (moon)|Phoebe]], sending back high-resolution images and data.

The orbiter completed two Titan flybys before releasing the [[Huygens probe|''Huygens'' probe]] on December 25, 2004. ''Huygens'' descended onto the surface of Titan on January 14, 2005, sending a flood of data during the atmospheric descent and after the landing. During 2005 ''Cassini'' conducted multiple flybys of Titan and icy satellites.

On March 10, 2006, NASA reported that the ''Cassini'' probe found evidence of liquid water reservoirs that erupt in [[geyser]]s on Saturn's moon [[Enceladus]].<ref>{{Cite web|url=http://saturn.jpl.nasa.gov/news/press-release-details.cfm?newsID=639|archiveurl=https://web.archive.org/web/20080303154427/http://saturn.jpl.nasa.gov/news/press-release-details.cfm?newsID=639|url-status=dead|title=Cassini–Huygens: News<!-- Bot generated title -->|archivedate=March 3, 2008}}</ref>

On September 20, 2006, a ''Cassini'' probe photograph revealed a previously undiscovered planetary ring, outside the brighter main rings of Saturn and inside the G and E rings.<ref>[http://www.cnn.com/2006/TECH/space/09/20/saturn.ring.reut/index.html New Ring Spotted Around Saturn] {{webarchive|url=https://web.archive.org/web/20060920225736/http://www.cnn.com/2006/TECH/space/09/20/saturn.ring.reut/index.html |date=2006-09-20 }} – Article on CNN.com.</ref>

In July 2006, ''Cassini'' saw the first proof of hydrocarbon lakes near Titan's north pole, which was confirmed in January 2007. In March 2007, additional images near Titan's north pole discovered hydrocarbon "seas", the largest of which is almost the size of the [[Caspian Sea]].

In 2009, the probe discovered and confirmed four new satellites. Its primary mission ended in 2008, when the spacecraft completed 74 orbits around the planet. In 2010, the probe began its first extended mission, the ''Cassini'' Equinox Mission. The ''Cassini'' Solstice Mission, the second mission extension, lasted through September 2017.<ref>{{Cite web|url=http://saturn.jpl.nasa.gov/mission/introduction/|title=Cassini-Huygens: Introduction|date=December 17, 2008|archive-url=https://web.archive.org/web/20081217142207/http://saturn.jpl.nasa.gov/mission/introduction/|archive-date=2008-12-17}}</ref> The mission ended on September 15, 2017, after a planned [[atmospheric entry]] into the planet Saturn.<ref name="NASA-20170915" /><ref name="NYT-20170914" />

== Future missions ==
NASA's [[Dragonfly (Titan space probe)|Dragonfly]] spacecraft will launch in 2028 to visit the Saturn system, with the objective of landing on the moon [[Titan (moon)|Titan]].<ref>{{cite web |last=Foust |first=Jeff |url=https://spacenews.com/nasa-postpones-dragonfly-review-launch-date/ |title=NASA postpones Dragonfly review, launch date |date=28 November 2023 |access-date=28 November 2023 |work=SpaceNews.com}}</ref>

==Proposed missions==
{{update|date=June 2024}}
[[File:Gas planet size comparisons.jpg|thumb|Missions to Saturn face competition from missions to other Solar System bodies]]
The [[Titan Saturn System Mission]] (TSSM) was a joint [[NASA]]/[[ESA]] proposal for an exploration of [[Saturn]] and its moons<ref>{{Cite web|url=https://sci.esa.int/web/tandem-tssm|title=ESA Science & Technology – TandEM/TSSM|website=sci.esa.int}}</ref> [[Titan (moon)|Titan]] and [[Enceladus (moon)|Enceladus]], where many complex phenomena have been revealed by the recent ''[[Cassini–Huygens]]'' mission. TSSM was competing against the [[Europa Jupiter System Mission]] proposal for funding. In February 2009 it was announced that ESA/NASA had given the EJSM mission priority ahead of TSSM,<ref>{{Cite web|url=https://www.nasa.gov/topics/solarsystem/features/20090218.html|title=NASA – NASA and ESA Prioritize Outer Planet Missions|website=www.nasa.gov|access-date=2021-08-18|archive-date=2010-10-04|archive-url=https://web.archive.org/web/20101004183307/http://www.nasa.gov/topics/solarsystem/features/20090218.html|url-status=dead}}</ref><ref>{{Cite news|url=http://news.bbc.co.uk/2/hi/science/nature/7897585.stm|title=Jupiter in space agencies' sights|date=February 18, 2009|via=news.bbc.co.uk}}</ref> although TSSM will continue to be studied for a later launch date. The Titan Saturn System Mission (TSSM) was created by the merging of the ESA's Titan and Enceladus Mission (TandEM) with NASA's Titan Explorer 2007 flagship study.

