Path: utzoo!attcan!uunet!husc6!rutgers!mailrus!nrl-cmf!ames!yee
From: yee@ames.arc.nasa.gov (Peter E. Yee)
Newsgroups: sci.space.shuttle
Subject: Shuttle-launched satellite passes early tests with flying colors (Forwarded)
Message-ID: <18257@ames.arc.nasa.gov>
Date: 16 Nov 88 17:54:45 GMT
Reply-To: yee@ames.arc.nasa.gov (Peter E. Yee)
Organization: NASA Ames Research Center, Moffett Field, CA
Lines: 73

Jeff Vincent
Headquarters, Washington, D.C.                  November 14, 1988

James Elliott
Goddard Space Flight Center, Greenbelt, Md.


RELEASE:  88-157
 
SHUTTLE-LAUNCHED SATELLITE PASSES EARLY TESTS WITH FLYING COLORS


     The Tracking and Data Relay Satellite (TDRS), launched by 
the Space Shuttle Discovery on Sept. 29, has performed flawlessly 
on all tests to date and may support the next Space Shuttle 
mission, NASA officials at Goddard Space Flight Center, 
Greenbelt, Md., announced today.

     Since its launch by the crew of Discovery, the 5,000-pound 
communications satellite, known as TDRS-3, has been moved for 
testing to 150 degrees west longitude over the Equator.  This 
location is best for communications with the White Sands Ground 
Terminal in New Mexico, for spacecraft antenna testing, for pre-
mission tests and mission support for STS-27.

     Following deployment of the satellite's antennas and solar 
arrays, the satellite's thrusters were first fired on Oct. 2 to 
start TDRS drifting towards the test location.  The satellite's 
movement was stopped by additional firings on Oct. 11 and 12 when 
it arrived on station.

     Spacecraft communication systems were activated between Oct. 
7 and 18.  All systems performed flawlessly and testing is ahead 
of schedule, according to Dr. Dale W. Harris, TDRS project 
manager at Goddard.  Although tests and calibrations will not be 
complete, NASA hopes to use the TDRS-3, along with TDRS-1 
launched in April 1983, for improved communications during the 
STS-27 mission.

     TDRS-3 is the third to be launched.  The first has been in 
operation since 1983 and is located at 41 degrees west 
longitude.  The second was lost with the Challenger.  The fourth, 
to complete NASA's constellation of three on-orbit satellites, is 
scheduled for launch on the Discovery in February 1989.

     TDRS provides comprehensive telecommunications services by 
relaying voice, television, digital and analog signals between 
low-Earth-orbiting spacecraft, including the Space Shuttle and 
the ground.

     The TDRS satellites are built by TRW Space & Technology 
Group, Redondo Beach, Calif.  The satellites are owned and 
operated by Contel Federal Systems of Fairfax, Va., which also 
operates the White Sands Ground Terminal under a lease agreement 
with NASA.

     Orbiting at 22,250 miles above the Earth, the tracking and 
data relay satellites look down on NASA's fleet of low-Earth-
orbiting spacecraft and shuttles, tracking them worldwide and 
relaying two-way communications between them and mission control 
centers through a single ground station at White Sands, N.M. 

     NASA established the Tracking and Data Relay Satellite 
System (TDRSS) to increase the flow of information between low-
Earth-orbiting spacecraft and the ground.  TDRSS will provide 
significantly greater geographical coverage than that provided by 
NASA's worldwide network of ground-based tracking stations.

     With two operational TDRS, low-orbit spacecraft are in 
communication with Earth for about 85 percent of each orbit.  
Before the TDRS system, spacecraft could communicate with Earth 
only when they were in sight above one of several ground tracking 
stations, typically less than one-sixth of an orbit.