Comments on the Challenger Disaster

Larry Nowak

Having watched all segments of the Netflix coverage of the Challenger disaster, I concluded that there are two basic questions being covered. The first is how did they decide to launch on such a cold day in January and how did our candidate Greg Jarvis get bumped from April 1985 to January 1986.

I was down at the Cape the previous year in January 1985 prepping our first LEASAT spacecraft for launch. There was a shuttle launch that afternoon around 3 PM; it was a very cold day. The launch was a success, but recovery of the solid motors showed major leakage around the seals and almost a total burn though.  I believe these photos were used in the Netflix documentary.

The Thiokol workers knew that the seals were a major problem and needed to be fixed.  A design change was initiated but had not been finalized and implemented for the Challenger launch.

The movie seemed to indicate that they didn’t know the cause of failure at the time of launch. With the history of seal leakage, I was surprised when they did launch on that fateful day when there were icicles hanging from the launch vehicle.

As Steve pointed out, NASA was trying to use the shuttle for all launches. Their aggressive schedule was to launch at least two per month and up to four spacecraft per launch. Any delays by one would probably bump the launch dates for all the others to later dates (my conclusion).  This would be a major cost overrun I’m sure.

Apparently, the new criteria to launch was changed from “Prove it is OK to launch” to “Prove it’s not OK to launch”.  Following the disaster, the launch schedule was delayed until the mod had been authorized and implemented. As the movie points out, there were no more rocket failures after this change had been implemented.

So how did Greg get bumped to this fateful launch date?  Greg was originally assigned to be on a launch in April 1985 along with our LEASAT F3 spacecraft.  Senator Jake Garn was assigned to a TRW spacecraft the previous month. That one had problems and was scrubbed. He then bumped Greg because the rules allowed him to do that. Greg could have been on the next launch in September with our F4 but F3, which Jake Garn took, failed to activate properly upon deployment. Subsequent meetings with NASA personal showed F3 could be saved by installing a bypass switch around the malfunctioning switch. This did not allow Greg to ride along.  

I think Greg could have taken the next flight scheduled for December but thought it would be a better choice to go with the schoolteacher, Christa McAuliffe in January and help her with her activities. I also heard a rumor that Rep Bill Nelson didn’t want to fly with Christa because she would get all the news coverage. Greg agreed to switch to the January 1986 flight and all were happy.

Netflix Challenger Documentary

Steven D. Dorfman

As head of HCI I was involved in a pitched battle between NASA and Arianne for a contract to launch 10 future Hughes spacecraft. It was important for NASA to win to demonstrate their ability to serve the commercial market. We were skeptical when the government shut down all US Expendable Launch Vehicle launches of commercial satellites but we were pressured to accept the government position. NASA and Arianne both had very aggressive (and government subsidized} bids of about $30M per launch. In the heat of the competition NASA added the sweetener of permitting Hughes employees to fly on two of our launches as Payload Specialists though it soon became clear that they wouldn’t let us have much to do with our payloads. Frankly it was a marketing ploy that couldn’t be matched by Arianne. 

After we selected the Shuttle to launch our satellites (for other reasons) we decided to accept the NASA offer knowing that it would be a thrill for many at HSC to be in space despite the danger and a good morale booster for a dedicated workforce. We decided to post the opportunity and soon had 600 applicants! We narrowed it down to 10 and then selected a prime and backup for the two missions. Greg Jarvis as prime for the first mission and Bill Butterworth backup. After a schedule was posted for Greg’s flight NASA said they would like to bump him to a future flight in order to enable Senator Jake Garn to fly on the next Shuttle mission. I protested strongly but they wanted to placate an important source of funding for NASA so Greg was moved to another flight where the same thing happened for Representative Bill Nelson. That is how Greg wound up on the Challenger flight.

I was devastated after the explosion. Sometimes you make the right decision but you have the wrong outcome. This was such a case.

Later on, the government reversed the decision they had imposed on us and instead of all launches being on Shuttle… no commercial launches would be on Shuttle! And they unilaterally canceled our contract causing us to have several years of scrambling for ELVs. We ultimately sued the government for breach of contract and many years later won a $300M settlement.

