HS 393A: New Domsat A-Building at SCG—The SCG Journal November 1983 transcribed by Faith MacPherson

It all began with the HS 333. Hughes built eight of this nifty little number, the first-generation domestic satellite which linked together the nearly 14,000 islands of Indonesia, brought dependable telephone and other communications services to the farthest reaches of Canada, and provided the United States, through Western Union, with the nation’s first commercial domsat communications system. Then came the by-now familiar and famous HS 376 spacecraft – the most purchased bus in the world. As you’re probably aware, 30 have been bought to date – a number of them by the users of those venerable HS 333s.HS393

And now there’s a new bird in the wings. For the past year SCG engineers have been working to define a growth version of the immensely popular HS 376. What they’ve come up with does indeed resemble a bigger, 50-percent-huskier version, 12 feet wide and about 33 feet tall with telescoping solar arrays and antenna reflector deployed. This is Hughes’ third-generation domestic satellite, the HS 393 – visually, an amalgam of the HS 376 and the giant Intelsat VI vehicle. When the satellites are placed side by side, the parentage is obvious (see art above.)

Within the space of a few short months, the Group has formed a team to build two flight models of the new-generation bird. That effort, the HS 393A program, is now well underway. The team members – more than 200 strong – have moved quickly to bring reality, in the form of aluminum honeycomb shelves, electronic black boxes, and composites structures, to the photon-ray concepts glowing on CAD terminal screens in design centers throughout El Segundo North. As Program Manager Pat Dougherty put it, “We’re running hard.”

Indeed. SCG management has committed the resources of the Group to an ambitious, and to some, a daunting delivery milestone of May 1985 for the first Ku band, 16-channel craft, being built for a customer as yet unannounced. The plan is to launch HS 393A-1 onboard shuttle flight STS-30 in September 1985, less than two years from now – a challenging schedule.

Yet the pace of work on 393A could be favorably compared with the strong, measured strides of a seasoned long-distance runner. All over the plant site and beyond, portions of the first spacecraft are taking shape. In Bldg S12, modules for the bird’s comm payload are being assembled. At the Hughes Industrial Electronics Group’s Electron Dynamics Division in Torrance, engineering and flight models of the advanced Ku band (14/12 GHz) TWTAs are being built in parallel efforts. Power and Propulsion specialists in Bldg S34 are creating cells for the satellite’s nickel hydrogen batteries; fabricators are laying up the thrust tube – the core structure of the spacecom bus. And in S31, Digital Electronics and Power experts are manufacturing parts kits and units for 393A’s telemetry and command subsystem.

Apparently Hughes SCG’s competition is moving in a similar direction. Ford Aerospace’s Western Development Laboratories Division in Palo Alto, Calif., has filed with the FCC to launch in 1987 an enhanced domsat based on the Intelsat V bus. RCA Astro-Electronics, Princeton, N.J., is guilding a larger version of its “assembly line” Satcom domsat. Called Satcom 4000, the bird has a reserved seat on a shuttle flight in September 1985. The customer is RCA Americom.

“We’re envisioning the basic HS 393 bus as a follow-on spacecraft for our customers who want more power and enhanced capabilities,” said Dick Brandes, Division 43 manager. HS 393A-1 and A-2 will carry a total of 24 Ku band TWTAs each, but experts say that the 393 bus is capable of supporting up to twice the communications payload (48 transponders) of an HS 376 (24 transponders), and will be capable of generating more than 2,000 watts of electrical power. This is considerably more than the HS 376’s 900-watt capability, and approaches the powerful Intelsat VI’s 2,300 to 4,000 watt range.

While these first two HS 393s can’t fly on the European Ariane 4 launcher, as Intelsat VI can, future birds in the family will be launchable either by a space shuttle or European Space Agency’s Ariane 4 expandable rocket. Unlike Intelsat VI, however, the 393 will not take up half of the shuttle bay (30 feet). In fact, this new communications bird will only use about 50 percent more room than an HS 376. The Frisbee-ejected HS 393 will use slightly less than 15 feet of the bay.

For its size the big bird will indeed stow compactly – a fact largely due to its telescoping solar drums, and another design concept, this one borrowed from the Leasat widebodies: a built-in (or integral) perigee stage rocket motor (PKM).

“Particularly where the shuttle is concerned, compact spacecraft are cost-effective spacecraft,” Brandes pointed out.

Does the emergence of this bigger “son of HS 376” spell the end for the current Hughes best-seller? Not at all, said Steve Pilcher, Division 43 assistant manager who oversees the organization’s Advanced Programs Lab.

“The new HS 393 spacecraft fills a gap between the HS 376 and Intelsat VI. It will have its place in the Hughes satellite family, just as HS 376 does.”


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About Jack Fisher

Jack was a systems engineer at Hughes from 1961 to 1992. He contributed to various programs including Surveyor, Pioneer Venus, Galileo, Intelsat VI and innumerable proposals. He was the manager of of the Spacecraft Systems Engineering Lab until his retirement. Upon retirement Jack taught systems engineering at a number of national and international venues.

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