Hughes-Built Satellite To Upgrade NASA Fleet
The next
generation of communications satellites which link astronauts and
Earth, as well as orbiting satellites to their ground stations, will
be launched from Cape Canaveral on June 29.
The Hughes 601 satellite, named TDRS-H, is the first of three TDRS
satellites built by Hughes Space and Communications (HSC) under a
$481.6 million contract with NASA. The trio of satellites will
replenish and augment the current TDRS fleet which has served the
Space Shuttle and other orbiting spacecraft for almost two decades.
The Tracking and Data Relay Satellite-H (TDRS-H) will be launched
onboard an Atlas IIA rocket. The 40-minute launch window opens at
8:38 a.m. (EDT) (12:38 GMT).
“The capacity and flexibility with this new generation of
Hughes-built TDRS satellites is unprecedented,” noted Tig H. Krekel,
HSC President and CEO. “TDRS really is akin to a switchboard in the
sky. These next generation TDRS satellites will double the capacity of
data transmission and provide nearly continuous communications links
between Earth and space. As the flow of science data becomes a torrent
and astronauts build humanity’s bridgehead in space, the next
generation TDRS satellites will help fulfill NASA’s mission of service
to our nation and our planet.
“TDRS spacecraft are the lifeline of mankind in space,
safeguarding astronauts by providing direct contact with Earth,”
Krekel added. “Beyond human space activities, TDRS supports spacecraft
with research targets ranging from the birth of stars deep in distant
galaxies to subtleties of environmental phenomena on Earth.”
Research approaches and instruments are equally varied, yet TDRS’
two-way communications serve all the low and medium orbit customer
space vehicles generating this important information. The TDRS
satellites relay large volumes of user satellite data — including
voice, television and scientific — from manned missions or orbiting
scientific spacecraft back to ground control centers.
The new satellite will add Ka-band capability to the TDRS fleet,
allowing for higher data rates at a more favorable band and making it
less susceptible to interference from the increasingly busy radio
environment. TDRS-H receive data rates are 300 megabits/second (Mbps)
at Ku- and Ka-band, and 6 Mbps at S band. This spacecraft carries the
additional capability for Ka-band receive rates of up to 800 Mbps.
Transmit data rates are 25 Mbps for Ku- and Ka-band, and 300
kilobits/second (Kbps) for S-band. In addition, S-band phased array
antenna can receive signals from five spacecraft at once, while
transmitting to one.
The new TDRS spacecraft are equipped with innovative folding
antennas that meet NASA’s requirements for reflectors with a large
surface area, yet low weight. The pair of 15-foot-diameter, flexible
graphite mesh antenna reflectors fold up for launch, then “spring
back” into their original cupped circular shape on orbit. These
steerable, single-access antennas can simultaneously transmit and
receive at S-band and either Ku- or Ka-band, supporting dual
independent two-way communication.
When fully deployed, the TDRS-H satellite measures 68 feet, 10
inches in length and 43 feet, five inches in width. At beginning of
life, TDRS-H’s weight on orbit will be 3,918 pounds. On-orbit power
derives from two wings covered with silicon solar cells that generate
2300 watts. A nickel-hydrogen battery supplies payload power during
eclipses.
The TDRS fleet is also unique in its ability to follow the motion
of fast moving satellites, providing nearly continuous communication
with controllers and researchers on Earth. In addition to the Space
Shuttle, other NASA programs using the TDRS fleet include the Hubble
Space Telescope, STARlink, the Tropical Rainfall Measuring Mission
(TRMM), Landsat (LSAT), the Earth Observing System (EOS), Expendable
Launch Vehicle tracking, and soon the International Space Station.
“TDRS also establishes international compatibility with the
Japanese and European space relay programs, allowing mutual support in
case of emergencies,” noted Krekel. “These new TDRS spacecraft will
meet space communications needs for the next decade.”
The body-stabilized Hughes 601 model on which the new TDRS
satellites are based was introduced in 1987 and is the most widely
used satellite model in space.
NASA plans to launch TDRS-I and TDRS-J in 2002 and 2003,
respectively. The satellites will be placed in geosynchronous orbit in
strategic locations above the Pacific and Atlantic oceans. TDRS-H will
be located at 150 Degrees West longitude for on-orbit acceptance
testing and post-acceptance testing. It will then move to 171 Degrees
West longitude for its operational phase.
HSC is the world’s leading manufacturer of commercial
communications satellites, having built nearly 40 percent of those in
operation. It also is a major supplier of spacecraft and equipment to
the U.S. government, and a builder of weather satellites for the
United States and Japan. HSC is a unit of Hughes Electronics
Corporation, the world’s leading provider of digital television
entertainment, and satellite and wireless systems and services. The
earnings of Hughes Electronics, a unit of General Motors Corporation,
are used to calculate the earnings per share attributable to the
General Motors Class H common stock . More information about
Hughes Electronics can be found at its web site at www.hughes.com.
TV Editors:
Live video of the launch will be carried on NASA-TV
beginning at 7:30 a.m. EDT (coordinates GE-2, transponder 9C at 85
degrees West longitude.) You are welcome to use the feed in your
news broadcasts.
