Boeing Satellite Systems 702 Satellite, USA

In October 1995, Hughes Space and Communications Company, now Boeing Satellite Systems, announced an innovative new satellite series, called the Hughes 702. Evolved from Hughes' proven Hughes 601 and Hughes 601HP (high power) spacecraft, the body stabilised Hughes 702 is a giant in size, performance and cost efficiency. The satellites are now known as the Boeing 601, 601HP, and 702. As of April 2001, twelve of these powerful satellites had been ordered, with options for eight more. The first satellite was launched in 1999.

The first customer for the new model was Hughes Communications, Inc., which merged with PanAmSat Corporation in May 1997 to create the world's largest privately owned communications satellite company. The 702 was chosen for the Galaxy and PAS fleet, to expand video distribution, telephony and data services in North and Latin America.

TRANSPONDERS

The Boeing 702 can carry up to 118 high-power transponders, of which 94 are active and 24 are spares and, deliver any communications frequencies that customers request.

MODULARITY

For maximum customer value and producibility at minimum total cost, the Boeing 702 offers a broad spectrum of modularity. A primary example is payload/bus integration. After the payload is tailored to customer specifications, the payload module mounts to the common bus module at only four locations and with only six electrical connectors. This design simplicity confers major advantages. First, non-recurring programme costs are reduced, because the bus does not need to be changed for every payload and payloads can be freely tailored without affecting the bus. Second, the design permits significantly faster parallel bus and payload processing. This leads to the third advantage; a short production schedule.

XIPS PROPULSION SYSTEM

Further efficiency derives from the 702 advanced xenon ion propulsion system (XIPS), which Hughes pioneered. XIPS is ten times more efficient than conventional liquid fuel systems. Four, 25cm thrusters provide economical stationkeeping, needing less fuel than bipropellant or arcjet systems consume. Using XIPS for final orbit insertion conserves even more mass compared to using an on-board liquid apogee engine. Customers can apply the weight savings to substantially increase the revenue generating payload at small marginal cost, to prolong service life, or to change to a less expensive launch vehicle (when cost is based on satellite mass). The Boeing 702 also incorporates a bipropellant propulsion system, which can lift the satellite into final orbit after separation from the launch vehicle.

SOLAR POWER SYSTEM

Innovation extends to the Boeing 702 power systems as well. As a new feature on the Boeing 702, angled solar reflector panels along both sides of the wings form a shallow trough and concentrate the sun rays on the solar cells. The Boeing 702 offers a range of power up to 25kw in the "Plus" version. Dual and triple junction gallium arsenide solar cells enable such high power levels. The cells were developed by Spectrolab.

THERMAL ENVIRONMENT

The Boeing 702 separates the bus and payload thermal environments and substantially enlarged the heat radiators to achieve a cooler, more stable thermal environment for both bus and payload. This increases unit reliability over service life. Deployable radiators use flexible heat pipes, which increase packageable radiator area. Further thermal control occurs through passive primary rejection via heat pipes.

OTHER SATELLITES

The baseline Boeing 702 is compatible with current and soon-to-be-available launch vehicles. These include the Atlas III family, Delta III, Ariane 4 and 5, Proton and Sea Launch.