PUBLIC INFORMATION OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF. 91109. TELEPHONE (818) 354-5011
Contact: Jim Doyle
FOR IMMEDIATE RELEASEMarch 8, 1996
AUTOMATED GROUND TERMINAL TO REDUCE SATELLITE TRACKING COSTS
A new fully automated, miniaturized antenna station built
from off-the-shelf electronic components will significantly
reduce the cost of tracking NASA's low-Earth-orbit satellites.
The station, called a Low Earth Orbit (LEO) Terminal, was
built at NASA's Jet Propulsion Laboratory and tested to track and
command NASA's Cosmic Background Explorer (COBE) satellite
without operator intervention.
"Analysis of the terminal logs and spacecraft telemetry
indicated that the terminal worked flawlessly during the
demonstration," said Dr. Nasser Golshan, task manager of the
Development of the terminal was carried out in two phases by
a small team of engineers at JPL and SeaSpace Inc., a satellite
ground terminal manufacturer in San Diego, CA. In the first
phase, JPL upgraded a commercially available weather satellite-
tracking terminal and developed a receive-only terminal to gather
telemetry from NASA satellites.
That first phase was completed in 1994 with successful
demonstrations tracking NASA's Solar Anomalous and Magnetospheric
Particle Explorer and the Extreme UltraViolet Explorer. In the
second phase, command uplink capabilities were added and showed
that the terminal's operation could be completely automated using
The terminal antenna is enclosed in a fiberglass dome called
a radome. The radome protects the microwave electronics and the
tracking mechanism from the elements. A four-foot high cabinet
houses the station electronics. For testing purposes, the
terminal is located on the roof of an eight-story building at
Electronics include the telemetry receiver, a command
exciter, the antenna controller and a computer workstation. When
transmitting, the terminal uses a 200-watt solid-state
transmitter power amplifier.
The computer workstation allows for automated, unattended
operations of the terminal including automated scheduling,
calculation of orbital trajectories, control of the antenna
positioner for spacecraft tracking, automated uplink and
telemetry operations, communication interfaces for remote command
operations, as well as processing and distribution of spacecraft
engineering and science data to the mission operations and
science users of the data.
Commercial off-the-shelf software has been used extensively
to reduce cost and increase reliability. Costs of the equipment
and software are between $600,000 and $800,000 depending on the
The terminal can receive telemetry at rates up to 1.2
million bits per second. Uplink commands can be sent at up to
2,000 bits per second. Those rates and the operating frequency
can be modified with replacement equipment.
Equipped with a 3-meter (10-foot) antenna dish, the terminal
is capable of providing telemetry and command support to up to 55
percent of NASA's current and planned LEO missions. A 5-meter
(16-foot) dish could extend coverage to 70 percent of the
"This successful demonstration sets a benchmark for low-cost
support of Earth-orbiting missions," said Dr. Chad Edwards,
manager of the Deep Space Network Technology Program at JPL. "It
also shows NASA can work closely with industry to take the best
available commercial capabilities and quickly adapt them to meet
the needs of NASA science missions."
The concept for this project was conceived and sponsored by
NASA's Office of Space Communications, Washington, DC.