Remarks: "Endeavour's twang" at the moment of main engine start on her last night launch.I was 4 miles due south of Pad 39A and using a Canon 1Ds MKII with 1200mm L IS lens (600mm;2X). This shuttle launch phenomenon is affectionately referred to by astronauts as "the twang." When the main engines fire at T-5 seconds, the entire shuttle stack bends thanks to the instant spike of thrust. As soon as the shuttle snaps back upright, the solid rocket boosters ignite and the shuttle blasts off. As you can seen the stack has rocked forward and hence is not straight when compared to the launch pad. In a fraction of a second, the SRBs will fire and the resultant instantaneous water vapor cloud will envelop the stack and pad. On her last launch (5/16), the same events occurred except it was daylight.
