Category Something New Under the Sun
Individuals interviewed for the navigation section are as follows:
Bob Danchik* (Transit’s penultimate project manager), Bill Guier* (physics), George WeifFenbach* (physics), Lee Pryor* (software development and Transit’s last project manager), Carl Bostrom* (physics and later the director of APL), Henry Elliott* (antennas), Lee Dubois* (command, control, and tracking), Charles Pollow* (assistant program manager), Laurence Rueger* (time and frequency systems), Tom Stansill* (receivers), Russ Bauer* (software), Charles Bitterli* (software), Harold Black* (physics/orbital mechanics), Ben Elder* (memory designer), Eugene Kylie* (receivers), Barry Oakes* (rf systems), Charles Owen* (mechanical design), Henry Riblet* (antenna design on Transit), Ed Westerfield* (receiver design), John O’Keefe (satellite geodesist), Gary Weir (naval historian), Commander William Craft (commander and director of seamanship at the U. S. Naval Academy, in Annapolis), Brad Parkinson (GPS project manager), Group Captain David Broughton (director of the Royal Institute of Navigation), and Dave Smith (satellite geodesist, currently at the Goddard Space Flight Center, Greenbelt, Maryland).
An asterisk denotes that an individual was a member of the Transit team.
Some of the above were interviewed in great depth and over many hours, weeks, and in the case of Guier and WeifFenbach, months; a very few spoke to me for as little as half an hour.
When interesting things like this come up, many of the most important results come out of people’s curiosity, just following up something, and someone over in a corner who is not supposed to be doing anything about it usually comes out with the best answers.
—Homer Newell, science programs coordinator for Vanguard, discussing Sputnik at a meeting of the IGY’s Technical Panel on Earth Satellites, October 22, 1957
hen Wall Street opened on Monday, investors scrambled to buy stock in companies connected with missile programs, abandoning other issues and pushing prices to their lowest level in two years.
Two hundred miles to the south in Washington D. C., there was another scramble as the Naval Research Laboratory briefed President Eisenhower and congressional members on the status of Vanguard. James Lay, executive secretary of the National Security council, called the head of the National Science Foundation, Alan Waterman. The status of the U. S.’s satellite plans, Lay said, would be second on the agenda at Thursday’s security council meeting, immediately after a CIA presentation about Soviet defenses. Later that day, Lay called Waterman again; discussion of the U. S. satellite had, he said, now moved to the top of the agenda.
As for the general public, the Saturday morning papers greeted anyone who still did not know of the launch with three-deck banner headlines. Sputnik squeezed reporting of the drama surrounding desegregation in Little Rock and Jimmy Hoffa’s election as president of the Teamsters Union into a corner of the front page of the New York Times. By Sunday, nothing short of a declaration of war could have rivaled the satellite’s editorial supremacy. And a Times editorial stated soberly, “It is war itself rather than any designated enemy against which we must now defend ourselves.” At his home near the Applied Physics Laboratory, Bill Guier tuned in to every radio and TV broadcast. He was thirty-one, a theoretical physicist, and a news junky even in less exciting times. That weekend, Guier was as fascinated as the rest of the country He had no idea that the satellite would change his future.
Nor did George Weiffenbach, then a thirty-six-year-old experimental physicist. He too learned during the weekend of the launch of the satellite. Weiffenbach recalls that he was not particularly excited. His wife says otherwise and remembers eager calls to friends and colleagues.
On Monday afternoon, October 7, Guier and Weiffenbach unknowingly took their first steps in the development of a new method of orbital determination and prediction.
Orbital mechanics—the behavior of satellites in orbit—lies at the heart of space exploration. Without a detailed and accurate knowledge of the subject, man-made satellites would be useless, because no one would know where they were or were likely to be. And no one would know the time and position at which a satellite instrument made an interesting observation, such as of an atmospheric disturbance with the makings of a hurricane. Yet it is impractical to follow all satellites throughout their orbits. Hence observations are made of part of the orbit and that information feeds into the mathematical relationships that describe behavior in orbit. Once the orbit is determined, the satellite’s future behavior—its position at given times—can be predicted. Orbital predictions allow mission planners to determine, say, when the space shuttle should lift off if it is to dock with the Mir space station. They allowed the operators of the Transit navigation satellites to calculate exactly where the spacecraft would be at every two-minute interval in their orbits, thus providing navigators with a reliable celestial fix.
All of the groups observing Sputnik—amateurs and professionals alike—were tackling the problem of its motion within the framework of classical physics laid down over the previous three centuries by the likes of Johannes Kepler (working with Tycho Brahe’s data), Galileo Galilei, and Isaac Newton.
Brahe (1546 — 1601) was an astronomer who in the days before telescopes designed and built instruments that enabled him to measure the angles to heavenly bodies. His story is well known in the annals of science because he recognized the importance of basing theory on accurate observations rather than philosophical speculation. His observations of the orbit of Mars were invaluable to Kepler (1571 — 1630) when Kepler was seeking a fundamental description of planetary motion.
Kepler assumed, though this was far from generally accepted at the time, that Copernicus had been correct in asserting that the planets moved around the sun. With this assumption, Kepler explored numerous mathematical models, seeking one that would lead to a description of planetary motion consistent with Brahe’s data.
Kepler’s belief in the integrity of Brahe’s data kept him at his calculations through years of poverty and illness, calculating and recalculating until finally, theory was consistent with observation. Kepler found that to fit Brahe’s observations, the planets must move in ellipses—a geometric figure that has two foci; in the case of Earth-orbiting satellites, one focus of the satellite’s orbit is the center of mass of the earth. Kepler next described in a mathematical relationship how a body in orbit sweeps out equal areas of an ellipse in equal times. In a third law, he described how planetary orbits relate to one another mathematically.
In reaching these conclusions Kepler was forced to burn his intellectual bridges, cutting himself off from both views of the universe that were accepted in his day. First, by accepting the Copernican assumption, he was no longer in sympathy with the Catholic Church; second, he had given up the Greek view of the planets moving in circles. This second view was particularly hard for Kepler to abandon. Indeed, it was a view that Galileo was never able to abandon.
At one stage, Kepler thought that the orbits might be circular, but when he made calculations based on this assumption there was a small discrepancy with Brahe’s data that kept him at his calculations until he finally concluded that the planetary orbits are elliptical. With less confidence in Brahe, Kepler could easily have stopped his laborious calculations before reaching his fundamental insight.
Kepler was ecstatic. Soon after he formulated the last of the three laws that bear his name, he wrote, “Nothing holds me; I will indulge my sacred fury…. If you forgive me, I rejoice; if you are angry, I can bear it; the die is cast, the book is written, to be read either now or by posterity, I care not which….”
Though Galileo (1564-1642) never accepted elliptical orbits, his giant strides in mechanics provided, along with Kepler’s work, a solid scientific basis for Isaac Newton (1642— 1727). Among other things, Newton discerned and formulated the all-important law that force is equal to mass times acceleration. All of the different methods of observing the satellite’s position, Guier’s and Weiffenbach’s included, sought different ways to gather information that could make use of this law—the so-called second law of motion—within the concept of orbits established by Kepler.
Newton’s second law (F = MA) and Kepler’s second law allow mathematicians to deduce six numbers that give an approximate description of an orbit. In tribute, these numbers—or elements—are named after Kepler. One gives the orbit’s shape, that is, how elliptical it is, whether it is extremely elongated or close to circular. This element, termed eccentricity, is defined as the distance between the two foci divided by the length of the major axis. The closer the value of eccentricity is to one, the more elliptical the orbit. An eccentricity of zero describes a circle.
A second element, the semimajor axis, gives the size of the orbit. Two more describe the orbit’s orientation in three dimensions with respect to the celestial sphere, and a fifth pinpoints that orientation with respect to the earth (respectively, inclination, ascending node, and argument of perigee). The sixth element is the time at which the satellite is at the ascending or the descending node, that is, the time at which the satellite crosses the plane of the equator heading either north or south. It is more usual to use the ascending node.
Kepler’s elements, however, are only averages. Any additional force, such as an inhomogeneity in the earth’s gravitational field, that acts on the satellite causes it to deviate from the average path described by Kepler’s elements. The deviation might be small and local or might cause the entire orbit to precess; that is, the orbit can rotate about an axis in such a way as to sweep out a conical shape. Thus a description of a satellite in near-Earth orbit requires eight parameters: the six Keplerian elements and two precession terms. While such a description is more accurate than that provided by the Keplerian elements alone, it is still only an approximation. Only by giving the positional coordinates at given times can an accurate orbit be described, and this is what the Transit team eventually did.
On Monday, October 7, people were still struggling simply to observe Sputnik. The Minitrack stations were being adapted; only some of the Baker-Nunn cameras were in place; the first confirmed Moonwatch sightings, in Woomera and Sydney, Australia, would not be made until the next day.
Across the ocean in England, at Jodrell Bank and the Royal Aircraft Establishment, radio telescopes were waiting for Sputnik. They tracked the satellite by keeping its signal at the focus of their dishes, and the angle of the telescope relative to a fixed north-south line and to the horizon gave respectively the azimuth and elevation of the satellite. These data can be used to determine the Kepler elements. When in April 1958 Guier and Weiffenbach published a brief summary of their methods and results in scientific correspondence to the journal Nature, they compared the orbit they calculated for Sputnik I with those from Jodrell Bank and the RAE. There was good agreement.
Once their technique was developed, Guier and Weiffenbach’s orbital determination could, unlike those from Minitrack and the Smithsonian Astrophysical Observatory, be based on observations from a single satellite pass. Eventually, for truly accurate orbital determinations their technique would be applied to the observations collected by many ground stations over a twelve to eighteen hour period. When reversed, the technique allowed position to be fixed at a receiver on Earth from one satellite pass, the basis of Transit.
As Guier and Weiffenbach made their separate ways to work that Monday, all this was shrouded in the future. They knew each other slightly as fellow members of the research center. They had worked together on some of the same projects during the previous few years. By chance, that Monday they ate lunch at the same table in the canteen. Just as at the White House and the Pentagon, Sputnik was the focus of conversation.
Guier thought the satellite was superb. Yet his history was not one that obviously suggested an admirer of Soviet ingenuity. As a graduate student in the late 1940s, he had heard Edward Teller, “father of the hydrogen bomb,” call for physicists to fight a new kind of technological war. In a world newly afraid of atomic power and rife with the political tensions that would lead to the Berlin Wall, Teller’s call to arms seemed logical to Guier. Guier joined APL’s research center in 1951.
Like Guier, Weiffenbach believed in the importance of weapons research and in the protection that technological supremacy could afford. He had been in Europe during the war and had been among those waiting in the summer of 1945 for orders to go to the Pacific. On his demobilization, the government paid for his education, something his parents could not have afforded to do, through the provisions of the GI Bill. It seemed right to Weiffenbach to work to strengthen national security, both because of what he had seen in Europe and to repay the nation for his education.
Guier’s choice had a consequence that, though small in the scheme of things, was indicative of the times. He had a German friend behind the
Iron Curtain. Their correspondence helped Guier with the language studies necessary for his doctorate. Guier did not see this man through a political lens, and he was staggered when his thesis director advised him to end the correspondence. The Soviets might exploit the relationship, said the professor, and even if they didn’t, the letters could damage Guier’s career.
At first Guier ignored the advice, but a summer internship at Los Alamos changed his mind. Assigned to work on computer models of nuclear explosions, he learned of the secrecy surrounding nuclear weapons, of the comparative simplicity of some of the physics, and the great fear in government circles that the Soviets would soon have similar technology. These fears were heightened when the Klaus Fuchs and Rosenberg scandals erupted. Fuchs, a British physicist, and Julius and Ethel Rosenberg, an American couple, gave atomic secrets to the Soviets. Fuchs was imprisoned, the Rosenbergs executed. In this climate, Guier became acutely aware of the Cold War and reluctantly ended his correspondence.
Accepting the political realities of their world, Guier and Weiffen- bach settled down to conduct basic research in support of weapons systems. The Soviets were the enemy.
Here was something new, the first foothold in space. The lunch group asserted, with the scientist’s classic understatement, that Sputnik was not trivial. APL staff, deeply involved in missile and radar work, knew this well. And despite its provenance, Sputnik was intriguing.
The lab was not involved with the IGY. Thus people at APL, certainly at Guier’s and Weiffenbach’s low level, had no inside track to what little was known about Sputnik. Nor was there any involvement with the planning for Minitrack. Their ignorance of the IGY’s discussions about the limitations of Doppler and the advantages of interferometry freed Guier and Weiffenbach from the conventional wisdom about satellite tracking and orbital analysis and ultimately stood the pair in good stead.
