From: utzoo!decvax!harpo!eagle!karn
Newsgroups: net.columbia
Title: Re: Shuttle"s Roll
Article-I.D.: eagle.724
Posted: Wed Jan 12 14:46:14 1983
Received: Fri Jan 14 20:04:38 1983
References: houxq.250

That is to put the shuttle on the correct launch azimuth, depending on
the desired orbital inclination.  Since the stack must fly with the
orbiter down, in order to facilitate SRB and ET separation, this
involves rolling the shuttle from the position on the pad shortly after
liftoff.  This is easier than rotating the entire pad!

Phil