Group’s Propelling Idea to Boost Satellites—The SCG Journal November 1983 transcribed by Faith MacPherson

(Ed. Note: When Challenger launched two SCG satellites this past June, the spacecraft were boosted up from the shuttle’s low-earth orbit by payload assist modules – standardized upper stage rockets which were attached to the satellites’ aft ends. Although these PAMs have worked well in five out of five shuttle satellite deployments, problems and controversy surround the ongoing development of more complex, large upper stages for heavier satellites and planetary spacecraft. In the following viewpoint article, originally published in a longer form in Aviation Week, SCG President Dr. Albert Wheelon offers the Group’s approach to cost-effectively propel payloads into their final orbital tracks.)

Our nation is now transitioning its space programs – both civilian and military – to the space shuttle fleet. It is gradually turning off the supply lines for traditional launch vehicles: Titan, Delta, and Atlas Centaur. However, these traditional launchers have one important advantage over the shuttle: they place spacecraft directly into a high elliptical orbit. Satellites can either remain in this high orbit or, using an apogee kick motor, transfer to the geosynchronous stationary orbit used by all commercial communications satellites. On the other hand, the shuttle carries spacecraft only to low-earth orbit, and a large additional boost must be supplied by other rocket stages to move vehicles into other, higher tracks. NASA recognized this shortcoming early in the shuttle program and encouraged the development of a few standard upper stages. For example, the space agency encouraged the Air Force to undertake the development of the inertial upper stage (IUS). In return for a regulated market franchise, NASA also induced McDonnell Douglas to develop the payload assist module PAM-D, used for our HS 376 satellites, and the PAM-A stage, planned to boost Atlas Centaur-class payloads like Ford’s Intelsat V.Boost1

PAM-D has been a reasonable success; 22 have been ordered to lift satellites from shuttle low-earth orbit into transfer orbit, and five have already flown successfully.

PAM-A is another story. Eight have been built and there are no users in sight. The IUS has been an extraordinarily costly development, and its rising launch price is rapidly discouraging its use both by commercial and military customers.

The Air Force and NASA are now embarked on the development of a new standard upper stage – the Centaur – which shows every promise of following the path of IUS.

This raises two important questions. The first is, what is wrong with these generic standard rocket upper stages? The second is, is there an alternative? Fortunately for the country, there are clear, positive answers to both of these questions.

The fundamental problem with standard upper stages is the premise on which they are based. It is assumed that such a rocket stage is a good thing to have, that a single upper stage can be used by all spacecraft, thereby spreading the nonrecurring development cost among all user programs and avoiding expensive duplication. What this argument ignores is the enormous increase in recurring costs for each program that is forced to employ a standard stage which is designed for the most demanding user.

The basic problem is that each customer must pay for all the capability needed by all customers, whether that capability is used for a particular mission or not. This situation exists for several reasons:

• A standard upper stage must be sized to the largest, heaviest spacecraft.

• Such a stage must be prepared to fly into all possible orbits.

• The upper stage’s guidance system must be extraordinarily capable to accommodate all possible requirements. (IUS has three redundant guidance systems for this reason.)

• The most valuable spacecraft sets the reliability standard for all users, and each must pay the maximum bill.

Upper Stage Inflation

These relentless pressures progressively increase the price of any standard stage. We believe that these pressures are the driving forces behind the IUS rise from the $2 million per shot promised in 1974 to the $125 million per shot now projected for the mid-80s. As the unit price increases, users shy away from employing a standard upper stage and look to other launch methods. The Air Force Satellite Data System and Navstar programs have abandoned IUS for this reason, and no commercial firm is even contemplating IUS use. This dwindling customer base further accelerates the rise in launch prices. This situation worsens with time, compelling one to ask if there is a better, cheaper solution to the problem.

Integral Propulsion

The premise of integral propulsion is that each spacecraft program can supply its own post-shuttle propulsion most economically by incorporating it directly into the satellite. This has been done for 20 years by all commercial communications satellites which provide a solid rocket motor as an integral part of the spacecraft. This motor is fired at apogee and provides the thrust for transfer to synchronous orbit. The apogee impulse can also be supplied by a liquid propulsion system.

Most Air Force programs have not used integral propulsion because of their commitment to the Titan III/Transtage, or Titan 34D/IUS booster/upper stage combinations which provide the apogee boost as part of their service. (However, the FLTSATCOM and NATO satellite systems have used integral apogee propulsion.) Integral propulsion can also provide the perigee boost needed to shift a satellite from shuttle orbit to transfer orbit. This is the path that all commercial and some military users are taking.