Lunch wound down.
Guier and Weiffenbach decided to rectify the surprising fact that in a lab bristling with antennas and receivers nobody was listening to Sputnik’s signal. That was all: an indulgence of curiosity. They did not intend to make a serious attempt to determine and predict Sputnik’s orbit, but only to calculate roughly when the satellite would reappear over Washington.
When he got back to his lab, Weiffenbach attached a wire to the back of a receiver and prepared to tune in. He knew—how, given the widespread publicity, could he not—that Sputnik was broadcasting an intermittent signal at about twenty megahertz.
Serendipity, that great friend to science, now lent a hand for the first time. Weiffenbach’s receiver, working on the same principle as any ham radio operator’s equipment, added the satellite signal of approximately twenty megahertz to a reference frequency of twenty megahertz, resulting in an audible “beat” note—Sputnik’s distinctive beep beep. But Weiffenbach’s reference frequency was special; it was broadcast by the nearby National Bureau of Standards as a service to scientific laboratories, and it was at a precise twenty megahertz.
Some few hours later, when their rampant curiosity turned slowly to a controlled scientific interest, Guier and Weiffenbach started recording the beat frequency along with the national time signal during each pass of the satellite from horizon to horizon. And that was the raw data from which they developed a new technique for orbital analysis and provided the scientific underpinning for a satellite navigational system. Without a precise reference signal, they could not have extracted the information they did. Had the reference signal been broadcast from a more distant site, its quality would have been degraded on passage through the atmosphere, and again they could not have extracted the information they did.
As they waited for the satellite to come over the horizon, Weiffenbach fiddled with the knobs of his receiver. The airwaves were buzzing. Disembodied voices mimicked the satellite’s signal. Others repeated, “this is your Sputnik … this is your Sputnik.” Then—faintly—Weiffenbach picked up an English-language broadcast from Moscow. It gave the times when the satellite would be over the world’s capitals. They knew when to listen.
By now a crowd had gathered. During the next few days there would at times be so many people in the lab that Weiffenbach could scarcely squeeze through to his receiver. As they waited, there were a few murmurs, not serious, that perhaps the signal was a fake. Most wondered whether the signal would carry information; measurements, perhaps, of the satellite’s temperature—the first remote measurements (telemetry— measurement at a distance) from space.
The same question arose at a meeting of the IGY’s satellite panel on October 22. Inevitably, the main topic on the agenda was a discussion of when America would be ready to launch its own satellite. But the panel also discussed, without reaching a conclusion, whether it could squeeze money from the budget to analyze Sputnik’s signal for telemetry Bill Pickering said that even if the signal did carry temperature or pressure measurements, they would be useless without knowing how the Soviet instruments were calibrated. Homer Newell observed that maybe someone unconnected with the IGY’s work would decipher Sputnik’s message. (The Soviets had said, incidentally, that there would be no telemetry from their first satellite.)
The discussion was academic: Sputnik stopped transmitting a few days after that meeting. And long before October 22, Weiffenbach and Guier had concluded that there was no telemetry.
In Weiffenbach’s lab, the crowd heard Sputnik’s beep for the first time late on Monday afternoon. Guier, an amateur musician with good relative pitch, cocked an ear. Surely the pitch of the beat note was changing. Of course, he said, it must be the Doppler shift. The change was subtle, a matter of about an octave over twenty minutes. It was this phenomenon, known to every physics student, that was to provide the key to the Applied Physics Laboratory’s work on geodesy and Transit.
The Doppler shift is, at heart, conceptually quite easy to grasp. Its consequences can reveal much about the natural world. Astronomers, for example, find it of great utility when studying the motion of stars. But, as with much else in physics, once one goes beyond the basic description of a phenomenon, things become complicated, and the Doppler effect is not easy to exploit in the real world. For this reason, some mistrusted Guier’s and Weiffenbach’s work. Others were suspicious of their mathematical analysis. The two scientists, recalled Guier, would be told “reliably” what criticism this scientist or another had made of their work and were all but told they were cheating.
A straw poll soliciting descriptions of the Doppler effect elicited comments ranging from the general statement that it has to do with the way the sound of a car’s engine changes, to the statement that frequency increases as a source moves toward you and decreases as it moves away. Given its importance to Transit and the understandable vagueness of many, it seems worth describing the basic concept in some detail.
The Doppler shift, which is a consequence of a moving frequency source, is usually introduced to unsuspecting physics students through a discussion of how and why the pitch of a train’s whistle changes as the train races past. It is pointed out that the change in pitch occurs even though the pitch of the whistle would not be changing if you were sitting next to it on the train’s roof.
I’d prefer to start at the seaside, and to tackle the train analogy later.
Imagine facing the ocean for twenty seconds and counting the waves as they crash into you. Now imagine walking into the ocean to meet the waves head on. More waves will reach you in those twenty seconds than if you had stood still. Now imagine walking out of the ocean directly away from the waves, and you can see that fewer crests will reach you in twenty seconds than if you had remained stationary. So the number of waves generated by the ocean in a given amount of time (the transmitter frequency) remains constant, but the number of wave crests encountered (received frequency) increases or decreases because of your motion relative to the waves. The difference between the transmitter frequency (ocean waves rolling in per second) and the received frequency (wave crests encountered) can be thought of as the Doppler frequency—the amount by which the received frequency differs from the transmitter frequency because of relative motion between a frequency source and a receiver.
Now imagine that the ocean is unnaturally well behaved and that the wave crests are spaced evenly (the transmitter frequency is constant). You are walking into the ocean at a steady pace. In the first twenty seconds you encounter a certain number of wave crests. If your pace and direction forward stay the same, how many wave crests do you encounter in the next twenty seconds compared with the first twenty seconds?
The same number, of course, because nothing about the ocean waves or about your motion with respect to them has changed between the consecutive twenty-second intervals. So the frequency received, which was Doppler-shifted upwards by your initial motion forward, remains constant. A graph of received frequency against time would be a straight line parallel to the horizontal, or x-axis. When you turn around and retrace your steps at exactly the same pace, the frequency received will be Doppler-shifted downwards and will remain constant at that value. A graph of received frequency against time would also be a straight line parallel to the x-axis, but this time at a value below the transmitter frequency. Momentarily, as you stop and turn, you will be buffeted by waves at the natural frequency of the ocean.
Once you make it to dry land, turn back to the waves. They are now behaving in a very peculiar way The wave fronts are aligned exactly parallel to one another, wave crests evenly spaced. They roll in at a rate of 100 per second. You walk directly into them, along a path perpendicular to the wave front. You are walking at a pace which in one second permits you to cover a distance equal to six wavelengths. So in one second you encounter 106 wave crests. (Transmitter frequency is 100 waves per second, or cycles per second; the received frequency is 106 cycles per second and the Doppler frequency is 6 cycles per second.)
Now instead of walking a path perpendicular to the wave front, walk into the ocean at a slant. The number of waves crests you encounter in a second will still be greater than if you stood still (will be Doppler shifted upwards), but it will not be as great as if you took the perpendicular path. The received frequency and whether or not it is shifted upwards or downwards and by how much depends on the relative motion between you and the wave front. See the diagram below.
The same logic can be applied to the sound waves of a train’s whistle and to radio waves from a satellite.
Let’s take the train. If you and the train remain stationary, the number of sound waves emitted by its whistle in a given time is the number that you hear in that time, just as the number of waves rolling ashore in a given time interval was equal to the number of wave crests that hit you when you stood still.
If you are standing on the track and the train is moving directly towards you at a constant speed, the rate at which the range between you and the train changes remains constant just as when you were moving into the water along a path perpendicular to the wave front at a pace of six
wavelengths per second. So the frequency received from the train’s whistle is shifted upwards because of forward motion and remains constant at the new value as long as that relative velocity (speed and direction) remain constant. Then as the whistle moves through you, for a moment you hear the natural frequency of the whistle (the Doppler shift is zero). Then the train moves away and the frequency is Doppler shifted downwards, and that Doppler shift also remains constant while the relative velocity remains constant. This is all logically equivalent to what happens as you walk in, turn, and walk out of the ocean.
Now what happens if you are standing off at some distance on one side of the track? The rate at which the distance between you and the train changes is no longer constant. That is, the relative velocity between you and the source is no longer constant. So the Doppler shift is no longer constant.
The diagrams below, where marks on the track represent the train’s position at, say, fifteen-second intervals, show how the rate of change of distance between train and observer changes with time, and how that change depends on how close the listener is to the track.
Again there is a logical equivalence between walking into the ocean at a constant angle or changing the angle as you walk into the waves. Thus, the amount by which the Doppler frequency is shifted above the transmitter frequency decreases gradually as the train moves towards you, until at the point of closest approach the received frequency is affected neither by the forward nor retreating motion of the train. Afterwards, the frequency continues to decrease.
Graphs of received frequency against time would look like those in the next two diagrams.
The observer is further away from the track in the example below compared with the one above. If you look at the way distance is changing with time in the train diagrams, that is, at the way the relative velocity changes with time, the graphs make sense. This relative velocity, on which the Doppler shift depends, changes less the further away the moving source remains from the listener. Hence the change in frequency is less pronounced in the diagram below.
Sputnik was in motion, so its transmission was Doppler-shifted. Unlike the train whistle of our example, however, the frequency arriving at the lab was way outside the range of human ears. Instead, the received frequency was combined with a reference signal to give a “beat” signal in the audible range. Guier’s musician’s ear detected changes in the beat frequency as a change in pitch.
Many amateur listeners who heard the phenomenon dismissed it as receiver drift. Guier and Weiffenbach did not, first, because they were physicists listening to a moving frequency source and the concept of Doppler shifting was probably hovering not too far from conscious thought; second, they both knew that they had a good reference source and that Weiffenbach’s experimental experience would have enabled him to recognize receiver drift or the consequences of a poor reference source for what it was.
Before Guier and Weiffenbach heard the Doppler shift, they were listening to Sputnik out of the same curiosity that drove the Moonwatchers and the rest of the country. Once they recognized the Doppler shift, they became more serious.
As Sputnik’s beep faded over their horizon for the first time, they decided to record the sound of the Doppler shift simultaneously with the national time signal. Although they had no particular idea of what they would do with the recordings, they knew that those beeps, which were exciting imaginations across the world, would give them the scientist’s bread and butter: data. And with application and imagination, data can become information.
Another pass was to occur that night. Guier went home to collect a high-quality tape recorder he had recently bought. Back in the lab, Weiffenbach tuned in well before the satellite appeared. They wanted to collect the complete Doppler shift resulting from a pass from horizon to horizon. During the remaining two and a half weeks that Sputnik transmitted, they recorded the Doppler shift every time the orbit carried the spacecraft within range of the lab. And thus the Soviets provided the experimental setup that was the first step to enabling the Polaris submarines to fix their position at sea more accurately and opened the way to a global navigational system.
Serendipity, in the form of timing and human relationships, now made its second appearance. Weiffenbach, the experimentalist, and Guier, the theoretician, found they worked well together. Experimental and theoretical physicists, and this is something of an understatement, do not always see eye to eye. During the coming six months, the two men’s skills and outlooks would mesh, gearing up their productivity In later years as they got to know one another better and were part of the team developing Transit, they would have their offices close together so that they could more easily discuss the problems they encountered.
Sputnik’s launch came at the right time for both men. Each was ready for a new project. Guier was feeling a new-found confidence, having emerged recently from chairing an APL committee doing technical work on long-range missile guidance systems for the president’s Science Advisory Committee. Weiffenbach had things to prove. He had been scooped twice, once on work for his doctorate.
By Tuesday, Guier and Weiffenbach knew that there was no telemetry, but they had the recordings. With these they intended to calculate roughly when the satellite would next appear over their horizon. To estimate the satellite’s next appearance, they decided to apply physics in the way that the lab had when designing the proximity fuze which detonates a shell on its closest approach to a target. All they needed to do was to find the distances at the point of closest approach between the satellite and the lab—the point where the Doppler frequency was zero—during several passes. If they found these distances, they would have enough data to determine approximate values for the Keplerian elements and to predict roughly when a satellite in that orbit would next be at its closest to the lab.
In taking this approach, Guier and Weiffenbach were applying physics in a well-known way, but the difficulties they encountered were to lead to an innovative interpretation of the Doppler data.
Given APL’s previous work with proximity fuzes, perhaps it was inevitable that Guier and Weiffenbach should have started as they did. An artillery shell emits a radio signal that is reflected from the surface of the target. At the point when the shell has made its closest approach to the target and begins moving away, the Doppler shift is zero and the fuze detonates the shell. The technique was important, too, to the lab’s missile work. Missiles would telemeter the Doppler-shifted radio signals that were reflected from the target back to APL’s engineers, who would analyze them to ascertain how closely the missile had approached its target.
