Path: utzoo!attcan!uunet!husc6!rice!titan!phil
From: phil@titan.rice.edu (William LeFebvre)
Newsgroups: sci.space.shuttle
Subject: Re: Launch Window question
Message-ID: <1897@kalliope.rice.edu>
Date: 19 Sep 88 19:01:01 GMT
References: <15019@ames.arc.nasa.gov> <2234@ssc-vax.UUCP>
Sender: usenet@rice.edu
Reply-To: phil@Rice.edu (William LeFebvre)
Organization: Rice University, Houston
Lines: 43

In article <2234@ssc-vax.UUCP> adolph@ssc-vax.UUCP (Mark C. Adolph) writes:
>If the purpose of the mission is to deploy a geosynchronous satellite,
>why is there a launch window?  What difference does it make when one
>launches into earth orbit?

The launch window is not for the benefit of the payload (at least, not in
this case).  It is primarily for the benefit of the orbiter, to ensure
that all the aborts are safe to take.  It is also effected by the
scheduled duration of the flight.

The following things (at least---there may be others) effect the launch
window:  sunset at the trans-atlantic abort sites (to insure that they can
still see to land if a TAL is necessary), sunrise at the landing site on
the scheduled end of mission (EOM) day, sunrise at the landing site on EOM
+ 1 day and EOM + 2 days (in case the orbiter has to stay up longer than
planned, perhaps because of problems on board or on the ground) and
probably EOM - 1 day if the launch is scheduled during the spring, the 3
hour crew constraint (the crew is not allowed to sit in the orbiter more
than three hours after the window opens for fear of fatigue, boredom,
muscle cramps, and certain natural functions---see below).  There are also
constraints imposed by the payload:  even a geosynchronous one.  I'm not
too clear on the reasons behind the payload constraints, but it may have
something to do with launching the payload in daylight (or with the sun in
a specific place).

I don't understand the 9:59 EDT launch time.  The chart I have shows that
the window for the 29th doesn't open until 10:07 EDT.  Maybe they came out
with a different window schedule (the one I have is dated May 24, 1988).

"Other natural functions":  What's the first thing the crew does after
getting into orbit?  Look out the windows.  What's the second thing?  Line
up for the bathroom!  I'm serious.  Think about it....

Something else I heard:  the flight deck only holds 4 crew members during
ascent and entry.  The remainder must ride it out on the middeck.  You
might think that those on the middeck really lose out because they can't
see out during launch.  But there's an advantage that makes up for it:
they're the first in line for the "waste disposal facility"!

			William LeFebvre
			Department of Computer Science
			Rice University