On April 1st, 1961 Fred Adler was asked to form a Space Systems Division within the Hughes Aircraft Company. At that time, only 4 years after the launch of Sputnik, several important events were taking place. As a result of a major loss in Hughes business resulting from the cancellation of the Air Force’s F-108 interceptor, the space race beckoned. Hughes was starting a contract from JPL to build a lunar lander called Surveyor. That program was to build up a cadre of Hughes space engineers and an organizational infrastructure that ultimately served as a basis for many future space programs at Hughes. The Air Force and CIA were initiating space programs to observe Soviet activities from space. Hughes would ultimately be a major player in those programs. Finally, a small team, led by Harold Rosen, was developing the first geostationary communication satellite called Syncom. Syncom was successfully launched in 1963 and in 1964 Syncom 3 transmitted television from the Tokyo Olympics to the USA. The successful demonstration of Syncom ended the controversy of which orbit was best for commercial communication satellites and launched a new industry which ultimately changed the world and also Hughes in a profound way. A new organization, Intelsat, was formed to provide international communication and Hughes provided their first satellite, Early Bird or Intelsat I in 1965. Many more were to follow.
The world’s largest and most powerful communications satellite, built by HAC for the Department of Defense and launched Sunday from Cape Kennedy by the Air Force aboard a Titan-3C booster, now is in synchronous orbit over the Pacific.
HAC Program Manager Tom Mattis and other Hughesites who witnessed the launch described it as “beautiful, beautiful, adding “it was a glorious day for it.”
All the tests scheduled to be completed by Wednesday had been accomplished and all systems were operating well.
The 1600-pound experimental tactical communications satellite (TACSAT), two stories high and more than 8 feet in diameter, carries a cluster of antenna systems capable of radiating signals that can be received by all types of ground terminals including those with antennas as small as 1-foot in diameter.
Construction of the spin-stabilized spacecraft, built under a USAF contract totaling $30 million, was directed by the Air Force Space and Missile Systems Organization (SAMSO).
The giant satellite will be used by the Army, Navy and Air Force to test the feasibility of suing synchronous satellites for tactical communications with small mobile ground stations, aircraft, and ships at sea.
Mr. Mattis said the tests will determine whether hundreds of small mobile terminals with varying power levels can be used effectively with a single satellite. Another objective of the mission will be to determine the best frequency bands to be used for tactical service. The tests will be in the ultra high frequency (UHF) and the super high frequency (SHF) ranges.
The satellite’s communication antennas are mechanically “despun” to keep them pointed toward earth.
“The new satellite,” Mr. Mattis said, “will test for the first time in space a new Hughes concept of stabilization called “Gyrostat” which defies the theory that all spin-stabilized satellites must be “short and squat” and look like over-sized hat boxes.”
Heretofore, satellites have been designed for the inertia characteristics of a disc rather than a rod. The Gyrostat principle, however, is designed to permit stabilization of long slender bodies.
Some Parts Spin
The new principle holds that satellites can spin around their minor axes and permit some parts to spin while other parts remain stationary, with never a wobble in the spacecraft, he explained.
The concept not only permits variations in the length configuration of communications satellites, thus allowing full utilization of the booster shroud, but it also enable important payloads, such as antennas or telescopes to remain stationary so that they may be precisely pointed in any direction.
Don Williams was thought of by many people at Hughes Aircraft as an engineering genius. He was revered for his role in the design of SYNCOM and his patent that enabled attitude and orbital position control of a spin stabilized satellite. The patent that Don Williams obtained, assigned to Hughes Aircraft, was the keystone for the development of spin stabilized communications satellites built by Hughes over the 30 years following the patent application on August 21, 1964. Williams stunned his friends and colleagues at Hughes by taking his own life on February 21, 1966.
Williams was involved with the geostationary satellite design effort from the very beginning in early 1959. He was very concerned that Hughes Aircraft would retain any patent rights evolving from this design effort. In November 1959 he traveled to NASA Headquarters in Washington DC to brief NASA executives on the Hughes design activities. He began his briefing by stating that Hughes wished to retain all patent rights with his discussion of the Hughes design. NASA personnel agreed to this premise.
