Comet 67P/Churyumov-Gerasimenko by Rosetta’s OSIRIS narrow-angle camera. Image: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA
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Rosetta becomes the first spacecraft to ever go into orbit around a comet

After a ten year chase, Rosetta became the first ever spacecraft to intercept and go into orbit around a comet - and over the next 18 months will begin searching for clues left over from the earliest moments of our Solar System.

Yesterday, after ten years of chasing, the European Space Agency’s (ESA) Rosetta spacecraft became the first ever to intercept and go into orbit around a comet. Now scientists can begin the next step in one of the most exciting investigations into how the Solar System formed that we’ve seen so far.

ESA scientists brought Rosetta to within 100km of the comet – a 3km by 5km rock called 67P Churyumov-Gerasimenko – and established a stable orbit by slowing it down with its thrusters. Perhaps surprisingly, while it’s taken ten years to get there, 67P was only discovered 50 years ago, but while not as famous a comet as Halley it’s just as scientifically interesting. Comets are considered to be primitive building blocks of the Solar System, and relics of the formation of the planets, while some even believe that they provided Earth with both water and other key ingredients too which were necessary for igniting the evolution of life. 

67P was first discovered in 1969 by Soviet astronomers Ivanovych Churyumov and Svetlana Ivanova Gerasimenko. The hope is that Rosetta will unlock the secrets of this early history – which is why it was named after the Rosetta Stone, the discovery of which in 1799 provided the key to translating Ancient Egyptian hieroglyphs and Demotic script into Ancient Greek (and thus any other language). It was launched from Europe’s spaceport in Kourou, French Guiana, in March 2004, into a long journey of loops around the Sun as it aimed to get onto the same trajectory as 67P.

Rosetta has trekked over 6bn km, passing by Earth three times, Mars once, and soaring past two asteroids, using the gravitational pull of those objects to change velocity and catch up with 67P. The riskiest part of this was when it was put into hibernation mode for 31 months to conserve power as its orbit brought it out to a distance roughly equal to the orbit of Jupiter and then back in again – where it was successfully awakened in January of this year, for the final part of the voyage.

Since May, Rosetta has performed a series of ten rendezvous manoeuvres to gradually fine-tune the spacecraft’s speed and trajectory to match those of the comet, which travels through space at speeds of up to 135,000km/h. Despite the unprecedented complexity of the mission, Rosetta’s smooth arrival was confirmed yesterday morning.

Here’s a video from the ESA showing Rosetta’s near-decade-long journey, and here’s how it’s going to orbit around 67P closer and closer:

The spacecraft now has quite the adventure to come, edging closer to the comet over the next six weeks in two triangular-shaped trajectories, first from a distance of 100km and then at 50km. Depending on the activity of the comet, it will further attempt a near-circular orbit from a distance of 30km, simultaneously scrutinising the comet’s surface for a suitable landing site for its small lander probe - Philae, named after an obelisk that was also used to decipher Egyptian hieroglyphs in the 19th century.

Philae will, sometime in November, detach from the main body of the spacecraft and anchor itself to the surface of the comet with a high-powered harpoon. Meanwhile, Rosetta will spend the next 18 months analysing the comet from every angle, retrieving crucial data enabling scientists to investigate how planets were created. The spacecraft will also accompany the comet around the Sun as it moves back out towards the orbit of Jupiter.

The mission has some similarities with Japan’s 2005 Hayabusa mission, which rendezvoused with and landed on an asteroid named Itokawa. It was meant to scoop up material from the asteroid’s surface, and return it to Earth for study – those samples arrived in 2010, but we know that its capture mechanism malfunctioned. To this day, there is some uncertainty as to whether the capsule managed to successfully collect the asteroid rock fragments.

The Rosetta mission is significantly more complex, too – while both Itokawa and 67P have miniscule gravitational pull, the former’s orbit around the Sun is relatively simple, and Hayabusa simply chased Itokawa closely around the Sun in the same orbit. Rosetta will, by reducing its speed to less than a metre per second, genuinely orbit 67P. As the comet moves towards the Sun and heats up, there are also likely to be gas and dust particles shed off into space to form its tail – and initial photographs sent to us by Rosetta, the clearest ever of a comet, do show some emissions already.

Yesterday, the elated ESA science and mission control experts celebrated the long awaited arrival, jokingly describing it as being similar to arriving at “Scientific Disneyland”. The arrival was streamed live on the ESA’s website, and Rosetta is already sending back incredible high-resolution images of the surface of 67P. So far, it looks a lot rockier and more solid than expected – less like a “dirty snowball”, and more like an asteroid.

