Geologists at the University of California, Davis, are using neutron beams from a nuclear reactor to see inside rocks. The method could be used to look for traces of life in rocks from Mars or very ancient rocks from the Earth. “Normally, we’d make a three-dimensional image by cutting the rock in slices. With this method, we can do it without destroying the rock,” said UC Davis geology professor Charles Lesher. Researcher Martin Wilding, geology assistant professor Dawn Sumner and Lesher have already used the method, called neutron tomography, to find bacteria living inside rocks collected in the Mars-like environment of Antarctica’s dry valleys and Israel’s Negev desert. They’re also using it to study the structure of volcanic rocks and glasses, and of “black smoker” chimneys collected from the deep ocean floor. Neutron tomography could also be used for biology experiments, such as filming water movement inside plants, Wilding said. “We’re just scratching the surface of what we can do,” he said.