Editing Tethys (moon) (section)

== Exploration ==
[[File:Tethys.gif|thumb|Animation of Tethys's rotation]]

''[[Pioneer 11]]'' flew by Saturn in 1979, and its closest approach to Tethys was 329,197&nbsp;km on 1 September 1979.{{sfn|Muller, Pioneer 11 Full Mission Timeline}}

One year later, on 12 November 1980, ''Voyager 1'' flew 415,670&nbsp;km from Tethys.{{sfn|Stone|Miner|1981}} Its twin spacecraft, ''Voyager 2'', passed as close as 93,010&nbsp;km from the moon on 26 August 1981.{{sfn|Muller, Missions to Tethys}}{{sfn|Voyager Mission Description}}{{sfn|Stone|Miner|1982}} Although both spacecraft took images of Tethys, the resolution of ''Voyager 1'''s images did not exceed 15&nbsp;km, and only those obtained by ''Voyager 2'' had a resolution as high as 2&nbsp;km.{{sfn|Stone|Miner|1982}} The first geological feature discovered in 1980 by ''Voyager 1'' was Ithaca Chasma.{{sfn|Stone|Miner|1981}} Later in 1981 ''Voyager 2'' revealed that it almost circled the moon running for 270°. ''Voyager 2'' also discovered the Odysseus crater.{{sfn|Stone|Miner|1982}} Tethys was the Saturnian satellite most fully imaged by the ''Voyagers''.{{sfn|Moore Schenk et al.|2004|pp=424–30}}
[[File:PIA18318-SaturnMoon-Tethys-20150411.jpg|thumb|left|150px|Tethys near Saturn (11 April 2015).]]
The ''[[Cassini-Huygens|Cassini]]'' spacecraft entered orbit around Saturn in 2004. During its primary mission from June 2004 through June 2008 it performed one very close targeted flyby of Tethys on 24 September 2005 at the distance of 1,503&nbsp;km. In addition to this flyby the spacecraft performed many non-targeted flybys during its primary and equinox missions since 2004, at distances of tens of thousands of kilometers.{{sfn|Muller, Missions to Tethys}}{{sfn|Jaumann Clark et al.|2009|pp=639–40|loc=Table 20.2 at p. 641}}{{sfn|Seal|Buffington|2009|pp=725–26}}

Another flyby of Tethys took place on 14 August 2010 (during the solstice mission) at a distance of 38,300&nbsp;km, when the fourth-largest crater on Tethys, [[Penelope (crater)|Penelope]], which is 207&nbsp;km wide, was imaged.{{sfn|Cook|2010}} More non-targeted flybys were planned for the solstice mission in 2011–2017.{{sfn|Cassini Solstice Mission}}

''Cassini''{{'}}s observations allowed high-resolution maps of Tethys to be produced with the resolution of 0.29&nbsp;km.{{sfn|Roatsch Jaumann et al.|2009|p=768}} The spacecraft obtained spatially resolved near-infrared spectra of Tethys showing that its surface is made of water ice mixed with a dark material,{{sfn|Filacchione Capaccioni et al.|2007}} whereas the far-infrared observations constrained the bolometric [[bond albedo]].{{sfn|Howett Spencer et al.|2010|p=581|loc=Table 7}} The radar observations at the wavelength of 2.2&nbsp;cm showed that the ice regolith has a complex structure and is very porous.{{sfn|Ostro West et al.|2006}} The observations of plasma in the vicinity of Tethys demonstrated that it is a geologically dead body producing no new plasma in the Saturnian magnetosphere.{{sfn|Khurana Russell et al.|2008|pp=472–73}}

Future missions to Tethys and the Saturn system are uncertain, but one possibility is the [[Titan Saturn System Mission]].