{"id":7197,"date":"2014-04-03T19:25:59","date_gmt":"2014-04-03T19:25:59","guid":{"rendered":"http:\/\/hobbyspace.com\/Blog\/?p=7197"},"modified":"2014-04-03T19:31:55","modified_gmt":"2014-04-03T19:31:55","slug":"saturn-moon-enceladus-holds-a-sea-beneath-its-ice-crust","status":"publish","type":"post","link":"https:\/\/hobbyspace.com\/Blog\/?p=7197","title":{"rendered":"Saturn moon Enceladus holds a sea beneath its icy crust"},"content":{"rendered":"

The ESA\/NASA\u00a0Cassini Mission<\/a>\u00a0investigating the Saturn system has detected a large body of liquid water below a thick crust of ice on the moon Enceladus:<\/p>\n

Icy moon Enceladus has underground sea<\/a><\/strong><\/p>\n

Saturn\u2019s icy moon Enceladus has an underground sea of liquid water, according to the international Cassini spacecraft.<\/p>\n

\"\"<\/a>Inside Enceladus<\/em><\/p>\n

Understanding the interior structure of 500 km-diameter Enceladus has been a top priority of the Cassini mission since plumes of ice and water vapour were discovered jetting from \u2018tiger stripe\u2019 fractures at the moon\u2019s south pole in 2005.<\/p>\n

Subsequent observations of the jets showed them to be relatively warm compared with other regions of the moon and to be salty \u2013 strong arguments for there being liquid water below the surface.<\/p>\n

But planetary scientists have now been able to investigate the interior of the enigmatic moon directly, using Cassini\u2019s radio science experiment.<\/p>\n

\"\"
\n<\/a>Enceladus plumes<\/em><\/p>\n

On three separate occasions in 2010 and 2012, the spacecraft passed within 100 km of Enceladus, twice over the southern hemisphere and once over the northern hemisphere.<\/p>\n

During the flybys, Cassini was pulled slightly off course by the moon\u2019s gravity, changing its velocity by just 0.2\u20130.3 millimetres per second.<\/p>\n

As tiny as these deviations were, they were detectable in the spacecraft\u2019s radio signals as they were beamed back to Earth, providing a measurement of how the gravity of Enceladus varied along the spacecraft\u2019s orbit. These measurements could then be used to infer the distribution of mass inside the moon.<\/p>\n

\"\"
\n<\/a>Enceladus’ craters and complex, fractured terrains<\/em><\/p>\n

\n

For example, a higher-than-average gravity \u2018anomaly\u2019 might suggest the presence of a mountain, while a lower-than-average reading implies a mass deficit.<\/p>\n

On Enceladus, the scientists measured a negative mass anomaly at the surface of the south pole, accompanied by a positive one some 30-40 km below.<\/p>\n

\u201cBy analysing the spacecraft\u2019s motion in this way, and taking into account the topography of the moon we see with Cassini\u2019s cameras, we are given a window into the internal structure of Enceladus,\u201d says Luciano Iess, lead author of the results published in\u00a0Science<\/i>.<\/p>\n

\u201cThe perturbations in the spacecraft\u2019s motion can be most simply explained by the moon having an asymmetric internal structure, such that an ice shell overlies liquid water at a depth of around 30\u201340 km in the southern hemisphere.\u201d<\/p>\n

While the gravity data cannot rule out a global ocean, a regional sea extending from the south pole to 50\u00baS latitude is most consistent with the moon\u2019s topography and high local temperatures observed around the tiger stripes.<\/p>\n

\u201cThis experiment provides a crucial new piece of information towards understanding the formation of plumes on this intriguing moon,\u201d says Nicolas Altobelli, ESA\u2019s Cassini project scientist.<\/p>\n

—<\/p>\n

More information<\/strong><\/p>\n

\u201cThe gravity field and interior structure of Enceladus,\u201d by L. Iess et al, is published in\u00a0Science<\/i>, 4 April 2014.<\/p>\n

The Cassini\u2013Huygens mission is a cooperative project of NASA, ESA and ASI, the Italian space agency. NASA\u2019s Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA\u2019s Science Mission Directorate, Washington.<\/p>\n<\/div>\n

<\/div>\n","protected":false},"excerpt":{"rendered":"

The ESA\/NASA\u00a0Cassini Mission\u00a0investigating the Saturn system has detected a large body of liquid water below a thick crust of ice on the moon Enceladus: Icy moon Enceladus has underground sea Saturn\u2019s icy moon Enceladus has an underground sea of liquid water, according to the international Cassini spacecraft. Inside Enceladus Understanding the interior structure of 500 … Continue reading Saturn moon Enceladus holds a sea beneath its icy crust<\/span> →<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"jetpack_post_was_ever_published":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":""},"categories":[87,13],"tags":[],"class_list":["post-7197","post","type-post","status-publish","format-standard","hentry","category-et-al","category-space-science"],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"jetpack_shortlink":"https:\/\/wp.me\/p34aWK-1S5","jetpack-related-posts":[{"id":13919,"url":"https:\/\/hobbyspace.com\/Blog\/?p=13919","url_meta":{"origin":7197,"position":0},"title":"Cassini: Magnetic anomaly leads to an ocean world circling Saturn","author":"TopSpacer","date":"February 16, 2017","format":false,"excerpt":"Saturn's little moon Enceladus has turned out to be one of the most interesting objects in the solar system: Cassini: Mission to Saturn: An Ice World...With an Ocean? 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