The excellent Netflix documentary brought back all these memories and reminded me how badly NASA had screwed up and caused Greg’s death. It was painful but motivated me to share my thoughts.

Caught Blue Handed or Rewriting History Can Be Problematic–Bernie Bienstock

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.



In early 1963 as a young 31-year-old engineer I was assigned the task of developing a method for mobile users to communicate through a synchronous satellite.  A brief study of the problem indicated that for truly mobile communications the user should be able to use a simple dipole antenna. This led to a company funded effort to demonstrate the reception of the one-half watt Syncom 2 VHF telemetry signal on a simple dipole antenna. On 21 February, the one-half watt Syncom2 VHF telemetry signal was successfully received on a dipole antenna. Three months later, on 8 May 1964, a teletype message was repeated through Syncom 2 telemetry and command system to a ground transmitter with a power of 19 watts using 12 and 14 db. gain Yagi antennas.

When news of these tests reached Frank White of the Air Transport Association he set in motion a series of events that led NASA to fund the ATS VHF Experiment.  His plan was to demonstrate two-way communication between a Pan-Am jet leaving Hong Kong with the NASA ground station at Camp Roberts California via the Syncom telemetry and command system.  On Jan 27 1964, these tests were successful and within weeks NASA funded the ATS VHF experiment.

The ATS-1 is the first of a series of five spacecraft built for NASA Goddard Space Flight Center by the Hughes Aircraft Company. The objectives of the VHF repeater are as follows:

• Demonstrate feasibility of providing continuous voice communications link between a ground control station and aircraft anywhere within the area covered by the satellite

• Demonstrate feasibility of providing a network in which data from small- unmanned stations or buoys are collected via satellite and disseminated

• Evaluate feasibility of VHF navigational systems

• Evaluate airborne and ground stations required in the above ­ mentioned networks

A fifth objective area was later added to demonstrate two-way voice and teletype communications from ships at sea anywhere in the satellite coverage area.

The VHF communications experiment is a frequency ­translation limiting (Class C) repeater receiving at a frequency of 149 Mhz and transmitting at 135 Mhz. The repeater both receives and transmits through an eight-element, phased-array antenna; Table 1 presents the repeater characteristics.

Operation of the repeater is as follows: incoming-signals at 149 mHz arereceived on each dipole element, routed through diplexers, amplified by a low-noise receiver, and shifted in phase to compensate for the relative position of each dipole antenna. The electronically controlled phase shifter in the receiver unit, driven by the waveform generators, causes the output s of each receiver to be in phase only for those signals originating from the earth. Reference sinusoids used to drive the waveform generator s are obtained from the same phased-array control electronics used to position the microwave beam toward the earth. The eight receiver outputs are summed together, filtered, down­ converted to an intermediate frequency (IF) of 29 megacycles, amplified, and passed through a crystal filter to limit the receiver bandwidth.

The IF is then amplified, up converted to 135 mHz, further amplified, and divided into eight equal parts. Each of the eight signals is routed to a transmitter where it is amplified, phase-shifted, and further amplified to a power level of 5 watts. Each transmitter output is routed through its respective diplexer to one of the antenna elements.

The transmitter phase shift is controlled by the waveform generator, which causes the signals from each antenna to reinforce in the direction of the earth. Provision is made to operate only odd or even sets of four transmitters, if desired, to reduce the DC power required.

It is also possible to drive the waveform generator from either the redundant Phased Array Control Electronics or to shut down this unit entirely creating a pancake antenna pattern, approximately 60 x 360 degrees that will encompass the earth during most parts of the launch trajectory and at all times after satellite reorientation.

The ATS spacecraft power supply and thermal design allow for continuous operation of the VHF experiment except during periods of eclipse. The repeater elements are supplied with -24volt and 23.4-volt regulated power. Switches are provided that allow operation of the equipment according to commands from the ground stations. Telemetered outputs are also provided which can be transmitted to earth either by the VHF or microwave telemetry systems.

The repeater is made up of nine subassemblies: eight units containing one transmitter, receiver, and diplexer; and one unit containing an up converter, down converter, waveform generator, and two voltage regulators. These units are shown in Figures 3 and 4.


