SP-4308 SPACEFLIGHT REVOLUTION

6

The Odyssey of Project Echo

The vitality of thought is an adventure. Ideas won't keep. Something must be done about them. When the idea is new, its custodians have a fervor. They live for it.

- Dialogues of Alfred North Whitehead

For the things we have to learn before we can do them, we learn only by doing them.

- Aristotle

[ 153 ] In the early hours of 28 October 1959, five days after the close of the first NASA inspection, people up and down the Atlantic coast witnessed a brilliant show of little lights flashing in the sky. This strange display, not unlike that of distant fireworks, lasted for about 10 minutes. From New England to South Carolina, reports of extraordinary sightings came pouring into police and fire departments, newspaper offices, and television and radio stations What were those mysterious specks of light flashing overhead? Was it a meteor shower? More Sputniks? UFOs? Something NASA finally managed to launch into space?

Several hours later, the press was still trying to solve the mystery. At about three o'clock in the morning, a night watchman roused NASA Langley rocket engineer Norman L. Crabill from a sound sleep in a dormitory near the launchpads on Wallops Island. The watchman told Crabill that a long-distance telephone call was waiting for him in the main office. A reporter for a New York City newspaper wanted a statement about, as he put it, "the lights that you guys had put up." Crabill, an irascible young member of Langley's PARD, had not been able to celebrate his thirty-third birthday properly the night before because of what had happened, and now he had gotten out of a warm bed, put on his pants, and taken a walk in the cool night [ 154 ] air just to explain the situation to some newspaper guy. "My statement is, 'It's three o'clock in the morning,' " growled Crabill, slamming the receiver down. As he would later remember, "It was the only time I, a government employee, ever told off the press and got away with it." 1

Given the events of that evening, Crabill's anger was understandable. Although the disaster that had occurred was minor, it was big enough to potentially damage Crabill's NASA career. The initial test of a 110-foot-diameter inflatable sphere for the Echo 1 Passive Communication Satellite Project had ended abruptly with the sphere blowing up as it inflated. Floating back into the atmosphere, the thousands of fragments of the aluminum-covered balloon had reflected the light of the setting sun, thus creating the sensational flashing lights.

The inflatable sphere had been launched from Wallops Island at 5:40 p.m. For the first few minutes, everything went well. The weather was fine for the launch, and the winds were not too high. PARD engineers were worried about the booster called "Shotput," an experimental two-stage Sergeant X248 rocket, because the performance of the rocket's second-stage Delta was to be the initial test of the U.S. Thor-Delta satellite launching system. However, in the early moments of its test flight, Shotput I had performed flawlessly. The rocket took the 26-inch-diameter, spherical, 190-pound payload canister-inside of which the uninflated 130-pound aluminum-coated Mylar-plastic satellite had been neatly folded-to second stage burnout at about 60 miles above the ocean. There, the payload separated successfully from the booster, the canister opened, and the balloon started to inflate. The first step in Project Echo had been taken with apparent success.

Then, unexpectedly, the inflating balloon exploded. The payload engineers had left residual air inside the folds of the balloon by design as an inflation agent. The air expanded so rapidly, because of the zero pressure outside, that it ruptured the balloon's thin metallized plastic skin, ripping the balloon to shreds. Shotput I was history; the use of residual air to help blow up the balloon had been, in Crabill's words, a "bad mistake." 2

After spending a depressing night reviewing why the test went wrong, the only thing for Crabill to do the next morning was to get to work solving the problem. After all, this was project work-the ultimate reality-not general research. No time to cry over spilled milk-or burst balloons.

At the NASA press briefing at Wallops, held about one hour after the explosion, Crabill and others had given their usual matter-of-fact postlaunch systems report. In the midst of taking a quick look at the telemetry records to make sense of the balloon failure, a NASA official sensitive to public affairs approached Crabill and told him, "Just tell them everything worked all right." 3 Sure, Crabill thought, no problem. No data pointed to the contrary. All the visual evidence on the Shotput launch vehicle, which was Crabill's responsibility, suggested that Shotput had worked as planned. Moreover, the....

[ 155 ] . L-93-8337 L-93-8339 L-93-8333

During a test of the Echo deployment in 1962, which was three years after Shotput's first failed deployment of the Echo satelloon, a structural load problem caused the balloon once again to explode. A camera aboard the launcher captured these images. The earlier Shotput failure would have looked very much the same.

....purpose of the Shotput phase of Project Echo * was to determine whether the mechanism designed to deploy an inflatable passive communications satellite of that size and weight would work, and it had; in that sense, Shotput I was indeed successful. To tell the whole truth about that scintillating collection of little moving lights tumbling through the upper atmosphere before all the records were examined and understood was premature-and the complete story would be too complicated for the press to understand. This was a time when launching any object into space was big news for the American people. Why let an otherwise uplifting moment be turned into another letdown?

Thus, for the initial newspaper stories about the launch of Shotput 1, the press would not be told enough even to hint at the possibility of a failure. For example, in a front-page article appearing in the next morning's Newport News Daily Press, the headline for military editor Howard Gibbons' article about the launch was: "Earthlings Stirred by NASA Balloon, Awesome Sight in the Sky." According to Gibbons, NASA had launched "the largest object ever dispatched into space by man, stirring the curiosity and awe of thousands of Americans residing on the Eastern Seaboard." The inflated sphere "rode for 13 minutes in the sun's rays ... before it fell again into the atmosphere and dropped into the Atlantic about 500 miles east of Wallops." Gibbons made no mention of the rupture. The balloon "was probably deflated on the way down into the atmosphere, NASA reported." Not a word appeared about a mistake involving the use of residual air as an inflation agent. According to Gibbons, "NASA's assessment of the operation was that 'it did what we wanted it to do."' 4

Also on the front page of the Daily Press that morning, next to the article on Shotput 1, was an Associated Press wire story from Washington, D.C, announcing the start of extensive congressional hearings. The House [ 156 ] Space Committee was investigating why the United States continued "to play second fiddle" to the Soviets in the exploration of space; the headline of this second article read: "Why U.S. Lagging In Space Explorations To Be Probed." The last thing NASA needed at the moment was to explain a burst balloon.

