Watch: this is what Mars looked like 3.7 billion years ago

While it seems to be a dead planet today, in the past the Red Planet would have felt very much like home to us - with clouds, oceans and blue sky.

We are nearly as certain as it is scientifically possible to be that there isn't any life on Mars. There is still every chance that there was life at some point, and we might still find it. The landscape is clearly marked with signs of water erosions, and Curiosity and Opportunity (the two rovers currently trundling around up there) have taught us a huge deal about its geology - including the discovery of "abundant" traces of water in Martian soil. Mars clearly had a lot of liquid water on its surface at some point.

The question, though, is why it doesn't have lakes, rivers, oceans, and streams any more - and what it looked like when it did. Nasa's Goddard Space Flight Center has taken a stab at visualising the Martian world of 3.7 billion years ago ahead of its Mars Atmosphere and Volatile Evolution (or Maven) mission which takes off on 18 November, producing a quite lovely animation:

It looks just like Earth because back then Mars had two Earth-like things going for it that it doesn't any more. Firstly, the habitable zone around the younger, larger Sun - that's the range of orbits around any star within which is neither too hot nor too cold for a planet to have liquid water on its surface - was further out, and secondly Mars also had a thick atmosphere. Without the pressure that comes with an atmosphere, liquid water will either freeze solid or evaporate instantly, as happens currently on Mars.

The habitable zone moving inwards had the happy side effect of making the Earth habitable, and eventually - as the Sun enters its final few billion years and swells in size, becoming a red giant - that zone may well move out further again and give Mars a chance at hosting liquid water again. That is, if it gets an atmosphere too, and that's the mystery. We know it must have been there once, but it isn't there now, and we can't be sure why that it. We're not even totally sure if the atmosphere's disappearance is wholly responsible for the transformation of Mars from wet, blue globe like you see above to dusty, red ball that looks like this:

That's a picture taken by the Curiosity rover.
Credit: NASA/JPL-Caltech/MSSS

One possibility for what happened to the atmosphere is that Mars' core cooled down and stopped generating both plate tectonics and a magnetic field, which would have formed a barrier that would have stopped too many atmospheric particles being stripped away into space by the solar wind. Without active volcanoes to generate gases to replace the lost particles, you end up with the situation today where the surface pressure on Mars is, on average, 0.6 percent that of what you'll find on Earth. That's equivalent to being 35km up in the sky on Earth, nearly twice as high as where commercial aeroliners fly.

Maven is an orbiting probe that will launch on 18 November and try to uncover more data about Mars' atmospheric past. Here's Joseph Grebowsky, the mission's project scientist:

Studies of the remnant magnetic field distributions measured by Nasa's Mars Global Surveyor mission set the disappearance of the planet's convection-produced global magnetic field at about 3.7 billion years ago, leaving the Red Planet vulnerable to the solar wind. 

Maven has been designed to measure the escape rates for all the applicable processes and will be able to single out the most prominent. Previous remote Mars observations from orbiting spacecraft have observed the geological features that have been used to estimate the amount of water that did exist and have analysed the global distribution of water ice and surface chemistry to infer that water was lost through time. Mars Curiosity rover has the ability to analyse the chemical composition of the solid surface, which contains information of the atmospheric composition during the formation of the planet, in particular the isotope ratios, the lower atmosphere composition, and the current gas exchange with surface reservoirs. MAVEN is going to measure the current rates of loss to space and the controlling processes. Given the lower-atmosphere information and the nature of the escaping processes, one can extrapolate from current conditions into the climate of the past.

The probe will reach Mars in September 2014, and is scheduled to work for one Earth year on its mission of uncovering more Martian secrets.

Not Earth, but Mars before it lost its atmosphere. (Image: Nasa)

Ian Steadman is a staff science and technology writer at the New Statesman. He is on Twitter as @iansteadman.

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“I was frozen to the spot”: the psychological dangers of autoplay video

Videos that play automatically are now ubiquitous across social media, but the format leaves many viewers vulnerable to harm and distress.

Have you ever seen a dog being skinned alive? Witnessed a child, whimpering for his mother, getting beheaded? Have you watched a man, pinned down by two police offers, being shot multiple times in the chest and back?

A few years ago, if you answered “yes” to these questions, you might have been considered deranged. Possibly, you would have been on a list somewhere, being monitored for seeking out disturbing and illicit videos online. Now, you’re more than likely just a victim of social media’s ubiquitous autoplay function.

No one likes autoplay. Back in the Nineties, homepages often came with their own jaunty background tune that would automatically play, but it didn’t take long for this annoying and invasive practice to die out. Nowadays, when you click on a website plastered with noisy adverts and clips, you immediately click off it. But although users frequently bemoan them, autoplay videos remain a huge business model for social media sites such as Twitter, Facebook, and Tumblr.

That’s fine, of course, when the autoplaying video in question is a bird’s-eye view tutorial on how to make nacho-chicken-pizza-fries (though even then, the videos might be gobbling up your data allowance without your consent). The problem arises when disturbing content is posted by users, and even media outlets, without any warnings or disclaimers.