By early 1960 Hughes had a satellite design in place that was clearly prototypical for the yet-to-come SYNCOM. The mission plan utilized the four-stage NASA-developed SCOUT launch vehicle with an Altair solid motor as the spin stabilized unguided fourth stage. A fifth stage solid rocket added to SCOUT would boost the satellite into a geosynchronous transfer orbit. The satellite included a solid rocket motor to attain the final geostationary orbit. The mission plan included launch from the near-equatorial Jarvis Island about 1600 miles south of Hawaii.
In Reference 1, published in early 1960, Williams describes the mission plan and his control system. The system consists of a sun sensor with two slits at a 350 angle, used to determine satellite attitude relative to the sun and spin rate, and two jets, one parallel to and one normal to the satellite spin axis, used to precess the spin axis and control orbital velocity. These features are described a patent application dated April 18, 1960. Williams determined that jet performance for the selected valves was a thrust of 1.3 pounds and a specific impulse (ISP) of about 60 seconds for a system pressurized with 3000 dry nitrogen. At this time Williams had tested a lab model that would allow a claim for reduction to practice for his control system.
With the NASA contract received by Hughes in August 1961 the mission ground rules were modified to utilize a launch from Florida with the Delta launch vehicle. NASA adopted the name SYNCOM for this mission. A successful geostationary orbit was achieved with the launch of SYNCOM III on July 26, 1964.
On August 21, 1964 Williams reapplied for a patent on his control system. He states in this application, “This is a continuation in part of my prior co-pending application Ser. No. 22,733, filed Apr. 18, 1960 now abandoned. In order to disallow any NASA claims of rights to the patent the application describes in detail the satellite and mission as of the 1960 design prior to the NASA contract of August 1961. The application includes the sun sensor and jets of the control system as well as a nutation damper.
In 1966 the U. S. Patent Office allowed Hughes patent claim. However, NASA requested that the patent be issued to NASA as it was first used on NASA satellite. The Court of Customs and Appeals ruled Hughes owned the patent and the U. S. Patent 3758051 Velocity Control and Orientation of a Spin Stabilized Body, was granted on September 11, 1973. The first page of the patent is shown below.
In November 1973 Hughes filed suit in U. S. Court of Claims charging that the government had used the patent without authority and sought compensation. The first trial in 1976-77 ended when the judge was disqualified. The next trial in 1979 ruled for NASA. This was appealed and the appeals court ruled that the judge had erred and returned the case to the lower court. In 1982 the court ruled in Hughes favor but limited royalties only to those satellites that were under control from the ground. This was appealed by Hughes and in 1983 the Appeals Court ruled that the patent also applied to satellites that controlled by onboard computers. This expanded the royalties claim to military as well as NASA satellites.
In February 1988 a trial in the U. S. Court of Claims, under Judge James Turner began to determine royalty payments to Hughes. To be determined: what satellites infringed the patent, what are reasonable royalties, and what is the interest on the unpaid royalties going back as far as 1963. Hughes asks for royalties of 15% for a total of $1.2 billion on 100 satellites. Early in the trial Judge Turner, court clerks, attorneys, and reporters made a visit to the Hughes high bay in El Segundo. After donning the obligatory smocks they heard Dr, Albert Wheelon, Hughes CEO, describe in detail the satellite assembly process and the operations required to maintain a satellite in orbit.
During the trial it was revealed that in 1974 Hughes offered licenses for the use of the Williams patent to Philco-Ford, TRW and Messerschmitt-Bolkow-Blohn for 2 to 5% of the satellite cost. Hughes at the time had filed suit against Philco-Ford for patent infringement. This suit was settled out-of-court with a payment rumored to be $75 million. This seriously undermined Hughes claim for a 15% royalty.
Patent rights expire in 17 years or September 1990 for the Williams patent. It was rumored that some government satellite programs might be delayed past this date to avoid any patent royalty liability.
Judge Turner finally ruled that 81 satellites violated the patent and had a value of $3.6 billion with a royalty rate of 1% or $36 million. Added to this is $118 million for delay compensation for loss of unpaid royalties for a total of $154 million. The 81 satellites were all government and about 75% were military.
Hughes appealed the judgment of the United States Court of Federal Claims awarding Hughes compensation based on a 1% royalty rate. On June 19, 1996 the U. S. Court of Appeals affirmed that a 1% royalty was the court determined that a royalty rate of 1% would be reasonable.