The integral propulsion concept is simple. The shuttle itself carries a superb guidance system which can provide the satellite’s initial orientation. By spinning the satellite as it leaves the bay, the attitude reference is preserved. After a suitable separation delay, a rocket motor fires and the satellite proceeds into transfer orbit. Onboard the spacecraft is a guidance system that will position and orient the satellite for almost a decade after launch; the same spacecraft guidance system can easily control the satellite’s orientation during transfer orbit and during kick motor firing. This “integral guidance” does the job that the three inertial measurement systems of the IUS are designed to do.

Are there any limits to the application of integral propulsion? Does it place any restrictions on the design of the satellite which make it unattractive, either in terms of size or type of stabilization?

The general answer to each question is no.

The nation has a rich inventory of liquid and solid propulsion rocket elements, a result of the Apollo, space shuttle, Minuteman, PAM and IUS programs. By combining these elements appropriately, satellites have been designed whose sizes cover the spectrum of shuttle capacity.

Advocates for the new Centaur standard upper stage argue that it is needed to put very large payloads into synchronous orbit. The fact is that a version of the Hughes integral propulsion multimission bus (MMB) is under design and development that will place nearly 11,000 pounds into stationary orbit. Integral propulsion does not restrict satellite size.

Dollars and Sense

One can compare the launch costs of various spacecraft by plotting the total launch cost – shuttle charge plus upper stage – vs. the initial in-orbit weight. This is illustrated by the chart below, using civilian spacecraft examples. Military programs follow the same trend.Boost2

This plot shows some dramatic differences. The TDRS and Intelsat VI spacecraft will have the same initial weight in synchronous orbit. TDRS gets there with the IUS (government-furnished) and Intelsat VI uses its own integral propulsion.

These two similar satellites have an enormous launch cost difference: $89 million (1986 launch, 1982 dollars), which explains why no commercial user is planning to go with IUS. Most of this difference is IUS cost, but a small component is additional shuttle user charge. TDRS plus IUS takes an entire shuttle bay while Intelsat VI takes half a shuttle. Leasat also uses integral propulsion and lies on the dotted line that characterized this approach.

Also shown on this curve is Intelsat V as it would be launched by shuttle and the PAM-A standard upper stage. The large launch cost of this combination explains why the original plan to launch Intelsat V on shuttles has been dropped in favor of Atlas Centaur and Ariane, even though these are expensive rockets.

Integral Propulsion Loomed Large in I-VI Win

Another compelling example of the economics attached to integral propulsion was provided by the Intelsat VI competition in 1981. Hughes proposed an integral propulsion spacecraft. Ford subcontracted with McDonnell Douglas for a new standard upper stage. Both avoided the IUS.

The Hughes cost was $50 million less for the initial development program and resulted in a $16 million advantage in launch cost for each additional satellite placed in service. This cost difference was overriding and resulted in INTELSAT’s contracting with Hughes.

Commercial satellite users are forced to face the launch cost issue squarely – their system cost is the sum of satellites and launches. The procedure in military programs is often different. Most spacecraft program managers do not budget for launch vehicles. Launchers and upper stages are developed and budgeted for in separate, parallel organizations. Since the combined expenditures of satellite and launch meet only at much higher levels, military spacecraft programs have no incentive to reduce launch costs. Indeed, satellite managers are often discouraged from second-guessing the programs of their comrades, who have been committed for three decades to providing standard upper stages. This independence is reinforced by the industrial base that provides these standard vehicles.

Propulsion proponents submit that continued development of standard rocket stages is necessary to maintain a healthy propulsion industry. In developing a rocket stage, however, only a minor fraction of the funds is spent on propulsion elements.

Other Issues

Standard stages have several other negative influences which are not commonly understood. Because of their size, both the IUS and Centaur rocket stages involve dedicating an entire shuttle launch to a single mission. Using these large stages thereby undermines the efficiency of launching several satellites in one mission, as is common in the commercial arena. Further, big stages lead to large spacecraft, with many payloads, and frustrate the commonsense objectives of proliferating our military space assets for both survivability and flexibility.

Integral propulsion provides a decisively cheaper solution for space systems. It has made standard upper stage approaches like IUS and Centaur completely obsolete. The country can no longer ignore the new technology.

The old solutions represent an unwarranted tax on space systems, a tax that the nation can no longer bear in silence.


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.”


Wheelon Meets the Press to Discuss Largest Commsat Program—The SCG Journal April 1982 transcribed by Faith MacPherson

Round of International Press Conferences Kicked Off With High Bay Meeting in El Segundo

A full-size rendering of the Intelsat VI satellite served as a towering backdrop for a well attended press conference held earlier this month by SCG and INTELSAT executives to officially announce the awarding of the Intelsat VI program to Hughes.

