Every day, the Earth is showered with about 100 tons of cosmic dust, sub-millimeter mineral particles that have been floating around since before our solar system formed 4.6 billion years ago. They enter Earth’s atmosphere at speeds of at least 7 miles per second, and despite their small size, they account for most of the extraterrestrial material on Earth by weight.
Since the astronomer Fred Whipple coined the term ‘micrometeorite‘ in 1950, hundreds of samples of cosmic dust have been collected all over the world. All of these samples are collected at pristine sites far away from human activity, such as by drilling into the polar icecaps or using a magnetic sled to dredge the ocean floor. But last year Matthew Genge, a planetary scientist at Imperial College London, joined forces with Jon Larsen, a professional Norwegian musician moonlighting as an amateur scientist, who has been hunting and photographing micrometeorites for nearly a decade and recently found the first micrometeorite in an urban environment.
As detailed in a paper published last December in Geology, Genge and Larsen collected some 300 kilos of dust from rooftops in Paris, Berlin and Oslo for their project. Using magnets to separate the cosmic dust from the terrestrial, the pair managed to find some 500 micrometeorites in their dust collection. Now, Larsen has collected these specimens into a forthcoming book of truly stellar photography called In Search of Stardust.
I caught up with Larsen to see what the process of hunting for cosmic dust in some of the world’s largest cities is like, and why he and Genge succeeded where many others have failed.
Motherboard: How do you photograph such small objects with so much detail?
Jon Larsen: Parallel with the search for the micrometeorites I have worked with Jan Braly Kihle to construct a photographic instrument to document the micrometeorites in hi-res color. It has taken us several years, but with a combination of already existing lenses and an Olympus camera, custom built adaptations and new inventions both in hardware and software we now have an instrument that allows us to take color photos of micrometeorites with up to 3,000 times magnification. This allows us to see these small grains from space like nobody has seen them before. Up until now micrometeorites from Antarctica have been documented via SEM section images: black and white pictures full of structural details, but ofter rather misleading as to what micrometeorites actually look like.
Was it easier to find micrometeorites once you knew what you were looking for?
Today I find them everywhere. The problem was that no one had documented what micrometeorites look like. All micrometeorites from the Antarctic collections had been molded in resin and grinded down to a section which had been analysed, but these black/white images from the electron…