Site: Hughes Space and Communications Company (HSC)
Bldg. S-10, M/S S312
2260 E. Imperial Highway
P.O. Box 92919
Los Angeles, CA 90009

Date Visited: June 24, 1997

WTEC: C. Mahle (report author) K. Bhasin, W. Brandon, N. Helm, E. Senesak, S. Townes



Hughes Electronics Corp., the parent of Hughes Space and Communications, is currently a $16 billion company with 86,000 employees. Raytheon is in the process of acquiring the defense business following its spinoff from Hughes Electronics. After completion of the transaction, the resulting company will focus on telecommunications with Hughes Space and Communications, Hughes Network Systems (HNS) and DirecTV. The current telecommunications and space segment of Hughes consists of the galaxy business of Hughes Space and Communications (HSC), Spectrolab, a 71% share of the merger of Hughes Communications (HCI) with Panamsat (it has the holding in AMSC, the Spaceways proposal and multimedia business; it will have 731 transponders and 21 satellites in 1998), and HEDD. Hughes Research Labs will be a cooperative effort of Raytheon and Hughes.

DirecTV now has 2.6 million subscribers and 11 brands of receiving equipment, including one provided by HNS. Service was scheduled to begin in Latin America in the summer of 1997 and in Japan in 1998.

Hughes' business has vertically integrated with content and packaging offered by DirecTV, and communication services by Galaxy (Panamsat).

HSC has 7,350 employees, approximately $2 billion in revenue and a backlog of $4 billion. The core business is communications satellites. The revenue is split about half government and half commercial.

HSC delivered 11 satellites in 1996, 24 in the next two years; 37 satellites are in backlog. Of 120 satellites built and launched, 64 are still in service.

As of February 1997 HSC had manufactured 50 HS 376 models, a spin stabilized satellite with 0.5 - 2 kW prime power, 67 HS 601, a three axis stabilized satellite with 2 - 8 kW prime power. Currently, 3 HS702s, a large three axis stabilized satellite with 8 - 15 kW prime power, are under construction.

HSC has worked to improve manufacturing operations for the HS 601 program and achieved a 47% productivity improvement and 30% cycle time reduction over the last 4 years. An HS 601 satellite can now be built in two years or less.


In the past, most commercial communications satellites were "bent pipe" satellites; in the future, satellites with multibeam antennas and onboard processing will be used; eventually the satellite may contain an ATM switch in the sky.

Since 1995 HSC has performed an extensive exercise in technology planning. Technology road maps for the next 20 years were developed, and technology development work for the next few years was defined. The technology road map included predictions of possible achievements and technology needs.

In the prime power area further growth of payload power requirements is foreseen. This requires work on solar arrays, batteries and heat dissipation.

Further work in TWTs will improve the efficiency and producibility.

Work in the industry is extending gate count in CMOS chips. Efforts to increase the speed of InP devices and to develop new Si GE HBT devices are in progress.

Phased array antennas and processors are considered very important for future communications satellites.

Prudent spectrum management will call for further bandwidth efficiency and the use of advanced modulation methods.

Intersatellite links may use rf up to 15 Gbps; optical links will be able to support higher data rates. Optical crosslinks may be in use in a few years.

Current satellites use nickel-hydrogen batteries that may be as heavy as the payload for a 15 kW satellite. Future satellites may use lithium - ion batteries with up to 50 Whrs/lb energy density, ultimately lithium - fluoride batteries may be developed with up to 140 Whrs/lb. Flywheel storage of energy may be a possibility in the far future.

Current solar arrays are using dual junction GaAs cells with concentrators; 30% efficiency may be expected in a few years with array power possibly increasing to the 20 to 30 kW range.

Propulsion systems for station keeping in the past used chemical propulsion; in the HS 601 HP and HS 702 satellites, xenon ion engines manufactured by HEDD are used for the first time in an operational commercial satellite.

In response to a question, HSC is also looking at LEO systems to keep informed on their capabilities.


Hughes acquired Spectrolab (SPL), a solar cell manufacturer, several years ago. Spectrolab has seen substantial growth since and has approximately 800 employees today. In addition to solar cells (both silicon and GaAs cells are in production) and related test systems, products include laser diodes and a variety of other items. Spectrolab's strength is affordable manufacturing using epitaxy. A substantial portion of the output is used by the internal customer. SPL assembles cells on panels specified by the spacecraft manufacturer but does not design the panel structure or array deployment mechanisms.

Silicon solar cells have reached efficiencies of 17%. Sharp in Japan produces the highest efficiency commercial cells with 17-18% efficiency. SPL commercial cells offer about 15% efficiency with other manufacturers at about the same level. SPL uses 4" wafers for commercial production.

SPL has developed dual junction GaAs solar cells with an efficiency of 25.5% peak and 21% in production. SPL uses a Ge substrate with GaAs and GaInP layers on 4" wafers. The Ge wafers are currently procured from overseas as no suitable U.S. supplier could be found at the beginning of the program. In the future, GaAs solar cell efficiencies are expected to increase to 35% with compound structures (triple junctions) and to 40% with concentrators. SPL GaAs cells are already used on commercial spacecraft.

