A Cosmic Rarity Found in Antarctic Snow
The isotope iron-60, produced when a star explodes, is hidden in some of Earth’s most isolated places
By Marina Koren
The snow arrived at the laboratory in Munich inside Styrofoam boxes. It came from a German research station in Antarctica, where summer made the snow, whisked around in the wind like sand on a beach, easy to lift. A pair of scientists had shoveled in thousands of pounds of the stuff. The boxes, kept under freezing conditions, traveled by plane to the ice shelf and then by ship to South Africa and Germany. In the lab, researchers melted the snow, sifted out any buried solids, and chucked them into an incinerator.
When the scientists analyzed the ash, they found something unusual: a radioactive form of iron. The isotope, known as iron-60, is rare on Earth. But it is produced in abundance in space, when a star, having exhausted the fuel that makes it shine, explodes.
The burst releases newly forged chemical elements into the universe like tufted dandelion seeds. The radioactive iron, carried inside microscopic particles of dust, glides across space and can settle on whatever it encounters. Sometimes, it ends up here.
“It’s actual stardust,” says Dominik Koll, a physicist at the Australian…
