View source for Astronomy:Exploration of Uranus

{{short description|Exploration in space}}
[[File:Uranus Final Image.jpg|thumb|A colour photograph of Uranus, taken by ''Voyager 2'' in 1986 as it headed towards the planet Neptune]]
The '''exploration of Uranus''' has, to date, been through telescopes and a lone probe by [[Organization:NASA|NASA]]'s ''[[Astronomy:Voyager 2|Voyager 2]]'' spacecraft, which made its closest approach to [[Astronomy:Uranus|Uranus]] on January 24, 1986. ''Voyager 2'' discovered 10 [[Astronomy:Moons of Uranus|moons]], studied the planet's cold [[Astronomy:Uranus#Atmosphere|atmosphere]], and examined its [[Astronomy:Rings of Uranus|ring system]], discovering two new rings. It also imaged Uranus' five large moons, revealing that their surfaces are covered with [[Astronomy:Impact crater|impact crater]]s and [[Earth:Canyon|canyon]]s.

A number of dedicated exploratory missions to Uranus have been proposed,<ref>{{cite news|url=http://www.planetary.org/blogs/jason-davis/2017/20170621-revisiting-ice-giants.html |title=Revisiting the ice giants: NASA study considers Uranus and Neptune missions |work=Planetary Society|date=21 June 2017 |access-date=24 June 2017}}</ref><ref>{{cite news|url=http://www.lpi.usra.edu/icegiants/mission_study/ |title=Ice Giant Mission Study Final Report |work=NASA / Lunar and Planetary Institute|date=June 2017 |access-date=25 June 2017}}</ref> but {{as of|2023||lc=y}} none have been approved.<ref name=Uran1/><ref name=Uran2/>

==''Voyager 2''==
{{main|Astronomy:Voyager 2}}

''Voyager 2'' made its closest approach to Uranus on January 24, 1986, coming within {{convert|81,500|km|abbr=in}} of the planet's cloud tops. This was the probe's first solo planetary flyby, since ''[[Astronomy:Voyager 1|Voyager 1]]'' ended its tour of the outer planets at [[Astronomy:Saturn|Saturn]]'s moon [[Astronomy:Titan (moon)|Titan]].

[[File:Miranda - January 24 1986 (30906319004).jpg|left|thumb|The Uranian moon Miranda, imaged by ''Voyager 2'']]
Uranus is the third-largest and fourth most massive planet in the [[Astronomy:Solar System|Solar System]]. It orbits the [[Astronomy:Sun|Sun]] at a distance of about {{convert|2.8|e9km|e9mi|abbr=off|sp=us}} and completes one orbit every 84 years. The length of a [[Day#Astronomy|day]] on Uranus as measured by ''Voyager 2'' is 17 hours and 14 minutes. Uranus is distinguished by the fact that it is tipped on its side. Its unusual position is thought to be the result of a collision with a planet-sized body early in the Solar System's [[Astronomy:Formation and evolution of the Solar System|history]]. Given its odd orientation, with its polar regions exposed to sunlight or darkness for long periods and ''Voyager 2'' set to arrive around the time of Uranus's [[Astronomy:Solstice|solstice]], scientists were not sure what to expect at Uranus.

The presence of a magnetic field at Uranus was not known until ''Voyager 2''{{'s}} arrival. The intensity of the field is roughly comparable to that of Earth's, though it varies much more from point to point because of its large offset from the center of Uranus. The peculiar orientation of the magnetic field suggests that the field is generated at an intermediate depth in the interior where the pressure is high enough for water to become electrically conductive. ''Voyager 2'' found that one of the most striking influences of the sideways position of the planet is its effect on the tail of the [[Physics:Magnetic field|magnetic field]], which is itself tilted 60 degrees from the planet's [[Physics:Axis of rotation|axis of rotation]]. The magnetotail was shown to be twisted by the planet's rotation into a long corkscrew shape behind the planet.

[[Physics:Radiation|Radiation]] belts at Uranus were found to be of an intensity similar to those at [[Astronomy:Saturn|Saturn]]. The intensity of radiation within the belts is such that irradiation would quickly darken (within 100,000 years) any [[Chemistry:Methane|methane]] trapped in the [[Earth:Ice|icy]] surfaces of the inner [[Astronomy:Natural satellite|moon]]s and ring particles. This may have contributed to the darkened surfaces of the moons and ring particles, which are almost uniformly gray in color.

