Technology
Earth Stations
Overview
The ACTS network comprised a variety of terminal types. Two
general categories of terminals were developed: fixed and
mobile earth stations. Some of the terminals were developed
at Glenn Research Center. Outside investigators also developed
their own terminals. Terminals were designed to operate in
either BBP mode or MSM mode.
The two types of earth stations used in control of and experiments
with ACTS are the Master Ground Station (MGS) and Satellite
Operations Center (SOC); and Experimental Terminals.
The Master Ground Station (MGS) and
the Satellite Operations Center (SOC)
 The
ground control segment of ACTS includes the Master Ground
Station (MGS) located at NASA Glenn Research Center in Cleveland,
Ohio; and the Satellite Operations Center (SOC) located at
Lockheed Martin's Commercial Space Systems facility in Newtown,
Pennsylvania. Basically, the MGS controls the experimental
equipment onboard the spacecraft, while the SOC controls the
maneuvering of the spacecraft.
The Master Ground Station provides spacecraft and network
control, manages experiments and user investigations, and
records spacecraft and system data. Traffic requests are processed
and set up and traffic channels are assigned on an on-demand
basis. Command, ranging and telemetry information is sent
to and from ACTS via the MGS. All communications, including
commanding and telemetry, to the spacecraft are done through
this facility. A 5.5m tracking antenna is used. The command
link has approximately 25dB of link margin.
The Satellite Operations Center provides 24 hour monitoring
of the spacecraft health and status. Its primary responsibility
is generating flight system commands and analyzing, processing
and displaying the data from the flight system's instruments.
The center also handles orbital maneuvering as well as housekeeping
functions. The SOC is linked by terrestrial line to equipment
in the Master Ground Station.
 Experimenter
Terminals
In addition to the satellite, a network of earth terminals was developed by
NASA to serve certain classes of user application experiments as well as some
unique terminals developed by experimenters. The user terminals consisted of
a variety of earth terminals operated by industry, university and government
entities located across the United States. More than one hundred investigators, using over 53 earth
stations participated in the ACTS program.
The primary experimenter terminals developed by NASA included:
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