On March 1, 1999 the U. S. Supreme Court denied a government petition to review Judge Turner’s decision for Hughes. Federal Claims Court entered judgment for Hughes on March 12,1999. Payment of $154 million was made to Hughes on March 30, 1999.
Final note: patent royalties are taxable as ordinary income less, of course, litigation expenses.
Note: I cannot attribute the facts in this paper to any particular source. All of the references listed below were necessary to establish my understanding of this history. The only exception is Reference 1 that provides Don Williams description of his system as patented.
- Dynamic Analysis and Design of the Synchronous Communication Satellite, D. D. Williams. Engineering Division Hughes Aircraft Company TM-649 May 1960.
- U S Patent 3758051 Velocity Control and Orientation of a Spin-Stabilized Body Donald D Williams
- The Origins of Satellite Communications 1945-1965. David J. Whalen. Smithsonian Institution Press, 2002.
- NASA Announces Project SYNCOM NASA Press Release No. 61-178 August 11, 1961
- SYNCOM Design and Operation NASA Press Release No. 61-223.
- The Syncom III Launch NASA TN D-3377 Forest H. Wainscott, April 1966
- Hughes Case Could Send Patent Claims Into Orbit, Evelyn Richards. The Washington Post August 13, 1989.
- Hughes Awarded Judgment in Long Running Case Defense-Aerospace.com source Hughes Electronics March 1999
- Patent Case May Cost U. S. Billions Edmund L. Andrews New York Times April 22, 1989.
- 10.HAC Receives Basic Patent On Spin-Stabilized Satellites—Hughes News September 14, 1973.
- Hughes Aircraft Asks 1$ Billion From U.S. Over Satellite Patent Ralph Vartabedian Los Angeles Times February 3. 1988
- Judge in $1.2 Billion Case Sees How Satellite Are Built—Hughes Aircraft Patent Suit Shifts to Plant. Ralph Vartabedian, Los Angeles Time February 6, 1988.
- Legal Blunder May Be Costly to Hughes Aircraft Could Lose $270 Million Claim; Judge In Patent Case Cite Error By Lawyers. Ralph Vartabedian Los Angeles Times February 6, 1988.
- U. S, in Last-Ditch Effort to Thwart Suit by Hughes Aerospace: The Pentagon Allegedly Stole Satellite Technology. A Judgement of up to $1.2 Billion is Expected in 23-Year Case. Ralph Vartabedian Los Angeles Times May 23, 1994.
- Hughes Wins $114 Million In Patent Case Technology: It Is the Largest Such Award Ever Against U. S. Government, But It Falls Far Short of the Company’s Expectations. Ralph Vartabedian, Los Angeles Times June 18, 1994.
- Death Ends Work of Satellite Star Donald Williams. Hughes News February 25,1966.
- United States Court of Appeals for the Federal Circuit. Hughes Aircraft Company, Plaintiff-Appellant, v. The United States, Defendant/Cross Appellant June 19, 1996.
The table of contents for our website has been updated so that it lists all posts and provides a correct link to each. See http://www.hughesscgheritage.com/table-of-contents/
In 2003, when Boeing was collaborating with JPL on a probe proposal, it occurred to me that a brochure should be developed for the upcoming 2ndInternational Planetary Probe Workshop at NASA Ames. I convinced Boeing management of the merit of this concept and began working with Jim Santoni, our resident graphics guru. We reviewed the archives of the Pioneer Venus and Galileo programs to find the photos that would most convincingly send the message that we had the experience needed to design planetary entry probes for future NASA missions.
One photo caught my eye. It captured our skilled technicians deep in the final assembly of the Galileo probe. They were carefully positioning the aft cover on the descent vehicle installed in the deceleration module. There was only one problem with the photo: the technicians were touching extremely valuable hardware with their bare hands. One was even wearing a ring. Knowing this 1980’s practice was certainly not consistent with the rules enforced in the early 2000s, I asked Jim to retouch the photo. For the brochure, he graphically applied gloves to the technicians’ hands. The cover of the brochure is included below, with the blue-gloved hands of the technicians clearly visible.
Several years later, as I was chatting with a young engineer about my experiences on the Pioneer Venus and the Galileo probes, he mentioned that he had seen the original photo of technicians. He recalled that the photo captured the technicians working without gloves. There I was, caught blue-handed as I explained how we had retouched the original photo for the brochure.
