The biggest challenge in recovering miners is locating them quickly so that engineers can drill a borehole for fresh air and, ultimately, rescue. Sago, like most of the country's nearly 900 active mines, relied on radios that transmit signals over a thin wire that's easily damaged in a cave-in. InSeTa a wireless radio network to provide real-time locations. Miners wear walkie-talkie-size transmitters that hold a battery and an inertial-motion sensor, a device similar to those used in guided warheads and Nintendo Wii controllers to track motion on three axes.

Radio transceivers bolted into the mine's roof pick up the transmitter's signal and relay the positions of miners to an aboveground computer, which places them on a map of the mine. The transceivers are covered in bulletproof plastic, but even so, Breeding's plan calls for a highly redundant radio grid with 30 hours of battery power so that signals will get through even if several transceivers go down.

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