Guier’s and Weiffenbach’s first step, therefore, was to turn their recordings into the tables of frequency versus time needed to plot a graph of the satellite’s Doppler shift, because the information from that graph, the Doppler curve, was needed in the equation to find the distance when the satellite was closest to the lab (in missile parlance—the miss distance).
Today, and indeed not too long after Weiffenbach and Guier began their work, automated equipment, the inner mysteries of about which the scientist need not be concerned with, would have done the job. That October, Weiffenbach operated the equipment—a wave analyzer—manually. It was standard equipment, and the natural frequency of the electrical circuits it contained could be adjusted by hand. When a frequency on a recording coincided with that of the analyzer’s circuitry, the analyzer would record a spike. All of the recordings were fed through by hand and the circuitry adjusted laboriously until fifty values of frequency and time had been extracted for each pass.
Sometime early in the process, Guier and Weiffenbach had been joined by two engineers, Harry Zinc and Henry Elliott. Zinc had also been keen to listen to Sputnik. Unknown to Guier and Weiffenbach, he and Elliott had put together equipment with a moderate-gain antenna that was capable of providing a stronger signal than that obtained by the wire attached to Weiffenbach’s receiver.
The four took turns with the tedious job of turning the recordings into tables of frequency and time. An unglamorous task, but an essential part of the scientist’s life—data reduction.
Work began in earnest on Tuesday, October 8. Very quickly, things began to look ambiguous and complicated. Eventually, from this confusion came the idea that led the scientists to being able to determine an orbit from a single satellite pass—the idea that, when turned on its head, was the basis for the Transit system.
Details scattered through chapter 15 come from the following: Interviews with Verner Suomi, Bob Ohckers, Bob Sutton, and Leo Skille.
“Initial Technical proposal for a ‘Storm Patrol’ Meteorological Experiment on an ATS Spacecraft” by V. E. Suomi and R. J. Parent, September 28,1964;
“Spin Scan Camera System for a Synchronous Satellite” prepared for NASA by V. E. Suomi and R. J. Parent—July 1965; and “The Spin Scan Camera System: Geostationary Meteorological Satellite Workhorse for a Decade.” Optical Engineering 17 (1),January—February 1978.
Books of Value for the Meteorology Section
Planet Earth: The View from Space, by D. James Baker (Flarvard University Press, 1990).
Watching the World’s Weather; by W. J. Burroughs (Cambridge University Press, 1991).
Weather Cycles: Real or Imaginary; by W. J. Burroughs (Cambridge University Press, 1992).
Direct evidence of field strength above the earth’s atmosphere could be obtained byV2 rocket technique, and it is to be hoped that someone will do something about this soon as there must be quite a surplus stock somewhere.
—Extra terrestrial relays: can rocket stations give world-wide radio coverage, by Arthur C. Clarke. Published in Wireless World
n October 4, 1957, only thirty-six people in the United States could call Europe simultaneously, via AT&T’s recently installed transatlantic submarine cable—TAT-1. If the ionosphere was stable that day, about a further one hundred high-frequency radio circuits would have been available.
AT&T laid TAT-1 in 1956. It was a power-hungry coaxial cable, costing $2 million. To provide enough bandwidth (a wide enough range of frequencies) for live television would have needed twenty such cables. It was not until the mid 1970s that live cable TV was theoretically possible. By then satellites already spanned the oceans, though submarine cables made from optical fibers would mount a stiff challenge to satellites in the 1980s. But that, as they say, is another story.
So, in 1957, two or three people per state could have called Europe at the same time; even fewer could have called countries on the Pacific rim; there was no live transoceanic TV; and the information superhighway was an idea beyond even the most exotic pipe dream. Though computers, television, and telephone all existed, the oceans were truly barriers to communication. And the world that contained these familiar-sounding technologies was very different from our own. After October 4, satellites, too, became a reality. Within decades, communications satellites had done much to change the world. Satellite communication is now a multibillion dollar business. Where did the story begin?
Before there were spacecraft, there were science fiction writers. Most imagined that ground controllers would communicate via radio with their spacecraft. Then in 1945 a junior officer in the Royal Air Force spotted the unique advantages for communication of putting a satellite into an orbit where it maintained the same position with respect to its subsatellite
point—geostationary orbit. The satellite would be like a huge microwave tower. Any antenna on Earth within sight of the satellite could beam a signal to it, which the satellite would then amplify before beaming it back to another antenna at a different spot on Earth.
For a satellite to seem to remain stationary, it must meet two conditions: the orbit must take the same time to complete as the Earth takes to rotate once around its axis (be geosynchronous), and the plane of its orbit must coincide with the plane through the equator (zero inclination). If a geosynchronous satellite has an inclination of zero degrees, it is geostationary, and its place in orbit is designated by the longitude of its subsatellite point on the equator. A satellite is travelling at the velocity needed—more or less—to maintain a geosynchronous orbit when it is at an altitude of about 22,300 statute miles. At such an altitude, the satellite is within site of nearly one third of the Earth’s surface, excluding the poles. In 1959, satellites in this type of orbit were referred to as a 24-hour rather than geostationary satellites.
The junior officer in the RAF imagined that this orbiting telecommunications relay station would carry a crew, which, though wrong, was not a strange thought given the future science fiction career of the young man—Arthur C. Clarke. Clarke ran through some calculations, and in July 1945, he sent an article on the subject to the magazine Wireless World.
The editors were reluctant to publish something that seemed to them like science fiction, and they balked at acceptance. By October, they had relented, and the article appeared in print. It talked of field strengths and transmitter power, of solar power, and of how little time the satellite would spend in the shadow of the earth; and it suggested the best positions in orbit to provide a global system. Clarke’s predictions turned out to be prescient.
At the other side of the Atlantic, an electrical engineer at the Bell Telephone Laboratory, John Robinson Pierce, who knew nothing of Clarke’s article, spent his leisure hours writing short science fiction stories and his working hours immersed in the complexities of microwave communication. Later, it was Pierce who was largely responsible for persuading NASA to carry out communication experiments with the passive Echo spacecraft in August 1960. Like the Moon, which reflected military communications between the East coast and Hawaii, Echo, which acted as a huge mirror in the sky, bounced a signal across the U. S. The two-way Moon relay was operational between 1956 and 1962 and was manned when the Moon was in radio sight of both stations, usually for three to eight hours at a time. Often, when ionospheric storms shut down the usual radio channels, the Moon provided the only link to and from Hawaii for several hours at a time. In 1953, Pierce first suggested that if an artificial reflecting surface could be launched, it could bounce radio signals across oceans.
Pierce joined Bell Laboratories after being awarded his doctorate by the California Institute of Technology in 1936. During World War II, he came across publications by an Austrian refugee, Rudi Kompfner, who was working for the British Admiralty. In 1943, Kompfner invented a class of vacuum tube, known as a traveling wave tube (TWT), that was to have an enormous impact on missile guidance and on communication through submarine cables and via satellite. In 1945, Pierce wrote his first paper about the new concept of traveling wave tubes and developed the first practical application of the technology. Kompfner would later say that he had invented the traveling wave tube but that Pierce had discovered it.
Pierce may as well be allowed to define a TWT in his own words, written in 1990 for a Scientific American publication, Signals, the Science of Telecommunication.
The traveling wave tube is a type of vacuum tube that gives high gain over a broad band of frequencies. An electromagnetic signal wave travels along a spring-shaped coil of wire, or helix, while electrons in the high voltage beam travel through the helix at close to the speed of the signal wave. The electrons transfer power to the wave, which grows rapidly in power as it travels down the helix.
Essentially, the vacuum tube allows electrons to flow from cathode to anode with few collisions and permits an energy exchange from the electron beam to a radio wave constrained to travel the length of the tube. Thus the radio wave is amplified. There have been many versions of TWTs since 1945.
Pierce was impressed by what he knew of Kompfner’s work, and after the war he encouraged senior staff at Bell to recruit Kompfner. They were eventually successful, and Kompfner joined the lab in 1951. Pierce and Kompfner worked together cooperatively and productively for many years, and Kompfner was supportive of Pierces interest in satellites. Their work was the starting point for the Bell team that designed a second type of communications satellite, one with an active repeater that would, like the satellites envisaged by Clarke, amplify the signal before radiating it to Earth. This satellite became known as Telstar.
Telstar was not a twenty-four-hour satellite but rather was planned for a medium-altitude orbit, and so could only be seen by two ground stations simultaneously for about twenty minutes. AT&T calculated that about forty 150-pound satellites in random medium-altitude orbits could provide a communications system with Europe. As soon as one satellite disappeared over the horizon, the transmitting and receiving antennas would lock on to the next mutually visible spacecraft. Such a system, said AT&T in the spring of 1961, could provide sixty channels by 1963 from North America to Europe and three thousand by 1980. The system would give ninety-nine percent probability of a satellite being simultaneously within sight of ground stations located in Maine and in Brittany.
In the summer of 1959, while the lab was still working on Echo, Pierce, Kompfner, and their colleagues at Bell were beginning to think that medium-altitude active repeaters rather than passive satellites were the most promising technology for transatlantic communication. For sound technical reasons, it seemed to them that geostationary satellites would not be feasible for many years.
On the West Coast, unbeknownst to Bell, a handful of engineers— Harold Rosen, Donald Williams, Tom Hudspeth and John Mendel— would soon solve, at least on paper, the problems then facing engineers considering a geostationary orbit. When Leroy Tillotson, at Bell, finished a technical paper on the specifications for a medium-altitude satellite in August 1959 and sent it to Pierce, Kompfner, and other senior members of the research department, Rosen and Williams were putting the finishing touches to their proposal for a twenty-four-hour satellite. The lightweight TWT designed by John Mendel, who had learned his trade in John Pierce’s lab, was critical to the proposal. The proposal, in Rosen’s and Williams’s names, was the beginning of a development that led to Syncom, the first geosynchronous satellite, and to Early Bird, the first commercial communications satellite.
In Arthur C. Clarke’s view, Pierce and Rosen are the fathers of communications satellites. During the early 1960s, however, there was little love lost between the two men. Rosen saw Pierce as obstructionist; Pierce thought that Rosen was making wild claims and would say anything to win support for his twenty-four-hour satellite. It is said they almost came to blows on stage during one conference. Yet they had far more in common than either could have imagined. Both were told at different times by their superiors that they could not go ahead with their work. “Cease and desist,” is what Mervin Kelly, head of Bell Telephone Laboratories, told Pierce in 1958. Both had a fine disdain for the Department of Defense’s plans for a twenty-four-hour satellite and for NASA’s specifications for a medium-altitude active repeater called Relay. Both wanted to keep the government out of communications satellites.
Both, too, had been educated at Caltech, which in the 1930s was like an American Gottingen for the physicists and engineers who would become America’s leaders in aerospace. Pierce was a contemporary ofWilliam Pickering and sought his cooperation for the Echo experiments. Rosen was Pickering’s student and says that he was one of the teachers from whom he learned most. Each left Caltech in little doubt of his own intellectual ability.
The players, then, were John Pierce, Harold Rosen, and Donald Williams, with Tom Hudspeth, Rudi Kompfner, and John Mendel in strong supporting roles. Passive, medium-altitude active, and twenty-four – hour active satellites were the engineering concepts they contemplated.
Men and ideas fitted into a larger, more complex tapestry. It was not just that communications satellites were now within the state of the art, but there was also an increasing commercial and military demand for better communications.
TAT-1 remained the only transatlantic cable for telephony until AT&T laid a second link in 1959, bringing the number of simultaneous calls that cable could carry across the Atlantic to seventy-two. Adding these to the number of high-frequency radio circuits available on a good day, as many as four people per state could simultaneously have called Europe on the day of John Kennedy’s inauguration as president in January 1961. It was still not possible to make live transoceanic TV broadcasts. Instead, recordings were flown by jet or fed slowly down cables.
In response to growth in demand, particularly for calls to and from Europe, AT&T planned to lay a third transatlantic cable in 1963, adding a further two hundred telephone circuits. Even this would not be enough to meet predicted growth in demand. But there seemed to be insurmountable engineering obstacles to developing higher-capacity cables, and the radio spectrum was already overcrowded. Worse still, solar minimum would occur between roughly 1962 and 1966. With less solar energy enveloping Earth, the ionosphere could be less active and thus would not reflect certain frequencies. Experts calculated that this would cut by two – thirds the available high-frequency radio channels worldwide.