1) The first VHF phased array in orbit

2) The first phased array to operate on both transmit and receive frequencies

3) The first deployable antenna on a spinning spacecraft

4) The first spacecraft repeater to use separate receivers and transmitters for each antenna element

The VHF antenna consists of eight full-wave dipoles arranged in a circle of one wavelength diameter (86 inches). Volume limitations in the Atlas-Agene shroud dictated the use of a deployable antenna. The eight-dipole elements were mounted on a radial arm attached to the forward solar panel and pivoted to place the antennas in a three-foot circle directly over the apogee motor nozzle during launch.

At separation from the Agena, the spacecraft is spun up; centrifugal force causes the antennas to deploy to the 86-inch diameter at 50 rpm. Deployment takes place during the normal spin up of the spacecraft without the use of ground commands.  When the spacecraft apogee motor is fired, the antennas are subjected to high Mach numbers and high heat fluxes. The rocket motor in the center of the array contains 750 pounds of propellant and burns for 40 seconds increasing the spacecraft’s apogee velocity by 6000 fps.

To withstand the severe thermal environment, the antenna elements were constructed of beryllium, flame-sprayed with aluminum oxide, and further covered with a Teflon ablative material. The high heat capacity of the ablative material and of the beryllium itself maintains the antenna temperatures below the unprotected equilibrium temperature of 3000° F.


The following report is taken from a presentation given in May 1967 at a meeting of the RTCM in Las Vegas Nevada by Roland Boucher.

ATS-1 was launched into orbit on 6 December 1966.  The VHF repeater was first operated 3 days later. Since then, it has been used to successfully communicate voice and data between NASA ground stations at Rosman, North Carolina; Mojave, California; and Kooby Creek Australia. It has sent weather facsimile pictures and has been used to determine propagation properties of the ionosphere.

Simplex air to ground communication tests have been conducted with aircraft operated by Pan American, Eastern, TWA, United, American, and Qantas airlines as well as those operated by the FAA and the U.S. Air Force. Both simplex and duplex communications were successful with a shipboard terminal   constructed by Hughes. This terminal was leased to the U. S. Coast Guard and has operated successfully on the Coast Guard Cutter, Klamath at Ocean Station November in the Pacific Ocean which was described by a member of the U.S. Coast Guard.  In May 1967, the VHF repeater experiment had operated successfully for over 5 months with no signs of degradation.

Prior to the launch of ATS-1, there was considerable skepticism as to the feasibility of VHF satellite communications in mobile service despite the fact that nearly every satellite to date had used the VHF band for its primary mode of telemetry and weather photo video transmission.


The uneven diffractive properties of a disturbed ionosphere can cause deep fades at VHF frequencies. These fades are normally of a very brief nature lasting typically from 8 to 30 seconds. Examination of this phenomenon by Hughes Aircraft Company under NASA contract NAS-510 174 indicated that fades of greater than 6 db. depth could be expected 0.002 percent of the time in the mid-Pacific area, Tests with ATS – 1 during the first 5 months in orbit have failed to yield any statistically significant data on scintillation fades. The rarity of their occurrence makes it almost impossible to detect them in a normal push-to-talk circuit. They do not present a serious problem to this type of communications.


Mobile terminal noise was also cited by some as a nearly insurmountable problem as late as a few months before the ATS-1 launch. Tests on aircraft and on the cutter Klamath have shown this problem can be cleared up by normal RFI practices.


Multi-path fades were held up as an obstacle to VHF mobile communications with fades up to 30 db predicted. Tests with the ATS-1 to date have shown multi-path propagation not to be a serious threat. In examining the records of many hours of shipboard and aircraft communication, no clear evidence of multi-path propagation fades could be found. This despite the fact that Hughes intended to use the evidence of such fades as a requirement for the development of a new type antenna for the NASA/Hughes ATS C. The fades were not found. The antenna was not funded.


Earth-noise temperature was cited as a possible deterrent to VHF satellite communications. The proponents of this concept reasoned that many spurious emissions from the large number of earth transmitters would form a noise blanket which would jam the satellites receivers.

