Overheating is a game mechanic in Space Agency that occurs when parts enter the atmosphere of a particular planet such as HOM or GOL and end up overheating and turning red in colour until they explode and trigger a chain reaction of explosions among interconnected or nearby parts, similar to ones caused by collisions or self-destructing parts. It is survivable if you do not stay within the atmosphere for long periods, and affected parts will cool down.
However, parts specifically designed to re-enter an atmosphere (such as the Orion Crew Capsule or Atmospheric Probe) instead trigger the re-entry sequence, even if the camera is not focused on it, unless still attached to parts not designed for such.
Re-entry vehicles have to be stabilised while descending down an atmosphere, otherwise they will also overheat and explode.
Certain payloads (such as the Automated Transfer Vehicle), when not protected by any fairing during launch, will overheat and explode as the rocket reaches full speed.