In 2143 Jonathan Archer and A.G. Robinson took the experimental NX-Beta on an unauthorised flight that broke the warp 2 barrier and reached warp 2.5.
The NX test programme aimed to push Earth's ships beyond warp 2. When Robinson's NX-Alpha broke apart during a test, with Robinson ejecting at the last moment, the programme was halted. Archer, Robinson and Trip Tucker believed the design was sound.
Without permission, Archer and Robinson took the NX-Beta out while Tucker monitored the flight from the ground. The ship passed warp 2 and reached warp 2.5, a new record that kept the programme alive, and within months a later test craft broke warp 3.