“There are many incidents where the autoplay feature has affected me negatively,” says Sarah Turi, a 19-year-old college student from Boston, USA. Turi suffers from anxiety, and says that anything related to horror or gore can keep her awake for multiple nights on end. She has previously experienced anxiety attacks after viewing autoplaying horror movie trailers.

“Recently though, many of the videos that begin playing have to do with police brutality or terrorism or riots,” she says. “There was one incident where someone had shared a video of an execution. The video started playing, and before I could scroll away, I watched a man get beheaded by a terrorist organisation. It left me pretty shaken to say the least. I wasn't crying, but I was frozen to the spot. Even just thinking about it now leaves me feeling somewhat ill.”

Dr Dawn Branley, a health and social psychologist specialising in the risks and benefits of internet and technology use, tells me that autoplay videos on social media raise a variety of ethical concerns.

“Social media is more personal in nature compared to news channels and it is also often idly browsed with little conscious effort or concentration, and, as such, users may not be mentally prepared for the sudden appearance of a distressing video,” she says. “Suddenly witnessing a beheading, rape or graphic animal cruelty whilst scrolling through photos of your friends and family, holiday snaps, baby videos and wedding announcements may provide a real shock to the viewer.”

Branley says that, in her line of work, she has spoken to users who have experienced distress at photos of abuse and violence on social media, and speculates that autoplay video could only exacerbate this problem. She also notes that they can trigger vulnerable users, for example, people who suffer from eating disorders or PTSD.

Even those without pre-existing conditions can be negatively affected, however, as anyone who has seen disturbing footage before knows how it can pop into your head intrusively at any time and refuse to budge, remaining plastered to the edges of your skull. Even trolls are aware of this, as some tweet distressing footage at people, aware that it will autoplay.

In January 2015, Facebook responded to these issues by adding warnings to videos users flagged as graphic, meaning the footage wouldn’t autoplay and was preceded by a warning message. Viewers under 18 would be shielded from seeing violent content on their feeds. Yet just over seven months later, in August, autoplay meant thousands inadvertently watched footage of the shooting of TV journalists Alison Parker and Adam Ward.

Remember when I said no one likes autoplay? That’s not strictly true. You have three seconds to scroll away from an autoplaying video before Facebook counts it as a view. In a world where Facebook, and the users of it, are desperate to tally up as many views as possible, autoplay is considered a smart business model.

“Autoplay video originated as a way to capture viewers’ attention and prevent them from ignoring or scrolling past website content,” says Branley. “The autoplaying nature of a video is likely to capture the viewers’ attention and may potentially be harder to resist watching – compared to a static image and text.”

For those profiting, it seems not to matter that some people who can’t look away are viewers like Turi, frozen on the spot by distress.

Because of how profitable autoplay is, then, many news outlets continue to upload sensitive footage that might better be suited on their website – a consensual click away. They might add their own pre-roll warnings, but Branley notes that these are easy to miss if the video is autoplaying. If you were online yesterday, you might have seen this in action, as footage of a boy – or rather the boy – in an ambulance, distressed and bloodied, autoplayed repeatedly across social media.

News outlets have been called out for this before, and have admitted their mistakes. In August 2015, New York Times social media editor Cynthia Collins told The Media Briefing that she wishes she’d added a warning to a video of men being shot and killed at sea. After backlash from their audience, she said:

“If we could do it all again . . . there would have been a discussion about whether or not we should upload the video at all. But if we decided to upload the video I absolutely would have added a warning.”

The video ended up on the website, and viewers had to click through a handful of warnings before watching it. News footage has always had the potential to alarm and distress, but at least in the past viewers had a choice about whether they watched it. Although many news outlets have guidelines on graphic content (such as, for example, the famous breakfast test), these haven’t always been updated for social media.

It’s important that users are made aware of potential solutions to this problem,” says Branley, noting that Facebook and Twitter include options in their settings to turn off autoplay, and your browser or phone may also allow you to disable all autoplay. “However, that does not detract from the moral obligation that internet platforms should consider when introducing autoplay.

“I would suggest that an ‘opt-in’ approach (where users are required to switch on the autoplay setting if they wish to enable this function) would be much more appropriate than the current ‘opt-out’ approach, which requires users to find the settings to switch off autoplay if they do not wish to use it.”  

This seems like the simplest and fairest answer. It’s hard to argue that distressing videos shouldn’t be posted on Facebook – last month, the footage of Philando Castile’s shooting dramatically shed light on police brutality – but it seems only natural that viewers should have a choice about what they watch.

“It is possible that autoplay videos could be used to raise awareness of sensitive topics and/or to grab users' attention for positive reasons like charity campaigns,” says Branley. “However, it is a fine line between raising awareness and distressing the viewer and what one viewer finds acceptable, another may find highly distressing. Therefore, care and consideration is required.”

Right now, both care and consideration are lacking. In its current iteration, autoplay is like Anthony Burgess’ Ludovico technique – pinning our eyes open and forcing us to watch violence and horror without our consent. There are things I know I never want to watch – the curb stomp in American History X, an Armenian weightlifter dislocating their elbow during the Olympics – that could be sprung upon me at any time. Why? Because someone, somewhere, profits.

“I don't think autoplay is necessary in Facebook,” says Turi. “I think that people should decide for themselves whether or not they want to watch something. And yes, I think that it should be banned.”

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