Norm Crabill knew that NASA was not telling the press the truth, but he and the rest of the Langley crew responsible for the shot understood and accepted the subterfuge. This was project work, and it had to succeed. For public consumption, both failure and the inability to achieve complete success need not be admitted, at least not immediately. Sometimes mistakes could not be concealed, such as a missile blowing up on the launchpad before hundreds of cameras, as so many had been doing But a balloon bursting in space, especially one producing such a sensational show of flashing lights, could be presented as a total success. This age of the spaceflight revolution was a new epoch. Research activities were now exposed to the nontechnical general public, and so many old rules and definitions no longer were applicable. Some discretion in the discussion of results seemed justified.

The International Geophysical Year and the V-2 Panel

As with so many early NASA projects and programs, Project Echo originated in NACA work. In fact, the idea predated the Sputnik crisis by several months and at first had nothing to do with proving the feasibility of a global telecommunications system based on the deployment of artificial satellites. Rather, the original purpose of Echo was to measure the density of the air in the upper atmosphere and thereby provide aerodynamic information helpful in the design of future aircraft, missiles, and spacecraft. Like so many other matters affected by the spaceflight revolution, the concept that led to Project Echo had modest and circumscribed beginnings that ballooned into sensational results.

The father of the Echo balloon was Langley aeronautical engineer William J. O'Sullivan, who was a 1937 graduate of the University of Notre Dame (and Langley employee since 1938) and a former staff member of PARD. The idea for the air-density experiment first came to O'Sullivan on 26 January 1956, nearly two years before the launch of Sputnik 1. All that raw winter day, the 40 year-old O'Sullivan sat in a meeting of the Upper Atmosphere Rocket Research Panel, which was being held at the University of Michigan in Ann Arbor. Originally known as the "V-2 Panel," this body had been formed in February 1946 to help the army select the most worthwhile experiments to be carried aboard the captured and rebuilt German V-2 rockets. ** After World War II, scientists from around the country....

[ 157 ]

William J. O'Sullivan, the father of the Echo balloon, was also the father of five children. They, too, were caught up in the enthusiasms of the spaceflight revolution. Notice the homemade NASA emblems on the blazers worn by the two teenage sons. The NASA public affairs office distributed copies of this family portrait to the news media along with stories about O'Sullivan's ingenious invention of the Echo balloon. L-61-7786

....had flooded the army with requests for an allotment of space aboard the V-2s, and the army had handled the awkward situation rather adroitly by instructing the scientists to form a panel of their own to decide which experiments should go on the rockets. Thus, the V-2 Panel came to life as a free and independent body, with no authority to enforce its decisions, but with a voice that carried the weight of the scientific community behind it. By the early 1950s, the name of the panel changed to the Upper Atmosphere Rocket Research Panel, signifying both a wider agenda of research concerns and the use of rockets other than the V-2s as flight vehicles. 5

The purpose of the Ann Arbor meeting was to choose the space experiments for the forthcoming International Geophysical Year (IGY). This event, to be celebrated by scientists around the world beginning 1 July 1957, stimulated many proposals for experiments, including the stated ambition of both the American and Soviet governments to place the first artificial satellites in orbit about the earth. The panel's job was to sort these proposals into two groups: those that could most satisfactorily be conducted with sounding rockets and those that could be performed aboard "Vanguard," the proposed [ 158 ] National Academy of Sciences/U.S. Navy earth satellite. Then, after hearing 20-minute oral presentations in support of each proposal, the panel, chaired by University of Iowa physicist James Van Allen, was to choose the most deserving experiments. 6

As the NACA representative to this panel, O'Sullivan sat through the day-long meeting and grew increasingly frustrated with what he was hearing. He was particularly disappointed by the methods proposed to measure the density of the upper atmosphere. As an aeronautical engineer, he understood that information about air density might prove vital to the design of satellites, ICBMs, and every aerospace vehicle to fly in and around the fringes of the earth's atmosphere. In 1952 and 1953, O'Sullivan had belonged to a three-man study group supported by Langley management for the purpose of exploring concepts for high-altitude hypersonic flight. With fellow Langley researchers Clinton E. Brown and Charles H. Zimmerman, O'Sullivan had educated himself in the science of hypersonics and helped the group to conceptualize a manned research airplane that could fly to the limits of the atmosphere, be boosted by rockets into space, and return to earth under aerodynamic control. In essence, the Brown-Zimmerman-O'Sullivan study group had envisioned a "space plane" very similar to the future North American X-15 and its related heir, the Space Shuttle. 7

Given his enthusiasm for spaceflight, O'Sullivan was disappointed to hear respected scientists offering such defective plans for obtaining the critical air-density data. One proposal, developed by a group at the University of Michigan, involved the use of a special omnidirectional accelerometer whose sensitivity, according to O'Sullivan, would have to be "improved by between 100 and 1000 times before the experiment would work." Another proposal, one of two submitted by Princeton University physicist Lyman Spitzer, Jr., called for the measurement of drag forces on a satellite spiraling its way back to earth. In O'Sullivan's view, the principle behind Spitzer's proposal was sound, but not practical. The experiment would work, he predicted, "only at altitudes much below that at which practical satellites of the future would have to fly in order to stay in orbit long enough to be worth launching, probably at least five years." 8 Several of the day's proposals, including the ones just mentioned, were based on the presumption that somebody could build and launch a lightweight structure strong enough to remain intact during its turbulent ballistic shot into space. But as far as O'Sullivan knew, nobody had yet discovered how to do this. At that moment, still more than a year and a half before Sputnik, no one had yet succeeded in launching even a simple grapefruit-sized object into space, let alone objects as big and complicated as those being suggested by the scientists that day in Ann Arbor.

