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The man who collects stardust

Starman

Every day, 100 tonnes of celestial dust lands on Earth, bringing with it the secrets of our early solar system. Tom Whipple meets the Norwegian musician who identified the rocks from our stars

Every day, 100 tonnes of celestial dust lands on Earth, bringing with it the secrets of our early solar system. Tom Whipple meets the Norwegian musician who identified the rocks from our stars

Tom Whipple | July 10th 2017

A few hundred thousand years before Jon Larsen, a jazz musician, carried a wooden broom onto a Norwegian roof, two asteroids bumped into each other.

These asteroids were old when the sun was new. Never responsible for anything so exciting as a dinosaur extinction, for billions of years they remained cold and lifeless – time capsules from a more primitive solar system. But when they collided, they at last did something interesting: they shed some fragments. One of those fragments was as small as this full stop.

For aeons, this particle was buffeted by solar winds, adrift in the cold of interplanetary space. Then one day it found itself in the path of a watery planet with a thick atmosphere. Travelling at 12,000 metres per second, melting in the intense heat, this tiny rock, once part of the oldest rocks in our solar system, dropped onto a Norwegian rooftop.

According to the world’s micrometeorite experts, that should have been that. On every square metre of the planet, every year half a dozen such alien rocks land. You have most likely had one on your head. But every year so, too, does all the non-alien detritus: dust from construction, metal spherules from lorry brake pads, sand from the Sahara. These terrestrial particles outnumber the micrometeorites by a billion to one.

Undeterred, standing on that Norwegian roof, Larsen swept it all up together and put it in a jiffy bag. Somewhere in those sweepings was the micrometeorite, and he was going to find it.

When he began searching for stardust eight years ago, even Larsen thought he would probably be unsuccessful in separating these extraterrestrial needles from their dusty terrestrial haystacks. The scientists he contacted, from the small international community of micrometeorite experts, were certain he would be.

Until then, the only micrometeorites that had been identified were ones that had fallen to Earth aeons ago, and been locked into rock and ice or eroded by the sea. Scientists knew how important it was to understand these tiny rocks and the clues they gave us to our own planet’s formation. They also knew that there was a tantalising prospect that the complex molecules they contained might give us a hint as to how life started afterwards. Yet they had all failed to find fresh examples. In fact, so ludicrous such a search appeared that they hadn’t even tried.

They were the experts. How could a Norwegian jazz musician without a degree ever succeed?

Under the microscope 
HERE AND MAIN IMAGE  Micrometeorites from Larsen’s collection; like snowflakes, each is different

As a child growing up in Oslo, Larsen was always interested in rocks. But he was also interested in music and shortly after he had left school, fate, in the form of the Norwegian singles chart, chose his path.

“I took it for granted I’d study natural sciences,” he says, extending his brush into a shallow gutter. “But things happened. Two of my friends from school were playing jazz and I hooked up with them. When we were still around 20 we got a radio hit.” That song, “Tanta til Beate” – Norwegian gypsy jazz, a niche genre – was Norway’s summer hit of 1982. It changed Larsen’s life. “Back at that time we had only one channel in Norway. When it was played five times a day, everyday, everyone knew it. We have been nearly fully booked since then. It was a miracle.” So he forgot about his scientific plans – at least for a while.

Jazz is not a matinee kind of music. Even with a full schedule of concerts, it gives you a lot of free time in the day – in which, for instance, to read about micrometeorites. On one of those days, Larsen was sitting outside when he spotted something he couldn’t explain.

“I was in the countryside south of Oslo, preparing to eat some strawberries. I cleaned the tablecloth, put away the cloth and noticed in the very sharp sun that something was glittering. A very tiny, small particle. I could feel it on my fingers; it was not completely smooth. It was faceted. I thought, ‘Oh could this be one of those?’”

He put it in a matchbox and started researching micrometeorites in earnest. So began the journey that would end with an autodidact gypsy-jazz musician publishing a scientific paper in a prestigious American geology journal, alongside some of the biggest names in the field.

Given the history of the discipline, it was oddly fitting. The first to discover these tiny visitors were not astronomers or geologists, but oceanographers.

In the 1870s, HMS Challenger was sent by Britain’s learned societies to investigate the oceans. Before the voyage her guns were stripped out and scientific equipment put in their place: laboratories, photographic apparatus, vats of pure alcohol. In the service of Enlightenment ideas she was to plumb the depths, dredge them and pickle anything that moved.

