The Voyager<\/a> data remains a treasure trove of information on the planets<\/a>\u2019 interiors, atmospheres and diverse satellites.<\/span><\/p>\n But with only a single encounter recorded for each planet, we haven\u2019t even scratched the surface of these worlds. Out there on the \u2018frozen frontier\u2019, discoveries await the next robotic explorers.<\/span><\/p>\n This leads many to ask why we haven\u2019t sent any more spacecraft or orbiters to visit Uranus and Neptune.<\/p>\n Today, the international community is lobbying space agencies to mount a mission to these ice giants, the only major class of planet yet to have a dedicated orbital explorer.<\/span><\/p>\n The scale of the challenge is matched by the scientific importance of these two worlds.<\/span><\/p>\n As we gaze out to exoplanets<\/a>, we\u2019ve realised that worlds of a similar size to our ice giants are commonplace.<\/span><\/p>\n By contrast, the larger gas giants like Jupiter<\/a> and Saturn<\/a> seem rare. And yet we still struggle to understand how Uranus and Neptune<\/a> formed.<\/span><\/p>\n Giant planet formation is essentially a race between accretion of gas onto an embryonic rock-ice core, and the dissipation of that gas.<\/span><\/p>\n To achieve worlds similar in size to Uranus and Neptune requires fine-tuning of this relationship and we need to know much more:<\/span><\/p>\n To understand their evolution, we need a mission capable of measuring gravitational and magnetic fields<\/a>, directly sampling the planetary composition, and studying the atmospheres and magnetospheres.<\/span><\/p>\n The ice giants are the missing link, the piece of the puzzle to help us unlock the mysteries of planet formation.<\/span><\/p>\n Uranus<\/a> presents extreme seasons and magnetic fields, a consequence of the cataclysmic impact that tilted it onto its side, whereas Neptune<\/a>\u2019s powerful meteorology is driven by heat from within that\u2019s absent (or locked away) on Uranus.<\/span><\/p>\n Uranus has a classical system of satellites and delicate rings. Neptune, conversely, possesses an interloper from the Kuiper Belt<\/a>: the massive moon Triton (incidentally, the target of a future planned mission called Trident<\/a>).<\/span><\/p>\n These worlds can\u2019t be effectively studied remotely: we have to visit them with sophisticated new spacecraft in order to reveal terrains that were in total darkness for Voyager 2, 30 years ago.<\/span><\/p>\n With such tantalising potential for discoveries, why haven\u2019t we returned to the ice giants since the 1980s?<\/span><\/p>\n Reaching 20 or 30 AU requires an international effort and some good timing. With today\u2019s rockets and chemical propulsion, we need to slingshot around Jupiter, to get as much mass as possible into orbit around Uranus or Neptune.<\/span><\/p>\n That means Jupiter must be in just the right place, which happens once every 12\u201313 years.\u00a0<\/span>The next window is in the early 2030s, so we have no time to lose.<\/span><\/p>\n ESA and NASA are currently developing plans for planetary exploration over the next decade, and if they see the ice giants as the highest priority, then we can be ready.<\/span><\/p>\n Because the discoveries could be astonishing and they\u2019re out there, waiting for us.<\/span><\/p>\n This article originally appeared in the November 2021 issue of BBC Sky at Night Magazine.