Books: Howard Hughes
Hughes: The Private Diaries, Memos and Letters. Richard Hack. New Millennium Press, 2001.
Howard Hughes Aviator. George J Marrett. Naval Institute Press, 2004.
Howard Hughes H-4 “Hercules.” Northrop Institute of Technology, Aviation History Library. Historical Airplanes, 1962. Many photos of the aircraft being transported from Culver City to Long Beach.
Howard Hughes and His Flying Boat. Charles Barton. Self published, revised edition 1998.
Howard Hughes, His Life and Madness. Donald L. Barlett & James B. Steele. W. W. Norton & Company, 1979.
Seduction: Sex, Lies and Stardom in Howard Hughes Hollywood. Karina Longworth. Custom House, 2018.
Books: Hughes Aircraft
As I Remember: A Walk Through My Years at Hughes Aircraft 1951-1997. Scott Walker. Hawthorne Publishing, 2010.
Call Me Pat: The Autobiography of the Man Howard Hughes Chose to Lead Hughes Aircraft, Downing Company, 1993.
Hughes After Howard: The Story of Hughes Aircraft Company. D. Kenneth Richardson. Sea-Hill Press, 2011.
The Origins of Satellite Communications. David J Whalen. Smithsonian Institute Press, 2002. Excellent account of Syncom development.
Something New Under the Sun: Satellites and the Beginning of the Space Age. Helen Gavaghan. Copernicus, 1998. Detailed account of the Syncom development.
The Rise and Fall of Comsat. David J. Whalen. Palgrave Macmillan, 2014. Open Skies, Anik, COMSTAR and SBS.
NASA and the Space Industry. Joan Lisa Bromberg. Johns Hopkins University Press, 1999. Covers Syncom and the NASA Ka-band satellite controversy.
Paving the Way for Apollo 11. David M. Harland. Springer Praxis Publishing, 2009. Surveyor I description and mission.
To Reach the High Frontier, A History of U. S. Launch Vehicles. Roger Launius, Dennis R Jenkins Editors University Press of Kentucky, 2002. Great source of historical data on launch vehicles.
Communication Satellites Fourth Edition. Donald H. Martin, Aerospace Press AIAA 2000. Hughes satellite data from Syncom to HS-601.
Mission to Jupiter: A History of the Galileo Project NASA SP 2007-4231. Michael Meltzer 2007.
Mission Jupiter, The Spectacular Journey of the Galileo Spacecraft. Daniel Fischer Copernicus Books 2001.
Pioneer Venus. NASA SP-461. Richard Fimmel, Lawrence Colin, Eric Burgess, 1983.
Galileo: Exploration of Jupiter’s System, NASA SP-479. C. M. Yeates, et al, 1985.
SYNCOM Engineering Report Volume I, NASA TR R-233. Syncom Projects Office Goddard Space Flight Center. March 1966. Syncom II description and mission.
SYNCOM Engineering Report Volume II, NASA TR R-252. Syncom Projects Office Goddard Space Flight Center. April 1967. Syncom III description and mission.
NASA Compendium of Satellite Communications Programs, NASA TM X-751-73-178. Goddard Space Flight Center, June 1973.