[[File:Uranian rings PIA01977.jpg|thumb|A ''Voyager 2'' image of the Uranian dark rings]]
A high layer of haze was detected around the sunlit [[Astronomy:Poles of astronomical bodies#Magnetic poles|pole]], which also was found to radiate large amounts of ultraviolet light, a phenomenon dubbed "electroglow". The average [[Physics:Temperature|temperature]] of the atmosphere of the planet is about {{cvt|59|K|C}}. Surprisingly, the illuminated and dark poles, and most of the planet, show nearly the same temperature at the cloud tops.

''Voyager 2'' found 10 new moons, bringing the total number to 15 at the time. Most of the new moons are small, with the largest measuring about {{convert|150|km|abbr=on}} in diameter.

The moon [[Astronomy:Miranda (moon)|Miranda]], innermost of the five large moons, was revealed to be one of the strangest bodies yet seen in the Solar System. Detailed images from ''Voyager 2''{{'s}} flyby of the moon showed huge oval structures termed ''coronae'' flanked by faults as deep as {{convert|20|km|abbr=on}}, terraced layers, and a mixture of old and young surfaces. One theory holds that Miranda may be a reaggregation of material from an earlier time when the moon was fractured by a violent impact.

The five large moons appear to be ice–[[Earth:Rock (geology)|rock]] conglomerates like the satellites of Saturn. [[Astronomy:Titania (moon)|Titania]] is marked by huge fault systems and [[Earth:Canyon|canyon]]s indicating some degree of [[Earth:Geology|geologic]], probably tectonic, activity in its history. [[Astronomy:Ariel (moon)|Ariel]] has the brightest and possibly youngest surface of all the Uranian moons and also appears to have undergone geologic activity that led to many fault valleys and what seem to be extensive flows of icy material. Little geologic activity has occurred on [[Astronomy:Umbriel (moon)|Umbriel]] or [[Astronomy:Oberon (moon)|Oberon]], judging by their old and dark surfaces.

All nine previously known [[Astronomy:Rings of Uranus|rings]] were studied by the spacecraft and showed the Uranian rings to be distinctly different from those at [[Astronomy:Jupiter|Jupiter]] and Saturn. The ring system may be relatively young and did not form at the same time as Uranus. Particles that make up the rings may be remnants of a moon that was broken by a high-velocity impact or [[Physics:Tidal force|torn up by gravitational effects]]. ''Voyager 2'' also discovered two new rings.

In March 2020, NASA astronomers reported the detection of a large atmospheric magnetic bubble, also known as a [[Astronomy:Plasmoid|plasmoid]], released into [[Astronomy:Outer space|outer space]] from the planet [[Astronomy:Uranus|Uranus]], after reevaluating old data recorded by the ''[[Astronomy:Voyager 2|Voyager 2]]'' [[Engineering:Space probe|space probe]] during a flyby of the planet in 1986.<ref name="NASA-20200325">{{cite news |last=Hatfield |first=Mike |title=Revisiting Decades-Old Voyager 2 Data, Scientists Find One More Secret – Eight and a half years into its grand tour of the solar system, NASA's Voyager 2 spacecraft was ready for another encounter. It was Jan. 24, 1986, and soon it would meet the mysterious seventh planet, icy-cold Uranus. |url=https://www.nasa.gov/feature/goddard/2020/revisiting-decades-old-voyager-2-data-scientists-find-one-more-secret  |date=25 March 2020 |work=[[Organization:NASA|NASA]] |access-date=27 March 2020 }}</ref><ref name="NYT-20200327">{{cite news |last=Andrews |first=Robin George |title=Uranus Ejected a Giant Plasma Bubble During Voyager 2's Visit – The planet is shedding its atmosphere into the void, a signal that was recorded but overlooked in 1986 when the robotic spacecraft flew past. |url=https://www.nytimes.com/2020/03/27/science/uranus-bubble-voyager.html |date=27 March 2020 |work={{wipe|The New York Times}} |access-date=27 March 2020 }}</ref>

