Strings of Digital Optical Modules (DOMs) are lowered into the deep holes, surveying the ice for neutrinos. When a neutrino collides with an atomic nucleus, a new particle called a muon is produced, which emits a faint blue glow in the transparent ice that the DOMs can detect.

A string of DOMs is essentially a telescope pointed at the ground: The DOMs will look for neutrinos that originated in the northern sky, passed through the Earth without resistance, and lodged themselves in the South Pole's ice.