In his hotel room that evening, O'Sullivan could not let go of the problem None of the proposals he had heard were satisfactory. But were there better alternatives? Even if he could think of one himself, technically, as a panel member, he was supposed to judge the suggestions formally submitted by [ 159 ] others, not make any of his own. With a pad of paper from the hotel desk in hand, however, he could not resist making some rough calculations. Over the next several hours, O'Sullivan was engaged in a process of creative problem solving, which he would later outline in seven major points of analysis. 9

O'Sullivan's Design

(1) Aero theory . O'Sullivan naturally started his analysis from the point of view of aerodynamic theory. He knew from theory that "the drag force experienced by a satellite in the outer extremities of the earth's atmosphere was directly proportional to the density of the atmosphere." This meant that "if the drag could be measured, the air density could be found." Thus, in the first few minutes of his analysis, O'Sullivan had reduced the entire problem to measuring the satellite drag. 10

(2) Shape and size . How big should the satellite be and what shape? O'Sullivan chose a sphere. Such a fixed shape eliminated the problem of the satellite's frontal area relative to the direction of motion, and it also simplified the question of the satellite's size.

(3) Drag forces . O'Sullivan turned next to a consideration of celestial mechanics. On his pad of paper, he began to play with the classical equations for the drag forces on a body as it moves on a ballistic trajectory through the atmosphere and into orbit around the earth. After several minutes of mathematical work, during which he constantly reminded himself that the success of the experiment depended on making the satellite extremely sensitive to aerodynamic drag, O'Sullivan realized that he must devise a satellite of exceedingly low mass relative to its frontal area. The satellite could be a large sphere, but the sphere's material could not be so dense as to make the satellite insensitive to the very air drag it was to detect. Only an object with a low mass-to-frontal area ratio could be pushed around by an infinitesimal amount of air.

(4) Design considerations . No researcher who worked at such a diversified place of technical competence as Langley, which was the only NACA aerodynamics laboratory with a Structures Research Division, could long proceed with the analysis of a flight-vehicle design without considering matters of weight, loads, elasticity, and overall structural integrity. The Structural problems of O'Sullivan's sphere might prove serious, for the lighter the weight (or lesser the mass), the weaker the structure. With this conventional knowledge about structural strength in mind, O'Sullivan contemplated the magnitude of the loads that his satellite structure would have to withstand. Calculations showed that the loads on his sphere, once in space, would be quite small, amounting to perhaps only one-hundredth to one-thousandth the weight that the sphere would encounter at rest on the surface of the earth. From this, he concluded that the satellite need only be a thin shell, as thin perhaps as ordinary aluminum foil.

[ 160 ] But herein was the dilemma. In orbit, the sphere would encounter negligible loads and stresses on its structure, but to reach space, it would have to survive a thunderous blast-off and lightning-like acceleration through dense, rough air. O'Sullivan knew that he could not design a satellite for the space environment alone; rather, a structure must be designed to "withstand the greatest loads it will be exposed to throughout its useful life." The satellite would have to withstand an acceleration possibly as high as 10 Gs, which was 1000 to 10,000 times the load the structure would be exposed to in orbit. To survive, the satellite could not consist merely of a thin shell; it would have to be so strong and have such a high mass-to-area ratio that it would be insensitive to minute air drag and thereby "defeat the very objective of its existence.'' 11

Midnight was approaching, and O'Sullivan, the scientific wizard of Langley's PARD, still sat at the hotel desk, perched on the horns of this dilemma. Finally, in the early hours of the morning, he arrived at a possible solution: why not build the sphere out of a thin material that could be folded into a small nose cone? If the sphere could be packed snugly into a strong container, it could easily withstand the acceleration loads of takeoff and come through the extreme heating unscathed. After the payload container reached orbit, the folded satellite could be unfolded and inflated pneumatically into shape. Finding a means of inflation should not be difficult. Either a small tank of compressed gas such as nitrogen, or a liquid that would readily evaporate into a gas, or even some solid material that would evaporate to form a gas (such as the material used to make mothballs) could be used to accomplish the inflation. (He apparently had not yet thought of using residual air as the inflation agent, as in Shotput 1) Almost no air pressure existed at orbiting altitude, so a small amount of gas would do the job. "Clearly then," O'Sullivan concluded, "that is how the satellite had to work.'' 12

(5) Construction materials . Other critical questions still needed answers. Surely, if he presented his notion of an inflatable satellite to the prestigious scientific panel the next day, someone would ask him to specify its construction material. The material had to be flexible enough to be folded, strong enough to withstand being unfolded and inflated to shape, and stiff enough to keep its shape even if punctured by micrometeoroids. O'Sullivan reviewed the properties of the materials with which he was familiar and quickly realized that "no one of them satisfied all the requirements." Next he tried combining materials. The forming of thin sheet metal into certain desired shapes was a standard procedure in many manufacturing industries, but sheet metal thin enough for the skin of his satellite would tear easily during the folding and unfolding. Perhaps, thought O'Sullivan, some tough but flexible material, something like a plastic film, could be bonded to the metal foil. 13

Here was another critical part of the answer to O'Sullivan's satellite design problem: a sandwich or laminate material of metal foil and plastic [ 161 ] film. "I could compactly fold a satellite made of such a material so that it could easily withstand being transported into orbit, and once in orbit, I could easily inflate it tautly, stretching the wrinkles out of it and forming it into a sphere whose skin would be stiff enough so that it would stay spherical under the minute aerodynamic and solar pressure loads without having to retain its internal gas pressure." 14 Such a thin-skin satellite would be so aerodynamically sensitive that even a minute amount of drag would cause a noticeable alteration in its orbit. Researchers on the ground could track the sphere, measuring where and when it was being pushed even slightly off course, and thereby compute the density of the air in that part of the atmosphere.