Measurements taken in late 1966 by Boeing Aircraft to determine receiver noise temperatures in flight from a commercial aircraft indicated that cities could be found quite easily by the noise they created. This noise was seldom evident more than 10 or 20 miles from the city centers. Noise temperatures even at relatively low altitudes seldom were in excess of 20 db. with a 10-db-background level being more nearly an average figure.

A simple calculation involving the area of the world covered by cities indicated that this noise would not be a serious problem at synchronous altitude. Corroborating evidence was the fact that most satellite command systems operate in the VHF band. Any serious problems in the uplink would certainly have been discovered before 1966.

The launch of ATS-1 proved this point. Up-link receiver sensitivity of the ATS-1 spacecraft is essentially that measured in the laboratories.


The ATS uplink is in the land mobile band. In the early phases of the in-orbit test program, strong signals were heard in the satellite s passband. Many of these were conversations in English from what appeared to be military personnel. The conversations contained description of maintenance operations on jet aircraft indicating that a ground terminal used to communicate with mobile airport vehicles was transmitting to the spacecraft. Other signals in the spacecraft ‘s pass band that have been annoying at times have contained considerable 60 cycle modulation, indicating they originate from an earth borne transmitter.

None of these emissions proved detrimental to the test program after December 12. On that day, the severity of the jamming indicated that up link ERPs in excess of 2 kilowatts were present

A number of interested parties, through the cooperation of NASA and Aeronautical Radio listened for a one-week period in an effort to determine the origin of these strong signals. They were not present during this one-week period and have not returned. In the first 5 months as equipment and operating procedures have improved both in the aircraft and shipborne tests, this problem, which seemed so serious on 12 December, has been nearly forgotten.  Today VHF communications via satellite have been shown to be feasible for aircraft and maritime mobile application.


Spacecraft operating at microwave frequencies operate their transmitters well below peak power (transmitter Back-Off).  The VHF Experiment on ATS-3 Replaced the Class C RF amplifiers used on ATS-1 with linear RF amplifiers. This was important because it greatly reduced the inter-modulation distortion inherent in multi-channel transmitters. These transmitters were solid state and used a class A/B final stage; The DC power required was reduced 1/2 db. for every 1 db. of back off. This was a very important discovery since power is a very expensive commodity on any Spacecraft.

At low elevation angles multipath can cause a significant loss in signal for short periods of time as the reflected signal alternately cancels and adds to the direct signal. Circular polarization can eliminate this problem when used by receiver and transmitter that was later verified in field tests with TACSAT in 1969.

Hughes designed and tested circular polarized replacements for the dipole antenna elements on ATS-3.  Unfortunately, NASA did not approve their use.  Meanwhile Boeing designed a circular polarized flush mounted VHF antenna for the 747 aircraft.  C.A. Petry at ARINC worked with the airlines and FAA to produce a spacecraft compatible aircraft radio set in ARINC Specification 546.

When the first Boeing 747 was delivered to Pan Am, it was equipped with and ARINC 546 communication transceiver and a circular polarized antenna. This aircraft was equipped for satellite to aircraft communications.

ATS-3 was launched successfully on November 5, 1967, and positioned over the Pacific Ocean. Together with ATS-1 nearly global communications were possible at VHF frequencies.

Hughes designed a small inexpensive VHF terminal for the US Coast Guard that was installed on the USS Glacier, the ship used to resupply the Antarctic Base.  Sun spot activity was heavy during the 1967-68 winter, and HF radio was unusable for long periods of time.  The $4000 Hughes satellite terminal got through every time.

In the fall of 1969 I was selected as a representative of the State Department to the CCIR Conference on satellite communications.  Captain Charles Dorian and I were able to persuade the Russian delegate to support the US position to authorize VHF aircraft communications by satellite.  France led the opposition. The Russians brought along the eastern bloc, even Havana supported us. The French opposition was defeated – WE WON

Unfortunately, France played politics better than we did. As I understand it, they got NASA to oppose Aerosat in exchange for France support of the Space Shuttle. In any case, I received a phone call in Geneva from Hughes saying NASA pulled the plug – ITS ALL OVER.  I had spent nearly almost 10 years in the pursuit of a VHF Aeronautical Satellite to no avail.

