Path: utzoo!utgpu!attcan!uunet!husc6!cfa!cfa250!mcdowell
From: mcdowell@cfa250.harvard.edu (Jonathan McDowell)
Newsgroups: sci.space.shuttle
Subject: Re: Shuttle *Launch*
Message-ID: <1113@cfa237.cfa250.harvard.edu>
Date: 5 Oct 88 12:47:06 GMT
References: <1055@orion.cf.uci.edu>
Distribution: na
Organization: Harvard/Smithsonian Center for Astrophysics
Lines: 20

From article <1055@orion.cf.uci.edu>, by dkrause@orion.cf.uci.edu (Doug Krause):
> Okay, I have question.  Everybody's saying "that was a great launch"
> and "wasn't that launch beautiful" and "there goes another perfect
> launch".  Just what is the launch?  I imagine it starts at T0 (or
> T+0.0000001) but when does it end?  My roommate says when they reach
> orbit, I have no idea.  Any takers?
> Douglas Krause                     "APL is for martians" -Al Stevens

Well, I have to agree with your roommate.  I would say that the launch
ends at the end of powered flight, when you're no longer riding a pillar
of fire to avoid ending up in the ocean.  However on a mission like
STS26, at MECO (SSME Main Engine Cutoff) when the External Tank
separates, T+8.5 min, the orbit perigee is only 65 km which is low
enough that you'd reenter in 90 min if you stay in that orbit.  So
the OMS-2 circularization burn at 44 min into the flight (making the orbit
295 km circular) is really still part of the launch in a wider sense, although
normally it would not be considered enough. I start breathing again at MECO and
ET sep. (OK, I know, I'm pretty blue in the face by then!)

Jonathan McDowell