(6) Temperature constraints . Would a satellite made out of such material grow so cold while in the earth's shadow that the plastic film would embrittle and break apart? O'Sullivan reckoned that this would not be a problem as he knew of several plastic films that could withstand extremely low temperatures. The real concern was heat. Exposure to direct sunlight might melt or otherwise injure the outer film. But this, too, seemed to have a remedy. Rough calculations showed that high temperatures could be controlled by doping the outside of the satellite with a heat-reflecting paint. Some heat-reflecting metals might even do the job without paint, if they could be made into a metal foil.

(7) Satellite tracking . One problem remained: the means of tracking the satellite. As a member of the Upper Atmosphere Rocket Research Panel, O'Sullivan was familiar with current tracking techniques. These included the radio method built into the navy's Minitrack network in which the object to be tracked carried a small transmitter or radio beacon. This system would be adopted for the Vanguard satellite project. Unfortunately, the radio-tracking method would not work for O'Sullivan's satellite concept. If a radio beacon was attached to his sphere, it would add significantly to the structural mass, thereby reducing the sphere's sensitivity to air drag. The only way to track the sphere, it seemed, was optically, with special cameras or telescopes.

Tracking a satellite optically when the satellite would be made out of something as bright and highly reflective as polished sheet metal would not be difficult; however, optical tracking limited satellite observation to the twilight hours. At all other times, reflections from the satellite would not be practical. At night the satellite would be in the earth's shadow and hence would receive no sunlight to reflect to tracking instruments or observers on earth; in daylight, the satellite would reflect light, but that light would be Obliterated from view by the scattering of the sun's rays in the earth's dense lower atmosphere.

O'Sullivan knew that tracking a satellite at all times of the day and at night was possible only by radar. As a member of Langley's PARD, he was intimately familiar with the radar tracking of rocket models; at Wallops Island, it had been a routine and daily procedure for several years. As [ 162 ] O'Sullivan suspected, the problem was that radars powerful enough to do the job, even if the satellite were as big as a house, would not be available for several years because they were still in development.

Extraterrestrial Relays

These thoughts about radar tracking led O'Sullivan to a much higher level of technological speculation. "As I thought about this ability to reflect radio and radar waves, there came a stream of thoughts about the future possibilities of such a satellite when there would exist ... rockets capable of launching big enough satellites, and when powerful enough radars and radios [would exist] to be able to use such satellites for radio and television communication around the curvature of the earth, and as navigational aids that could be seen by ship and airplane radars night and day, clear weather or cloudy: satellites that some day might take the place of the stars and sun upon which navigators have depended for so many generations." 15

On many occasions in the history of modern technology, science fiction has blazed the way to an understanding of real possibilities and has motivated scientists and engineers to seek practical results; perhaps O'Sullivan's concept for the inflatable satellite was one of those occasions. Several years earlier, in October 1945, the British science-fiction writer Arthur C. Clarke had published a visionary article in the popular British radio journal Wireless World suggestively entitled "Extraterrestrial Relays." In the article, Clarke predicted the development of an elaborate telecommunications system based on artificial satellites orbiting the earth. 16

The key to such a system, according to Clarke, would be the "geosynchronous" satellite. Such a satellite, launched to a distance of roughly 22,000 miles high in an equatorial orbit, would, according to the laws of celestial mechanics, take exactly 24 hours to complete one orbit, thereby staying fixed indefinitely over the same spot on the earth. The satellite would act as an invisible television tower, which could maintain line-of-sight contact with one-third of the earth's surface. If three satellites were put into geosynchronous orbit above the equator and made to communicate with one another through long-distance "extraterrestrial relays," as Clarke called them, electronic signals, be they radio, television, or telephone, could be passed from satellite to satellite until those signals made their way around the globe. For the first time in history, people all over the world would be able to communicate instantaneously.

The impact of a global communications system would be revolutionary, Clarke was sure. "In a few years every large nation will be able to establish (or rent) its own space-borne radio and TV transmitters, able to broadcast really high-quality programs to the entire planet." This would mean "the end of all distance barriers to sound and vision alike. New Yorkers or Londoners will be able to tune in to Moscow or Peking as easily as to their [ 163 ] local station." The new communications technology might even lead to a new order of world cooperation and peace. "The great highway of the ether will be thrown open to the whole world, and all men will become neighbors whether they like it or not." Inevitably, peoples of all nations will become 'citizens of the world.'' 17

We do not know if Langley's William J. O'Sullivan (who died from cancer in 1971 at age 56) had read any of Arthur Clarke's writings or was in any other way acquainted with Clarke's ideas about communications satellites at the time of the Ann Arbor meeting in 1956. Most likely O'Sullivan knew something of them, given the intellectual proclivities of the flight-minded community in which he worked and the extent to which some of the bolder ideas about space exploration were making their way into the mainstream of American culture during the early 1950s through books, magazines, and movies. Some of the ambitious ideas about space, including the scheme for a global system of communications satellites, were beginning to appear in the serious technical literature.

