{"id":442612,"date":"2026-05-24T06:15:14","date_gmt":"2026-05-24T06:15:14","guid":{"rendered":"https:\/\/www.newsbeep.com\/nz\/442612\/"},"modified":"2026-05-24T06:15:14","modified_gmt":"2026-05-24T06:15:14","slug":"its-cracked-and-frozen-but-its-one-of-the-best-places-to-search-for-alien-life-meet-saturns-icy-moon-enceladus","status":"publish","type":"post","link":"https:\/\/www.newsbeep.com\/nz\/442612\/","title":{"rendered":"It’s cracked and frozen, but it’s one of the best places to search for alien life. Meet Saturn’s icy moon Enceladus"},"content":{"rendered":"

Saturn’s icy moon Enceladus is one of the best places to search for signs of alien life in our Solar System.<\/p>\n

The moon has a liquid ocean beneath its frozen crust, meaning it could have the conditions needed to support life.<\/p>\n

It’s a fascinating world. When the Cassini spacecraft conducted its plume dives in 2015, flying through icy eruptions from beneath the surface of Enceladus, it found evidence of organic material.<\/p>\n

Clearly, there’s more to Enceladus than meets the eye. Here are 22 facts about the Saturnian moon.<\/p>\n

\"ImageImage of Saturn’s moon Enceladus. Credit: NASA\/JPL\/Space Science Institute
\nEnceladus is the the 18th-largest moon in the Solar System<\/p>\n

Quite a lot of the Solar System\u2019s natural satellites are bigger, but Enceladus can at least claim to be the sixth-largest moon of Saturn (beaten by Titan, Rhea, Iapetus, Dione and Tethys)\u2026 and sixth out of 292 or so isn\u2019t bad!<\/p>\n

It has a diameter of 500km (310mi)<\/p>\n

That makes Enceladus around 1\/7th the size of Earth\u2019s own Moon, and approximately 1\/10th the size of Saturn\u2019s largest moon, Titan.<\/p>\n

\"AA view of Saturn’s moon Enceladus captured by the Cassini spacecraft on 28 June 2007. In the background can be seen the shadows of Saturn\u2019s rings, cast on the planet\u2019s cloud tops. Credit: NASA\/JPL-Caltech\/Space Science Institute
\nEnceladus is made of rock and ice<\/p>\n

We used to think it was made entirely of ice, but NASA\u2019s Cassini mission<\/a> (2004\u201317) showed that it must have a much higher proportion of metals and silicates than had previously been assumed, based on the gravity it exerted upon the Cassini craft.<\/p>\n

It\u2019s a scalene ellipsoid<\/p>\n

This means that, like a lot of objects in space, it\u2019s a slightly deformed sphere.<\/p>\n

A sphere has three axes of symmetry, all of the same length. Earth \u2013 because it\u2019s flattened slightly at the poles, like a basketball with someone sitting on it \u2013 has two axes of symmetry that are the same and one that\u2019s different, and is classed as an oblate spheroid.<\/p>\n

But Enceladus\u2019s three axes of symmetry are all of different lengths, so it\u2019s a scalene ellipsoid.<\/p>\n

Its diameter can be measured as 497, 503 or 513km, depending on whether you measure between the north and south poles, between the trailing and leading hemisphere, or between the sub-Saturnian and anti-Saturnian poles.<\/p>\n

\"AA plume of water erupting from Saturn’s icy moon Enceladus. Credit: NASA\/JPL-Caltech<\/p>\n

\"Enceladus:Credit: NASA\/JPL-Caltech\/Space Science Institute
\nEnceladus is covered in snow<\/p>\n

Enceladus is one of the most reflective bodies in the Solar System \u2013 and that\u2019s because the entire surface is covered in a layer of snow.<\/p>\n

We\u2019re not talking a light dusting here, either \u2013 the blanket of snow in which this natural satellite is wrapped is up to 700 metres (2,300 feet) deep in some places!<\/p>\n

It has an icy crust<\/p>\n

Debate rages as to how differentiated or otherwise the interior of Enceladus may be \u2013 is it neatly stratified into layers, like Earth\u2019s interior, or are different materials all jumbled up together?<\/p>\n

But what we do know is that it has an icy crust that is unconnected to its core, and that said crust ranges in thickness from just a few kilometres at the poles to a maximum depth of 30-40km, with an average thickness of c.20-25km.<\/p>\n

\"Artist'sArtist’s impression of the interior of Saturn’s moon Enceladus. Credit: NASA\/JPL-Caltech
\nEnceladus has a vast subsurface ocean<\/p>\n

The reason Enceladus\u2019s crust is detached from its core is that it\u2019s basically floating atop a vast underground ocean.<\/p>\n

