Hackerspace Charlotte created a radio that would transmit packets of data containing three important things: location, altitude and speed. Once the balloon got above a few thousand feet, it’s strikingly hard to see. The on-board GPS helped solve the problem. Hackerspace’s August Flassig assigned his HAM radio call sign to the balloon, then used other HAM radio receiving stations across North Carolina to pull in the signal from the balloon. During the three hour flight, we didn’t lose contact with the balloon until the very end, when it dipped below 2,800 feet and was too low to be tracked by faraway stations.