Around the internet, there was excitement at the arrival of Rosetta. The hashtag #RosettaAreWeThereYet flooded Twitter, as people from all over the world eagerly awaited the news, like impatient school kids – even the Philae lander’s own Twitter account got involved:

But it didn’t stop there - after Rosetta finally reached its destination, even former Star Trek captain William Shatner joined the fun by engaging in playful chitchat, checking on operations with the Nasa and ESA Twitter account.

Although we know what the comet looks like from the outside, we don’t know what it looks like from the inside, and that’s what Rosetta and Philae will be uncovering over the next few months - as long as they have enough power from the craft’s huge solar panels, that is, as unlike most probes that venture out past the orbit of Mars, it has no onboard nuclear generator.

As one mission controller explained, Rosetta is going to finally “unlock the treasure chest of our own history”.

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Don’t shoot the messenger: are social media giants really “consciously failing” to tackle extremism?

MPs today accused social media companies of failing to combat terrorism, but just how accurate is this claim? 

Today’s home affairs committee report, which said that internet giants such as Twitter, Facebook, and YouTube are “consciously failing” to combat extremism, was criticised by terrorism experts almost immediately.

“Blaming Facebook, Google or Twitter for this phenomenon is quite simplistic, and I'd even say misleading,” Professor Peter Neumann, an expert on radicalisation from Kings College London, told the BBC.

“Social media companies are doing a lot more now than they used to - no doubt because of public pressure,” he went on. The report, however, labels the 14 million videos Google have removed in the last two years, and the 125,000 accounts Twitter has suspended in the last one, a “drop in the ocean”.

It didn’t take long for the sites involved to refute the claims, which follow a 12-month inquiry on radicalisation. A Facebook spokesperson said they deal “swiftly and robustly with reports of terrorism-related content”, whilst YouTube said they take their role in combating the spread of extremism “very seriously”. This time last week, Twitter announced that they’d suspended 235,000 accounts for promoting terrorism in the last six months, which is incidentally after the committee stopped counting in February.

When it comes to numbers, it’s difficult to determine what is and isn’t enough. There is no magical number of Terrorists On The Internet that experts can compare the number of deletions to. But it’s also important to judge the companies’ efforts within the realm of what is actually possible.

“The argument is that because Facebook and Twitter are very good at taking down copyright claims they should be better at tackling extremism,” says Jamie Bartlett, Director of the Centre for the Analysis of Social Media at Demos.

“But in those cases you are given a hashed file by the copyright holder and they say: ‘Find this file on your database and remove it please’. This is very different from extremism. You’re talking about complicated nuanced linguistic patterns each of which are usually unique, and are very hard for an algorithm to determine.”

Bartlett explains that a large team of people would have to work on building this algorithm by trawling through cases of extremist language, which, as Thangam Debonnaire learned this month, even humans can struggle to identify.  

“The problem is when you’re dealing with linguistic patterns even the best algorithms work at 70 per cent accuracy. You’d have so many false positives, and you’d end up needing to have another huge team of people that would be checking all of it. It’s such a much harder task than people think.”

Finding and deleting terrorist content is also only half of the battle. When it comes to videos and images, thousands of people could have downloaded them before they were deleted. During his research, Bartlett has also discovered that when one extremist account is deleted, another inevitably pops up in its place.

“Censorship is close to impossible,” he wrote in a Medium post in February. “I’ve been taking a look at how ISIL are using Twitter. I found one user name, @xcxcx162, who had no less than twenty-one versions of his name, all lined up and ready to use (@xcxcx1627; @xcxcx1628, @xcxcx1629, and so on).”

Beneath all this, there might be another, fundamental flaw in the report’s assumptions. Demos argue that there is no firm evidence that online material actually radicalises people, and that much of the material extremists view and share is often from mainstream news outlets.

But even if total censorship was possible, that doesn’t necessarily make it desirable. Bartlett argues that deleting extreme content would diminish our critical faculties, and that exposing people to it allows them to see for themselves that terrorists are “narcissistic, murderous, thuggish, irreligious brutes.” Complete censorship would also ruin social media for innocent people.

“All the big social media platforms operate on a very important principal, which is that they are not responsible for the content that is placed on their platforms,” he says. “It rests with the user because if they were legally responsible for everything that’s on their platform – and this is a legal ruling in the US – they would have to check every single thing before it was posted. Given that Facebook deals with billions of posts a day that would be the end of the entire social media infrastructure.

“That’s the kind of trade off we’d be talking about here. The benefits of those platforms are considerable and you’d be punishing a lot of innocent people.”

No one is denying that social media companies should do as much as they can to tackle terrorism. Bartlett thinks that platforms can do more to remove information under warrant or hand over data when the police require it, and making online policing 24/7 is an important development “because terrorists do not work 9 to 5”. At the end of the day, however, it’s important for the government to accept technological limitations.

“Censorship of the internet is only going to get harder and harder,” he says. “Our best hope is that people are critical and discerning and that is where I would like the effort to be.” 

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