Meteorite impacts leave behind time-capsules of ecosystems

Glass beads that form inside hot meteors as they fall to Earth capture particles from the atmosphere, creating a kind of permanent record of historic climates.

Meteorite impacts can be very destructive. One that fell in Mexico around 66m years ago created a 180km crater and caused the extinction of dinosaurs while spewing debris and molten rock into the air. Now, in what is a fascinating tale of serendipity, researchers have found that these events don’t entirely destroy all traces of life at the site of impact. Molten rocks can capture and preserve organic matter as they cool down to form glass beads.

When a meteor enters Earth’s atmosphere, the air around the meteor gets very quickly compressed causing it to heat up, scorching everything in its path. Most of the time that is where the story ends, as the meteor burns up in the sky as a “shooting star”. But sometimes it is big enough to reach all the way to the surface and transfer its remaining energy to the ground.

This energy is dissipated, as mild earthquakes, sound shockwaves – but mostly as heat. The heat energy can be so great that it melts rocks on the surface and hurls them up in the atmosphere. Anything that comes in contact with this molten rock would presumably get burnt, leaving nothing but rocky material that cools down in the atmosphere, forming glass beads and tektites (gravel-sized natural glass). This is what City University of New York researcher Kieren Howard assumed, but he was able to show that his assumptions were wrong.

For his PhD, Howard was studying the glass beads and tektites found near the Darwin crater in Tasmania. The 1.2km wide crater was created by a meteorite impact about 800,000 years ago.

The natural glass formed during cooling is (as implied by the term glass) not crystalline. Instead of a regular arrangement of atoms, the atoms inside it are randomly arranged. Howard’s analysis, however, kept showing the presence of crystals. At first, he dismissed this as a problem with the machine or with his method of analysis. But when it kept showing up, as a good scientist, he thought he should ask an expert to look at his data.

“This is unusual,” says Chris Jeynes, a physicist at the University of Surrey. “If there were indeed crystals, then it was the result of uneven cooling, which can occur when something gets trapped inside these glass beads.”

Jeynes used proton-beam analysis, a method to peer inside the glass to reveal its elemental make-up. Inside he found carbon. “Howard had no idea what his samples were, and he was very surprised when I told him,” Jeynes says.

The natural glass formed should contain only silicon, titanium, oxygen and other metallic elements in trace amounts. Detection of carbon meant that there was some organic matter inside. The only hypothesis was that, somehow during the formation of these glass beads, they captured organic matter that was floating in the atmosphere. That organic matter might have already been in the air, but it might also include material thrown up by the impact.

Howard then went to another expert to break open these glass beads and reveal what the carbon-rich matter was. It turned out that it included were cellulose, lignin and other biopolymers. This meant that somehow this matter, which originated from plants, had survived the temperature of more than 500°C, which is what the molten rock would have reached before cooling into a glass bead. Usually these temperatures will break down the organic matter, but clearly it didn’t in this case.

Mark Sephton, a geochemist at Imperial College London, was surprised and pleased: “What the results show is that these glass beads can capture an aliquot of the atmosphere of the planet at impact. It is like a time capsule of that ecosystem.” These results are published in Nature Geoscience.

The implications are enormous. It shows that other meteorite impacts, like the one that wiped out the dinosaurs, could have created such time capsules too. Sephton is now working on finding glass beads from other impact sites to reveal information about Earth’s ancient atmosphere.

This method of analysis means that we could also go looking for similar beads on other planets, like Mars, where meteorite impacts are common. They could also reveal vital information about the past atmosphere of those planets. Maybe they captured organic matter – if it ever existed there.

“We would not know any of this if it wasn’t for Howard,” Jeynes says, adding that Howard’s persistence to find out what “the wrong results” led the researchers to a phenomenon that nobody knew existed.

This article was originally published at The Conversation. Read the original article.

The Conversation

Meteor Crater in Arizona. (Photo: Angle Schatz/Flickr)
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Politicians: it's no longer OK to know nothing about technology

It’s bad enough to joke about not being "techy"; it's worse to back a piece of legislation from a position of ignorance. 

Earlier this week, facing down a 600-strong battalion of London’s tech sector at a mayoral hustings in Stratford, Zac Goldsmith opened his five minute pitch with his characteristic charm. “I’m not very techy!” he exclaimed. “I understand coding about as well as Swahili!”

Pointless jibe at a foreign language aside, this was an ill-chosen way to begin his address - especially considering that the rest of his speech showed he was reasonably well-briefed on the problems facing the sector, and the solutions (including improving broadband speeds and devolving skills budgets) which could help.

But the offhand reference to his own ignorance, and the implication that it would be seen as attractive by this particular audience, implies that Goldsmith, and other politicians like him, haven’t moved on since the 90s. The comment seemed designed to say: “Oh, I don't know about that - I'll leave it to the geeks like you!"

This is bad enough from a mayoral hopeful.  But on the same day, the Intelligence and Security Committee of Parliament filed its report on the Draft Investigatory Powers Bill, the legislation drafted by the Home Office which will define how and how far the government and secret services can pry into our digital communications. Throughout, there's the sense that the ISC doesn't think the department behind the bill had a firm grasp on the issues at hand. Words like "inconsistent" and "lacking in clarity" pop up again and again. In one section, the authors note:

"While the issues under consideration are undoubtedly complex, we are nevertheless concerned that thus far the Government has missed the opportunity to provide the clarity and assurance which is badly needed."

The report joins criticism from other directions, including those raised by Internet Service Providers last year, that the bill's writers didn't appear to know much about digital communications at all, much less the issues surrounding encryption of personal messages.

One good example: the bill calls for the collection of "internet connection records", the digital equivalent of phone call records, which show the domains visited by internet users but not their content. But it turns out these records don't exist in this form: the bill actually invented both the phrase and the concept. As one provider commented at the time, anyone in favour of their collection "do not understand how the Internet works". 

Politicians have a long and colourful history of taking on topics - even ministerial posts - in fields they know little to nothing about. This, in itself, is a problem. But politicians themselves are often the people extolling importance of technology, especially to the British economy - which makes their own lack of knowledge particularly grating. No politician would feel comfortable admitting a lack of knowledge, on, say, economics. I can’t imagine Goldsmith guffawing "Oh, the deficit?  That's all Greek to me!"  over dinner with Cameron. 

The mayoral candidates on stage at the DebateTech hustings this week were eager to agree that tech is London’s fastest growing industry, but could do little more than bleat the words “tech hub” with fear in their eyes that someone might ask them what exactly that meant. (A notable exception was Green candidate Sian Berry, who has actually worked for a tech start-up.) It was telling that all were particularly keen on improving internet speeds -  probably because this is something they do have day-to-day engagement with. Just don't ask them how to go about doing it.

The existence of organisations like Tech London Advocates, the industry group which co-organised the hustings, is important, and can go some way towards educating the future mayor on the issues the industry faces. But the technology and information sectors have been responsible for 30 per cent of job growth in the capital since 2009 - we can't afford to have a mayor who blanches at the mention of code. 

If we’re to believe the politicians themselves, with all their talk of coding camps and skills incubators and teaching the elderly to email, we need a political sphere where boasting that you're not "techy" isn’t cool or funny - it’s just kind of embarrassing. 

Barbara Speed is a technology and digital culture writer at the New Statesman and a staff writer at CityMetric.