Take the relevant case of John R. Pierce, the visionary American electrical engineer working at Bell Telephone Laboratories. In 1952, Pierce began to develop his own ideas for a communications satellite system but, fearing the ridicule of his colleagues, decided to publish his ideas under a pseudonym. They appeared in a popular magazine, Amazing Science Fiction. In the next few years, however, the climate of opinion changed; the electronics revolution, as well as the notion of integrating rockets, transistors, computers, and solar cells, progressed far enough to make a serious technical discussion of the possibility of "comsats" (communication satellites) professionally acceptable. Pierce then came out of the closet; in April 1955, he published "Orbital Radio Relays" under his own name in the respected trade journal Jet Propulsion. 18

In the same month, another provocative article by Pierce appeared in the Journal of the American Rocket Society; in it, the Bell engineer specified the use of large spherical reflector satellites, much like the one being designed by O'Sullivan, for long-range telecommunications. Such satellites would be "passive" rather than "active." A passive satellite served simply as an electronic mirror, retransmitting back to earth only those signals that were intercepted. *** The chief advantage of a passive system, Pierce indicated, was that a passive satellite was less complicated electronically than an active satellite. Unlike a passive satellite, an active one could receive and amplify signals before retransmitting them to the ground, but, in order to do so, it had to carry its own power supply or possess the means of deriving power from external sources. 19

A global communications network based on a series of geosynchronous satellites like those suggested by Pierce and Clarke interested O'Sullivan, but [164] in January 1956, as a member of the Upper Atmosphere Rocket Research Panel, his sights were set on a much more limited and immediate goal, the upcoming IGY. So just as quickly as he began to speculate about the potential of communications satellites in earth orbit, the Langley engineer once again narrowed his focus and concentrated on the requirements of the air-density experiment at hand. These other applications "were things for a few years in the future," he said to himself, "not for the year 1956." 20 Little did he know how quickly those wildly ambitious applications would be realized once the spaceflight revolution began.

Finessing the Proposal

Having pondered the problems of designing an air-density flight experiment into the wee hours of the morning, O'Sullivan finally went to bed. But he could not sleep. He tossed and turned, worrying that when he disclosed his idea to the Upper Atmosphere Rocket Research Panel the next day he would find that he had "overlooked some factor that would invalidate the whole idea." At one point, he sat up in bed, laughed, and said aloud, "It will probably go over like a lead balloon!'' 21 His plastic-covered, inflatable metal-foil sphere was about as close to a lead balloon as any professional engineer would ever want to get.

The next day, January 27, after hearing several members of the panel express their disappointment in the proposed methods of measuring satellite drag and air density, O'Sullivan mustered enough courage to tell a few of the panel members about his design. He talked to Fred L. Whipple, then of the Harvard College Observatory (and soon to be named director of the Smithsonian Astrophysical Laboratory), as well as to Raymond Minzer of the U.S. Air Force Cambridge Research Center. Their principal concern was that the payload space in the Vanguard satellite was almost completely taken up by other experiments. All that was left for O'Sullivan's inflatable balloon was a tiny space the size of a doughnut. Could the balloon be made to fit? And could it be made to weigh no more than seven-tenths of a pound? O'Sullivan was not sure about meeting either requirement, but, puffing on a cigarette, said he would try to work it out. That was enough of an answer for Whipple and Minzer. Both men urged O'Sullivan to put his proposal in writing and submit it to the U.S. National Committee/International Geophysical Year (USNC/IGY) Technical Panel on the Earth Satellite Projects, which was being formed in Ann Arbor that afternoon. 22

For O'Sullivan, the proposal posed a problem. Most technical panels of the USNC/IGY had already been formed, and he had just accepted an appointment, with the NACA's permission, on the Technical Panel on Rocketry. Not only was he a member of this panel, but he also was responsible for coordinating the NACA's development of two sounding rockets: the Nike-Deacon (DAN) and an improved version of it, the Nike-Cajun (CAN). Both [ 165 ] were to become mainstays of the USNC/IGY sounding rocket program. Furthermore, O'Sullivan knew that a rather strict USNC/IGY policy required that a "principal experimenter" accept complete responsibility for carrying out his experiment from beginning to end. The USNC/IGY would deal only with him, not with any organization with which he was associated, in all matters pertaining to his experiment, including funding. The purpose of this policy was to ensure that every scientist, regardless of institutional affiliation or backing, would enjoy an equal opportunity to propose experiments and to obtain the necessary funding from the USNC/IGY if the experiment was accepted. Taking on the heavy duties of a principal experimenter would be a full-time job that O'Sullivan could not possibly do and still hold his civil service position with the NACA. The options appeared to be either to resign his 18-year position with the NACA and obtain funding to do the experiment from the USNC/IGY or to forget about the inflatable satellite. 23

O'Sullivan found another option, which was to share the satellite project with someone else. He talked again with Raymond Minzer, this time about joining him as a "co-experimenter." Minzer agreed, and within a few weeks, the two men submitted a successful proposal to Dr. Richard W. Porter, the General Electric engineer in charge of the V-2 test program at White Sands and chairman of the Technical Panel on the Earth Satellite Projects. Unfortunately, after the proposal was accepted, the air force withdrew its support of the experiment, and Minzer had to bow out. Once again, O'Sullivan was left alone with his lead balloon, and by that time, O'Sullivan explains, the USNC/IGY Technical Panel on the Earth Satellite Projects was "hounding [him] to get the experiment under way." 24

Upon returning to Langley, the only option left open to O'Sullivan, besides dropping the experiment, was to secure full support from his employer. As the NACA's representative on the Upper Atmosphere Rocket Research Panel, O'Sullivan had reported all of his activities in travel reports and memoranda that were routed to the office of the Langley director (still Henry Reid), with copies forwarded to NACA headquarters. In mid-June 1956, Associate Director Floyd Thompson and Bob Gilruth, then the assistant director responsible for PARD, had heard all about the concept for an inflatable satellite. They advised O'Sullivan to prepare a formal memorandum giving the complete theory of the experiment and requesting that the NACA sponsor the experiment for development at Langley as another NACA contribution to the IGY.