At least the military did not have to play these politics.  Both Russia and the US adopted VHF communications (TACSAT).  The Syncom and ATS experiments produced at least two winners.

Completely independent of my employment with Hughes, I had developed the concept of an electrical powered battlefield surveillance drone and a Solar Powered high altitude spy plane. Dr. Bob Roney told me Hughes was not interested.

I left Hughes Aircraft in January 1973 and successfully proposed both aircraft to DARPA. The prototype electric powered battlefield drone flew that year and was shown on Los Angeles television. The 32-foot span proof of concept model of the spy plane flew on solar power alone in 1974.  A patent for the electric powered aircraft was granted on May 18, 1976.


On September 29, 1995, Ben McLeod and Bob Bohanon (Both from Pan American) organized a 30th anniversary celebration in Washington DC. Personnel from ATA, ARINC, Bendix, Comsat, FAA, FCC, Hughes, NASA and or course Pan-AM were in attendance. We all were all thrilled that the aging Frank White was able to attend and were sad that other important contributors from Comsat, Collins Radio, and the US Coast Guard were unavailable or deceased.

Surveyor I and the American Flag–Jack Fisher

The miraculous landing of the first Surveyor spacecraft to reach the Moon on June 2, 1966 has been described in The Story of Surveyor I. After the landing it was discovered that an American flag had been placed in the spacecraft as arranged by Sheldon Shallon, the Surveyor Project’s Chief Scientist at Hughes Aircraft. The presence of this flag was unknown to NASA, JPL and became quite controversial. The documents included below, provided by Susanne Shallon, Sheldon’s daughter, describe the aftermath quite well. Unfortunately Sheldon passed away last April and will not be with us to celebrate the upcoming 50th anniversary of this mission in June.

ShallonSheldon Shallon describing the Surveyor Spacecraft


SCG’s Tom Hudspeth Celebrates the Common Sense of Inventing: SCG Journal June 1984—Transcribed by Faith MacPherson

Hyland Award Winner’s Reaction: “Happy…I Felt Like a Lucky Fool!”

Tom Hudspeth didn’t set out to be an engineer. “In high school I was really interested in bacteriology,” he confessed recently. “I wanted to be a scientist when I grew up, but that didn’t seem practical. So I became an engineer.   I was handy at making things work…it seemed like a good way to make a living.”

“A living,” indeed. Judging from the Technology Division senior scientist’s 43-year career in radio electronics as an engineer, renowned inventor, and innovator, Tom Hudspeth has made more than just a living. Certainly Hughes, the firm with which he has been associated for the past 38 years, sees it that way. For when the 1984 recipients of the Lawrence A. Hyland Patent Awards, the company’s most prestigious recognition for inventors, were announced recently, Tom Hudspeth’s name was among them – again.HudspethTwo-Time Winner

Since the Hyland honors were inaugurated by Hughes in 1968, Hudspeth is only the second inventor to be so recognized twice. James Ajioka of Ground Systems Group also is a two-time award winner.

The award is named for former Hughes Chairman of the Board Lawrence A. “Pat” Hyland, who headed the company from 1954 until his retirement in 1980.

Helped Birth Syncom

During the recent award dinner held to honor the five 1984 Hyland awardees, Hughes Chairman and Chief Executive Dr. Allen Puckett cited Hudspeth for his trail-blazing achievements in the field of satellite communications. As Dave Brown, SCG’s manager of Technical Operations, put it recently, “It’s fair to say that Tim Hudspeth is one of the small handful of people whose engineering genius is directly responsible for the seed of what today is a multibillion-dollar-a-year industry, one of the fastest-growing segments of aerospace – communication satellites. Without Hal Rosen (SCG vice president, Engineering), Don Williams, and Tom – working together and with other company space pioneers – it’s doubtful whether geosynchronous spacecraft, let alone Hughes’ success in the market, would have come so far over the past 20 years.”

In 1968 Rosen and Hudspeth received one of the first Hyland Awards in recognition of the pioneering efforts which led to the development, by Hughes for NASA, of the first geosynchronous communications satellite, Syncom. They, along with Williams, co-invented the bird which became the first in a line of more than 120 Hughes-built communications spacecraft.

