Dr Tim Gregory Works with a Meteorite That's Older Than The Earth

Interview: Ashley Carter
Wednesday 14 August 2019
reading time: min, words

Armed with a childlike sense of wonder, a natural gift for talking with passion and a boundless sense of enthusiasm, it’s clear to see why Dr. Tim Gregory is so well liked. After appearing on BBC shows The Sky at Night: Expedition Asteroid and Astronauts: Do You Have What It Takes?, the cosmochemist and research scientist is now working at the British Geological Survey in Nottingham studying Allende, the famous meteorite that predates Earth itself… 


Let’s start things simple and build up from there. In layman’s terms, what is cosmochemistry?
To understand cosmochemistry, you need to know how it came to be. Geology is the study of rocks and how they formed, which can inform us about things that happened in the past. For example, the history of life on Earth is contained within the rock record of the Earth; the only way we know about all of the plants and animals of the past is by geology and fossils. But it's much more than just a history of life on Earth, it's the history of the planet itself; the positions of the continent, the comings and goings of mountain ranges, the formation of seas. All of it’s contained within the rock record. So, geology is really a science of storytelling. It's piecing together the story of our planet. 

But rocks on Earth are always being unmade by natural forces; they get molten, they get ground to pieces, they get dissolved. So geological tales are being written anew all the time, but it means there’s a limit to how far back in time the rocks of the Earth can take us. The rocks that were around immediately after the Earth formed, for example, have long been destroyed.

To go to the deepest crevices of geological time, you need the rocks that existed before the Earth: meteorites. The reason that meteorites preserve this epoch of the Solar System’s history is because they originate from asteroids. Because they’re so small, many asteroids never melted after they formed – they were essentially frozen in time, which means the rocks from which they are made were frozen too – and they record the earliest history of the Solar System. You put the study of space and geology together and, in essence, you’ve got cosmochemistry. 

Does it take a particular type of mind to comprehend the scale of this kind of subject? 
I deal with deep time every single day in my job, and I cannot get my head around it. We’ve evolved with brains capable of comprehending time on the scale of hours, days, weeks, months, years and maybe even a decade. A century is just about on the edge of our comprehension. But geology operates on a timescale that dwarfs even the longest human timescales; we’re talking hundreds of millions of years. And cosmochemistry really takes the biscuit: we work in billions of years. The oldest known rock in the Solar System is 4.5 billion years old. If you compress that timescale down to a 24-hour day, humans have only been around for a few seconds, and dinosaurs went extinct about twenty minutes ago. We think of dinosaurs as these ancient animals that roamed the Earth during the deepest recesses of geological time, but they were practically yesterday compared to the rocks that I study and the Solar System itself. 

How do you make a complex subject like this seem tangible and accessible when you’re giving talks or teaching?
I think everybody has a fascination with rocks. There isn’t a child on the planet that doesn’t like picking a rock up and bashing it against another rock to see what’s inside – the people who don’t lose that interest are geologists! One of my aims in life is to share that joy with as many people as possible. 

When we talk about the history of the Earth, whether it’s Pangaea breaking up, the trilobites 500 million years ago, or the extinction of the dinosaurs, it can often seem really disconnected. But the beautiful thing about Earth sciences – and all sciences – is that it’s something we’re all part of. By understanding the history of the Earth, and the history of the Solar System, we're understanding our own history as well. Human history didn't start when humans first evolved, about 200 thousand years ago; we're the product of 4.5 billion years of Solar System evolution. There is an unbroken line that we're at one end of. That’s something I think about every day. 

I love my job as a scientist – it’s fantastic. But every time I’m in the lab with a meteorite, I’m not looking at it thinking, ‘Oh my gosh, this is a piece of history.’ It would just be too overwhelming! You can’t live your life like that; you have to zoom in a bit; you’ve got to commute to work, make your breakfast and brush your teeth. Life takes over. But sometimes I’ll be looking down a microscope looking at this meteorite and it will hit me: this is older than the planet that I’m sitting on right now. Trying to give people a glimpse of that feeling can only enrich life, I think. 

It doesn’t matter how famous you are, or whether you’ve got a knighthood, there’s no such thing as authority in science. There are only experts. If the evidence does not support what you’ve said, then it’s wrong.

