Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Posting-Version: version B 2.10.2 9/18/84; site ames.UUCP
Path: utzoo!watmath!clyde!burl!ulysses!allegra!bellcore!decvax!genrad!panda!talcott!harvard!seismo!hao!ames!al
From: al@ames.UUCP (Al Globus)
Newsgroups: net.space
Subject: re: re: launch windows
Message-ID: <867@ames.UUCP>
Date: Tue, 12-Mar-85 16:25:18 EST
Article-I.D.: ames.867
Posted: Tue Mar 12 16:25:18 1985
Date-Received: Fri, 15-Mar-85 02:41:57 EST
References: <983@mordor.UUCP>
Organization: NASA-Ames Research Center, Mtn. View, CA
Lines: 29

> 
> Wait a minute.  That explains why the satalite needs a launch window, not
> the shuttle itself.  The shuttle is in LEO, which is not Geo-sync.  So the
> satalite could be launched from any point, provided the shuttle could acheive
> the correct orbit, right?  Maybe the calculations would be too difficult to
> do on the fly, and have to be done long beforehand?
>          Jim Rachiele

I'm not sure where this started, but there are a number of launch constraints
that I know of.  Some are:

To get a satellite from shuttle orbit you must start your burn when the
shuttle orbit crosses the plane of the equator.  This only happens twice
per orbit.  This 'node crossing' must occur in the correct place to get
the satellite to the right place in geo-sync.  It's possible to drift
a satellite around in geo-sync, but the initial location must be within
line of site of a ground control station for check-out.

Most satellites have thermal constraints that require launch from the
shuttle on the dark or light side, but not either.

There are constraints on the shuttle due to various abort options.  E.g.,
there must be sufficient light at the Dakar runway used for some
contigencies.


I'm sure there are plenty of other constraints.  When it comes down to
actually getting a satellite into orbit, it's amazing how complicated
things become.