‘Prolific Inventor’

Hudspeth hasn’t rested on his laurels. Since Syncom he has cogitated his way to 18 patents, all inventions related to his work on high frequency communications systems. The most recent patent, issued this past January, was for a diplexer – an elegant amalgam of microwave “plumbing” used on the HS 376 Westars, Galaxy, Palapa-B birds, and Telstar 3 – which simplifies the antenna subsystem by allowing one dish simultaneously to handle transmit and receive frequencies.

“Judging on patent alone, Hudspeth is one of the most prolific inventors in the Group,” Brown stated. His overall impact on space communications goes far beyond that, however. Every Hughes satellite ever orbited has carried one or more devices or electronic innovations devised by Hudspeth. Examples of Hudspeth-inspired hardware include:

  • the omnidirectional bicone telemetry and command antenna, standard equipment on all Hughes spacecraft since Intelsat II;
  • phase converters used to simplify feed networks of the original HS 333 satellite line, and a technology being incorporated into the Group’s new low-cost HS 399 satellites;
  • a small, simple waveguide switch, developed for the Comstar satellites, from which he derived a similar, though much more complex switch to reshape the regional microwave “footprints” on the big Intelsat VI birds, now under development;
  • and, possibly most important, squareax – a method of designing and building microwave feed networks in “printed circuit board” fashion for economy of space in a satellite’s communications payload, and for efficiency and reliability in operation. “In our current competitive and increasingly complex multifeed horn spacecraft antenna systems, the critical need to shape, switch, power divide, and test a multiplicity of antenna beams has been successfully met by Tom’s inventions of squareax transmission line switches, hybrids, crossings and adapters,” Brown said.

Old ‘Solder Jockey’

The man who’s the center of all the fuss demurs at the superlatives. Tom Hudspeth terms most of his inventions “dumb little ideas that seemed to come naturally to me…many important problems don’t require great subtleties in their solutions. Getting the decimal point in the right place sometimes does the trick,” he said, grinning. When he heard that he’d been selected for the Hyland Award a second time, “I felt like a lucky fool,” he remembered. He pointed out that “there are people around here doing tremendous things, with great subtleties, imagination, and elegance. I could never hope to come up to their level.”

It is perhaps both a mark of the man, and the esteem I which he is held by those who’ve known him for years, that such remarks are considered characteristic of Tom Hudspeth. He attributes his brainstorms to “common sense,” his success to “dumb luck.” ‘I’m just an old solder jockey,” he cracked. Perhaps. But if so, he’s an extremely talented solder jockey.

Hudspeth’s 18 patented inventions are by no means the totality of his brain trust. Over the years he has written 44 patent disclosures. A disclosure is a description of an invention which provides the basis for a patent application. Tom has four patents pending in the U.S. Patent Office.

Impact on Programs

While it’s difficult to estimate the dollar value of his contributions during the past 16 years, every Group program, according to Brown, has felt the impact of Tom Hudspeth’s inventions. This impact manifests itself in the performance and reliability of his brainchildren.   None have ever failed in orbit – a remarkable circumstance when one considers that perfect performance for 10 years or more is a standard requirement. In turn, the success rate in space translates into success for Hughes’ satellite business: Beginning with Intelsat I and including defense programs through 1983, Hughes satellite sales total nearly $3.8 billion.

He’s considered a valuable resource, not only by SCG but by other Hughes organizations as well. SCG’s Murray Neufeld, who has known Hudspeth for years, said, “Whenever somebody over at Ground Systems Group has an antenna problem, they call Tom.”

As part of his Hyland Award recognition, Hudspeth received a $5000 honorarium and a commemorative plaque.


Stoolman Leaves Behind 36-Year Legacy—SCG Journal May 1985 Transcribed by Faith MacPherson


On June 1, 1966, a three-legged robot craft powered its way to the soft lunar terrain, making Surveyor 1 the first spacecraft to make a controlled landing on the moon. It was an event to remember for millions of Americans, especially Leo Stoolman, the young engineer who headed the Hughes team that designed and developed Surveyor.

