What is the primary requirement for a rocket motor ignitor?

The primary requirement for a rocket motor ignitor is that it must transfer sufficient heat to the propellant to assure ignition. This is critical because the ignitor's main function is to initiate the combustion process within the rocket motor. If the ignitor does not provide enough heat to exceed the ignition temperature of the propellant, the engine will not fire, which could lead to the failure of the launch or a complete lack of propulsion.

While factors like weight, compatibility with various propellants, and ease of maintenance can be important considerations in the overall design and operation of a rocket system, the fundamental role of the ignitor is to ensure that the propellant combusts effectively. Therefore, the ability to produce adequate heat is paramount to achieving reliable ignition and, consequently, successful rocket flight.