Voyaging across the remote South Pacific, those onboard analysed the composition of the sea floor. The sailors were surprised to find hundreds of bones; in a single sample there were shark, whale and dolphin bones. Some were mineral-crusted by time, some were fresh. All came from one small layer of red clay – a cetacean cemetery the likes of which had never been seen.

This was a mystery. “We cannot suppose that sharks and whales so abounded in the sea at one time as to cover the floor of the ocean with a continuous stratum of their remains,” the sailors pointed out in their expedition log.

The alternative, then, was that there was almost no other sedimentation – that bones were the only thing that ever dropped here. “No doubt each haul of the dredge, which brought up so many bones, represented the droppings of many generations,” the log continued. In the middle of the world’s largest ocean there was none of the debris that accumulated on Jon Larsen’s roof – except for one kind. There, among the bones, were “numerous minute spherular particles of metallic iron”.

This was just the sort of mystery to excite the attention of Charles Wyville Thomson, Challenger’s chief scientist. Employing the sort of deductive principles that would, just a few years later, be popularised by Sherlock Holmes, he first eliminated the impossible and was left with the truth, however improbable. The spherules, he confidently stated, could only come from space.

Hit the roof 
Jon Larsen hunting for micrometeorites.

LEFT A phial of dust, some of which may be celestial.
RIGHT The tools of his trade: a magnet and a plastic bag

Since then, radar readings have confirmed that our planet is under constant bombardment. A few specks of dust falling on every square metre a year might not sound much, but across the planet it comes to 100 tonnes a day, far more than from the showier fireballs of all the visible meteorites. Billions of years ago, when bombardments of all sizes were more common, the weight of space dust would have been many times higher.

The idea that this space dust was the majority of the rock that reached us from space is what drew Larsen to the micrometeorites. It was why, for six fruitless years, he would put on some Frank Zappa or Django Reinhardt, set up the microscope and spend hours sifting through the detritus of Norway’s gutters. He was driven by the idea that this much cosmic material may, over geological time, be important, particularly as 12% of that mass – 12 tonnes a day today – is water, locked up in the rock. (The early Earth quite probably did not have water.) Furthermore, some of the rest is complex organic molecules of the sort required, for instance, for DNA. So this abundant rain of particles is also a literal rain that brings, as well as water, the stuff of life itself.

Yet if they fell in such volume, where were they? “It was a very obvious contradiction,” says Larsen. “Most people were agreed that micrometeorites were everywhere. On the other hand most people were also agreed that it was not possible to find them. So I thought, well, I had to try this.” He got in touch with some of the leading scientists in the field, to ask for advice on how to proceed.

He was met, largely, with kindly resignation. He was not the first to have this thought. “For years we had seen amateurs posting on the internet about collecting cosmic dust,” says Matthew Genge, a senior lecturer at Imperial College London. “We are a bit dubious – very dubious – and when people contact us we tell them it’s not possible.” That’s what he told Larsen. “But Jon was very persistent. He kept emailing me possible particles.” At this stage his colleagues in the community, all of whom had also been emailed by Larsen, had started ignoring this Norwegian guitarist and his quixotic quest. “Maybe because I’m British,” says Genge, “I kept replying.”

Larsen, to be fair, agreed that he was extremely unlikely to succeed. He had a humbler, but also in some ways grander, vision for his project. “When artists made Byzantine mosaics, they were trained to make them all in the same style,” he says. “This was because they knew it would take longer than their life, and someone would have to take over. Imagine starting a pro­ject, knowing that you will not finish? That is what I thought this would be.” His idea was to make a start, and perhaps devise a system for removing the earthly particles, that would eventually be perfected by those who followed. Neither he nor Genge seriously thought that they would become scientific collaborators.

The first stage in getting the odds from a billion to one to something more manageable begins on the roof. Flat roofs are ideal – they are above the dirt of the streets and the particles have nowhere to go. Ones with small walls around the edges help to keep the particles corralled, too. Driving along the motorway, to a particularly prime spot, with both small walls and a vinyl covering (“I do like vinyl,” says Larsen), he points wistfully at all the flat roofs yet to be surveyed. His youngest daughter, in her late teens, has negotiated access for him to her school’s roof, and he is excited.

These days, aside from Norwegian rooftops, the only reliable known source of micrometeorites is the Antarctic. To extract them, you drill into the ice, preferably to a stratum of snow that predates the soot of the Industrial Revolution, and melt the water. Here, at the bottom of the Earth on a vast ice sheet, the odds are at last stacked in the micrometeorite’s favour – but the ones found there up to now have been degraded by time.