COMSAT Technical Review Volume 2 No 2 Fall 1972. Issue devoted to Intelsat IV. The Intelsat IV Spacecraft. Launch and Orbital Injection of Intelsat IV Satellites. The Intelsat IV Communications System. (http://www.comara.org/legacy/ctr/CTR_V02-2_Fall_1972-Intelsat_IV.pdf)
COMSAT Technical Review Volume 7 No 1 Spring 1977. The COMSTAR Program. The COMSTAR Satellite System. (http://www.comara.org/legacy/ctr/CTR_V07-1_Spring_1977-Comstar.pdf)
COMSAT Technical Review Volume 7 No. 2 Fall 1977. MARISAT A Maritime Satellite Communications System. (http://www.comara.org/legacy/ctr/CTR_V07-2_Fall_1977.pdf)
COMSAT Technical Review Volume 20 No. 2. Intelsat VI The Communications System. (http://www.comara.org/legacy/ctr/CTR_V20-2_Fall_1990-Intelsat_VI_Comms_System.pdf)
COMSAT Technical Review Volume 21 No. 1 Spring 1991. Intelsat VI Spacecraft Design. (http://www.comara.org/legacy/ctr/CTR_V21-1_Spring_1991-Intelsat_VI_Spacecraft_Design.pdf)
COMSAT Technical Review Volume 21 No. 2 Fall 1991> INTELSAT VI: From Spacecraft to Satellite Operations. (http://www.comara.org/legacy/ctr/CTR_V21-2_Fall_1992-Intelsat_VI_Spacecraft_Operation.pdf)
COMSAT Technical Review Volume 22 No. 1 Spring 1992. INTELSAT VI: System and Applications. INTELSAT 603 Reboost. (http://www.comara.org/legacy/ctr/CTR_V22-1_Spring_1992-Intelsat_VI_Signal_Processing.pdf)
COMSAT Technical Review Volume 22 No. 2 Fall 1992. SSTDMA in the INTELSAT VI System. (http://www.comara.org/legacy/ctr/CTR_V222_Fall_1992_Intelsat_VI_SSTDMA.pdf)
U. S. National Security and Military/Commercial Concerns With the People’s Republic of China. Volume II Satellite Launches in the PRC: Hughes. Report of the Select Committee on U. S. National Security and Military/Commercial Concerns With the Peoples Republic of China, May 1999. (https://www.govinfo.gov/content/pkg/GPO-CRPT-105hrpt851/pdf/GPO-CRPT-105hrpt851-1-2.pdf)
Hughes Industrial Historic District (http://www.hugheshistoricdistrict.com/howard-hughes/)Includes history of Hughes Aircraft, visual tour of remaining buildings, timeline of life of Howard Hughes, Hughes H-1 Flying Boat (Spruce Goose) including video of flight, Historical Development Photos, and a bibliography
Abandoned and Little-Known Airfields: California, Western Los Angeles Area, Paul Freeman
(http://members.tripod.com/airfields_freeman/CA/Airfields_CA_LA_W.htm#hughes)Many photos and information about the Hughes Culver City Airfield.
Historic American Engineering Record Hughes Aircraft Company HAER CA-174 (https://cdn.loc.gov/master/pnp/habshaer/ca/ca2100/ca2172/data/ca2172data.pdf) Document describing Hughes Culver City facility including development of facility, history of Hughes Aircraft.
Hughes Aircraft Company, 6775 Centinela Avenue, Los Angeles, Los Angeles County, CA Photos From Survey HAER CA-174. (https://www.loc.gov/resource/hhh.ca2172.photos?st=gallery&c=40)
Santa Barbara Research Center History https://sbrc-sbrs.com
Richard ‘Dick’ Switz was born on May 18, 1928 in a farmhouse in Switz City, Indiana, son of Henry ‘Bud’ and Lucille Switz with older brother Donald and younger brother Hal. Switz City was named for his great grandfather. He grew up working on the family farm and attended Switz City High School.
Dick graduated from Purdue University, for which he maintained lifelong affection and pride, earning a Bachelor of Science in Civil Engineering. He was drafted after graduation into the U.S. Army, serving two years assigned to the Corps of Engineers in the Pentagon. After his discharge from the Army Dick accepted a job with Ryan Aircraft, and relocated to sunny San Diego, beginning the California adventure lasting the rest of his life. He enjoyed music, photography, traveling, time with family and friends and adored his grand/great-grandkids.
Dick spent most of his career with Hughes Aircraft, moving to El Segundo in 1966 from Reseda and played a key roles in designing Surveyor—the first spacecraft to successfully soft land on the Moon—many communication satellites and exploring other planets with Pioneer Venus and Galileo. After retiring in the mid-80s as Chief Scientist, Dick was elected for four years to the El Segundo City Council to proudly serve his hometown and was a parishioner of St. Anthony’s for over 50 years.
Dick passed away peacefully on October 14 at Torrance Memorial Hospital surrounded by family. He is survived by children Jim Switz and Rita Nelson (both of WA State) and Lauren Harger in Manhattan Beach, grandchildren Laura, Jenna, Sean and Megan and great-grandchildren Linken and Olia.
Visitation will be from 5 to 9pm on October 22 at the Rice Mortuary at 5310 Torrance Blvd in Torrance. A service will be held on October 23 at American Martyrs Catholic Church located at 624 15thStreet in Manhattan Beach at 10am followed by a reception at 11am.
