Hughes Space
and Communications Co. (HSC) has shipped to Lockheed Martin Space
Systems the last in a series of powerful medium-data-rate (MDR)
communications payloads for the U.S. Air Force Milstar satellites.

The MDR payload provides jam-resistant communications to the
military through unique onboard signal and data processing

Milstar is the tactical and strategic multiservice satellite
system designed to provide secure, survivable communications for U.S.
forces worldwide. The constellation can transmit voice, data and
imagery, in addition to offering video teleconferencing capabilities.
The program is managed by the U.S. Air Force Space and Missile Center.

HSC is responsible for supplying the MDR communications and
crosslink payloads on Milstar. HSC subcontracts with TRW for the MDR
antennas and digital subsystem. Lockheed Martin Space Systems Co.
(LMSSC), the prime contractor, is responsible for the space and
mission control segments of the program.

The MDR payload dynamically sorts incoming data and routes the
data to the proper downlinks to establish networks and provide
bandwidth on demand. If necessary, it crosslinks the data between
satellites. These crosslinks provide rapid, ultra-secure
communications by enabling the satellites to pass signals to one
another without assistance from ground stations.

The payload HSC has just delivered is for the F-6 spacecraft,
scheduled for launch in 2002. After conducting a series of
thermal-vacuum and antenna range tests, HSC integrated antennas and
electronic units onto the MDR structure, called the -X (minus X) wing.
The F-6 wing is HSC’s fourth MDR payload and the sixth crosslink
payload delivered to LMSSC.

HSC is a major supplier of state-of-the-art radio frequency,
microwave and antenna subsystems on Milstar. In addition to the
crosslink payloads on the first two satellites, HSC provided elements
of a low-data-rate (LDR) payload under subcontract to TRW. The MDR
payload was incorporated with Milstar beginning with the F-3
spacecraft, also called the first Milstar II satellite.

Unfortunately, that satellite was lost in a launch vehicle failure
last year. Two Milstar I satellites are in orbit. The remaining three
in the Milstar II series will be launched over the next two years,
with the next one scheduled for this fall.

In addition, HSC, LMSSC and TRW have formed a national team to
build the follow-on to Milstar, called the Advanced EHF (Extremely
High Frequency) system. Production is planned to begin next year, with
first launch scheduled for 2004.

“Our work on Milstar is complete, but the legacy continues,” said
Tig H. Krekel, HSC president and chief executive officer. “We are
leveraging our systems integration, manufacturing and digital
processing experience on both commercial and government new programs.
We look forward to continuing our team effort with Lockheed and TRW
for the Milstar follow-on, the Advanced EHF system.”

The MDR payload uses a 32-channel extremely high-frequency (44
GHz) uplink and a super-high-frequency (20 GHz) downlink. It sends
real-time voice, video and data to military personnel in the field at
rates that range from 4.8 Kbps to 1.5 Mbps.

That is up to 50 times faster than a common PC modem. The
crosslinks provide communications capability at 60 GHz between Milstar
satellites for both the MDR payload and the 2.4 Kbps LDR
communications payload on the satellites.

The MDR antennas consist of eight narrow spot-beam antennas: six
distributed user coverage antennas (DUCAs), and two narrow spot beams
with nulling capabilities, known as nuller antennas. In contrast to
commercial communications satellites, whose beams can cover entire
continents, Milstar’s beams are very narrow, providing less
opportunity for enemy detection and penetration.

HSC is the world’s leading manufacturer of commercial
communications satellites, having built about 40 percent of those
satellites in operation. It also is a major supplier of spacecraft and
equipment to the U.S. government, and a builder of weather satellites.

HSC is a unit of Hughes Electronics Corp., 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
Corp., are used to calculate the earnings per share attributable to
the General Motors Class H common stock . For more
information about HSC and Hughes Electronics, visit their respective
Web sites at and