The meeting was the first in a series of I-VI new conferences. Group President Dr. Albert Wheelon later conducted press conferences in Germany, Italy, Britain, and Japan in support of Hughes’ international subcontractors on the program.

Participating in the high bay news conference with Wheelon were SCG’s Dr. Harold Rosen, vice president, Engineering; INTELSAT Director General Santiago Astrain; and Francis Latapie, INTELSAT’S deputy director general, Administration.

In a sense, the imposing image of the Intelsat VI spacecraft set the tone of the meeting. Extending from the floor to just short of the high bay’s 40-foot-plus ceiling, it dwarfed the full-size model of Intelsat I which stood next to it. Intelsat I, also known as Early Bird, was the first satellite that Hughes built for the International Telecommunications Satellite Organization back in 1965. Astrain pointed out that Early Bird could handle 240 telephone calls at one time, or one black and white television show. In contract, Intelsat VI is capable of transmitting 33,000 simultaneous phone calls and four color television channels. The visual underscored Wheelon’s statement that “Intelsat VI is by far the largest commercial satellite program ever undertaken – as large as or larger than the very big programs that we do for the U.S. Department of Defense.” The first five satellites will cost INTELSAT about $700 million. If the organization later decides to pick up its options on another 11 of the tall spacecraft, the program could grow to over $1.5 billion in 1982 dollars.

The program’s size and cost are indicative of the growing demand for satellite communications by the nations of the world. INTELSAT, which has 106 shareholding member nations, supplies spaceborne telephone and television to 150 countries through its global network. The international organization’s system of 14 satellites, most of which were built by Hughes, carries more than 60 percent of the world’s overseas traffic and almost all international television. And Astrain indicated that there’s nowhere to go but up. INTELSAT is already projecting that by the time the first Intelsat VI is launched in 1986, the not-yet-launched Atlantic Ocean Intelsat VA, with 15,000 circuits, will be saturated. Even Intelsat VI’s 33,000 circuites may not be enough for long. By 1990, Astrain said, INTELSAT may need the capacity to handle 110,000 telephone calls. The demand could reach 500,000 circuits by the end of the century.

However, new technology and growth capabilities built into Intelsat VI by SCG will help prevent a communications gap. Intelsat VI’s satellite-switched, time division multiple access (SS/TDMA) digital communications technology will greatly increase its capacity and efficiency in handling traffic. And its frequency reuse scheme will allow six-fold use of the same frequency band.

In citing the satellite’s design flexibility for growth, Wheelon pointed out that the communications payload can be increased by half. Its basic power of 2,200 watts can be doubled to accommodate increased demands as well.

Astrain said that in theory, such advances combined with other techniques could make it possible for one Intelsat VI satellite to cope with as many as 100,000 telephone calls at one time, “And while we don’t intend to go to an all-digital operation in the foreseeable future, this program must be seen as the first step in that direction,” he said.

Wheelon said that the workload generated by the I-VI program will mean adding to the already growing SCG population. Partly to meet Intelsat VI staffing requirements, between 500 and 1,000 new people will be hired in the next year. The Group president emphasized that the number of new hires is driven not only by new business, but by ongoing programs as well. He said that 2,400 specialists around the world will be working on Intelsat VI – 1,000 at SCG and 1,400 at Hughes subcontractors abroad.

Asked whether the new Intelsats will be assembled and tested here at El Segundo or at the planned Titusville facility in Florida, Wheelon said, “Some of the Intelsat VI’s down the road will be assembled and tested in Florida. Whether the first five will be is something I can’t be sure of today.”

Wheelon noted that all the Group has in Titusville at the moment is bare land. “Whether the Florida assembly and test facility emerges in time to do Intelsat VI is not yet clear.”

Intelsat VI may be a big job, but the Group is equal to the task, Wheelon pointed out. “It’s an exciting program. The first satellite will be delivered forty-four months from program go-ahead. More significantly, we have to make and deliver one of the large satellites every four months. That really is a challenge.”

Despite unseasonably cold and rainy weather the day of the press conference, a sizeable number of media representatives turned out for the event. The story of Intelsat VI made the front page of the Los Angeles Times and was carried over the airwaves by TV channels 4 (KNBC), 5 (KTLA) and 7 (KABC).

Note:  It would most interesting to add some comments to this post regarding the Intelsat VI proposal.  Anyone who worked on that proposal or has information about it please send us your comments.