Dwayne Brown

Headquarters, Washington, DC

(Phone: 202/358-1726)

Susan Hendrix

Goddard Space Flight Center, Greenbelt, MD

(Phone: 301/286-7745)

RELEASE: 00-98

NASA is poised to launch the first of three of the most
advanced communications satellites ever designed, to replenish the
existing on-orbit fleet that has served the space community since
1983. The newest generation Tracking and Data Relay Satellites
(TDRS) will provide vital communication links with the Space
Shuttle, International Space Station, Hubble Space Telescope and
other spacecraft and launch vehicles.

“The average age of the existing fleet is more than 10 years,
which is beyond the mission design lifetime,” said Anthony
Comberiate, TDRS Project Manager at NASA’s Goddard Space Flight
Center, Greenbelt, MD. “The new series will replenish our existing
fleet and allow users to migrate to the new Ka-band,” allowing a
threefold increase in data throughput.

The Tracking and Data Relay Satellite-H, or TDRS-H, will be
launched June 29 aboard a Lockheed Martin Atlas IIA rocket from
Cape Canaveral Air Force Station, FL, during a 40-minute launch
window, which opens at 8:38 a.m. EDT.

Engineers will insert the spacecraft into a geosynchronous
orbit about 22,300 miles above the Earth. Maintaining its fixed
position above Earth, TDRS-H will provide nearly continuous
communication links with controllers and researchers on the ground.

Total cost for the TDRS-H mission is $395 million, which
includes the spacecraft, launch vehicle and modifications to the
White Sands Complex. (The White Sands, NM, ground terminal is the
TDRS operational control center, which also provides customer
telecommunications services.) Cost for all three satellites (TDRS-
H, -I and -J) is $485 million and includes the White Sands Complex
modifications. NASA plans to launch TDRS-I and TDRS-J in 2002 and
2003, respectively.

After testing and acceptance of the spacecraft, TDRS-H will be
called TDRS-8, relaying enormous volumes of user data — voice,
television and science — from various orbiting scientific and
manned missions to ground control centers. The spacecraft also
will track user satellites, determining their exact location in

TDRS-8 features the following new and improved services:

* S-band Single Access: Two 15-foot diameter steerable
antennas used at the 2.0 to 2.3 GHz (Giga Hertz) band will supply
robust communications to user satellites with smaller antennas and
receive telemetry and range-safety data from expendable rockets
during launch.

* Ku-band Single Access: The same two large antennas,
operating at 13.7 to 15.0 GHz, will provide high data-rate support
to the International Space Station with high-resolution digital
television, and will dump large volumes of data at rates up to 300
Mbps (Megabits per second). This rate is more than 5,000 times
faster than the standard “56K” (56 Kilobytes per second) home-
computer modem.

* Ka-band Single Access: A new higher-frequency (22.5 to 27.5
GHz) service that increases data rate capabilities to 800 Mbps will
provide communications with missions like the International Space
Station and future multi-spectral instruments for earth science

* Multiple Access: Using a phased array antenna and operating
in the 2.0 to 2.3 GHz range, the system receives and relays data
simultaneously from five lower data-rate users and transmits
commands to a single user.

Hughes Space and Communications of El Segundo, CA, designed,
built and tested the spacecraft under a fixed-price agreement with
NASA. By specifying performance requirements, the new approach
allowed the contractor to custom-design a spacecraft that met
NASA’s needs. Because it was allowed more latitude to use
commercial practices, Hughes was able to reduce the costs
associated with such a venture.

The Space Network Project at Goddard will manage TDRS-8
operations through NASA’s Consolidated Space Operations contract.
More information about TDRS-H, -I and -J can be found at: