Self destruct

A self-destruct is a mechanism that can cause an object to destroy itself after a predefined set of circumstances has occurred.

Self-destruct mechanisms are typically found on devices and systems where malfunction could endanger large numbers of people.

Some types of modern land mines are designed to self-destruct, or chemically render themselves inert after a period of weeks or months to reduce the likelihood of friendly casualties during the conflict or civilian casualties after the conflict's end. The Amended Protocol II to the Convention on Certain Conventional Weapons (CCW), amended in 1996, requires that anti-personnel land mines deactivate and self-destruct, and sets standards for both. Land mines currently used by the United States military are designed to self-destruct between 4 hours and 15 days depending upon the type. The land mines have a battery and when the battery dies, the land mine self-destructs. The self-destruct system never failed in over 67,000 tested land mines in a variety of conditions. Not all self-destruct mechanisms are absolutely reliable, and most land mines that have been laid throughout history are not equipped to self-destruct. Land mines can also be designed to self-deactivate, for instance by a battery running out of a charge, but deactivation is considered a different mechanism from self-destruction.

The Space Shuttle Solid Rocket Boosters were equipped with explosive charges so that the boosters could be destroyed in the event that control was lost on launch and a populated area was in danger. Physically, this is done by detonation cords running along the booster. As they are set off, they cut open the booster's casing. This not only causes the solid rocket fuel to burn up rapidly by exposing a large reaction surface, the cut-open casing also allows combustion gases to escape sideways instead through the nozzle. Therefore, the booster no longer produces a significant thrust.

This feature can be seen in videos of the Challenger disaster. After the initial disintegration of the shuttle, the two solid rocket boosters continued firing until they exploded simultaneously 37 seconds later. This occurred when the Range Safety Officer decided that the separated boosters had the potential to endanger those on the ground and activated the self-destruct system.

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