The Department of Defense, with troops stationed around the world, often in places with which it was difficult to communicate, was deeply concerned.
With such a paucity of communications infrastructure coupled with the commercial and defense advantages of enhancing communications, it is not surprising that the Kennedy administration placed a high priority on the development of communications satellites. Communications satellites (and meteorology satellites) figured in Kennedy’s famous moon speech of May 25, 1961.
And there were strategic advantages for the United States in developing communications satellites. Communications technology looked as though it could serve as a versatile foreign policy tool that could extend American influence throughout the world. John Rubel, deputy director of defense research and engineering (DDR&E) and for a while the acting director, pointed out in a white paper written in April 1961 that countries newly emerged from colonialism were often reliant for communication on their former colonial powers. He cited the cases of Guinea and Nigeria, which had to go through France and England to communicate with one another. It would be of “incalculable value” in the battle for men’s minds, wrote Rubel, for the United States to maintain a lead in communications technology. “Many feel that the United States should support satellite – based telecommunications systems to achieve these aims, even though there were no immediate commercial advantages resulting therefrom.”
The DDR&E held the third highest civilian position at the Pentagon, roughly on a par in some circumstances with the chairman of the Joint Chiefs of Staff. Thus Rubel was in a position of some influence. He had exerted that influence once, at the prompting of NASA administrator T. Keith Glennan, to change an agreement that NASA and the Defense
Department had made in November 1958, confining NASA to work on passive communications. It was an agreement that deeply frustrated NASA’s engineers at the Goddard Space Flight Center. A new agreement, formalized in August 1960, permitted NASA to work on active communications satellites. Both parties observed a tacit understanding that NASA would work only on medium-altitude satellites, while Department of Defense developed twenty-four-hour satellites.
By April 1961, Rubel seems to have been feeling his way through a complex strategy that would also set aside this second agreement and permit NASA to develop Rosen’s twenty-four-hour satellite. This was necessary because the Defense Department’s own plans for a twenty-four-hour satellite, called Advent, were going disastrously wrong, but there would have been too much opposition to simply canceling the satellite and replacing it with Rosen’s. If, however, the agreement between NASA and Defense could be set aside, then NASA could place a contract for the Rosen proposal. The agreement was dropped.
By August 1961, NASA had placed a sole-source contract with the Hughes Aircraft Company for a twenty-four-hour satellite, and the Department of Defense was to make the Advent ground stations available. The idea was that the twenty-four-hour proposal, now called Syncom, would be a cheap interim satellite to meet military needs until Advent could be developed. A year later, Advent was canceled.
The Syncom decision was a sweet triumph for Harold Rosen and Donald Williams. Before placing a contract for Syncom, both NASA and the Defense Department had been dismissive of Rosen’s and Williams’ engineering concepts. The first Syncom satellites were transferred to the military, and in the mid 1960s these provided links to Southeast Asia in support of America’s growing presence in the region. Thirty years have passed, and Harold Rosen is not yet tired of telling people how the Army and Air Force rejected [his ideas] but within a few years had to rely on Syncom.
By funding the development of Syncom, launching Telstar (at AT&T’s expense) and developing Relay, NASA enabled two approaches to a global satellite communications system to be demonstrated. When the International Telecommunication Satellite Organization (Intelsat) was formed in 1964, it was not yet clear whether international communications would be based on twenty-four-hour satellites or constellations of medium-altitude satellites. If one twenty-four-hour satellite operated successfully, however, Intelsat would know that it was well on the way to providing a global system, whereas tens of Telstar (or Relay-like) satellites would have had to be launched to prove that a global communications system of medium-altitude satellites would work. Thus it was sensible to first launch one twenty-four-hour satellite, and the success of three Syncom satellites was encouraging. The successful launch of Early Bird settled the question, and most commercial communications satellites today occupy geostationary orbits (the countries of the former Soviet Union use another orbit, one better suited to communications at high latitudes).
Though the decision to “go geostationary” has been validated since 1965, the merits of the alternative technological approaches were still being debated in the early 1960s. The technical arguments were enmeshed in and obfuscated by a highly charged policy debate about the role of government versus private industry in the development of communications satellites.
The debate began during the closing months of the Eisenhower administration, when T. Keith Glennan announced that NASA would facilitate the development of communications satellites by providing launch opportunities for industry on a “cost reimbursable basis,” which meant that industry would pay for the launch, but not at a true commercial rate. Glennan, like President Eisenhower, believed that private industry should be involved in the development of communications satellites. At the time, the most aggressive private industry in this field was AT&T. By October 1960 it had started Project TSX, which became Project Telstar, and had begun spending millions. Senior NASA staff and the attorney general were leery of AT&T. The company already had a virtual monopoly on voice transmissions. Neither NASA nor the Justice Department wanted to make decisions that would exclude from the new field companies that were not starting from the strong position of an existing monopoly.
When President Kennedy took office and James Webb replaced T. Keith Glennan, the emphasis shifted somewhat to a concern about how much control the government should retain over the development ol communications satellites given their strategic importance. Webb, whom
AT&T viewed as anti-industry, said that he did not want to put AT&T up against the whole Soviet Union.
Engineers at Bell perceived that the debate had become truly heated in February 1961 when Lloyd Berkner, whose proposal of an International Geophysical Year ten years earlier had set so much in motion, said in a speech that communications satellites would be a billion-dollar business in ten to fifteen years. The newspapers picked up the comment. Congress took note, and the Justice Department quoted Berkner in submissions to the Federal Communications Commission and Congress. Berkner’s comments were used to bolster the argument that space communication was too big for one company. Though his prediction was to prove correct, Berkner modified his views shortly after making them known, making the not unfamiliar claim that the media had exaggerated them.
But verbal arabesques could not change the course of the debate. Berkner had tapped into some widespread and deeply felt issues: the previous administration’s concern about extending AT&T’s monopoly; the current administration’s desire to have some control over the development of a technology with strategic implications for the military, for commerce, and as a foreign policy tool; the current administration’s concern that a private company should not represent the United States in negotiations for a global system; and industry’s objection to being excluded by monopoly power from a potentially lucrative new market.
By February 1962, the Kennedy administration had sent a communications satellite bill to Congress. The bill set up a private company called Comsat under strict governmental control. Half the stock was offered to the general public and half to the common carriers. The Federal Communications Commission was responsible for distributing stock fairly between the common carriers, including AT&T. Key members of Congress had their own ideas about the bill, but by the end of the summer, the Senate had passed it, 66 to 11, and the House by 354 to 9.
President Kennedy signed the Comsat Act on August 31, 1962. It was the death knell for Telstar, though the concept of medium-altitude satellites had not yet been abandoned. Comsat would be the driving force behind the formation of Intelsat and thus behind the “go geostationary” decision. In the larger world of national and international policy, it was surely the right decision. To the engineers at Bell and to John Pierce, the man who pioneered the idea of commercial communications satellites and developed some of the critical technologies, the Comsat decision was a bitter disappointment.
More than thirty years later, in his home in Palo Alto, John Pierce disposes concisely and precisely of questions about his pioneering days, tugging all the while at a bushy eyebrow. With his sloppy yellow Labrador retriever in attendance, Pierce reminisces politely about Echo and Telstar. Clearly, he has told the story many times, and he says,“I prefer to look forwards rather than back.”
Asked to explain how a klystron works, he grows more animated. He becomes even more interested when writing down the names of mystery and science fiction writers he has not previously come across or talking of the Chinese poetry he translates, the haiku he writes, his admiration for Milton and Blake. Only when I asked him about the Comsat decision did passion flash with the sharpness of a disappointment almost, but not quite, forgotten. Pierce, a loyal son of “Ma Bell,” would not leave Bell Labs, so the Comsat decision that excluded AT&T from international communication via satellites excluded him personally from a field he had pioneered.
As Pierce talks, his movements and speech are like those captured on video in the early 1960s, when he was the executive director of research at the Bell Telephone Laboratories. They are characteristically incisive movements, suggestive of someone who does not suffer fools or pretenders gladly. For a while, he thought that Harold Rosen was a pretender. “I was wrong,” he says. He is less charitable about some of those he encountered at NASA headquarters during the Echo and Telstar days.
Pierce retired from Bell Labs in 1971 at sixty-one, an age when, as he says, he was still young enough to do something else. He joined the faculty of the California Institute of Technology for nine years, then moved briefly to the Jet Propulsion Laboratory as chief technologist. He is now visiting professor of music emeritus at Stanford, where he pursues an interest in the psychophysics of music—the relationship between acoustic stimulus and what we perceive internally. It is an interest he developed at Bell in his postsatellite days.
John Pierce’s interest in science started when he was very young and his mother read to him from “very unsuitable books.” Long before he could read, John could say words like electromotive force, even if he didn’t
quite know what they meant. “She was the mechanical member of our family,” recalled Pierce. She also seems to have had faith in Pierces mechanical ability, because when he and his friend Apollo built a glider, she went up with him, apparently unfazed by the earth flashing by beneath her feet. This, despite knowing that the first glider they had built had fallen apart as it taxied for takeoff. “I was crazy in those days,” says Pierce, “doing things with very little information. I call it gadgeteering.”
Pierce studied at Caltech, and after changing his major a few times, he settled for electrical engineering. He graduated in 1933, looked around at his Depression-era employment prospects, and decided he would be better off staying at Caltech. He gained his master’s in 1934 and his doctorate in 1936. This time the world outside the ivory tower was less hostile to him, and Pierce got a job at Bell Laboratories.
He was told to work on vacuum tubes and left to get on with it, despite knowing next to nothing about the topic. This was typical of Bell Laboratories, where there was a lot of intellectual freedom to pursue research as well as the money to pay for it. Perhaps that accounts for the nobel prizes awarded to physicists at the lab.
By the time World War II broke out, Pierce was expert in the basic theory and design of various classes of vacuum tube. He applied that knowledge during the war and learned a lot about electron optics and broadband amplification. Pierce contributed to the body of work that opened the spectrum above thirty megacycles, which before World War II was almost empty of artificial signals. Developing that technology was essential to the feasibility of communications satellites.
It was while undertaking a mathematical analysis of broadband amplification that Pierce came across Rudi Kompfner’s work on traveling wave tubes. He was impressed. He wrote to Kompfner in 1946, adding his voice personally to that of the management whom he had persuaded to recruit Kompfner.
After working on traveling wave tubes, Pierce and others at Bell Labs turned their attention to MASERs (Microwave Amplification by Stimulated Emission of Radiation). These devices generate or amplify microwaves. When they amplify a weak signal, they add little noise. It was the MASER at the heart of the ground antenna that made it possible to pick up the reflected signal from Echo, which was only a million-million-millionth of the ten kilowatt signal beamed to the satellite for reflection across the country. The MASER improved the antenna’s sensitivity by a factor of one hundred compared with what Pierce had envisaged when he first speculated on the use of an Echo-like satellite for communication. And it was this MASER, protected from extraneous ground noise by a horn-shaped dish, with which Penzias and Wilson detected the cosmic background radiation.
So by 1954, many of the ideas and devices that were crucial for Bell’s satellite communication work existed. And it was about now that Pierce became the first of the pioneers of communications satellites, which came about because he wrote science fiction stories (under the pseudonym J. J. Coupling, a concept familiar to electrical engineers). As a science fiction fan and author, Pierce was asked to give a talk on the subject of his choice to the Princeton, New Jersey, branch of the Institute of Radio Engineers. He must have had an erudite audience, given that RCA and Princeton University were nearby
Over the years, Pierce had given talks about man in space, but he decided that for this audience he wanted a less fanciful subject. He began to wonder what role satellites could play in his own field of communication. At the time, says Pierce, communications satellites were “in the air,” though it was a rarefied air. In 1952 he had written an article about interplanetary communication and had concluded that it was easier to communicate between the moon and Earth than across the United States. Now he did some quick calculations of the power needed for transmission to and from orbiting spacecraft and was surprised to discover that communications satellites were feasible.
Pierce gave the talk, which was to form the basis of his pioneering ideas for communication satellites.
Professor Martin Summerfield told Pierce that he should publish his talk. So, in November 1953, Pierce sent an article to Jet Propulsion, the journal of the American Rocket Society, which published it in April 1954.
The paper proposed three types of communications satellite: a one- hundred-foot sphere that could reflect a signal; a hundred-foot mirror in a twenty-four-hour orbit; and an active repeater in a twenty-four-hour orbit. The latter two, while theoretically stationary with respect to the ground, would actually be affected by solar and lunar gravity and so would need steerable ground antennas and stabilization by remote control.