This ocean is believed to have an average depth of around 26-31km (16-19mi); for comparison\u2019s sake, average ocean depth on Earth is around 3.6km (2.2mi), though the deepest areas can reach 11km (7mi).<\/p>\n

That ocean may support life<\/p>\n

Enceladus is thought by astrobiologists to be one of the best places in the Solar System to look for extraterrestrial life.<\/p>\n

That\u2019s partly because there\u2019s so much water there, and partly because there\u2019s evidence of hydrothermal activity in its subsurface ocean.<\/p>\n

On Earth, there are extremophile bacteria that live around hydrothermal vents on the ocean floor, in an environment that would be extremely toxic to humans.<\/p>\n

There is no obvious reason why similar vents on Enceladus shouldn\u2019t support similar forms of life.<\/p>\n

\"AA plume of water vapour emanating from the subsurface ocean of Saturn’s icy moon Enceladus, as seen by the James Webb Space Telescope. Credit: NASA, ESA, CSA, Geronimo Villanueva (NASA-GSFC). Processing: Alyssa Pagan (STScI)
\nEnceladus’s ocean is highly alkaline<\/p>\n

Earth\u2019s oceans have a pH of around 8.1 \u2013 down from 8.2, where we were a century ago (which is why environmentalists talk about the \u2018acidification\u2019 of the oceans), but still alkaline.<\/p>\n

The pH of Enceladus\u2019s sub-surface ocean, however, is around 11 or 12 \u2013 roughly the same as household bleach.<\/p>\n

It\u2019s got beautiful plumage!<\/p>\n

Perhaps the most interesting thing about Enceladus are the huge, water-rich plumes that erupt from its south polar region.<\/p>\n

These are similar to the geysers we see here on Earth, except that they more closely resemble \u2018curtains\u2019 of water rather than narrow jets \u2013 and that they can extend up to 310km (500mi) out into space, travelling at speeds in excess of 2,000km\/h (1,250mph) and transporting 200kg of water and water vapour out into space every second.<\/p>\n

\"AA global map of Enceladus produced using data captured by the Cassini spacecraft during its first 10 years at Saturn. Credit: NASA
\nEnceladus is the source of Saturn\u2019s E Ring<\/p>\n

Enceladus\u2019s orbital path lies entirely within Saturn\u2019s E Ring, the outermost of its main rings (though the faint Phoebe ring is even more distant), and scientists now believe that the ring is in fact composed of material ejected in Enceladus\u2019s plumes.<\/p>\n

It\u2019s cold and it snows a lot<\/p>\n

Material from the plumes that doesn\u2019t get whisked off into outer space to form the E Ring instead falls back to Enceladus in the form of snow.<\/p>\n

So it\u2019s no surprise that it\u2019s a bit parky there: the average daytime surface temperature is -198\u00b0C.<\/p>\n

\"TheThe plumes of Enceladus feed into Saturn’s E-ring, a wide ring made up of tiny particles, rather than larger blocks of ice. Image Credit: NASA
\nEnceladus was discovered by William Herschel<\/p>\n

German-British astronomer William Herschel became the first person to view Enceladus through a telescope on 28 August 1789\u2026 though he was, it should be pointed out, using the world\u2019s largest telescope at the time!<\/p>\n

The name was suggested by Herschel\u2019s son<\/p>\n

In 1847, William Herschel\u2019s son John, also a keen astronomer, published his Results of Astronomical Observations made at the Cape of Good Hope, in which he suggested that Saturn\u2019s moons should be named after characters from Greek mythology. His proposal was adopted.<\/p>\n

\"TheThe heavily-cratered north pole of Enceladus. Credit: NASA\/JPL\/Caltech
\nEnceladus takes 32.9 hours to orbit Saturn<\/p>\n

Enceladus whizzes around its host planet so fast that its motion can be seen in a single night\u2019s observing (whereas an observer on Enceladus, looking at Earth\u2019s Moon, would need to study the satellite for several nights before any motion became apparent).<\/p>\n

It is tidally locked with Saturn, with its orbital path lying about 180,000km (110,000mi) above the Saturnian cloud tops, and about 238,000km (148,000mi) above Saturn\u2019s center.<\/p>\n

It has diverse terrain and topography<\/p>\n

Enceladus has regions of smooth plain, and other areas that show evidence of both impacts and tectonic activity, in the form of rilles, ridges, cliffs and so on.<\/p>\n

Such geological features are named after characters and places featured in Richard Francis Burton\u2019s 1885 translation of The Book of One Thousand and One Nights (AKA Arabian Nights).<\/p>\n

