Scientists look for micrometeorites on cathedral roofs

University of Kent scientists are roaming the roofs of cathedrals spread across the UK in search of dust particles that might have accumulated over the centuries. 

Dr Penny Wozniakiewicz and Dr Matthias van Ginneken are hoping to find cosmic dust on the buildings and use it to understand how much material from space reaches Earth and becomes part of the planet or its atmosphere.

Cosmic dust includes interplanetary dust particles (IDP) – particles from comets, asteroids and other bodies generally smaller than 0.1mm in diameter. IDPs are small and decelerate quickly enough when falling into Earth’s atmosphere. However, due to their inaccessibility, cathedral roofs might have held on to some of these particles. 

“You want the site as undisturbed as possible,” said Wozniakiewicz told The Guardian. “The dust is coming in everywhere, but the rooftops offer an opportunity to collect the dust and not have people trampling all over it.”

The dust particles come from asteroids and comets, and smash into the atmosphere at tens of thousands of miles per hour. Many burn up in the process, but some melt and resolidify to form tiny, distinctive spheres that are scattered across Earth’s surface.

Wozniakiewicz added: “We want to go to these rooftops because the particles we find are so fascinating. They are useful to get a feel for the number of particles that are arriving at the surface. That can be related back to the number arriving at the top of the atmosphere, so we can learn about the contribution of this material to Earth.”

Cathedrals are also a good place to look for these types of samples because of the quality of their record keeping, which allows the ages of different sections of roof – and how long they have been gathering dust – to be well documented, facilitating the researchers’ work.

“Initially, we did just collect the cosmic dust with a dustpan and brush, but we now have our own vacuum cleaner,” Wozniakiewicz said. “Generally, we collect from where it’s washed from sloping roofs to flat ones and into gutters.

“Cosmic dust is mixed in with far greater quantities of terrestrial dust created, for example, by welding, drilling or ash from combustion, but the proportion that is from space, and the number of different cosmic varieties, is likely to be greater on a cathedral than a house.

“Not many people get on church roofs to disturb the dust too. If you were collecting somewhere like a playground or road, identifying cosmic dust would be much harder.”

Micrometeorites are dust-sized particles continuously raining down from space and represent the main part of the flux of extraterrestrial matter to Earth. For this reason, they are fundamental to understanding the inventory of matter in the Solar System and its history.

Over 100 million dust micrometeorites land on Earth every year, some of which offer samples of different types of asteroids. The particles that settle on Earth have an upper size limit of around 2mm, with an average size of around 0.3mm.

Until recently, micrometeorites were only found in environments mostly preserved from human activity, such as the deep ocean floor and Antarctica. However, recent studies proved that they can also be found in environments of intense human activities, such as roofs of buildings in densely populated areas.

The samples the University of Kent team have found so far have included grains that are up to seven billion years old that came from other solar systems and entered our own after its birth 4.6 billion years ago.

Wozniakiewicz and Ginnekento are expected to return to Canterbury in the next couple of weeks for more thorough research, after which their next stop will be Rochester Cathedral. The pair said they have a list of 13 cathedrals they want to examine during the course of the project.