The first of the three options—a hundred-foot sphere—was to be Pierce’s inspiration for the Echo communication experiments in 1958. In 1954, shortly after Pierce’s article was published, the U. S. Navy began experimenting with the voice transmissions to and from the moon that became the moon relay. But the moon is not an ideal reflective surface; its roughness gives multiple echoes at different wavelengths. A smoothly reflecting artificial satellite would, Pierce knew, provide a much higher – quality passive relay.
In 1954, few believed that satellites would be launched. Undeterred by the common view, Pierce told his audience in Princeton and wrote in his paper that if one found a way to build and launch a satellite, two classes of problem would remain, celestial mechanics and microwave communication. First, they would need to know where their satellite was and would be; then they would need to send and receive radio signals. All the satellite operators had to come to grips with celestial mechanics; some, like Transit, needed a very detailed understanding of the earth’s gravitational field and its impact on an orbit. Pierce’s paper acknowledged the problem but devoted more time to the issues of microwave communication: signal losses on passage from the satellite through the ionosphere and atmosphere to Earth (path losses); the diameter of transmitting and receiving antennas; signal frequency and strength; radio beam width; the method selected for superimposing the signal, such as voice or music, onto the radio carrier wave (modulation); the nature of the polarization of the radio beam; the frequency of the carrier radio wave; sources of noise (that is, other frequency sources that would make the signal difficult to hear); the power of the signal; the signal-to-noise ratio and the sensitivity of the receiver. These were among the topics that five hundred scientists and engineers would later address during the Telstar project.
The science fiction books that Pierce had begun reading as a teenager made spacecraft and radio communication commonplace ideas to him. So the topic of his talk to the Princeton radio engineers is not surprising. But his early love of science fiction also held him back. He had been so used to thinking of spacecraft as romantic fantasies that he did not at the time realize how close they were to realization in his own field of communication. Pierce discussed the idea of communications satellites with people around the lab, but he was concerned about the reliability of vacuum tubes (and who better to know their limitations) in space and the limited abilities of the primitive transistors that then existed. “I was conservative about satellites,” he says.
Nonetheless, Pierce was responsible for persuading NASA to conduct communications experiments with Echo.
The satellite that became Echo was not initially intended to be a communications satellite. It was suggested by William O’Sullivan from the Langley Research Center when James Van Allen’s satellite panel was selecting experiments for the International Geophysical Year. O’Sullivan wanted to launch a giant, aluminized Mylar balloon that could be inflated to a diameter of one hundred feet. With its small mass and large surface area, the balloons would be sensitive to comparatively small changes in force and thus would allow scientists to record how atmospheric density varied with position and solar activity and affected Echo’s orbit. Van Allen’s panel thought the balloon would be a good idea if they had sufficient resources for more than four launches.
In spring of 1958, Pierce and Kompfner read about the balloon and realized that it was exactly what Pierce had imagined would make an ideal passive communications satellite. They packed an ohmmeter and went to Langley to measure the conductivity of the plastic balloon. They decided that it would have a high reflectivity for microwaves. They took some samples of the aluminum-coated mylar back to the lab with them and confirmed its reflectivity. All they needed now was someone to launch the balloon. Unfortunately, the balloon was not one of the high – priority experiments for the IGY. NASA had not yet been formed, and the Department of Defense was already thinking in terms of the elaborate satellite that eventually became Advent and was to go so drastically wrong.
That summer, Pierce and Kompfner went to a meeting on communications satellites at Woods Hole. William Pickering (director of the Jet Propulsion Laboratory) was there and showed himself sympathetic to Pierce’s ideas. Pickering suggested to the meeting that O’Sullivan’s balloon would be ideal for a passive communication experiment. If Bell could find someone to launch the satellite, said Pickering, JPL’s Goldstone ground station would participate in coast-to-coast communication experiments. To
Pierce, it seemed that Pickering’s support was vital to the success of the lab’s subsequent discussions with NASA.
Pierce returned from the meeting to a mixed reception. Mervin Kelly, the president of Bell Telephone Laboratories, asked a mathematician to study Pierce’s proposal. The mathematician’s report was negative. Kelly told Pierce to “cease and desist.” Kompfner thought that their plans could go no further, but Pierce developed a severe case of deafness. He continued to think of Kelly as one of his heroes but concluded that “even great men” can be wrong. In October 1958, he delivered a paper on transoceanic communication via passive satellites to a national symposium on extended-range and space communications.
Later that same month, Pierce served as a consultant to the Advanced Research Projects Agency’s ad hoc twenty-four-hour satellite committee. He listened to what he thought were impractical and inefficient proposals from “these completely uninformed men.” It was clear after this meeting, in which elaborate satellites were discussed, that the Department of Defense was not going to launch the hundred-foot balloon. And shortly afterwards the Defense Department and the newly formed NASA agreed that the Department of Defense would develop active satellites and NASA would develop passive ones.
In the meantime, William Pickering had remained interested in a communication experiment, and NASA had been born. The new agency immediately inherited the Langley Research Center and the Jet Propulsion Laboratory.
In November 1958, T. Keith Glennan, NASA’s administrator; Hugh Dryden, the deputy administrator; and Abe Silverstein, the director of space flight development visited Bell. The purpose of the meeting was to discuss global communications problems. Pierce made a general presentation about communications and satellites, and Kompfner talked about components, data processing, and tracking and guidance philosophy. The NASA contingent was interested, but nothing seems to have come of the discussions.
At the end of December, NASA took over Project Vanguard, thus gaining control of a launch vehicle. By January, the agency was showing an interest in BTL’s ideas. On January 22, NASAJPL, and Bell discussed what they hoped to learn from transmitting a signal between the East and West Coasts. Kompfner wrote to Leonard Jaffe, who headed NASA’s communication satellite work, on February 10, urging him to let Bell know soon whether the project with JPL was to go ahead because of the large amount of work that had to be done. Less than a week later Kompfner warned all technical staff that a considerable amount of work of an unusual nature was coming up. Until now, Pierce had been deeply involved in selling the project to NASA. Now he took a back seat. The day-to-day running of the satellite work was handed over to Bill Jakes, who was responsible to Kompfner. At the end of February, Jakes was immersed in technical discussions with NASA about the MASER and how much bandwidth was needed given the signal and its Doppler shift. Pierce was already toying with the idea of active broadband satellite communication. NASA was by now enthusiastic and was contributing more money to Echos than was Bell. The lab was building the horn antenna for experiments.
On June 10, 1959, there was a large meeting of all those involved with the project. O’Sullivan reported that one full-size balloon, including its inflating mechanism, was already being tested.
The balloon was made of 0.0005-inch-thick Mylar, coated by a 2,000 angstrom layer of aluminum. It weighed 136 pounds and had an optical reflectivity of seventy-five percent for tracking and a radio reflectivity of ninety-eight percent. Being passive, it did not have the complicated electronics needed for active repeaters, but it did carry a radio beacon so that it could be tracked by Minitrack. The sphere was to be inflated in one second by the release of four pounds of water through a plastic nozzle in the sphere. Langley calculated that the vapor pressure would last for seven days, and they were testing six subliming solids in an effort to extend the lifetime. After seven days, they expected a gradual loss of pressure because of micrometeorite impacts. The sphere would get wrinkled, decreasing its usefulness as a reflector for communications. Between November 1959 and July 1960, BTL and JPL practiced bouncing signals to one another first off the moon and then, three times, off TIROS. Their pointing accuracy needed to be good because Echo’s dimensions at an altitude of 1,000 nautical miles would be the equivalent of an object a little over an inch long a mile away, and it would be moving at four and a half miles per second.
The first launch attempt failed because the balloon did not inflate. But the second attempt, on August 12, 1960, was a success. Tracking Echo turned out to be tricky. The original plan was that NASA, at Goddard, would compute the orbital parameters and turn them into tracking instructions for Goldstone and the Bell antenna. A. C. Dickieson, Transit’s project manager, writes in an unpublished manuscript that the tapes as received were late and full of errors. More success, he says, was achieved by taking orbital parameters generated by the Smithsonian Astrophysical Observatory and calculating tracking errors locally Errors in orbital prediction were, however, inevitable in the fall of 1960. Only a few months earlier Bill Guier had predicted Transits position in orbit and realized how much more complicated the earth’s gravitational field was going to be than anyone had thought.
From Bell’s perspective, Echo provided background information for system planning and the design of Earth stations—information that fed into the Telstar project. Echo also demonstrated the effectiveness of the lab’s low-noise receiving equipment as well as the predictability and stability of the transmission path.
Echo was the first satellite that was visible to the naked eye, and T. Keith Glennan had anticipated that it would cause a sensation. It did, bolstered by AT&T’s brilliantly executed publicity campaign. On the night of the launch, the company sponsored a news special on NBC. It was replete with portentous music and massive radio telescopes. Another AT&T-sponsored video opened with ‘America the Beautiful’ and tugged at the patriotic heartstrings. AT&T won the publicity stakes hands down, but alienated NASA. The company’s expropriation of Echo did not win it any friends at the agency. Pierce wonders whether AT&T’s publicity success with Echo influenced NASA’s selection of RCA for the Relay satellite. If it did, it was a minor influence compared with the much larger policy issues that were at stake.
Echo’s success, technically and with the public, encouraged AT&T to go ahead with the development of a medium-altitude satellite as a prototype of a global system of communications satellites. That satellite— Telstar—became every bit as famous as its predecessor.
Information about Polaris (pp. 49 and 51-53), its purpose and development, emerged during many hours of interviews with members of the Transit team.
Books that provided background for chapter five include The Polaris System Development: Bureaucratic and Programmatic Success in Government, by Harvey M. Sapolsky (Harvard University Press, 1972); Forged in War: The Naval—Industrial Complex and American Submarine Construction, 1940—1961, by Gary Weir (The Naval Historical Center, 1993).
The potted history of navigation in this chapter (pages 50 and 51) draws on interviews with Commander William Craft and Group Captain David
Broughton, and on From Sails to Satellites:The Origin and Development of Navigational Science, by J. E.D. Williams (Oxford University Press, 1992).
Transit’s status as brickbat-01 and the meaning of this terminology (page 53) emerged during interviews with Transit team members.
The fact that radars capable of detecting a periscope’s wake were being developed at the end of the 1950s and in the early 1960s (page 54) comes from George Weiffenbach.
How the technology of the Transit receivers evolved (page 55) comes from Tom Stansill and from papers and old sale brochures that he sent to me.
The history of APL (page 56) comes from The First 40 Years, JHU APL (Johns Hopkins University Press, 1983).
Notes about Frank McClure’s and Richard Kershner’s previous careers (page 56) come from The First 40 Years, JHU APL and from press releases and briefing papers sent to me by Helen Worth, the APL’s press officer.
The fact that Ralph Gibson was sounded out as a potential first director of the Defense Research Establishment is mentioned by Admiral William Raborn, head of the Fleet Ballistic Missile program until 1962, in an oral history at the Naval Historical Center, in Washington, DC (page 57).
Bill Guier sees an equation as paragraphs of lucid prose. There are nuances and implications stemming from the relationship that the equation establishes between different aspects of the physical world. To George Weiffenbach, numbers, their intrinsic values and relationship to one another, are like a film. How they change tells him how the physical events that they represent are unfolding. These ways of viewing the world are quite usual for physicists, and the one is typical of theoretician, the other of the experimentalist.
Each understood something of the others outlook and could, to some extent, see from the other’s viewpoint. The combination proved invaluable.
Some textbooks still describe the miss-distance method that Guier and Weiffenbach initially adopted as the basis for Doppler tracking. It is not the technique that APL developed. Had Guier and Weiffenbach stuck to determining miss distances, they would not have had tracking data that were accurate enough for a good orbital determination, because one of the values needed in the calculation is satellite transmitter frequency. Sputnik’s oscillator, though loud and clear, was varying slightly from its nominal value in an unknown way. Those at the IGY who had discounted Doppler as a means of obtaining tracking data had done so precisely because they were concerned about the stability of the oscillators that generated the radio signals. Oscillator stability would be of concern, too, in the method that Guier and Weiffenbach developed, but their approach offered a way to tackle the problem.
On Tuesday morning, October 8, Guier and Weiffenbach were still thinking in terms of miss distance. And they were conceptualizing the problem. As is usual when creating a mathematical model of a physical phenomenon, they simplified the problem. In this way, they would find out what general principles were at play before turning to the inherent complexities of this particular case. They assumed that the satellite was moving in a straight line, just like our train. Since they were looking only for the range at the point of closest approach, the simplification was reasonable.