Immediately, O'Sullivan wrote the proposal, dated 29 June 1956. In it, he explained why the NACA, an organization hitherto devoted to the progress of aircraft, "not only should, but must" become engaged in development of earth satellites. With the recent advances in rocket propulsion and guidance systems, O'Sullivan argued, "earth satellites can and will be developed and used for numerous defense and commercial purposes.... Not least among the foreseeable benefits is the lessening of world tension by bringing closer together the various nations through interest in a common [ 166 ] beneficial development." The development of earth satellites was therefore "inevitable." For the NACA not to be involved with satellites would be a serious mistake. "In every industry, failure to undergo evolution in pace with technological development inevitably leads to extinction. In the field of research, by virtue of it being the technological frontier, no time lag between recognition of an important problem and initiation of work upon it can exist without loss of ground." To begin, the NACA should perform research "particularly in the field of air drag measurement, employing lightweight inflatable spheres," with a special task group established at Langley to perform the necessary technical work. Given the low estimated cost of the experiment, which O'Sullivan placed very conservatively at just over $20,000, he was hopeful that NACA management would accept his proposal, even though he knew that his employer would have to bear all the expenses of developing the project because federal law prevented the NACA from accepting any funds from the USNC/IGY. 25

Very quickly the NACA accepted the proposal. Hugh Dryden, the director of research for the NACA in Washington, liked the concept and in September 1956 authorized John W. Crowley, his associate director, to report to the USNC/IGY Technical Panel on the Earth Satellite Projects with news of the NACA's willingness to develop the satellite. But the advocacy was not over. Not everyone on Dr. Richard Porter's newly constituted technical panel had heard about O'Sullivan's idea, and many of them needed to be convinced. O'Sullivan remembers, "I had to describe [the experiment] in minute detail and defend it against all scientific and technical objections the [panelists: could think of." This was "the acid test," for most members of this panel came from academe and not from government; everyone on the panel had a Ph.D., and O'Sullivan did not. After a careful presentation of his proposal, however, O'Sullivan managed to clear the hurdle and persuade the panel to accept the NACA project. At a meeting on 9 October 1956, Porter's committee put it on the official list of approved experiments and designated O'Sullivan as the principal experimenter. The committee was convinced that no other means for measuring satellite drag and thus deducing air density in the upper atmosphere approached the sensitivity of O'Sullivan's little inflatable balloon. 26

The "Sub-Satellite"

The panel's approval gave O'Sullivan's air-density experiment only the right to compete for what little space remained on the Vanguard launching rocket; it did not guarantee that the experiment would ever be flown. The sole allotment of space remaining in the payload amounted to a few cubic inches of space in an annular or ring-shaped area between the head end of the third stage of the rocket motor and the placement of an IGY magnetometer satellite developed by the NRL. Into these cramped quarters, O'Sullivan [ 167 ] and his helpers at Langley would have to squeeze their satellite, along with its inflation mechanism and surrounding container. All of it together could be no more than 20 inches in diameter or a mere seven-tenths of a pound. Because it was so little and was to be carried into orbit underneath the magnetometer satellite, O'Sullivan named the small inflatable vehicle the "Sub-Satellite." ****

Although the USNC/IGY technical panel designated O'Sullivan as the principal experimenter for the balloon project, too many problems had to be solved in too short a time for one man to do all the work alone. Therefore, in the fall of 1956, Floyd Thompson authorized the formation of a small team of engineers and technicians, mostly from PARD, to assist O'Sullivan in the preparation of the satellite project. Administratively, Thompson facilitated this in late December 1956 by appointing O'Sullivan as head of a new Space Vehicle Group placed inside PARD. The group would report directly to the division office, which was headed by Joseph A. Shortal. Jesse L. Mitchell of the Aircraft Configurations Branch and Walter E. Bressette from the Performance Aerodynamics Branch of PARD would assist O'Sullivan. Significantly, this small Space Vehicle Group was the first organizational unit at Langley to have the word "space" in its title. 27

First, the Space Vehicle Group tested dozens of plastic and metal foils (even gold) in search of the right combination to withstand the extreme range of temperatures that the little satellite would encounter: from 300°F in direct sunlight to -80°F when in the shadow of the earth. The group found half of the answer to the problem in a new plastic material called "Mylar." Made by E. I. du Pont de Nemours & Co., Mylar was being used for recording tape and for frozen-food bags that could be put directly into hot water. When manufactured in very thin sheets, perhaps only half as thick as the cellophane wrapper on a pack of cigarettes, Mylar plastic proved enormously tough. It showed a tensile strength of 18,000 pounds per square inch, which was two thirds that of mild (low-carbon content) steel.

The second half of the answer, that is, an effective metal covering for the plastic that could protect the satellite from radiation and make it visible to radar scanners, proved a little more difficult to find. For more than a month, the O'Sullivan group "tested metal after metal, looking for ways to paint them on Mylar in layers far thinner than airmail onionskin paper." 28 Then, one man in the Space Vehicle Group heard about a technique for vaporizing aluminum on plastic that the Reynolds Metals...