=={{anchor|Proposed Uranus missions}}Proposed missions==

{| class="wikitable floatright"
|-
! Mission concepts<br/> to Uranus !! Agency/country !! Type
|-
| [[Engineering:MUSE (spacecraft)|MUSE]] || ESA || orbiter and <br/> atmospheric probe
|-
| [[Astronomy:Oceanus (Uranus orbiter)|Oceanus]] || NASA/JPL || orbiter
|-
| [[Astronomy:ODINUS|ODINUS]] || ESA || twin orbiters around Uranus and [[Astronomy:Neptune|Neptune]]
|-
| [[Astronomy:NASA Uranus orbiter and probe|NASA Uranus orbiter and probe]] || NASA || orbiter and <br/> atmospheric probe
|-
| [[Astronomy:Uranus Pathfinder|Uranus Pathfinder]] || United Kingdom || orbiter
|-
| [[Astronomy:Tianwen-4|Tianwen-4]] || CNSA || flyby probe
|}


A number of missions to Uranus have been proposed. Scientists from the [[Organization:Mullard Space Science Laboratory|Mullard Space Science Laboratory]] in the {{wipe|United Kingdom}} have proposed the joint NASA–ESA ''[[Astronomy:Uranus Pathfinder|Uranus Pathfinder]]'' mission to Uranus. A call for a medium-class (M-class) mission to the planet to be launched in 2022 was submitted to the ESA in December 2010 with the signatures of 120 scientists from across the globe. The ESA caps the cost of M-class missions at €470 million.<ref>{{cite web| url=http://www.mssl.ucl.ac.uk/planetary/missions/uranus/|title=Uranus Pathfinder| year=2010| author=Arridge, Chris|access-date=January 10, 2011}}</ref><ref name=Uran1>{{cite news| first=Paul| last=Sutherland| title=Scientists plan Uranus probe| work=The Christian Science Monitor| date=January 7, 2011| access-date= January 16, 2011| url=http://www.csmonitor.com/Science/Cool-Astronomy/2011/0107/Scientists-plan-Uranus-probe}}</ref><ref>[http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=47570 ESA official website: "Call for a Medium-size mission opportunity for a launch in 2022"]. January 16, 2011. Retrieved January 16, 2011.</ref>

In 2009, a team of planetary scientists from NASA's [[Organization:Jet Propulsion Laboratory|Jet Propulsion Laboratory]] advanced possible designs for a solar-powered Uranus orbiter. The most favorable launch window for such a probe would have been in August 2018, with arrival at Uranus in September 2030. The science package would have included magnetometers, particle detectors and, possibly, an imaging camera.<ref name=Hofstadter2008>{{cite web| last=Hofstadter| first=Mark| url=http://www.spacepolicyonline.com/pages/images/stories/PSDS%20Sat1%20Hofstadter-Uranus%20and%20Sat%20Sci.pdf| title=The Case for a Uranus Orbiter and How it Addresses Satellite Science| year=2009| access-date=May 26, 2012| archive-date=May 16, 2018| archive-url=https://web.archive.org/web/20180516103222/http://www.spacepolicyonline.com/pages/images/stories/PSDS%20Sat1%20Hofstadter-Uranus%20and%20Sat%20Sci.pdf| url-status=dead}} See also a [http://www.lpi.usra.edu/decadal/opag/UranusOrbiter_v7.pdf draft].</ref>

In 2011, the United States National Research Council recommended a Uranus orbiter and probe as the third priority for a NASA Flagship mission by the NASA [[Astronomy:Planetary Science Decadal Survey|Planetary Science Decadal Survey]].
However, this mission was considered to be lower-priority than future missions to Mars and the Jovian System, which would later become ''[[Astronomy:Mars 2020|Mars 2020]]'' and ''[[Astronomy:Europa Clipper|Europa Clipper]]''.<ref name=Uran2>{{cite news| url=https://www.reuters.com/article/us-space-usa-future-idUSTRE7266XJ20110308?pageNumber=2| title=Lean U.S. missions to Mars, Jupiter moon recommended |work={{wipe|Reuters}}| author=Deborah Zabarenko| date=March 7, 2011| access-date=March 13, 2011}}</ref><ref name="2013-2022/Decadal">{{cite press release| publisher=National Academies| year=2011| title=Vision and Voyages for Planetary Science in the Decade 2013–2022| url=http://solarsystem.nasa.gov/docs/Vision_and_Voyages-FINAL.pdf| access-date=March 7, 2011}}</ref><ref>Mark Hofstadter, [http://www.spacepolicyonline.com/images/stories/PSDS%20GP1%20Hofstadter_Uranus%20Orbiter.pdf "Ice Giant Science: The Case for a Uranus Orbiter"], Jet Propulsion Laboratory/California Institute of Technology, ''Report to the Decadal Survey Giant Planets Panel,'' 24 August 2009</ref>