Guier and Weiffenbach knew all but one of the values needed to calculate miss distance, and that value—the range rate when the Doppler
shift was zero—was available experimentally from the slope of the curve as it passed through T = 0 in the graphs of frequency against time. It is the steepest part of the curve.
Guier recalls watching colleagues plotting graphs, fitting plastic splines to them and measuring the slope, then looping string around the lab to represent an orbit and marking the miss distances with rulers. It was for fun as much as anything, though such a physical representation of the orbit does give a conceptual idea of what is going on in three dimensions.
To two people who saw what Guier and Weiffenbach saw in equations and numbers, the ruler and string approach was not the way forward. They determined the maximum slope from tables of frequency and time using a mechanical calculator. Soon, they switched to the lab’s new Umvac ПОЗА, APL’s first fully digital electronic computer. With its combination of vacuum tubes and transistors, the ПОЗА could perform several thousand additions per second, zipping through the tables of time and frequency far more rapidly than was possible with a mechanical calculator. It was an advance on APL’s partly analog machine—a type of computer that performed arithmetic operations by converting numbers to some physical analogue, say length or voltage.
By the late 1950s, university departments were slowly converting to digital machines, but not all scientists and engineers had, as yet, seen the value of computers. So, even though their project was not sanctioned officially, Guier and Weiffenbach had no problem getting time on the computer, something that would not have been the case even a few months later.
When Guier and Weiffenbach first turned to the Univac, some of their colleagues asked, Why do you need a computer to calculate the slope of the curve? Given that they intended only a rough calculation, the question was reasonable. Guier, however, had worked with computers at Los Alamos. Though those machines were mechanical and rattled and banged around once Guier had fed in the numbers and instructed the machine to add or multiply, he had been won over by them. To him, the 1103A was a luxury, and he was happy to find a problem for the new machine.
It was no easy job, however, to program those early computers. A task that would take an hour to code in a higher-level language such as FORTRAN might take eight hours to code in assembly language, where each mathematical operation had to be coded for separately. If two numbers were to be multiplied together, the code needed to tell the computer in which memory locations to find each number, in what location to carry out the multiplication, and where to store the result.
Guier wrote instructions for those writing the code. As the orbital determination grew more elaborate, the number of code writers increased, and it not always possible to tell what each programmer had done. Guier started to insist that code be accompanied by notes describing why a particular approach had been taken, and, though it looked like a tedious task, he learned assembly language himself in order to provide some continuity in the software effort (of course, this all took place before the word software had been invented). Thus APL, like others at the time, started to formalize software development.
Today s computers can translate high-level languages, which are rich in symbolic notation, into the low-level assembly language that the machine “understands.” Computers then did not have the memory to hold the programs needed for such a translation. To make matters worse, code writers often had to go back to the basic binary words of zeros and ones, which the limited symbology of assembly language represents, in order to find errors.
Despite what today would seem to be daunting limitations, the Uni- vac ПОЗА was a godsend to Guier’s and Weiffenbach s research.
As the two sought values for the miss distance, they soon recognized the ambiguities inherent in the approach. In the case of the train, it is easy to see that the way the frequency varies depends on how close the listener is to the track. But if you have only a tape recording, how do you know whether that recording was made two yards to the east or two yards to the west of the track? In the two-dimensional case, you are stuck with the ambiguity. In the case of the satellite, the earth is rotating beneath its orbit, and the east-west symmetry is broken.
But there are other ambiguities. Consider the train again; a recorder two yards west of a north-south track will record the same frequency shift if it maintains its westward distance but moves a mile due north. Fortunately, satellites inhabit our three-dimensional world. Rather than moving in a straight line, the satellite’s path with relationship to the lab might be a shallow or pronounced arc, near to the lab or like a distant rainbow, low or high on the horizon, and the arcs could be at many different angles. For each arc, the relative motion between the lab and the satellite, and thus the Doppler shift, was different.
Guier and Weiffenbach began to recognize the richness of the situation, its complexity. The miss distance soon ceased to look like a particularly interesting value to calculate. They were beginning to suspect that their Doppler curves might contain a lot more information about satellite motion than was immediately apparent.
So they decided to explore, to find out how much information the data contained. To do this they needed to know how the Doppler data changed for different orbits. But only one satellite was aloft. Guier turned to the computer and created a general mathematical description of an orbit that would then generate the theoretical Doppler shift associated with a hypothetical satellite’s motion.
Guier pulled together the geometry, trigonometry, and algebra required to describe a generalized ellipse in space and the relationships between the ellipse, the lab, and the center of the earth. He drew up flow charts showing how his mathematical description of this physical phenomenon could be turned into a computer program.
The model assumed the earth to be spherical, which it is not, and orbits to be circular, which they are not, though Sputnik’s orbit was nearly so. The idea, again, was to deal first with the simplest possible situation in order to clarify the underlying principles. This construction of a generalized mathematical representation is akin to preparing a canvas for an oil painting. Guier’s and Weiffenbach’s painting would prove to be ambitious.
They began to generate theoretical Doppler curves. Of course, they were not creating curves but churning out lists of Doppler-shifted frequencies and times for the computer to work through, looking for ways in which the Doppler data varied as the orbital path varied. These numbers were octal rather than decimal, so instead of a counting scheme based on the digits 0 to 9, the digits run only from 0 to 7.
Guier and Weiffenbach pored over these numbers, and as necessary turned to their mechanical calculator to convert octal to decimal. They decided to make their model more realistic and so included mathematics describing the earth’s oblateness (a bulging at the equator caused by the centrifugal force resulting from the earth’s rotation). Oblateness causes orbits to precess because the Earth’s gravitational field is not uniform, as it would be around a homogeneous sphere. Inclusion of a term for oblateness was the first brush stroke on the newly prepared canvas.
In 1957, geophysicists thought they had a good understanding of the earth’s shape and structure and thus of its gravitational field. They turned out to be very wrong. Observations of satellites in near-Earth orbit showed all kinds of deviations from Keplerian orbits, each one representing some variation in the gravitational field, which in turn was a result of inhomogeneities in the earth. The field of satellite geodesy was established to tease a new understanding of the earth from these observations of satellite motion. In 1957, the revolution that satellite geodesy precipitated in our understanding of the earth had not yet begun, and the mathematical model that Guier devised to generate orbits was extremely rudimentary compared with what is possible today. In the years following Sputnik’s launch, observations of satellite motion would lead to many more brush strokes on Guier’s mathematical canvas, each representing a newly understood aspect of the Earth’s structure and its associated gravitational field.
Using their basic model in October 1957, Guier and Weiffenbach generated more theoretical orbits. They changed imaginary perigees, then the inclinations, ascending nodes, and eccentricity, and they observed what impact these changes in the Keplerian elements had on the theoretical Doppler curves generated by the computer. By this stage, they had completely lost interest in calculating miss distances.
Given the multiplicity of tasks and the extent to which they exchanged ideas, it is hard now for Guier and Weiffenbach to remember who did what when, but they agree that at some point in those first days, Guier recognized that the detail of the Doppler curve must change in a unique way, depending on the geometry of the satellite pass. This was the conceptual breakthrough that others failed to see or, if they saw it, did not use: that each ballistic trajectory of the satellite generates a unique Doppler shift. They asked, Could they find the Keplerian elements that would generate theoretical Doppler curves that matched experimental observations of a real pass? If they could—bingo! The Keplerian elements fed into the theoretical model would be the elements defining Sputnik’s orbit. They could test their findings by predicting the time that the real satellite would be at a given position if it had the Keplerian elements they had found by this method.
They knew enough from their observations and knowledge of physics to make rough initial guesses about Sputniks Keplerian elements. They fed these to the computer, generating theoretical lists of Doppler shifts. They watched the output, the reams of octal numbers, looking at how closely the theoretical values matched the observations for a particular pass.
Their project was still not sanctioned officially, but other members of the research center knew that something potentially interesting was afoot.
Their boss, Frank McClure, always insightful if not always diplomatic, was watching—at a discreet distance. From time to time, the trademark pipe of Ralph Gibson, APL’s director, appeared stealthily around a corner.
At some time in the first few weeks, when things happened in a less orderly fashion than this account suggests, Guier heard that Charles Bit- terli, one of APL’s few computer programmers, was writing an algorithm for a standard statistical tool, known as least squares fitting, that would be very useful in Guier’s and Weiffenbach’s research. Guier went in search of Bitterli.
Bitterli, who needed a real-life test problem, was happy to oblige by making his work available. An algorithm is a step-by-step set of instructions for carrying out a computational process. When translated into a computer program, it becomes a standard tool to be pulled out when needed. Today, thousands exist in software libraries. Back then the task of building such libraries had scarcely begun.
Guier’s and Weiffenbach’s problem was that vast numbers of theoretical Doppler curves could be generated by varying the Keplerian elements. If it were not for the fact that the physics ruled out some combinations, the number of options would have been impossibly large. Even with the limits that physics imposed, there were many possibilities.
Each theoretical curve had to be checked point by point against observations of Sputnik’s Doppler curves. One theoretical curve might at first look like the best match, but then a comparison point by point could well show that it was not. Further, once they found the best possible match, they needed some quantitative way of assessing how good that fit was, and thus what the errors in the Keplerian elements probably were. So an algorithm for least-squares curve fitting, a statistical technique for finding the curve that best represents a set of experimental data, was very desirable to Guier and Weiffenbach. Bitterli’s program, which was for linear equations only (those whose graph is a straight line), had to be generalized for nonlinear equations relating many parameters. It was now that it became apparent that new methods would have to be learned and that specialists in numerical analysis would be needed.
Bitterli’s algorithm worked well, and the comparison of theoretical and observed curves speeded up. Even so, and despite the fact that their intuition was working full time as they made informed guesses about the input values of the Keplerian elements, they couldn’t generate a match that was close enough to be of any help in defining Sputnik’s orbit. Yet, theoretically, the method should work.
What next? Check everything; examine the setup for recording the Doppler shifts—connection by connection. Review the raw data, the calculations. Weiffenbach combed through everything he could think of. He concluded that the data were good. Guier reviewed the theory, the equations, and the computer programs, which by now could have covered enough rolls of wallpaper to decorate a small room. They discussed the problem with one another and with colleagues, listened to critiques, and incorporated suggestions that seemed apt.
They continued to feed the computer the initial conditions that represented their best guess about the satellite’s orbit. Then the computer would run through the calculations to produce the Doppler shift associated with those elements. The process was iterative, with small changes being made to the starting conditions and fresh Doppler curves generated for each set of conditions. Sometimes, it looked as though they had found as good a fit as they were going to find. Listening still to their intuition, they were convinced they could find a set of Keplerian elements that would generate a theoretical Doppler curve even closer to the experimental data. The new Keplerian elements would sometimes make the curve first grow away from a fit, but then as small changes were made, the theoretical curve would grow closer than it had been before. The process was a little like finding yourself in a valley, only to climb through trees and find a deeper valley beyond. But still, the match was not good enough.
They grew despondent, questioned themselves, and searched some more. They noticed that from one experimental curve to the next, the frequency of the transmitter varied. Sputnik’s oscillator was not stable. Exactly as those planning tracking for the IGY had feared, transmission frequency could not be treated as a constant. But Guier and Weiffenbach needed to know the transmitter frequency in order to generate theoretical Doppler curves.
Now they started varying the value of the transmitter frequency. The same principle applied as when varying the Keplerian elements: if they could find a fit between theory and experiment, then the theoretical values of transmitter frequency as well as of the Keplerian elements must be the values of the actual setup. The task was now way beyond what would have been possible without the recently installed Univac.
The whole process was barreling along when Sputnik I suddenly stopped transmitting. Guier and Weiffenbach had data to work with retrospectively, much of which still had to be reduced. In practice therefore, Sputnik’s, silence made little difference, but psychologically it was disappointing to Guier. The pair were also beginning to suspect that an aspect of the physical world that they had thought could be ignored—the ionosphere—was, in fact, significant. They were right. But to solve the problem they needed another satellite transmitting two frequencies.
Once again the Soviets obliged. Sputnik II was launched November 3, 1957. It transmitted at twenty and forty megahertz. With these two frequencies they could make the correction necessary to solve their problem. Theory and experiment started to come together.
Shortly after the launch of Sputnik II, they did it—found a theoretical curve that gave them Sputnik’s orbit. It was nowhere near as accurate as later orbital determinations would be, but they had a method to determine all the Keplerian elements and the transmitter frequency from data collected during one satellite pass over one ground station. Guier and Weiffenbach were delighted. It was the first time, recalls Guier, that they jumped for joy. Henry Elliott, who with Harry Zinc had joined Guier and Weiffenbach shortly after their work started, recalls being ecstatic. Bitterli, who went on to code far more complicated programs than a least-squares algorithm, came to see this work as one of the most important accomplishments of his professional career.