Other proposed missions to the Saturn system were:
* 2010 JPL: [[Journey to Enceladus and Titan]] (JET)<ref name="JET 204">{{cite news |last=Kane |first=Van |title=Discovery Missions for an Icy Moon with Active Plumes |url=http://www.planetary.org/blogs/guest-blogs/van-kane/20140402-discovery-missions-for-an-icy-moon-with-plumes.html |work=The Planetary Society |date=3 April 2014 |access-date=2015-04-09 }}</ref>
* 2011 [[Titan Mare Explorer]] (TiME); an aquatic lander that would explore the methane lakes of the moon [[Titan (moon)|Titan]].  This mission was given US$3 million in May 2011 to develop a detailed concept study as a part of the NASA Discovery program.
* 2012 [[German Aerospace Center|DLR]]: [[Enceladus Explorer]] (EnEx), a lander with an ice mole.<ref>{{cite news |last=Brabaw |first=Kasandra |url=http://www.space.com/28930-icemole-drills-glacier-saturn-moon-enceladus.html?cid=514630_20150408_43377416&adbid=10152745517721466&adbpl=fb&adbpr=17610706465 |title=IceMole Drill Built to Explore Saturn's Icy Moon Enceladus Passes Glacier Test |work=Space.com |date=April 7, 2015 |access-date=2015-04-09 }}</ref> 
* 2012 JPL: [[Life Investigation For Enceladus]] (LIFE) a sample-return.<ref name="Interview2012">{{cite news |last=Wall |first=Mike |url=http://www.space.com/18792-enceladus-sample-return-mission.html |title=Saturn Moon Enceladus Eyed for Sample-Return Mission |work=Space.com |date= December 6, 2012 |access-date=2015-04-10 }}</ref><ref name="Porco 2014">{{cite journal |title=LIFE – Enceladus Plume Sample Return via Discovery |journal=45th Lunar and Planetary Science Conference |year=2014 |last1=Tsou |first1=Peter |last2=Anbar |first2=Ariel |last3=Atwegg |first3=Kathrin |last4=Porco |first4=Carolyn |last5=Baross |first5=John |last6=McKay |first6=Christopher |url=http://www.hou.usra.edu/meetings/lpsc2014/pdf/2192.pdf |access-date=2015-04-10 }}</ref><ref name="Doc 2013">{{cite web|url=http://discoveringenceladus.com/downloads/LIFE%20-%20Life%20Investigation%20For%20Enceladus%20-%20A%20Sample%20Return%20Mission%20Concept%20in%20Search%20for%20Evidence%20of%20Life.doc |format=.doc |title=LIFE: Life Investigation For Enceladus – A Sample Return Mission Concept in Search for Evidence of Life. |last=Tsou |first=Peter |work=Jet Propulsion Laboratory |date=2013 |access-date=2015-04-10 |url-status=dead |archive-url=https://web.archive.org/web/20150901121008/http://discoveringenceladus.com/downloads/LIFE%20-%20Life%20Investigation%20For%20Enceladus%20-%20A%20Sample%20Return%20Mission%20Concept%20in%20Search%20for%20Evidence%20of%20Life.doc |archive-date=2015-09-01 }}</ref>
* 2015 JPL: [[Enceladus Life Finder]] (ELF)<ref>{{cite web |title=ENCELADUS LIFE FINDER: THE SEARCH FOR LIFE IN A HABITABLE MOON |url=https://www.hou.usra.edu/meetings/lpsc2015/pdf/1525.pdf |website=www.hou.usra.edu}}</ref>
* 2020 [[Applied Physics Laboratory]]: [[Enceladus Orbilander]]<ref name="MacKenzie Kirby Greenauer Neveu 2020">{{cite web | last=MacKenzie | first=Shannon M | last2=Kirby | first2=Karen W | last3=Greenauer | first3=Peter J | last4=Neveu | first4=Marc | last5=Gold | first5=Rob | last6=Davila | first6=Alfonso | last7=Lunine | first7=Jonathan I | last8=Cable | first8=Morgan | last9=Craft | first9=Kate | last10=Eigenbrode | first10=Jennifer | last11=Glein | first11=Christopher | last12=Hofgartner | first12=Jason | last13=Mckay | first13=Christopher | last14=Phillips-Lander | first14=Charity | last15=Waite | first15=Hunter | last16=Burton | first16=Dana | last17=Seifert | first17=Helmut | last18=Boye | first18=Jeff | last19=Brock | first19=Spencer | last20=Chen | first20=Michelle | last21=Coker | first21=Rob | last22=Colonel | first22=Grace | last23=Criss | first23=Tom | last24=Crowley | first24=Doug | title=Enceladus Orbilander: A Flagship Mission Concept for Astrobiology | website=NASA Technical Reports Server (NTRS) | date=2020-10-14 | url=https://ntrs.nasa.gov/api/citations/20205008712/downloads/enceladusorbilander_2020pmcs.pdf | access-date=2024-05-05}}</ref>

== See also ==
* [[Exploration of Mercury]]
* [[Exploration of Venus]]
* [[Exploration of Mars]]
* [[Exploration of Jupiter]]
* [[Exploration of Uranus]]
* [[Exploration of Neptune]]

==References==
{{Reflist|30em}}

==Further reading==
*{{citation
|author=Hannu Karttunen
|title=Fundamental Astronomy
|url=https://books.google.com/books?id=rn7vAAAAMAAJ
|access-date=February 21, 2012
|edition=3rd
|year=1996
|publisher=Springer
|location=New York
|isbn=978-3-540-60936-0
|postscript=.|display-authors=etal}}
*{{cite web |url= http://voyager.jpl.nasa.gov/science/saturn.html |title=Voyager Science Results: Saturn |author=NASA/JPL–Caltech |work=voyager.jpl.nasa.gov |date=October 18, 2010 <!--last update--> |access-date=February 21, 2012}}

==External links==
*[https://web.archive.org/web/20070426162116/http://saturn.jpl.nasa.gov/home/index.cfm NASA's ''Cassini'' mission to Saturn]

{{Saturn}}
{{Planetary exploration}}
{{Saturn spacecraft}}
{{Voyager program}}
{{Solar System}}
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