[ 168 ]

To determine the capacity of the 30-inch "Sub-Satellite" (right) to withstand the high temperature of direct sunlight in space, Langley researchers subjected it to a 450°F heat test (below). Results indicated that the aluminum-covered Mylar plastic would effectively reflect the dangerous heat. . L-57-3113 . L-58-4293

[ 169 ] ....Company of nearby Richmond, Virginia, was experimenting with for the development of everyday aluminum foil. This new and unique material was acquired and successfully tested. The fabrication problem was solved by cutting the material into gores, that is, into three-cornered or wedge-shaped pieces, and gluing them together along overlapping seams. Using this technique with this material, the Langley researchers built the outer skin of their first 20-inch domes for inflation tests.

Almost everyone involved was excited by the prospect of sending the experiment into space, and several individuals worked nights and weekends through the last months of 1956 to get the Sub-Satellite ready. The right blend of materials had been found for the inflatable sphere; now, two major problems remained: how to fold the sphere so that it could expand quickly without a single one of its folds locking up and causing a tear, and how to inflate the balloon. As for the means of inflation, the Langley researchers tried dozens of strange chemicals before discovering that a small bottle of nitrogen would inflate the little balloon, at the proper rate, so that the sphere would not blow apart. Learning how to fold the satellite was also a purely empirical process; no theory existed to guide the group. As one observer remembers, "Harassed by O'Sullivan, men who couldn't fold a road map properly found a way to fold his aluminum balloon." 29

However, this characterization gives O'Sullivan too much credit. Walter Bressette and Edwin C. Kilgore were the engineers who actually worked out not only the folding pattern but also the ejection method and inflation bottle pressure for the Sub-Satellite. Bressette, an airplane pilot in World War II and a 1948 graduate in mechanical engineering from Rhode Island College (now the University of Rhode Island), had spent the last 10 years working on ramjet propulsion systems, jet effects on airplane stability, and reentry problems using both rocket-propelled vehicles and a supersonic blowdown tunnel at Wallops Island. Kilgore, a 1944 engineering graduate from Virginia Polytechnic Institute and State University, had proved to be one of Langley's top machine designers. The two men conducted many trials in a small vacuum chamber in the PARD shop before solving the Sub-Satellite's problems. In addition, Bressette made frequent trips to the NRL in Washington to put the Sub Satellite package through what he called "the shake, rattle, and roll" of vehicle environmental tests. 30

By January 1957, the Sub-Satellite was almost ready. A front-page article appearing in the Langley Air Scoop on 5 January touted the little satellite for having originated at Langley, credited O'Sullivan with "having conceived the novel manner of construction," and told employees to look forward to its impending launch. Next to the article was a photograph of O'Sullivan holding in his right hand the shiny inflated Sub-Satellite, the emblem of the NACA wing on its side, and in his left hand, a folded uninflated Sub-Satellite. 31

However, just when everything was proceeding on schedule, a complication developed. The Baker-Nunn precision optical tracking cameras at [ 170 ] White Sands would not be able to follow and photograph such a small sphere; Fred Whipple urged O'Sullivan and the NACA to increase the size of the Sub-Satellite from 20 to 30 inches in diameter. The Sub-Satellite could not weigh more or take up more space on the Vanguard; it just had to be 10 inches bigger. On 7 February 1957, Whipple's panel made this request official, reconfirming assignment of the NACA experiment on Vanguard if the change was made. O'Sullivan believes that the new size requirement "would have been a deathblow to the Sub-Satellite had it occurred at the start"; however, with the experience gained at Langley through actually building the sphere, the increase to a 30-inch diameter was accomplished over the next few months without too much trouble. 32

After all Langley's work, the Sub-Satellite was finally on the launchpad at Cape Canaveral on 13 April 1959. Seconds after takeoff, the second stage of the Vanguard SLV-5 vehicle experienced a failure that sent the rocket and the Sub-Satellite crashing ignominiously into the depths of the Atlantic Ocean. With this launch failure, the attempt to determine air density with the Sub-Satellite came to an end. (This was Vanguard's third attempted launch.) However, other models of the 30-inch sphere were used for a short time both before and after the SLV-5 misfire as a calibration target for a new long-range radar being developed at MIT's Lincoln Laboratory at Millstone Hill Radar Observatory in Westford, Massachusetts. 33

Something the Whole World Could See

Even before the Sub-Satellite's fatal plunge into the ocean in April 1959, O'Sullivan had started to contemplate the benefits of a larger reflector satellite that could be the sole payload on a Vanguard. In November 1957, Fred Whipple presided over a space science symposium in San Diego, which was sponsored jointly by the air force and Convair Astronautics. At this symposium, O'Sullivan proposed that a large inflatable launched by a rocket more powerful than Vanguard could be used as a lunar probe. "It could be seen and photographed through existing astronomical telescopes, not only giving conclusive proof to everyone that such a probe had reached the moon, but its location as it orbited the moon or impacted on the moon would be known." Before sending a balloon to the moon, however, O'Sullivan felt that something must be put into earth orbit, perhaps a 12-foot-diameter satellite, which "the whole world could see." 34

For a professional engineer, O'Sullivan was something of a universalist. He worked on airplanes, missiles, and satellites; he knew aerodynamics, and he knew space. But he was not gracious about sharing credit. The idea for the 12-foot satellite was not O'Sullivan's but Jesse Mitchell's. An analysis performed by Mitchell had indicated that a 30-inch-diameter sphere would not make a suitable optical device for a lunar probe; the sphere would have to be several times larger. So in the summer of 1957 while O'Sullivan was away....

[ 171 ]

Space Vehicle Group engineer Jesse Mitchell examines the Sub-Satellite package in early October 1958, only days after NASA's establishment. Mitchell, who would later become head of the Geophysics and Astronomy Division at NASA headquarters, directed Langley's program development plan for Echo 1.

