The Superbird 4 satellite is prepared for shipment to Kourou for launch. Photo: Hughes

Space Communications Corporation (SCC) of Tokyo ordered its second spacecraft from Hughes Space and Communications International, Inc., on April 6, 1998. The new communications satellite will begin serving Japan around the turn of the century from its orbital slot of 162 degrees East longitude.

Called SUPERBIRD-4, the satellite is an HS 601HP model set for launch in 2000 on an Ariane rocket.

SUPERBIRD-4 allows SCC to meet increasing demand for business telecommunications services throughout Japan and the Asia-Pacific region, via its 23 active transponders in Ku-band and a steerable Ku-band spot beam. The satellite will also carry broadband and high-speed data services, via 6 transponders in Ka-band.

SUPERBIRD-4 provides 5.5 kw total power at end of life. This is made possible with two solar wings, each with three panels of silicon solar cells and one panel of dual-junction gallium arsenide solar cells.

The satellite is being built in the Los Angeles-area factory of Hughes Space and Communications Company (HSC), the world's leading manufacturer of commercial communications satellites. HSC also supplies spacecraft for communications to the U.S. government, and builds weather satellites for the United States and Japan.

Superbird 4 facts
Spacecraft	HS 601HP
Life	15 years
Orbital Slot	162 degrees East
Dimensions	86 feet long 23 feet wide
Weights	8,950-lb at launch 4,520-lb in orbit
Power	2 solar wings with 4 panels each 5.5 kw end of life
Payload transponders	23 Ku-band 6 Ka-band
Source: Hughes Space and Communications

HSCI is an HSC subsidiary that markets satellites internationally, and holds contracts with a number of launch vehicle providers for delivery of customers' satellites on-orbit.

All HS 601 spacecraft use the same basic bus design, allowing HSC to realize efficiencies gained by production volume, tooling investments, and quantity buys. HSC introduced the HS 601 in 1987. Whether in the "classic" or the "HP," for high-power, configuration, it has become the world's best-selling large satellite model, with more than 70 ordered by customers around the world.

The HS 601 body is composed of two modules. The first contains the primary structure that carries all launch vehicle loads and contains the propulsion subsystem. The second module is a structure of honeycomb shelves that hold the communications equipment, electronics, battery packs, and isothermal heat pipes. Reflectors, antenna feeds, and solar arrays mount directly to the primary module, and antenna configurations can be placed on three faces of the bus. This modular approach allows work to proceed in parallel, thereby shortening the manufacturing schedule and test time.

Hughes Space and Communications has built about 40 percent of commercial communications satellites in operation today.