Guier and Weiffenbach were now on the edge of new ground, surveying terrain that was full of quagmires and briars. The basic computational and statistical methods existed for a novel method of orbital determination and prediction, one that did not rely, as did every other, on measurements of angle. The same computational and statistical techniques would be applied, in an inverted manner, to satellite navigation.
Guier and Weiffenbach suspected that their method was correct to within two or three miles. McClure suggested checking their predictions against orbits determined by other groups. They compared their results with those from Jodrell Bank and the Royal Aircraft Establishment and found good agreement. Later they checked their orbital predictions for Sputnik II and the first American satellite, Explorer I, with Minitrack’s results. Again, the methods gave comparable accuracies.
The insight that each orbital trajectory had a unique Doppler shift associated with it was not new physics; rather, it was an inevitable consequence of the Doppler phenomenon in the dynamic, three-dimensional world. Nevertheless, Guier and Weiffenbach were the first to recognize that consequence and its implications for orbital determination.
More importantly, they got the process to work in the real world, where very little behaves ideally. If they had stopped to think about the task too much, they might have concluded that the method would never work to any useful degree of accuracy. If they had known more than they did initially about orbital mechanics, the ionosphere, or the discussions at the IGY, they might not have started their work as they did and thus not developed their techniques.
Some people who heard of their research found it hard to believe that all of the Keplerian elements and the transmitter frequency could be found by fitting a theoretical curve to one experimental set of data. But the trajectory of every satellite pass, part of a definable orbit, has a unique Doppler shift. And in three dimensions the ambiguities of two dimensions are eliminated. The method, to use their terminology, worked because of its exquisite sensitivity to the range rate. It was an excellent example of applied physics, and the danger is that it might sound trivial in the telling, particularly a telling that leaves out the mathematics. To fall back on scientific cliche, the task was nontrivial.
There was so much material for this section that the only way to make sense of it was to put it all together into one big pot, to arrange it chronologically, and to construct a series of calendars for the years in which I was interested. I also put the dates of major importance for world events and other developments in the space program on the same calendars. This gave me a good feel for what was happening when, and highlighted some nice ironies between the Telstar and Syncom programs that I would otherwise have missed.
Primary source material came from AT&T, the Hughes Aircraft Company, John Rubel, Bob Roney, the NAS, NASA, and the American Heritage Center.
Interviewees were John Pierce, Harold Rosen, Tom Hudspeth, Bob Roney, Robert Davis.
AT&T’s highly professional archive yielded masses of information about Telstar and some, though to a lesser extent, about Echo.
The НАС archives give a good sense of the work that Harold Rosen and Don Williams et al. did, as well as demonstrating the company’s internal wrangles and its lobbying of NASA and the DoD.
Bob Roney had personal papers that supplemented the more extensive records from the НАС archive.
John Rubel’s papers cover the ground from the perspective of the Office of Defense Research & Engineering. The view from this office is not always the same as that from other departments of the DoD.
NASA’s records (thanks once again to David Whalen for these) gave, not surprisingly, the agency’s side of the story
I had more material from AT&T and the НАС and John Rubel than from NASA, so the story unfolds primarily from their perspective, though I have tried to synthesize different policy and technical viewpoints.
Chapter sixteen: The Players
TAT-1 capacity (page 171) from Signals, The Science of Telecommunication, by John Pierce and Michael Noll. Scientific American Library (1990).
The Space Station (page 172), Its Radio Applications, by Arthur C. Clarke, 25 May 1945 (typed manuscript).
“Extra-Terrestrial Relays, Can Rocket Stations Give World-Wide Radio Coverage,” by Arthur C. Clarke, published in Wireless World, October 1945 (page 172) (From John Pierce).
“Orbital Radio Relays,” by J. R. Pierce, Jet Propulsion, April 1955 (pages 172-173).
Pierce’s views of Rudi Kompfner, medium-altitude satellites, and Harold Rosen (pages 174—175) from interviews with Pierce, his oral history at Caltech, memos, and his autobiography (see notes for chapter 17).
Telstar captured the popular imagination in a way that it is hard to believe any satellite, especially a communications satellite, could do today Perhaps it was the name; euphonious enough to make the satellite the eponymous star of its own pop song, released by the British pop group the Tornados. Certainly AT&T’s impressive publicity machine, one that rivaled even that of NASA, aided the process.
Telstar was launched at 8:35 GMT on July 10, 1962. According to AT&T, more than half the population of the U. K. watched its first transatlantic transmission, a remarkable percentage given that far fewer people than today owned television sets. Only two Telstar satellites were ever launched, because even before the first went into orbit it was clear that Comsat, not AT&T, would be responsible for operating international communications satellites.
Instigating the Telstar project was one of the boldest moves ever made by a private company. Fred Kappel, chairman of AT&T, said that the company would spend $170 million—a considerable sum for the time— on an international communications system if the government would either step aside or facilitate development.
Project Telstar had five objectives: to test broadband communication, to test the reliability of electronic components under the stress of launch into space, to measure radiation levels (electronic components fail and data are lost if radiation alters the dopants in semiconductor material), to provide information on tracking, and to provide a test for the ground station equipment.
A. C. Dickieson was appointed to head Telstar development in the fall of 1960. In his unpublished manuscript he says that he was told to go ahead in the shortest possible time and that he had whatever power and authority he needed to do his job. The team immediately started “spend
ing with gusto.” For a while Dickieson did not know to the nearest $5 million just how much money was pouring into the project. But by early in 1961 he had spending under control.
The project’s starting point was the early work by Pierce and Kompfner.
On January 6, 1959, while Bell and NASA were still discussing whether they would collaborate on a communication experiment with a passive satellite, John Pierce was arguing internally that Bell should assume a leading role in research in satellite communication, because it seemed likely that “satellites will provide very broad band transoceanic communication more cheaply than submarine cables.” He wrote, “Active repeaters in twenty-four-hour equatorial orbits stationary above one point of the earth have many potential advantages but pose severe problems of launching, orientation, and life, whose solutions lie beyond the present state of the art.” On the other hand, passive satellites were within the state of the art. Bell could, argued Pierce, undertake a program of research because more knowledge about low-noise MASERs and horn antennas would be valuable irrespective of the orbit that communications satellites would eventually occupy. There was so much activity in the field, wrote Pierce, and so little was known.
A few months later, Pierce and Kompfner were contemplating medium-altitude-active rather than twenty-four-hour satellites. There seemed to be just too many technical obstructions to developing the latter.
To John Pierce and his colleagues at Bell, the greatest drawback to twenty-four-hour satellites was the six-tenths of a second that would pass between one person speaking and the other person hearing what was said. The listener, thinking that a pause meant the speaker had finished, might then interrupt. Nothing could be done about the delay because that is how long it takes a signal to travel to and from a satellite in a twenty-four – hour orbit. Also, at that time, the equipment that suppressed echoes from the far end of the telephone line was not very effective, and Pierce was concerned that poor echo suppression coupled with the time delay would make communications via twenty-four-hour satellite intolerable. If, that is, one could have placed a satellite in a twenty-four-hour orbit in the first place. The launch vehicles and guidance and control systems needed to place a satellite in such an orbit were only then being developed.
Power was another problem. Imagine that power is distributed over the surface of a sphere and that the greater the distance of the receiver from the antenna, the greater the surface of the sphere over which the same power is distributed. Thus, if the distance increases by a factor of two, the power available at a particular point will be reduced by considerably more than twice—the square of the distance between transmitter and receiver.
The thinking was that if one was to receive a usable radio signal on Earth from a satellite 22,300 miles away, one needed a high-gain, directional antenna on the spacecraft that would not waste power by broadcasting needlessly into space (high-gain directional antennas are common today). But if the satellite was to carry a directional antenna, then the satellite’s orientation with respect to the earth—its attitude—would have to be controlled so that it remained constant relative to the earth. This called for a more complex, weightier design. Even at the best of times, satellite designers do not like to add weight. When no launch vehicle yet exists that can reach the desired altitude, the potential weight of a satellite is an even greater problem.
And then there was the all-important question of station keeping, which is essential for a satellite in a twenty-four-hour orbit. The satellite must maintain its position in orbit relative to the subsatellite point despite radiation pressure, lunisolar gravity, and inhomogeneities in the earth’s gravitational field. If the twenty-four-hour satellite was to be constantly accessible to many ground stations and its antennas were to stay pointing toward those ground stations, then some mechanism for station keeping was needed as well as the fuel to operate that mechanism: again, extra weight.
Finally, launch vehicles do not place satellites directly into a twenty – four-hour orbit. The satellite is injected first into an eccentric orbit with its perigee at the altitude at which it separates from the launch vehicle and its apogee at geosynchronous altitude. So a twenty-four-hour satellite would need a motor that could fire at apogee and circularize the orbit: yet more weight.
Pierce and Kompfner were aware of all these problems and the possible poor quality of communication via a twenty-four-hour satellite. Further, Pierce, who from the beginning had participated in the panels planning military satellites, was aware of and unimpressed by the Advanced Project Research Agency’s (later the Army’s) plans for a twenty-four-hour satellite.
So, in March 1959, when Pierce and Kompfner wrote a paper demonstrating the theoretical feasibility of active broadband satellite communication, it was a constellation of medium-altitude satellites that they had in mind, not twenty-four-hour satellites. Bell still intended to work first with passive satellites simply because they would be ready first, but, wrote Pierce, the research department would work towards simple active repeaters. “If we manage to make better components than others and if we make a sensible design, we might take the lead in this field with a comparatively modest expenditure of money and effort. The tendency of ARPA has been to project elaborate and complicated schemes… our own course has been to get into actual experimental work with NASA and the Jet Propulsion Laboratory as early as possible. In this way we will encounter in an experimental way certain problems such as large antenna, low-noise receivers, tracking, modulation systems, orbit computations and the reliability of components which we believe will be important in all satellite communication systems.”
Even though active satellites were at the forefront of Pierce’s mind from the spring of 1959, he was publicly cautious, writing in June of that year to Hugh Dryden, the deputy administrator of NASA, “Right now, we don’t feel we are able to evaluate the merits of active satellite systems as compared with passive systems well enough to propose any concrete steps as the next desirable thing to do.”
Bell’s efforts in the field of active repeaters began to solidify when Leroy Tillotson completed a major memo on active satellite repeaters on August 24, 1959. Much of what he described was similar to what would, after the launch of Echo in August 1960, become an internal Bell project, labeled TSX, which was later renamed Project Telstar.
Central to Tillotson’s plan was the development of a six-gigahertz traveling wave tube. Pierce and Kompfner requested more information and were briefed in October and November 1959. An active-satellite planning committee was formed. Kompfner and Tillotson, but not Pierce, who was more senior, were members. They continued to meet until the research effort on active repeaters turned into a full-fledged development project in the fall of 1960.
At the beginning of 1960, the work on Echo was proceeding well and the research staff were considering what to do next. One possibility was a larger passive satellite with enough antenna gain (on the ground), bandwidth, and transmitter power to relay television signals across the Atlantic. An internal ad hoc group put together an outline of such an experimental system for NASA. As it became apparent what kind of technical pirouettes would be needed for the successful transmission of even the lowest quality TV signal, those working on the proposal became convinced that active satellites were needed.
Thus consensus emerged at Bell that the main effort should be on active satellites—along the lines suggested by Tillotson. A memo from Pierce to Jaffe says that Bell would be putting a major effort into active satellites during the next couple of years. Another letter from Kompfner to Jaffe reviews Bells research on a long-life traveling wave tube and on the effects of radiation damage to solar cells and microwave circuitry. This work continued at a modest level in Bells research department until after the successful launch of Echo on August 12, 1960.
News of Bell’s interest in medium-altitude satellites did not filter out widely until the spring of 1960. When it did, some speculated that the passive scheme had been a smoke screen to cover Bell’s real intentions. If it was, it had not been embarked upon as a smoke screen, though perhaps it was allowed to become one.
While Bell’s scientists and engineers pursued theoretical calculations, AT&T’s management in New York had been working on policy issues. In July 1960, AT&T argued before the Federal Communications Commission that frequencies should be reserved for satellite communication because the company was convinced that satellites would be more economical than submarine cables for transoceanic communication. A filing on July 8 disclosed AT&T’s plans for a global communication satellite system costing $170 million. This plan called for fifty satellites without attitude control in a three-thousand-mile polar orbit. During the next twelve months the number of satellites, their altitude, and their design would change, but the idea of medium-altitude orbits remained.
