Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!cornell!uw-beaver!uw-june!uw-entropy!dataio!pilchuck!seahcx!phred!petej
From: petej@phred.UUCP (Pete Jarvis)
Newsgroups: sci.space.shuttle
Subject: Re: Shuttle-ground communication and payloadprices
Message-ID: <2516@phred.UUCP>
Date: 27 Mar 89 16:08:17 GMT
References: <2099@botter.cs.vu.nl> <1989Mar20.191412.23335@utzoo.uucp> <1194@ncrcce.StPaul.NCR.COM> <1989Mar22.175026.1247@utzoo.uucp> <2102@botter.cs.vu.nl>
Reply-To: petej@phred.UUCP (Pete Jarvis)
Organization: <2102@botter.cs.vu.nl>o
Lines: 19

In article <2102@botter.cs.vu.nl> wallagh@cs.vu.nl () writes:
>
>I still don't understand why you need 3 satelites to cover all the 
>communication with the Shuttle.
>Aren't there enough tracking stations on the ground? 
>There is (at least) a couple in the US, some in Europe and in Australia.
>That should be enough , I think. But it isn't. Why?
> 

The TDRS satelites are designed to replace the ground tracking stations
to save NASA $30 million a year. They also fill in the gaps that the
ground stations could not provide. They also provide for more timely
down-linking of telemetry data from the Shuttles so they don't have to
"save" it and down-link it later when they are over the appropriate
ground station. Last, but not least, the TDRS will provide an important
link to the Hubble Space Telescope allowing image data to be transmited
to its ground station (Reston, Virginia) on a continous basis.

Peter Jarvis - Physio-Control -- Redmond, WA.