Unlike here on earth, no pesky amateur radio eavesdroppers or curious hackers monitor the open sky between ground control and a drone—not to mention between that drone and its communication satellite perched miles higher up.

One small crew of hackers is trying to pierce that stratospheric secrecy zone with a high-altitude flying—or at least floating—machine of their own. The three members of a socially motivated movement of technologists known as Critical Engineering have developed and begun testing an "aerospace probe" they call the Deep Sweep. The invention, described in their own detailed writeup, is a 1-foot-diameter acrylic orb packed with radio equipment and attached to a 8.2-foot diameter helium-filled weather balloon.