zraphy 
March 15, 1978 
.Tracking and Data Relay Satellite System (TDRSS) 
PURPOSE: To track and provide 2-way data communications with up to 22 satellites 
(except those with geosynchronous or highly elliptical orbits) 
Wideband communications link for high data rates required by Landsat-D, 
' Space Shuttle, and Spacelab. 
Eliminate need for tape recorders, which have often malfunctioned 
Save cost of modernizing and operating global network of ground stations. 
LAUNCH DATE: July 1, 1980 (tentative), in 8th Space Shuttle flight, boosted by 
Interim Upper Stage 
ORBIT: Geosynchronous. One satellite to be positioned over the Atlantic Ocean, 
and one over the Pacific Ocean. 
Altitude: 33,000 km 
SYSTEM: Identical spacecraft (advanced Westar) will carry payloads for NASA and 
Western Union. Two satellites will be configured on orbit for NASA use, 
two for Western Union use, and one for shared use as a spare. 
High data rate users : 
Data rate Satellite 
Single access forward return antenna 
S-Band to 300 12 mbps 
(2.0-2.3 gHz) kbps two 4.9 m . 
giubalied antennae 
K-Band to 25 to 300 mbps 2.5? beam 
(13.8-15.1 mbps Shuttle-geared 
gHz) service: 
a) 3 digital channels 
50 mbps 
or b) 2 digital channels 
to 2 mbps and 
4.2-mc analog or 
  
TV channel 
Low data rate users 
Multiple access 
S-Band 10 kbps 50 kbps 30-element 
phased array antenna 
13.5? FOV 
GROUND STATION: White Sands, New Mexico, for data reception 
Landsat data to be transmitted vía Domsat to Goddard for 
processing (to avoid backlog at White Sands). 
Tracking network operations control center at Goddard 
REFERENCE: Aviation Week & Space Technology, Oct. 17, 1977, P. 97, 99, 155, 157. 
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