<\/strong><\/em><\/p><\/body><\/html>\n By Leigh Fletcher Published: Monday, 25 October 2021 at 12:00 am During the 1980s, the Voyager 2 spacecraft transformed our view of the ice giants Uranus and Neptune from mere wandering points of light to complex and beautiful planetary systems. The Voyager data remains a treasure trove of information on the planets\u2019 interiors, atmospheres and […]<\/p>\n","protected":false},"author":24,"featured_media":25919,"template":"","categories":[1],"acf":{"readingTimeMinutes":"4"},"uagb_featured_image_src":{"full":["https:\/\/c01.purpledshub.com\/uploads\/sites\/77\/2021\/10\/why-we-need-to-return-to-uranus-and-neptune-scaled.jpg",2560,1280,false],"thumbnail":["https:\/\/c01.purpledshub.com\/uploads\/sites\/77\/2021\/10\/why-we-need-to-return-to-uranus-and-neptune-150x150.jpg",150,150,true],"medium":["https:\/\/c01.purpledshub.com\/uploads\/sites\/77\/2021\/10\/why-we-need-to-return-to-uranus-and-neptune-300x150.jpg",300,150,true],"medium_large":["https:\/\/c01.purpledshub.com\/uploads\/sites\/77\/2021\/10\/why-we-need-to-return-to-uranus-and-neptune-768x384.jpg",768,384,true],"large":["https:\/\/c01.purpledshub.com\/uploads\/sites\/77\/2021\/10\/why-we-need-to-return-to-uranus-and-neptune-1024x512.jpg",800,400,true],"1536x1536":["https:\/\/c01.purpledshub.com\/uploads\/sites\/77\/2021\/10\/why-we-need-to-return-to-uranus-and-neptune-1536x768.jpg",1536,768,true],"2048x2048":["https:\/\/c01.purpledshub.com\/uploads\/sites\/77\/2021\/10\/why-we-need-to-return-to-uranus-and-neptune-2048x1024.jpg",2048,1024,true]},"uagb_author_info":{"display_name":"importmanagerhub@sprylab.com","author_link":"https:\/\/c01.purpledshub.com\/bbcskyatnight\/author\/importmanagerhubsprylab-com\/"},"uagb_comment_info":0,"uagb_excerpt":"By Leigh Fletcher Published: Monday, 25 October 2021 at 12:00 am During the 1980s, the Voyager 2 spacecraft transformed our view of the ice giants Uranus and Neptune from mere wandering points of light to complex and beautiful planetary systems. The Voyager data remains a treasure trove of information on the planets\u2019 interiors, atmospheres and…","_links":{"self":[{"href":"https:\/\/c01.purpledshub.com\/bbcskyatnight\/wp-json\/wp\/v2\/rss_feed\/25918"}],"collection":[{"href":"https:\/\/c01.purpledshub.com\/bbcskyatnight\/wp-json\/wp\/v2\/rss_feed"}],"about":[{"href":"https:\/\/c01.purpledshub.com\/bbcskyatnight\/wp-json\/wp\/v2\/types\/rss_feed"}],"author":[{"embeddable":true,"href":"https:\/\/c01.purpledshub.com\/bbcskyatnight\/wp-json\/wp\/v2\/users\/24"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/c01.purpledshub.com\/bbcskyatnight\/wp-json\/wp\/v2\/media\/25919"}],"wp:attachment":[{"href":"https:\/\/c01.purpledshub.com\/bbcskyatnight\/wp-json\/wp\/v2\/media?parent=25918"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/c01.purpledshub.com\/bbcskyatnight\/wp-json\/wp\/v2\/categories?post=25918"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}![\""An\"](\""https:\/\/images.immediate.co.uk\/production\/volatile\/sites\/25\/2019\/04\/04-Voyager-Uranus-03d6e09.jpg?quality=90&resize=620%2C350"\" "\\"\"An\\"\/")
<\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/picture><\/div>Why explore Uranus and Neptune?<\/strong><\/h2>\n
![\""Cloud\"](\""https:\/\/images.immediate.co.uk\/production\/volatile\/sites\/25\/2020\/08\/Voyager-Neptune-a71416a.jpg?quality=90&resize=620%2C490"\" "\\"\"Cloud\\"\/")
<\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/picture><\/div>![\""A\"](\""https:\/\/images.immediate.co.uk\/production\/volatile\/sites\/25\/2021\/10\/Voyager-crescent-Uranus-c3a971d.jpg?quality=90&resize=620%2C510"\" "\\"\"A\\"\/")
<\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/picture><\/div>![\""Neptune's\"](\""https:\/\/images.immediate.co.uk\/production\/volatile\/sites\/25\/2021\/10\/Neptune-great-dark-spot-c6f361a.jpeg?quality=90&resize=620%2C755"\" "\\"\"Neptune\\"\/")
<\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/picture><\/div>Why haven\u2019t we been back to Uranus or Neptune?<\/strong><\/h2>\n
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