Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!cs.utexas.edu!ut-emx!tca
From: tca@ut-emx.UUCP (Tobin C. Anthony)
Newsgroups: sci.space.shuttle
Subject: Re: Shuttle-ground communication
Summary: Reason for just two TDRS
Message-ID: <11563@ut-emx.UUCP>
Date: 29 Mar 89 14:18:20 GMT
References: <1194@ncrcce.StPaul.NCR.COM> <1443@cfa237.cfa250.harvard.edu>
Organization: Dept. of Aerospace Engineering. Univ. of Texas
Lines: 12


The reason that there are only two operational TDRS satellites is for sheer
economic reasons.  NASA only wants to have one TDRS ground station and they
want to keep it at White Sands.  Both TDRS spacecraft can see White Sands
from their positions.  Having a third TDRS would require an additional
ground station on the opposite side of the Earth from White Sands.  The 
logistical implications of maintaining this site and have it communicate
with WS must have been cost-prohibitive.  The TDRS system covers 85% of
satellite orbits anyway.

Tobin C. Anthony
tca@gunaco.ae.utexas.edu