WHEN GEOLOGIST AND nuclear security researcher Rodney Ewing left the University of Michigan for Stanford in 2014, he left some of his belongings back in the Midwest. Hundreds of his belongings, actually. All of them radioactive.
He wasn't trying to poison anybody: It was a collection of minerals from around the world—some unearthed himself, some donated—each with uranium enmeshed inside. And soon, scientists would use this legacy in a novel Department of Homeland Security project—one that aims to hunt down the source of illegal nuclear material that could end up in bombs.
Ewing bequeathed the samples to his former postdoc, Peter Burns, then a professor at Notre Dame. And along with his colleague Antonio Simonetti, he set off to build a global forensic database of uranium ore to help the DHS identify the perps. Each sample has its own chemical and isotopic fingerprints, unique to the geological and geochemical forces that formed it. That way, if authorities find someone trafficking radioactive material, they can figure out where it came from.