Without the advantage of the most pristine environment on the planet, the odds are not stacked in Larsen’s favour. He needs to engage in some brutal sorting. For the second stage of this process he has a strong magnet, which he uses to eliminate all the non-magnetic particles. Most, but not all, micrometeorites are magnetic – and for his purposes “most but not all” works fine.

Then he begins the laboratory work – or, more specifically, the kitchen-sink work, preferably while his wife is out. “Don’t tell her I’m doing this,” he says as he swills the dust in the sink like a gold-panner.

There is an ease to him as he works, an assured confidence that he will find a meteorite. It makes me forget that he spent six years doing this and achieving nothing. As he sieves the sludge through a laboratory-grade sieve, keeping only the particles in the micrometeorite range, I wonder why on earth he persisted. Can a fascination with micrometeorites really sustain such dedication? The closest he can get to an answer is that he likes rocks and he likes microscopes.

From a billion to one, the odds after the panning have dropped to a few hundred thousand to one. Now, though, there are no tricks left; it is simply a question of looking.

Under the microscope, grey dust becomes something magical. Over those six years, in his apartment in a tower block overlooking Oslo, with jazz in the background, Larsen would bend towards the eyepiece and enter a different world. At first, it was incomprehensible. The jagged jumble of purples and greens, intact crystals and weathered rocks, followed no obvious rules. But, slowly, patterns emerged. He began to classify them: the insulation fibres from walls, the cooled sparks from angle grinders.

The idea was not to look for things that were micrometeorites, but to look for the things that weren’t and, like a dust detective, to eliminate them from his enquiries. Then, one day two years ago, he found something he could not classify: it was smooth, dark, shiny, egg-shaped.

As we move from the kitchen to his office, he puts on his own album, at my request, and we sit for 20 minutes, me listening to his guitar as he gently sorts the dust. Then, without fanfare, he calls me over to the microscope; he has found one.

It is almost translucent. On its way through the atmosphere it must have melted completely. There is a spherical knobble at the top: the core. Like a molten planet in miniature, the heaviest material sank to the middle while it was still liquid and, as the micrometeorite slowed, this dense middle was pushed forward until it poked out of the front, as if greeting the approaching Norwegian rooftops.

It looks so unexpected, so odd, that it is only when I move my head away from the microscope – re-entering the macro-world – that I get a sense of why it took so long for Larsen to get this far. Without the magic of magnification it is a boring grey speck again, a single dot among tens of thousands.

It was one of these that, finally, Larsen was able to present to Genge, in person, when he came to visit the University of Bergen. “I showed him the image and he said, ‘Yes, that’s it’,” says Larsen. “The other professors asked how Matt [Genge] knew, and he said, ‘Because that’s what they look like.’” He was one of just a handful of scientists to have ever seen micrometeorites down a microscope – but those were from the Antarctic.

Genge’s is a rarefied discipline; there are perhaps a dozen scientists who work in the field. But it is important. “If I was to get arm wavy,” he says, “I’d say what’s cool about micrometeorites is you can start making predictions about the universe.” There is no reason to presume that cosmic dust is unique to our solar system. If it falls elsewhere, then in those other systems it will also be carrying water and complex organic molecules. And if that is the case, the implications are very exciting. “You can say that planets that have these bombardments are more likely to have life.”

Until Larsen’s rocks they did not have “fresh” micrometeorites to study, to help them investigate this. All the previous ones from the Antarctic and the sea floor had been weathered by centuries in the atmosphere. Genge and Larsen published a paper in the journal of the Geological Society of America, changing the field for ever.

Things have changed for Larsen, too. He still plays in his band, with a packed schedule of concerts planned, but now he has another life too. When I meet him he has just returned from giving a lecture at NASA – during which he took the opportunity to sweep their roof. He has gained an academic position, though not a salary, at Oslo University. In Norway he is a minor celebrity again, this time because of rocks rather than jazz. Even his two daughters, who spent most of their teenage years puzzled and mildly embarrassed by their father’s habit of sweeping the local roofs, now view his hobby with grudging pride.

For all his ability to sift those sweepings for stardust, there is one search in which he has failed. Somewhere, in his house he presumes, is a matchbox containing the particle that started it all, but that he never analysed. Somewhere is that speck that glinted at him from the tablecloth all those years ago. Was it a micrometeorite? He doesn’t know. No matter how hard he looks, he just can’t find it.

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