And that meteorite would be Allende, which I’ve seen described as one of the best-studied meteorites in history. What makes it so important? 
It fell in Mexico, just a few months before the Apollo 11 astronauts went to the Moon for the first time in 1969. Within 100 hours of it falling to Earth, pieces of it were in the Johnson Space Center being studied. Calling it one of the most studied rocks is a difficult thing to say with any certainty, but a lot of what we understand, or what we think we understand, about the early Solar System comes from Allende. It’s really special. As it’s a chondrite meteorite, which originate from asteroids that never melted, it preserved the dust from which it originally coalesced. 

What’s important about that dust?
It’s made from the building blocks of asteroids, planets and, by extension, the Earth as well. By looking at this dust, and studying its geological character, we're looking at the very beginning of the rock record of the Solar System.

What is your specific role at the British Geological Survey?
There are little round objects within Allende called chondrules, which are quite strange. Nobody really understands how they formed, but we do understand that they used to be little aggregates of dust. This dust got to the point where it melted, and upon melting formed these tiny little molten droplets of rock. These cooled really quickly, probably in a few days, to form little crystalline, spherical beads. 

My specific role here at the BGS is dating them using the uranium clock. There are really only one or two laboratories in the world where you could do this type of analysis; it’s incredibly difficult, detailed work. You need the cleanest lab, the expertise to know exactly how to handle the data and the right instruments – and the British Geological Survey is one of those places. It’s world-class. 

And elements of it are open to the public too? 
There’s a geological walk here that is absolutely fantastic – you can go right through the Earth’s history on a guided tour. The gift shop is pretty wonderful too – I have to really put my handbrake on every time I walk past it! There are other public spaces too, including the beautiful library, which has one of the oldest and most expansive collections of Earth-science literature in the world. Our collection goes back hundreds of years. We’ve actually got some books from the 1600s, right here in Keyworth of all places! This place is a jewel in the crown of Nottingham, and somewhere that the city should be very proud of. 

The oldest known rock in the Solar System is 4.5 billion years old. If you compress that timescale down to a 24-hour day, humans have only been around for a few seconds, and dinosaurs went extinct about twenty minutes ago.

Do scientists have grudges against each other in the same way two singers, writers or filmmakers might dislike each others’ work?
Definitely! It happens all the time. There are vigorous debates on the edge of human knowledge, but some points are universally agreed on. But with the more fringe issues, the Devil is really in the detail. We like to pretend that we’re totally objective, emotionless machines, but we’re not. We’re all humans – just salty bags of water – and debate is often passionate. It can get heated, but it’s always in good faith. Every time I see a mild spat between two scientists with competing hypotheses, I feel glad that there’s enough spirit left in the world to argue about things like chondrule formation, as opposed to the latest tweet by some politician. 

 I guess that’s the difference between science and something like religion or politics. Is there almost a virtue to being wrong in science?
An essential part of science is doubt. It’s very healthy, and it doesn’t matter how famous you are, or whether you’ve got a knighthood, there’s no such thing as authority in science. There are only experts. If the evidence does not support what you’ve said, then it’s wrong. 

I'm not religious, and I'm not diminishing the role that religion has to play in society. But in terms of answering questions about the natural world, science is the best thing we've ever invented. If we borrowed some of the key principles of science and applied them more widely across society, we’d live in a much better world. 

Nothing makes me cringe more than when a politician claims to have firmly held beliefs. There are no firmly held beliefs in science. There's no room for that. There are only beliefs supported by evidence. 

I read that you’re also a keen guitarist. What sort of music are you in to?
My favourite band is The Smiths. The Morrissey and Marr combination is music of the highest beauty. I love it. I’m really into Tranquillity Base Hotel & Casino by the Arctic Monkeys. The entire album is about a hotel, casino and taqueria on the Moon. It has a receptionist called Mark and a lounge band called the Martini Police. I would love to play there one day. 

If you had to choose between playing with The Smiths at Glastonbury and travelling into space, which would it be? 
Given a choice I’d travel into space, as long as I could take my guitar with me! 

The British Geological Survey will be holding an Open Day on Saturday 12 October

 British Geology Survey, Keyworth, Nottingham NG12 5GG

British Geology Survey website

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