Bob Varga, a longtime friend, passed away on October 2 as a result of complications from food poisoning. Bob spent many years at Hughes Aircraft and contributed greatly to a variety of proposals and spacecraft programs. Services and interment will be at the Green Hills Memorial Park at 11:30 am on October 17. Green Hills is located at 27501 South Western Avenue in Rancho Palos Verdes. Further information can be found at the Green Hills website–https://greenhillsmemorial.com/
Some time ago, perhaps several years, Maggy Murray, Bill’s wife, contacted me and volunteered some of Bill’s mementos for our website. Included were photographs of a number of launches of Hughes satellites. Unfortunately, these photos did not have a caption that identified the satellites being launched. I filed these away and forgot them until recently. Looking at the photos I realized that the launch vehicles were numbered and that would allow identification of the Hughes satellite being launched.
I found a website, KevinForsyth.net, that listed all the numbered Delta launches that allowed identification of the Hughes satellites. I also learned that the Delta is no longer in production and the last launch was on September 15, 2018 for a NASA mission, ICESAT-2. There were a total of 381 Delta launches with only 16 failures, a reliability of almost 96%.
Information on Centaur launches can be found on Gunter’s Space Page.
Delta B Syncom II launch July 26, 1963
Delta D Syncom III launch August 19, 1964
Delta D Earlybird on Launch Pad April 1965
Delta D Earlybird Launch April 6, 1965
Delta E1 Intelsat II F1 launch October 26, 1966
Atlas Centaur AC35 Intelsat IV F1 launch May 22, 1975
The Pioneer Venus Orbiter incorporated a payload of 12 scientific instruments one of which was a fluxgate magnetometer provided by Chris Russell of UCLA, the principal investigator. Previous flybys of Venus had revealed that the magnetic field of Venus was much weaker than Earth’s. The resulting system requirements for the Orbiter magnetic fields are shown in Figure 4-2 in Reference 1. The most challenging requirement is that the remnant field at the magnetometer (after a 50-gauss demagnetization of the spacecraft) be 0.5 gamma or less. A Gauss is the usual measure used in magnetics—a gamma is 0.00001 Gauss. The earth’s surface magnetic field varies from 0.3 to 0.6 Gauss.
These requirements presented some issues that Hughes had not dealt with previously. At the beginning of the PV program no one at Hughes that I knew had experience in this area. Very fortuitously at this time we received an application from a TRW engineer, Chris Thorpe, who had performed these tasks for the TRW Pioneer spacecraft and had worked with Chris Russell previously. We hired him very quickly into the Perry Ackerman lab and assigned him to PV program. Chris was a delightful Englishman with a wry sense of humor and supported me in systems engineering and Tony Lauletta in science integration throughout the program.
Chris quickly demonstrated his knowledge of spacecraft magnetics and instituted a magnetic control program that included:
- Formulating and maintaining a magnetic model of the Orbiter that predicted the magnetic field at the magnetometer
- Limiting the type and amount of magnetic materials used in fabrication.
- Using a nonmagnetic electroless nickel plate
- Controlling the location and orientation of magnetically troublesome units on the equipment shelf.
- Separating the magnetometer from the spacecraft by a deployable boom
- Provide for magnetic compensation of units that utilize permanent magnets in their operation to reduce their field contribution at the magnetometer
Based on Chris’ calculations the boom length was set at 15 ft 6 in. (4.72 meters). As I recall Chris’s prediction was 14.5 feet and one foot was added to provide some margin. Chris maintained the magnetic model throughout the Orbiter development.
The boom, consisting of three hinged segments, is folded together and stowed on the orbiter shelf until deployed shortly after launch. The boom is secured by two redundant pyrotechnic pinpullers either of which when fired would release the boom for deployment. As the three segments extend, each hinged joint locks in the deployed position. A spin rate of 6.5 rpm provides the centrifugal force that ensures deployment and positive latching.
System level testing of the magnetometer boom proved to be problematic. The boom root hinge, when pyrotechnically released, was to deploy with the spacecraft spinning at 6.5 rpm. However, aerodynamic drag prevented the boom from fully extending in sea level density air. In order to validate the design it was necessary to encapsulate the spacecraft in a large plastic tent filled with 90% helium that provide a gas mixture with one fifth the density of air. The deployment test in this environment was successful.
