Launch vehicle system tests

Wet dress rehearsals may be used on production launch vehicles before each flight[2] or on prototypes under development.

This tests engine startup while measuring pressure, temperature and propellant-flow gradients, and can be performed with or without payload.

Both were explicitly booked as wet dress rehearsals, but with the option to proceed to a static fire test.

[8] Wet rehearsal and static fire tests can fail catastrophically, such as that which resulted in a pad explosion of a SpaceX Falcon 9 on September 1, 2016.

[9] The failure resulted from a major breach of the cryogenic helium system of the second stage during propellant-loading operations.