\"TheThe south pole of Enceladus, produced using data captured by the Cassini spacecraft. Credit: NASA
\nEnceladus’s south polar region has four large, near-parallel depressions<\/p>\n

Known as the \u201ctiger stripes,\u201d these four depressions average 130km (80mi) long, 2km (1.25mi) wide and 500m (1,640ft) deep, with flanking ridges 100m (330ft) tall and 2-4km (1.25-2.5mi) wide.<\/p>\n

The ice in this region is rougher-grained than ice elsewhere on the surface, and they are believed to have resulted from cryovolcanism (ice volcanoes).<\/p>\n

It has a thin, tenous atmosphere<\/p>\n

There isn\u2019t much of an atmosphere at all on Enceladus. What there is, seems to be concentrated above the south polar region, and consist mostly of water vapour.<\/p>\n

\"AA close-up view of Enceladus captured by the Cassini spacecraft during its closest dive past Saturn’s icy moon. Credit: NASA
\nWe knew little about Enceladus for two whole centuries<\/p>\n

Herschel might have discovered Enceladus in 1789, but fast forward to the late 1970s and we still didn\u2019t know much about it except its location and its orbital path (and rough estimates of its mass and density).<\/p>\n

That all changed with the Voyager missions.<\/p>\n

Voyager 1 flew by at a distance of 202,000km (125,520mi) on 12 November 1980, sending back grainy images that revealed the presence of smooth plains on the surface, and confirmed its orbital position within the E Ring.<\/p>\n

The following year, Voyager 2 got closer, coming within 87,010km (54,065mi) of the surface on 26 August 1981, and sent back higher-resolution images that revealed the extent of tectonic activity on its surface.<\/p>\n

\"AA view of grooves in the southern region of Saturn’s icy moon Enceladus. In the centre is a strip of radar data, which has been laid over an earlier visible-light image of the same region. Both sets of data were captured by the Cassini spacecraft. Credit: NASA
\nMost of what we know about Enceladus is thanks to Cassini<\/p>\n

Funded jointly by NASA, ESA and the Italian space agency ASI, the Cassini-Huygens mission launched from Cape Canaveral on 15 October 1997.<\/p>\n

Cassini went into orbit around Saturn in 2004 and stayed there until 2017, carrying out numerous fly-bys of Enceladus during that time\u00a0\u2013\u00a0the closest coming within 49km (30mi) of the surface.<\/p>\n

Cassini first discovered the plumes that emanate from Enceladus\u2019s south pole, then flew through them \u2013 gathering a trove of scientific data for analysis.<\/p>\n

It\u2019s because of these fly-throughs, for instance, that we know the plumes don\u2019t just consist of water.<\/p>\n

There are also traces of carbon dioxide, molecular nitrogen and simple hydrocarbons such as methane, propane, acetylene and formaldehyde.<\/p>\n

Having that detailed information available enabled scientists to develop a much more informed picture of Enceladus\u2019s composition and structure.<\/p>\n

\"AnAn elevated view of Enceladus’s south pole, as seen by the Cassini spacecraft. The view looks across the region of Enceladus’ geyser basin and down on the ends of the Baghdad and Damascus fractures. Credit: NASA
\nEnceladus’s plumes contain compounds believed essential for life<\/p>\n

More detailed analysis of Cassini data has, in the past few years, thrown up several surprises.<\/p>\n

These include the presence in the plumes not just of hydrogen<\/a> (providing evidence for hydrothermal activity in its subsurface ocean) but also of hydrogen cyanide, other organic molecules and various phosphates.<\/p>\n

Such materials are often held up as \u201cthe building blocks of life,\u201d fuelling further interest in Enceladus as a good place to look for extraterrestrial life.<\/p>\n

Sadly, no further missions are currently planned<\/p>\n

With astrobiologists keen to learn more about Enceladus, several mission proposals have been put forward for consideration by different space agencies, but most of these have already been rejected.<\/p>\n

One or two are still under consideration, including NASA\u2019s Enceladus Orbilander and ESA\u2019s L4 lander and orbiter, but no such mission has yet been given the green light.<\/p>\n","protected":false},"excerpt":{"rendered":"Saturn’s icy moon Enceladus is one of the best places to search for signs of alien life in…\n","protected":false},"author":2,"featured_media":442613,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[23],"tags":[111,139,69,147,392],"class_list":["post-442612","post","type-post","status-publish","format-standard","has-post-thumbnail","category-space","tag-new-zealand","tag-newzealand","tag-nz","tag-science","tag-space"],"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/posts\/442612","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/comments?post=442612"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/posts\/442612\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/media\/442613"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/media?parent=442612"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/categories?post=442612"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/tags?post=442612"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}