In the midst of its political and technical preparations for an active satellite system, on August 9, 1960, the Department of Defense finally released NASA from its agreement to develop only passive satellites.
AT&T now focussed on persuading NASA to select its ideas for an agency led project to develop active communication satellites. On August 11, Pierce and colleagues were briefing senior NASA staff at headquarters in Washington on Bell’s medium-altitude active repeater work. They told NASA of AT&T’s discussions with the communication administrations of Britain, France, and Germany, and of those countries’ interest in joining AT&T in satellite communication experiments. Bell’s idea was that the Bell System would pay all costs, except those of general interest to the space community, such as investigating radiation effects. There was some discussion, too, about the technical difficulties of providing two-way channels (with Echo, voice went via satellite one way and came back over a terrestrial link).
The day after that meeting, Echo was launched. It was the brightest object in the night sky. In Ceylon, as Sri Lanka was then called, Arthur C. Clarke looked upwards and followed its passage with wonder. In the United States, AT&T’s highly efficient publicity machine ensured that when the public gazed upwards, it was AT&T’s name rather than NASA’s that sprang to mind.
AT&T’s publicity capsized discussions with NASA about launching a satellite based on AT&T’s ideas. A little over two months after Echo’s launch, in a meeting about Bell’s plans for transoceanic communication via active satellite, T. Keith Glennan told senior staff from Bell and AT&T that the company’s methods of publicizing its plans, including making misleading statements, had created difficulties for NASA. Glennan’s remarks about publicity were only a small portion of the criticisms he made. He said that AT&T was not taking account of the “facts of life” and acknowledging through its planning the limited availability of launch vehicles, the problems of scheduling launches, and the aims of NASA’s research and development program.
By the time of this meeting, on October 27, 1960, NASA’s plans were known publicly to include medium-altitude active repeaters, and AT&T was now one of several companies waiting for the agency’s formal announcement of a competition. Whichever company won, NASA also intended to further the development of communications satellites through “cost reimbursable launch support for private industry.”
So, despite Glennan’s stern admonishments in October 1960, the auguries were not entirely unfavorable for AT&T. NASA, under the leadership of T. Keith Glennan, favored the involvement of private industry in the development of communication satellites. AT&T had a vibrant research effort in the supporting technology for medium-altitude active repeaters, and Echo had been a spectacular success.
The days of the Eisenhower administration, however, were numbered. Transition to the Kennedy administration would soon be underway. Though both administrations were concerned about the antitrust implications of policies that favored AT&T, some in the Kennedy administration, notably James Webb, were additionally concerned about the strategic implications of communications satellites and thought that government should retain control over their development. The difference between the two administrations was apparent in a small but telling difference in the budgets that each submitted to Congress for FY62. Eisenhower called for private industry to contribute $10 million toward NASA’s communication satellite program. Kennedy’s budget allocated that $10 million from the public coffers.
This was the first faint stirring of the policy upheavals that would exclude AT&T from providing international satellite communications, a role that the company saw as its own as a matter of public trust. In the end, AT&T would have to be content with being one of the common carriers owning Comsat stock.
In January 1961, when John Kennedy was inaugurated, and for several more months, AT&T moved confidently forward with its plans. Bell Labs was working on ways to keep the satellites’ weight down by developing sensitive ground-based antennas that would allow the satellites to transmit at as low a power as possible. That month NASA issued a request for proposals for a medium-altitude satellite to be known as Relay. During the Relay competition, AT&T and NASA suspended discussions about the possibility of the agency launching the telephone company’s satellites. Bell, along with six other competitors, prepared a proposal. The others included RCA, which eventually won, and an outsider with no experience manufacturing satellites—the Hughes Aircraft Company.
Bell, which did not think much of NASA’s technical specifications, submitted three versions of its proposals. One matched what NASA wanted, including frequencies and a radiation experiment as specified by the agency. The second retained NASA’s radiation experiment but worked at the frequencies that Bell (AT&T was discussing frequency allocation with its overseas partners) thought would eventually be selected for an operational system (AT&T and Bell were correct). The third proposal was Bell’s own design.
On May 18, NASA announced it was awarding the contract to RCA. At the technical debriefing, NASA told Bell that it was the best of the “amateurs” to submit a proposal. Bell’s weaknesses in its bid, according to NASA, were many. The agency awarded the lab poor marks for solar cells made from n-on-p semiconductors rather than p-on-n. Yet Bell’s scientists knew that the Evans Signal Laboratory had found that n-on-p semiconductors were more resistant to proton and electron bombardment than p-on-n semiconductors. Bell had fabricated n-on-p solar cells in December 1960 and confirmed the finding (these are what are used now).
The Bell proposal got a particularly low score for the low power of its transmitters, which would call for a low-noise ground antenna, and particularly for further improvement of the MASER that was used for Echo. The agency considered that Bell’s tough specifications for a low-noise ground antenna would make the ground stations that NASA and others might build marginal. Its own course of action, said the agency, did not press the state of the art quite as hard. NASA judged, however, that Bell’s traveling-wave-tube design was excellent and that its radiation experiment was good. The agency asked Bell to design the radiation experiment for Relay. Bell’s view of this critique was that only one criticism—about a VHF antenna—was valid.
Preparing the stack of printed material for its proposal, wrote Dick – ieson, cost several hundred thousand dollars and “chewed up the time of a lot of key people who were sorely needed in designing the company’s own satellite and ground station. But we really had no choice but to bid; without launch support, all of our work would be wasted, and NASA controlled the launching.”
To the engineers at Bell, NASA’s announcement that RCA had won the contract meant that they could revert to their own ideas for what would be known as Project Telstar. The announcement also left them with one rather major difficulty—the matter of a launch vehicle. Pierce and Kompfner joked with a visiting Soviet scientist that perhaps his government would launch the satellite.
A more practical discussion was going on between James Webb and Fred Kappel. Webb had called Kappel on May 18 to notify him that RCA had won the contract for Relay and to say that NASA was prepared to launch AT&T’s satellite. Kappel responded that it was important for AT&T to go ahead with its satellite plans. Hard negotiations, led by Webb and Dryden, followed. NASA insisted on being reimbursed for launching the two satellites and that AT&T should assign any patents resulting from the development to NASA. AT&T agreed, and Telstar, which Wilbur L. Pritchard later said was superbly engineered, was underway.
An important aspect of the Telstar project was the two ground stations that Bell Laboratories built. The sophistication and sensitivity of these stations enabled Bell to put less power on the satellite. One station was in Andover, Maine, and the other in France. Britain used its own existing antenna but was unable to receive signals on the first night because of an unfortunate misunderstanding about the polarization of the signal.
The ground station in Maine was 170 feet long and three stories high, and rotated to follow the satellite from horizon to horizon. It was intended to be part of the eventual operational system and had to work in any weather, so Bell contracted for a radome (a radio transparent, domelike shell) to protect the antenna. The wall to which the radome was to be fixed was a massive structure. Someone quipped that in a thousand years, scientists would debate why the entrance door was in precisely that place. Excavation for the antenna foundations began in May 1961, and in January 1962, the antenna was complete. A temporary radome was erected until the special air-supported fabric of the final structure could be delivered. It sagged under the New England snow. Efforts to dislodge the snow failed until someone took a shotgun from the trunk of his car and shot holes in the temporary cover.
Testing of Telstar began in November 1961 and took 2,300 hours. The satellite was due at Cape Canaveral in May 1962 but was delayed for two weeks until a loose wire could be traced. The launch was set for July 10. In late May Bell heard about Project Starfish, a high-altitude atomic – bomb test. They were worried that if Telstar was in orbit, radiation from the explosion would seriously damage its electronics. They relaxed when they heard that the explosion was set for the day before their launch, believing that by the time Telstar reached orbit, the worst would be over. They later learned, as did APL, which had its TRAAC satellite aloft, that fallout persisted and precipitated along magnetic field lines. Telstar began to falter on November 18, 1962, and failed the following February.
Nonetheless, Telstar allowed an examination of the signal after passage at various angles through the ionosphere, the earths magnetic field, and the atmosphere. Different methods of frequency modulation were tested, and the impact on available bandwidth assessed. These and other results were published in the open literature. Harold Rosen, of the Hughes
Aircraft Company, said, “Telstar showed that there were no propagation anomalies, that it was easy to calculate what the propagation would be like. It was a confidence builder.”
Telstar attained orbit despite antagonism and suspicion between AT&T and Bell on the one hand and NASA on the other. Exactly how these tensions, which also existed under T. Keith Glennan, played out in the decision to select RCA for Project Relay is not easy to discern. Robert Seaman, who was NASA’s associate administrator at the time, said in his exit interview that the message came through loud and clear from the Kennedy administration that the AT&T design was not the one to pick. In 1966, Webb said that the RCA proposal was clearly the best proposal for the research requirements of NASA, even if it was “… not necessarily the best as the first step towards an operational satellite system as desired by AT&T.” Webb’s phrasing is telling.
The disagreements between NASA and AT&T covered everything from choice of frequency to operation of the ground stations and negotiations with foreign telecommunications companies. AT&T was particularly jealous of the relationships it had built over the years with common carriers in other countries. The transatlantic submarine cable TAT-t, for example, was a joint venture with the British and Canadians. A British cable ship had laid the cable.
It is also clear from Dickieson’s unpublished manuscript in the AT&T archives that Bell’s technical people did not respect the technical ability of some of those with whom they dealt at NASA and that they thought much of the required paperwork pointless. Dickieson wrote, “the NASA people assigned to receive this paper were interested in the shadow, and not the substance, so we were able to keep them happy without [having them] interfere with our work.”
The attitude of the Bell engineers comes through best in this following anecdote related by Dickieson. The National Physics Laboratory in the U. K. wanted to use Telstar in an experiment with the U. S. Naval Observatory to synchronize clocks in the two countries (this was before atomic clocks). Dickieson set things up. The experiment was performed and the results published. “At a subsequent meeting, Leonard Jaffe brought up the subject, and made it clear that the approved method was: first, discussions between the state departments of the two countries; second, reference to the technical organizations of the two governments, and finally down to scheduling by the Ground Station Committee.” Says Dickieson, “I did not argue the matter, because I thought that if another useful experiment appeared, we would do it first and argue later.”
Despite all this, the two organizations successfully launched the two Telstar satellites.
From February 1962, when President Kennedy submitted his Comsat bill to Congress, it was clear to Bell’s engineers that the lab and AT&T were out of international satellite communication. They still had both satellites to launch, and the team worked on, fueled by the need to prove that private enterprise could operate in the field. To the public, the battles behind Telstar were unimportant. To them Telstar was the satellite that first broadcast live transatlantic television and promised a new era of international communication. Among those watching were a group of engineers at the Hughes Aircraft Company, in Culver City, California. After rejections and ridicule, they had won a contract for their ideas for a twenty- four-hour satellite in August 1961—nearly a year before Telstar went into orbit. The engineers watching Telstars broadcast were envious. They had dispatched a telegram of congratulations to Bell but were eager to see their own satellite in orbit. One of them, Harold Rosen, said “It was interesting in two respects, one was the beautiful picture coming from overseas. And two, it didn’t last very long.” They knew their satellite would be altogether different.
The contents of the National Security Council’s agenda and mention of Lay’s phone calls to Alan Waterman (page 58) are among Waterman’s papers in the Library of Congress.
Information about Tycho Brahe and Johannes Kepler (page 59) comes principally from an essay on Kepler by Sir Oliver Lodge in The World of Mathematics, edited by James R. Newton (Tempus, 1956). Textbooks consulted for pages 60 and 61 are Introduction to Space:The Science of Spaceflight, by Thomas D. Damon. A foundation series book, chapter three deals with orbits (Orbit Book Company, 1989); The Feynman Lectures on Physics, volume one, chapter 7 (Addison Wesley, 1963).
Bill Guier and George Weiffenbach supplied the information for pages 61 to 65.
The textbook consulted for pages 65 to 69 is The Feynman Lectures on Physics, volume one, chapter 34 (Addison Wesley, 1963).
The material on pages 70 to 72 is based on the memories of George Weiffenbach, Bill Guier, and Henry Elliott. They all spoke to me independently. Guier and Weiffenbach spoke to me many times. Each remembered things a little differently, but their memories differed little in substance. These memories are, to my knowledge, the only sources of information for Guier’s and Weiffenbach’s work in October at APL. As far as I know, there are no written records, not even laboratory notes, that support the assertion that Guier’s and Weiffenbach s work was unofficial and an indulgence of curiosity.