pjm@utastro.UUCP (Phillip MacQueen) (09/30/88)
During the six-or-so seconds that separate the ignitions of the SSMEs and the SRBs, there is a brief period in which the orientation of the SSMEs rapidly varies. What is the purpose of/reason for this motion? Is it an intentional test of the SSME mountings before the decision to ignite the SRBs is made, or is it just a characteristic of the ignition process due to something like the direction of their thrust vectors being unstable during that period? As a side note, my first impression of the apparent flame at the side of the left SRB's nozzle was that it was a red flare from the camera lens due to the intensity of the immediately adjacent SRB plume. Unfortunately, the credibility of this (desirable) explanation dwindled as I continued to watch. Phillip MacQueen McDonald Observatory Austin, Texas.
henry@utzoo.uucp (Henry Spencer) (10/02/88)
In article <3200@utastro.UUCP> pjm@utastro.UUCP (Phillip MacQueen) writes: >... What is the purpose of/reason for this motion? Is it an intentional >test of the SSME mountings... It's a deliberate test of engine gimballing, as I recall. -- The meek can have the Earth; | Henry Spencer at U of Toronto Zoology the rest of us have other plans.|uunet!attcan!utzoo!henry henry@zoo.toronto.edu