A mission to Uranus is one of several proposed uses under consideration for the unmanned variant of NASA's heavy-lift [[Astronomy:Space Launch System|Space Launch System]] (SLS) currently in development. The SLS would reportedly be capable of launching up to 1.7 metric tons to Uranus.<ref>{{cite web| url=http://www.nasaspaceflight.com/2013/11/new-sls-options-new-large-upper-stage/| title=New SLS mission options explored via new Large Upper Stage|last=Gebhardt| first=Chris| publisher=NASAspaceflight.com|date=November 20, 2013}}</ref>

In 2013, it was proposed to use an [[Engineering:Electric sail|electric sail]] (E-Sail) to send an atmospheric entry probe to Uranus.<ref>[https://arxiv.org/abs/1312.6554 Fast E-sail Uranus entry probe mission]</ref>

In 2015, NASA announced it had begun a feasibility study into the possibility of orbital missions to Uranus and Neptune, within a budget of $2 billion in 2015 dollars. According to NASA's planetary science director Jim Green, who initiated the study, such missions would launch in the late 2020s at the earliest, and would be contingent upon their endorsement by the planetary science community, as well as NASA's ability to provide nuclear power sources for the spacecraft.<ref>{{cite web|url=http://spacenews.com/nasa-to-study-uranus-neptune-missions/|title=NASA To Study Uranus, Neptune Orbiters|last=Leone|first=Dan|publisher=Space News|date=August 25, 2015}}</ref> Conceptual designs for such a mission are currently{{when|date=April 2023}} being analyzed.<ref>Stephen Clark [http://spaceflightnow.com/2015/08/25/uranus-neptune-in-nasas-sights-for-new-robotic-mission/ "Uranus, Neptune in NASA's sights for new robotic mission"], ''Spaceflight Now,''
August 25, 2015</ref>

[[Engineering:MUSE (spacecraft)|MUSE]], conceived in 2012 and proposed in 2015, is a European concept for a dedicated mission to the planet Uranus to study its [[Astronomy:Atmosphere of Uranus|atmosphere]], interior, [[Astronomy:Moons of Uranus|moons]], [[Astronomy:Rings of Uranus|rings]], and [[Earth:Magnetosphere of Uranus|magnetosphere]].<ref name='Bocanegra 2015'>{{cite journal|title=MUSE Mission to the Uranian System: Unveiling the evolution and formation of ice giants
|first1=Tatiana 
|last1=Bocanegra-Bahamón
|url=https://mlaneuville.github.io/papers/Bocanegra+2015.pdf
|doi=10.1016/j.asr.2015.01.037
|journal= Advances in Space Research
|year= 2015|volume=55 
|issue=9 
|pages=2190–2216 
|bibcode=2015AdSpR..55.2190B}}</ref> It is suggested to be launched with an [[Engineering:Ariane 5|Ariane 5]] rocket in 2026, arriving at Uranus in 2044, and operating until 2050.<ref name='Bocanegra 2015'/>

In 2016, another mission concept was conceived, called [[Astronomy:Oceanus (Uranus orbiter)|Origins and Composition of the Exoplanet Analog Uranus System]] (OCEANUS), and it was presented in 2017 as a potential contestant for a future [[Astronomy:New Frontiers program|New Frontiers program]] mission.<ref>[https://www.hou.usra.edu/meetings/V2050/pdf/8147.pdf New Frontiers-Class Missions to the Ice Giants]. C. M. Elder, A. M. Bramson, L. W. Blum, H. T. Chilton, A. Chopra, C. Chu6, A. Das, A. Davis, A. Delgado, J. Fulton, L. Jozwiak, A. Khayat, M. E. Landis, J. L. Molaro, M. Slipski, S. Valencia11, J. Watkins, C. L. Young, C. J. Budney, K. L. Mitchell. Planetary Science Vision 2050 Workshop 2017 (LPI Contrib. No. 1989).</ref>

