Launch key
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Launch keys are a critical component aboard Colonial ships. They are used, apparently, to start up a ship's powerplant and engines, similar to the way a car key does for the average automobile. Their removal from a ship will immobilize it.
In "Precipice," a briefing aboard Galactica reveals that the grounded ships of the Fleet have had their launch keys removed. One of the resistance's goals is to recover them, which Sharon Agathon manages to do in "Exodus, Part I."