Atomic ant sand

During his first visit to New Mexico’s Trinity Site, where the world’s first atomic bomb test occurred, polymer scientist Robb Hermes could feel the military police watching him. Or maybe it was just his nagging conscience. Milling around with other tourists, he had to fight the urge to bend down, pretend to tie his shoes and swipe a piece of Trinitite — a glassy, mildly radioactive substance created by the explosion 68 years ago.

Removing Trinitite from the site is a federal crime. But Hermes was fascinated by the strange material and wanted to figure out how the little bits formed in the heart of an atomic blast. So he hatched a scheme. He returned to his office at Los Alamos National Laboratory, called up officials at the U.S. Army’s White Sands Missile Range (home to Trinity) and asked for a box of ant sand. Ants, he knew, build their mounds from mineral grains gathered up to 15 meters from their homes.

“I thought if I could get some ant sand, maybe I’d find at least a vial of little Trinitite pieces collected from around the site,” says Hermes.

When the sand arrived in the mail, Hermes and a geology club friend did indeed discover beads of Trinitite. The pieces were surprisingly spherical, which turned out to be the key to piecing together how the glass formed.

Waves of heat rippling outward from the plutonium bomb didn’t just sear the sand into glass like the surface of a crème brûlée, as many people had thought. Instead, Hermes found, the blast tossed sand up and melted it to form Trinitite, flinging droplets up to 1,800 meters from ground zero. Some drops solidified before hitting the ground, and some collected into puddles of molten material. In analyzing Trinitite’s makeup, Hermes even found colorful traces of steel and copper from the tower that held the bomb and from the wires connected to the instruments.

He has since gotten the Army’s blessing to do his Trinitite research. Hermes, now retired, supplies the ant sand to geologists who study meteorites. Microscopic spheres found at sites around the world resemble the Trinitite beads, evidence perhaps for a controversial theory that a meteor broke up in the atmosphere about 13,000 years ago and bombarded Earth with stones that burst in the air like miniature nuclear warheads. One theory holds that such an impact might have wiped out most of North America’s large animals, along with the Clovis culture that depended on them for food.