SPL also builds solar cell test systems that are sold worldwide. They also build their own manufacturing systems.

SPL currently has the capability to produce 500,000 wafers per year. The capability was developed with help from the MANTECH program. Air Force, NASA/GSFC and Phillips Lab contracts helped develop the dual junction GaAs cell technology.


The laboratory will be operated as a cooperative effort between Raytheon and Hughes. The lab has approximately 400 people and $25 million in outside contracts.

Research is concentrated in four areas: communications & photonics, information science, microelectronics and sensors and materials. Work is directed towards government applications and is applicable to future commercial communications satellites.

Work in the photonics lab includes optical beamforming for phased array antennas with true time delay beam steering. Work is also ongoing to distribute rf signals via optical fibers in airplane local area networks. Photonic and rf functions are combined on the same chip.

A development model of a photonic time shifter driving a 96 element L-band array (single beam) achieved a 50% bandwidth and 60 degrees. scan angle. The array was developed for Rome Labs. Optical time delay is used for the larger slices of delay; shorter slices are realized in a microwave chip.

This type of beam steering is considered too expensive when many beams must be realized. Work addressing the generation of multiple beams with optical manifolds has started; currently a two beam scheme feeding a 16 element array is under development.

Work on optical Rotman lens type beam forming using phase locked lasers is sponsored by DOD.

The optical phased array work is considered useful in the long-term for commercial satellite applications.


The main focus of this business unit is traveling wave tubes (TWTs) for space applications. Currently the worldwide tube market is about $500 million; the U.S. market is about $250 million. HEDD has sales of approximately $100 million generated by about 900 people. The TWT business is 2/3 space, 1/3 for ground applications. HEDD has developed the only 60 GHz TWT in the world.

Each year about 500 TWTs are manufactured of which 300 become TWTAs (includes power supply). Most of these TWTs have a guaranteed lifetime of 15 years.

In addition to TWTs, products include electronic power conditioners (EPCs) to provide the supply voltages needed by the TWT, xenon thrusters (recent addition) and multipactor protectors for radar systems.

Further developments of TWT technology will continue to improve performance.

In particular, increased efficiency, reduced mass, and improvements in producibility are goals. The availability of software to perform 3-D electromagnetic calculations (developed by a government program) has allowed HEDD to model TWTs much more accurately and assists in the design and optimization effort. Also, cooperation with the NASA Lewis Research Center TWT group has been beneficial to HEDD's development program.

In the future, TWT efficiency will climb over 70%, operating frequencies will increase and the mass of both TWT and EPC will further decrease.

Development work is proceeding to lower the EPC mass (current production models are 5.5 lbs for a 6 kV unit, 14 lbs for a 22.5 kV unit). A current Ku-band EPC masses 1,300g; with switching speed increasing to 150 kHz, this may drop to 850 g.


This bus is based on the HS 601. Prime power ranges from 8 to 15 kW; expected lifetime is 15 years; payload mass up to 1200 kg and payload power 7 to 13.5 kW, can be accommodated. Up to 88 TWTs and 33 SSPAs can be mounted in the communications payload module.

The bus uses deployable heat radiators with fixed panels to radiate the heat generated by the electronics into space. A concentrator type solar array is equipped with GaAs cells. Station keeping is performed with redundant ion engines (with xenon fuel, 170 mN thrust) which operate approximately 1-2 hours per day using approximately 4.5 kW (this power comes partially from the battery). The orbit injection engine is a bipropellant design (the engine is not used on station). Transfer orbit operation uses both types of engines to optimize fuel consumption.

The payload module is thermally insulated from the bus module, allowing changes in payload configuration without affecting the bus design. Antennas for a typical payload consist of two reflector antennas with 2.4 m diameter deployed on the east and west sides of the spacecraft, and one reflector antenna with 1.8 m diameter mounted on the nadir deck.

The bus processor is a 16 bit design (1750 type) with 64K ROM and 96K RAM. The flight software is ported from the HS 601 program with a few modifications. A databus connects the electronic equipment throughout the satellite. The battery consists of individual NiH2 cell assembled into four battery packs (up to 60 cells with 14 cm diameter). The solar array performs a 2:1 concentration of solar energy.

A tour of the satellite manufacturing facility, including the integration and test areas showed several HS 601 spacecraft and one HS 376 spacecraft in assembly and test. Some parts for the HS 702 satellite are already being manufactured.


HSC is one of the world's premier commercial communications satellite builders with many satellites built, most in orbit still in service and a large backlog. HSC has made major strides in making satellite manufacturing more efficient and faster. The HS 702 will further improve on this capability. There is substantial investment in new technologies and manufacturing streamlining for future generations of satellites, which will make Hughes very competitive.

Published: December 1998; WTEC Hyper-Librarian