A cutaway view of Saturn's moon Enceladus, showing possible hydrothermal activity that may be taking place on and under the seafloor of its subsurface ocean. Image: NASA/JPL
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The unexpectedly watery moons of our Solar System may be friendlier to life than we thought

Secret oceans on the moons Enceladus and Ganymede were discovered within days of each other, reshaping our belief that the Earth is the Solar System's most watery, life-friendly habitat.

Jupiter’s moon Ganymede is named after the cup-bearer of the Greek gods; Saturn's sixth-largest moon, Enceladus, is named after a giant. Both names seem extra fitting in the light of recent, and surprisingly big, news about water.

In the (best-ever) anime series Cowboy Bebop, Ganymede is depicted as an aquatic, terraformed world entirely covered in water - and this may well be more accurate than we first thought, as Nasa’s Hubble Space Telescope has confirmed the existence of subsurface water on the huge moon by watching how its aurora lights slither around its edges. Astronomers believe this ocean, hidden underneath around 153km of crusty ice, is ten times deeper than those of Earth.

This new discovery has hoisted Ganymede up the list of the top contenders for places in our Solar System which could potentially harbour life. It also has relatively good timing - the European Space Agency (ESA) is currently working on mission plans ahead of the launch of the Jupiter Icy Moon Explorer (or Juice for short) in 2022, with the aim of getting a closer inspection of Jupiter’s moons Ganymede, Callisto and Europa through the 2030s.

Speculation about Ganymede’s secret ocean is not a new one, as scientists have suspected its existence since the 1970s, despite inconclusive evidence. What sets Ganymede apart from any other moon (aside from its size - it's larger than Mercury) is its self-generating magnetic field, which, just like Earth, is caused by its liquid, iron-rich core. This makes the detection of a copious amount of subsurface liquid water easier - more so than any other icy moon in our Solar System - because a magnetic field causes auroras, brightly-coloured ribbons of hot, electrified gas in the atmospheric regions circulating north and south poles. Ganymede is also close enough to Jupiter that their magnetic fields are interlaced, enhancing the aurora even more than usual. When Jupiter’s magnetic field changes, so does Ganymede’s, "rocking" back and forth over about a five hour period.

The auroras of Ganymede give away the existence of a subsurface saltwater ocean because saltwater can generate its own magnetic field when sloshing around, and can also therefore weaken the effects of Jupiter's. Joachim Saur and his colleagues of the University of Cologne in Germany came up with the idea of applying the motions of the two auroras to determine the amount (if any) of saltwater underneath Ganymede’s crust using the Hubble Space Telescope. He told the NS that the data showed that Ganymede had low auroral oscillations compared to models without an ocean - or, in other words, that Ganymede does have a saltwater ocean underneath its crust.

Nasa’s Galileo mission measured Ganymede’s magnetic field in 2002 but couldn’t see the full extent of its magnetic variation as its fly-bys of Ganymede lasted just 20 minutes - far too brief to measure the magnetic field of this subsurface saltwater ocean. Saur’s team instead watched Ganymede using the Hubble Space Telescope for seven hours. The data suggests that the global ocean is between 150 and 250km deep, and this broad range of approximation is likely caused by the presence of what may be two layers of ice sandwiched between the oceans.

So, could there be life on Ganymede? Hubble found evidence of a tenuous oxygen atmosphere in 1996, but it would be far too thin to support life (or, at least as we know it). We’ll have to wait and see if Juice can freshly squeeze anything more concrete when it arrives there, more than 15 years from now. In addition, Saur said that the aruoral technique used for Ganymede can help identify life-friendly water on other planets (or moons) with subsurface oceans outside the Solar System. Hubble isn’t powerful enough to capture these auroras yet, however it's only a matter of time, as more powerful instruments - like the James Webb Space Telescope, due in orbit in 2018 - are on their way.

Enceladus, meanwhile, is slightly different. We know it has water of some kind on it, as it has a crust of fresh, white ice, of thicknesses stretching from 30 to 40km. This gives it a high albedo, meaning it shines light brightly back into space; and it, too, is believed to be hiding a secret, warm, liquid ocean beneath its surface. Ever since Nasa’s Cassini spacecraft first discovered water vapour and ice spewing from vents near the moon’s south pole in 2005, researchers have theorised about the possible presence of liquid water there. 

On Earth, the kind of hydrothermal activity that would cause the ejection of water from vents tends to happen when seawater interacts with gaps in the planetary crust, so the Cassini data seemed to suggest this was what was happening on Enceladus as well. This deduction was strengthened further by the detection of methane in the plumes, and microscopic granules of silica - exactly the kinds of materials that should be generated around underwater vents.

In a Nasa statement, Sean Hsu, a postdoctoral researcher at the University of Colorado and the lead author of the paper published in Nature, said: "It's very exciting that we can use these tiny grains of rock, spewed into space by geysers, to tell us about conditions on - and beneath - the ocean floor of an icy moon." Cassini hit the jackpot with the detection of silicates, which are believed to have come from inside the vents and then became wedged in icy structures called clathrates before being fired upwards into space. It indicates that these volcanic vents are still active, and generating new silicates - and that they're therefore also likely to still be warm enough to support microbial life, if it exists there.