Two system level magnetic tests are required—remanent and stray field determination. The remanent test is to determine the magnetic field of the quiescent spacecraft and requires a magnetic coil to cancel the earth’s magnetic field. The NASA Ames facility Magnetic Standards Laboratory and Test Facility in Mountain View, CA was used for this test and of course this required shipping the spacecraft to that facility. Tests were conducted with the spacecraft in a magnetized and demagnetized state. The stray field test to determine the magnetic field of the operating spacecraft was conducted in the Hughes high bay in the early morning to provide a magnetically quiet environment. The test results are presented in Figure 4.2 in from Reference 1. Chris Thorpe oversaw these tests.
According to Chris Russell: The most definitive measurements of the magnetic moment of Venus were obtained during the Pioneer Venus Orbiter mission in its first years of operation (1979-1981). Repeated low-altitude (~ 150 km) passes by that spacecraft over the antisolar region, coupled with dayside observations to the same altitude, proved the insignificance of a field of internal origin in near-Venus space. The observed fields for the most part could be explained as solar wind interaction-induced features. The new upper limit on the dipole moment obtained from the Pioneer Venus Orbiter wake measurements placed the Venus intrinsic magnetic field at ~ 10-5 times that of Earth.
At the conclusion of the Pioneer Venus program Chris and I were assigned to the newly started Galileo probe effort. After I left Galileo I lost track of Chris. Recently I learned that he passed away in 2000 at the age of 76. If someone can provide any biographical details for Chris I can add them to this post.
Reference 1. Pioneer Venus Final Report, Contract No. NAS 2-8300, December 1978, Bernard J. Bienstock.
The two Pioneer Venus spacecraft were designed to be launched by the Atlas-Centaur for the 1978 Venus opportunity. Earlier studies had considered the Thor-Delta launch vehicle, but the Atlas-Centaur was judged by NASA to provide superior science performance and potential cost savings due to the greater payload capability. The starting point for spacecraft design is the allowable mass for the two spacecraft that is determined by the performance of the designated launch vehicle. Our customer, NASA’s Ames Research Center, adopted a specification weight for us to work to allowing for a cushion or contingency below the Atlas-Centaur launch capability. The ARC specification values, as a function of time, are shown in Figures 4-1 and 4-2 for the Orbiter and Multiprobe spacecrafts.
The 1978 Venus launch opportunity can be divided into two phases. The earlier launch opportunity, late May-early June, has a greater flight time to Venus and is a Type II interplanetary trajectory traversing an arc of more than 180O about the sun. However, this launch requires greater launch vehicle performance and provide less payload capability. The later launches in August, use a Type I interplanetary trajectory (less than 180O solar arc) and provide more than a 50% greater payload capability. As neither Hughes nor NASA Ames could support two simultaneous launch campaigns the Orbiter and Multiprobe require using both the early and late launch opportunities for the 1978 Venus opportunity. The Orbiter weight was significantly less than the Multiprobe and could launched during the earlier opportunity. An advantage is the 60% lower ∆V required for orbit insertion at Venus. The August launch opportunity is then available for the 60% heavier Multiprobe.
The final mass properties measurements for the two spacecraft are shown in Table 4-1 from the Reference 1. Note that the first row in the Table which is labeled “Spacecraft height” should read “Spacecraft weight.” Both spacecraft are stable spinners based upon the HS-333 design.
Joe Lotta was responsible for the Pioneer Venus mass properties analyses. This involved collecting inputs from each design area on a monthly basis and calculating the overall mass properties for each spacecraft. As shown in Figures 4-1 and 4-2 from Reference 1, over the course of the nearly four-year program weight growth was a constant concern. Considerable effort was devoted to trying to control weight growth and finding weight savings. At every opportunity trade-offs were considered and lists of weight savings with the cost detailed for each saving would be considered. Those weight savings characterized by lower dollars per pound would be implemented. Reference 1 documents 90 pounds of savings implemented for the Orbiter and 105 pounds for the Multiprobe. NASA ARC was able to provide increases in their specification weights to accommodate our weight growth. Some must have been due to Atlas Centaur performance improvements and the rest due to reduced contingencies and weight reserves. In retrospect it all came together and we witnessed two very successful missions.
Reference 1. Pioneer Venus Final Project Report. HS507-7970. December 1978, Bernard J. Bienstock.