“I’ll never forget that evening when we went to JPL to observe the landing….I never saw so many TV cameras,” he recalls. “I remember thinking, ‘This is the most important part of the mission. If we fail, it’s going to be in front of millions.’

“The biggest worry for me was the possibility of spacecraft tumbling at main retro engine fire because we were never sure that the thrust would be close enough to the center of gravity not to tumble the spacecraft,” Dr. Stoolman remembers. “I was biting my nails until it was announced that the main retro had fired and the spacecraft was stable. Then I knew we were going to make it.”

Ten feet above the lunar floor, Surveyor’s engines were turned off and the spacecraft dropped softly to the surface. “At about 3 a.m., Surveyor’s TV cameras were turned on and for the first time in history man got the first close-up pictures of the moon’s surface,” he recounts. “That was the biggest thrill ever.”

This month, Leo Stoolman officially retires after 36 years with Hughes. Although he still considers Surveyor the diamond of his time at Hughes (“It’s the exploring missions that make your blood run”), his career has been studded with many such jewels. As one of the first recipients of the Howard Hughes Graduate Fellowship at Caltech, Dr. Stoolman came to Hughes in 1949, “on kind of an experimental basis.” After receiving his doctorate, “I decided to stay on and try it out….I thought it would be a few years,” he says. “But the more I stayed the more interesting it was. After a few years, I got involved in project work and was hooked. Then it was off to the races.”

In the 1950s, Dr. Stoolman headed the Aerodynamics Department of the Guided Missile Laboratories which developed the Falcon air-to-air guided missile. He also managed the Falcon GAR-II missile project.

After Surveyor’s success, Dr. Stoolman formed and managed SCG’s Systems Laboratories (49-00), a position he held for 15 years until last month. Under his leadership, the Labs’ systems engineering experts provided systems analysis and integration engineering support for the Group’s new and ongoing programs.

During his time as manager of the Labs, Dr. Stoolman has pursued methods of improving systems engineering practices such as bettering the “product memory.” He explains, “When there’s a problem on a program, it’s important that you keep a case history of the problem, noting what was done to solve it, and put the information into a data base. Cataloging this information may be dull but it will be a tremendous value later and will enable you to learn from, rather than repeat, past mistakes.”

Recognizing that much of the Lab’s staff comes from universities, Dr. Stoolman has worked closely with the institutions. He is a consultant and advisor for the overall Hughes Fellowship effort and manager of SCG’s program, a visiting engineering professor at Caltech, chairman of Stanford University’s Industrial Affiliated program, and chairman of the company’s Doctoral Fellowship Selection Committee.

“There are a lot of other companies out there also looking for the best and brightest, so we’ve got to be competitive,” he says. That includes developing close relations with a number of universities where SCG tries to identify those engineering students with potential early. “We must do our homework at schools for a couple of years before we actually go recruiting,” he says. “Education is such a big payoff. That’s our bottom line – to get good people.”

With 36 years experience at Hughes under his belt, Dr. Stoolman has some pearls of wisdom for engineers just starting their careers. “I keep telling young people that engineering is a fine career if you just take it seriously. Take on responsibility early, don’t be afraid to jump in with both feet, and get thoroughly involved,” he stresses.

“But the most important thing of all is don’t be a loner. No matter how good you are technically, if you can’t get along and communicate with people it just won’t work. It’s the synergism that’s important in this business. Five people working closely together can do much more than five people not talking to each other.”

Looking back on a career that almost spans the lifetime of Hughes, would he do anything differently? “I’ve worked for a fine company with super people and great projects,” he says. “We’ve had some rough times but on balance, when you add it all up, I wouldn’t do anything differently. I still love the work but there are other things which one must do.”

Those “things” include continuing work at SCG on a part-time consulting basis on the university interaction task; traveling with his wife, Alfreda, around the country and visiting their children; pursuing his hobby, woodworking; and learning to master his “darn computer,” a task he has finally come to accept as inevitable.

A longtime coworker seems to sum up best Leo Stoolman’s life and times at Hughes. “It is impossible to overstate Leo Stoolman’s contribution to Hughes Aircraft Co. and to SCG,” says Dr. Robert Roney, Hughes vice president. “Having led the effort that brought Hughes its very first spacecraft program, the Surveyor, Leo has continued to contribute enormously to the development of the technical resources of SCG. He is leaving a legacy that will serve us for years to come.”