This evidence all strongly suggests that Enceladus contains within it a 10km-deep ocean, with temperatures as high as 90oC in some parts - any little critters down there just have to swim to the hot bit to get to someplace comfy (though the chances of anything bigger than single-cell organisms existing there are extraordinarily slim). Enceladus and Ganymede are now part of a growing list of strong candidates for hosting alien microbial life, as well as Neptune’s moon Triton and Jupiter’s other moon Europa, as well as the dwarf planet Ceres.

Tosin Thompson writes about science and was the New Statesman's 2015 Wellcome Trust Scholar. 

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“Stinking Googles should be killed”: why 4chan is using a search engine as a racist slur

Users of the anonymous forum are targeting Google after the company introduced a programme for censoring abusive language.

Contains examples of racist language and memes.

“You were born a Google, and you are going to die a Google.”

Despite the lack of obscenity and profanity in this sentence, you have probably realised it was intended to be offensive. It is just one of hundreds of similar messages posted by the users of 4chan’s Pol board – an anonymous forum where people go to be politically incorrect. But they haven’t suddenly seen the error of their ways about using the n-word to demean their fellow human beings – instead they are trying to make the word “Google” itself become a racist slur.

In an undertaking known as “Operation Google”, some 4chan users are resisting Google’s latest artificial intelligence program, Conversation AI, by swapping smears for the names of Google products. Conversation AI aims to spot and flag offensive language online, with the eventual possibility that it could automatically delete abusive comments. The famously outspoken forum 4chan, and the similar website 8chan, didn’t like this, and began their campaign which sees them refer to “Jews” as “Skypes”, Muslims as “Skittles”, and black people as “Googles”.

If it weren’t for the utterly abhorrent racism – which includes users conflating Google’s chat tool “Hangouts” with pictures of lynched African-Americans – it would be a genius idea. The group aims to force Google to censor its own name, making its AI redundant. Yet some have acknowledged this might not ultimately work – as the AI will be able to use contextual clues to filter out when “Google” is used positively or pejoratively – and their ultimate aim is now simply to make “Google” a racist slur as revenge.


Posters from 4chan

“If you're posting anything on social media, just casually replace n****rs/blacks with googles. Act as if it's already a thing,” wrote one anonymous user. “Ignore the company, just focus on the word. Casually is the important word here – don't force it. In a month or two, Google will find themselves running a company which is effectively called ‘n****r’. And their entire brand is built on that name, so they can't just change it.”

There is no doubt that Conversation AI is questionable to anyone who values free speech. Although most people desire a nicer internet, it is hard to agree that this should be achieved by blocking out large swathes of people, and putting the power to do so in the hands of one company. Additionally, algorithms can’t yet accurately detect sarcasm and humour, so false-positives are highly likely when a bot tries to identify whether something is offensive. Indeed, Wired journalist Andy Greenberg tested Conversation AI out and discovered it gave “I shit you not” 98 out of 100 on its personal attack scale.

Yet these 4chan users have made it impossible to agree with their fight against Google by combining it with their racism. Google scores the word “moron” 99 out of 100 on its offensiveness scale. Had protestors decided to replace this – or possibly even more offensive words like “bitch” or “motherfucker” – with “Google”, pretty much everyone would be on board.

Some 4chan users are aware of this – and indeed it is important not to consider the site a unanimous entity. “You're just making yourselves look like idiots and ruining any legitimate effort to actually do this properly,” wrote one user, while some discussed their concerns that “normies” – ie. normal people – would never join in. Other 4chan users are against Operation Google as they see it as self-censorship, or simply just stupid.


Memes from 4chan

But anyone who disregards these efforts as the work of morons (or should that be Bings?) clearly does not understand the power of 4chan. The site brought down Microsoft’s AI Tay in a single day, brought the Unicode swastika (卐) to the top of Google’s trends list in 2008, hacked Sarah Palin’s email account, and leaked a large number of celebrity nudes in 2014. If the Ten Commandments were rewritten for the modern age and Moses took to Mount Sinai to wave two 16GB Tablets in the air, then the number one rule would be short and sweet: Thou shalt not mess with 4chan.

It is unclear yet how Google will respond to the attack, and whether this will ultimately affect the AI. Yet despite what ten years of Disney conditioning taught us as children, the world isn’t split into goodies and baddies. While 4chan’s methods are deplorable, their aim of questioning whether one company should have the power to censor the internet is not.

Google also hit headlines this week for its new “YouTube Heroes” program, a system that sees YouTube users rewarded with points when they flag offensive videos. It’s not hard to see how this kind of crowdsourced censorship is undesirable, particularly again as the chance for things to be incorrectly flagged is huge. A few weeks ago, popular YouTubers also hit back at censorship that saw them lose their advertising money from the site, leading #YouTubeIsOverParty to trend on Twitter. Perhaps ultimately, 4chan didn't need to go on a campaign to damage Google's name. It might already have been doing a good enough job of that itself.

Google has been contacted for comment.

Amelia Tait is a technology and digital culture writer at the New Statesman.