We're building a 3U CubeSat and have concerns about a ceramic PCB used in one of our experiments. Since ceramics have such a high melting temperature, we're not sure if the heat transfer during re-entry will happen quickly enough to disintegrate it. Obviously, this raises some questions from a legal perspective. Does anyone know about the liability and insurance requirements for CubeSats (in Canada, specifically)? Are there any resources that could point me in the right direction? Any help would be appreciated.
If re-entry heat destroys most of the cubesat, leaving only the circuit board intact, its flat shape will likely make it tumble and flutter down to earth intact, at a low terminal velocity, without much more heating or aerodynamic load. You could directly measure that speed (at least near the earth, where atmosphere is denser) by dropping it from a big kite or a tall bridge, and thereby estimate the damage its impact might cause.
If that's still too fast, give the board some weak points -- perforated lines like a matzo cracker -- to help it break into smaller parts with even slower terminal velocity and less kinetic energy.
Randall Munroe gives a good overview of re-entry of unusual items, and quotes a simulation:
calculations by Justin Atchison and Mason Peck have shown that an object shaped like a sheet of paper, curved to fall flat side first, could in theory enter the atmosphere “softly” without ever reaching especially high temperatures.