Dick Parfitt—Jack Fisher

I don’t remember that in the Pioneer Venus studies prior to the proposal that anyone had a great deal of concern about the spacecraft wire harness. For our proposal effort and program costing exercise the Design Integration organization would have been responsible for the design and construction of the harness and I’m sure that was taken into account in their bid. For my systems engineering bid I was blissfully ignorant of any responsibility for the wire harness.

When we started working under the contract in 1974 I was fortunate enough to recruit several very experienced systems engineers, one of whom was Dick Daniel. Shortly after he started Dick came to tell me that we needed to get Dick Parfitt to do the wire harness Interconnection List (ICL). The ICL is list of connections that the harness must provide and is essentially the starting point for the design of the harness—or the first set of harness requirements and was the responsibility of systems engineering. Well I couldn’t argue with that, but then I learned that Dick Parfitt was in the Commercial Division. I was reluctant until I learned that Dick had done the ICLs for all previous commercial and NASA satellites, with the exception of Surveyor. So Dick Parfitt did the Pioneer Venus ICLs—there were four to be done: the Orbiter, Multiprobe, Large Probe, and the Small Probe. I don’t remember any issues that arose, Dick worked unobtrusively and efficiently and got the job done. I wish I could write more about Dick Parfitt because he was a great asset to SCG. I would invite anyone who has recollections of Dick to add their comments to this post.

Don Williams and Einstein—Warren Howard Sierer

Don Williams hired me over the phone 1964 straight out of college and sight unseen. I doubt that my telephone interview impressed him much but I was probably the only person he could find back then who had taken astrodynamics coursework, programmed in FORTRAN …and didn’t cost much if he was wrong.

I joined Don’s small in-orbit control team whose other members were Murray Neufeld, Bill Snyder, Bernie Anzel, Roger Cole, Mel Richins and Marcelle Farr. Don’s team reported to Harold Rosen. Only years later did I realize how fortunate I was to “learn the ropes” from this unique group.

My first assignment was to become the team’s attitude determination specialist. Attitude (spin axis orientation) was determined using sun sensor data (a solar cell mounted behind two canted metal slits mounted on the spinning body) and “POLANG.” The dipole antenna on our early satellites emitted a linearly polarized signal. By measuring the “polarization angle” as received at a ground station, attitude data could be derived with the appropriate trigonometric calculations.

In 1965 we were keeping track of Syncom 3. Our team made attitude estimates on a regular basis. We expected attitude to remain fixed in space unless we maneuvered the spacecraft. (Newton’s first law: a body in motion….) I assumed small variations in determined attitude over time were due to estimation errors. Don Williams had a better idea.

Don noticed that Syncom’s attitude was drifting by small fractions of a degree each month in a direction perpendicular to the sun. He believed this gyroscopic precession could be due to solar radiation pressure, the force of photons from the sun “pushing” on the spacecraft. The concept of using solar sails as propulsion on interplanetary missions relies on this phenomenon.

Don walked into my office and without saying a word, wrote Einstein’s famous E = mc2 on my blackboard. In less than one minute, he said solar radiation pressure pushing on the side could change the attitude if the center of pressure was offset from the center of gravity, pointed at Einstein’s equation and walked out.

Scrambling around, I found estimates for the sun’s “E,” divided it by “c” and got solar radiation’s momentum, “mc.” The resulting force applied depends on how much radiation is reflected versus how much is absorbed. Having no idea what the reflectivity was or where the center of pressure was, I combined both unknowns into one parameter and used our attitude data to estimate the effective CG/CP offset. To no one’s surprise who knew Don, he was right.

While Syncom 3 may have been the world’s first definitive demonstration of solar radiation pressure in space, all Hughes spin stabilized satellites exhibited this slow precession in a direction perpendicular to the sun line. Both Albert Einstein and Don Williams were right!

Howard Sierer was known as “Warren” during his six years in El Segundo, but used “Howard” from 1970 forward in Denver.