In 2022, the Uranus orbiter and probe mission was placed as the highest priority for a NASA Flagship mission by the [[Astronomy:Planetary Science Decadal Survey#2023–2032, Origins, Worlds, and Life|2023–2032 Planetary Science Decadal Survey]], ahead of the [[Engineering:Enceladus Orbilander|Enceladus Orbilander]] and the ongoing [[Astronomy:Mars sample-return mission|Mars Sample Return]] program, due to the lack of knowledge about [[Astronomy:Ice giant|ice giants]].<ref>{{cite web |title=Planetary Science and Astrobiology Decadal Survey 2023–2032 |url=https://www.nationalacademies.org/our-work/planetary-science-and-astrobiology-decadal-survey-2023-2032 |access-date=17 May 2022 |website=National Academies}}</ref>

Future launch windows are available between 2030 and 2034.<ref>{{cite web|url=https://www.planetary.org/articles/20170621-revisiting-ice-giants|title=Revisiting the ice giants: NASA study considers Uranus and Neptune missions|access-date=31 July 2020|date=21 June 2017|last=Davis|first=Jason|publisher=Planetary Society}}</ref>

China plans to send its first exploration mission to Uranus in 2045 as part of ''Tianwen-4''.<ref>{{cite news|title=China wants to probe Uranus and Jupiter with 2 spacecraft on one rocket|first=Andrew |last=Jones|date=September 22, 2022|url=https://www.space.com/china-probes-jupiter-uranus-same-launch|website=space.com|access-date=February 5, 2023}}</ref><ref>{{cite web|url=http://www.chinadaily.com.cn/china/2017-09/20/content_32245016.htm |title=China's Mars mission 'going smoothly', chief designer says – China |publisher=Chinadaily.com.cn |date= |accessdate=2022-05-26}}</ref><ref name=AJ2023>{{Cite web |url=https://www.planetary.org/articles/chinas-plans-for-outer-solar-system-exploration|title=China's plans for outer Solar System exploration|author=Andrew Jones |date=2023-12-21 |publisher=
The Planetary Society|language=en |accessdate=2023-12-27}}</ref>

== See also ==
* [[Astronomy:Exploration of Mercury|Exploration of Mercury]]
* Exploration of Venus
* [[Astronomy:Exploration of Mars|Exploration of Mars]]
* [[Astronomy:Exploration of Jupiter|Exploration of Jupiter]]
* [[Astronomy:Exploration of Saturn|Exploration of Saturn]]
* [[Astronomy:Exploration of Neptune|Exploration of Neptune]]

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

==Bibliography==
*{{cite web | title=Uranus Science Results | work=Voyager Science Results at Uranus | publisher=NASA| url=http://voyager.jpl.nasa.gov/science/uranus.html | access-date=February 27, 2013}}
*{{Cite journal | pages = 39–43 | issue = 4759 | year = 1986 | pmid =  17812888| bibcode = 1986Sci...233...39S| volume = 233 | journal = Science | last2 = Miner | first1 = E. C. | first2 = E. D. | doi = 10.1126/science.233.4759.39 | title = The Voyager 2 Encounter with the Uranian System | last1 = Stone| s2cid = 32861151 }}
*{{cite journal| first= Gore |last=Rick|title=Uranus Voyager visits a dark planet|journal=National Geographic |year=1986 |volume=170|issue=2 |pages=178–195|bibcode=1986NaGe..170..178G}}

==External links==
* [http://voyager.jpl.nasa.gov NASA ''Voyager'' website]

{{Uranus|state=collapsed}}
{{Planetary exploration}}
{{Voyager program}}
{{Solar System}}

[[Category:Uranus]]
[[Category:Spaceflight]]
[[Category:Discovery and exploration of the Solar System]]

{{Sourceattribution|Exploration of Uranus}}