....from Langley, Mitchell and Bressette had consulted the model shop about building a larger sphere. The size of the sphere became 12 feet because of the ceiling height in the model shop, not because O'Sullivan had determined it to be the perfect size. 35

For millions of people, the spaceflight revolution began the first time they looked up in wonder at the bright twinkling movement of an artificial satellite. O'Sullivan was aware of this when he proposed his 12-foot inflatable With the appearance of Sputnik I a month earlier in October 1957, people around the world, especially Americans, developed a heightened if not exaggerated interest in searching the sky for UFOs. A widespread interest in UFOs had existed before the ominous overflights of the Russian satellites As historian Walter McDougall explains in his analysis of the onset of the space age, 10 years prior to the first Sputnik, "beginning in the midsummer of 1947 the American people began to see unidentified flying objects, kicking off a flying saucer 'epidemic' of such proportions that the air force launched a special investigation and began compiling thousands of case studies that, in the end, satisfied no one." 36 The cause of the epidemic was the new need of Americans to externalize their postwar fears about technology, about the atomic bomb, and about nuclear war destroying the world.

[ 172 ] Into the blackness of that anxiety-ridden mass psychology came the specter of Sputnik. Across the United States, people went outside with binoculars and telescopes, straining to see the faint blinking reflection of the tiny yet ominous metal globe tumbling end over end. For instance, in San Francisco on Friday night, 4 October 1957, volunteer crews of amateur astronomers with special "moon-watch" telescopes maintained a vigil atop the Morrison Planetarium in Golden Gate Park in hopes of sighting the Russian satellite. Crew members took up their prearranged stations as soon as reports of the satellite's launching were received. Six tireless individuals continued the lonely vigil until morning, when conditions for viewing were allegedly at their best. How many people actually spotted the satellite that night and over the next several months as it moved in its north-to south orbit is unknown, but certainly far fewer saw Sputnik 1 than said they did. 37

On that same evening in early October on a large ranch in Texas, Senate Majority Leader Lyndon B. Johnson was having a few guests in for dinner when the news of Sputnik I came over the radio and television. After eating, the party went outside rather nervously for what was supposed to be a calming stroll in the dark along the road to the Padernales River. But the walk only unnerved them. As one of the guests, Gerald Siegel, a lawyer with the Senate Democratic Policy Committee, remembers thinking at the time: "In the Open West you learn to live closely with the sky. It is a part of your life. But now, somehow, in some new way, the sky seemed almost alien. I also remember the profound shock of realizing that it might be possible for another nation to achieve technological superiority over this great country of ours." 38

On the Atlantic coast, among the millions of people all over the country and the world who were looking up in the sky that night to see Sputnik were O'Sullivan and his colleagues at NACA Langley. Bob Gilruth recalls seeing the satellite from his bayside home in Seaford, Virginia. In Gilruth's words, the sighting "put a new sense of value and urgency" on everything he and his co-workers were doing at Langley. Charles Donlan also remembers sighting the little satellite: "I was running around my yard in Hampton one evening, when I looked up and saw Sputnik go right over my house. I remember stopping and staring at it. What I remember thinking was how much better it would be if the thing belonged to America." 39

Everyone involved with decisions regarding U.S. satellites, including the State Department and the Central Intelligence Agency (CIA), felt the same way. In the wake of the Sputniks, virtually all government officials concerned expressed a desire to orbit a satellite that would be visible over Russia as well as the United States. O'Sullivan's 12-foot inflatable sphere seemed to fit the bill. Because of shocking world events, what had started out as a simple air-density experiment was becoming an instrument of propaganda in the cold war.

The idea for an inflatable sphere big enough for everyone to see received high priority. Whipple and other members of the USNC/IGY Technical [ 173 ] Panel on the Earth Satellites expressed serious interest in O'Sullivan's proposal for a bigger inflatable, but they had to wait a few months to see whether a booster more powerful than the Vanguard rocket could be obtained. Finally, in the spring of 1958, the USNC/IGY informed the NACA that some space was available inside the nose cone of a Jupiter C, an intermediate-range ballistic missile developed by the ABMA that was more powerful than the Vanguard rocket. If the Jupiter failed, and of course none of these boosters had yet proved reliable, a Juno II, a new vehicle similar to the Jupiter C, might be available as the backup. A Juno II would launch America's first successful lunar flyby, Pioneer 4, on 3 March 1959. 40

The NACA agreed to the project, and the Space Vehicle Group continued to construct and test its 12-foot inflatable. 41 Because it was to orbit at 300 to 400 miles above the earth and thus would appear as bright as the north star, Polaris, the satellite eventually came to be called "Beacon." Beacon would be easy to see with the naked eye and so could be tracked optically and photographically without difficulty. Big new radars, such as the one being developed by MIT at Millstone Hill, ***** were just coming on line and would be able to track day or night, regardless of the weather. 42

On 25 June 1958, the USNC/IGY officially assigned the 12-foot Beacon satellite as a payload for the launch of Jupiter C No. 49. To obtain the difficult orbit that O'Sullivan insisted on-it was circular rather than elliptical-the Jupiter C had to have a small "high-kick" rocket motor that gave an extra boost to help the satellite reach the desired orbit. Unfortunately, on 23 October 1958, the "high-kick" did not get a chance to "kick in," because the "low kicks" kept failing. As was the case with its 30-inch ancestor, the Beacon was not launched into orbit from Cape Canaveral because the booster failed. Fourteen months later, Juno II No. 19 was ready to carry a second 12-foot satellite into orbit but failed to do so when the rocket's fuel supply emptied prematurely. 43

With three failures in a row, O'Sullivan and the Space Vehicle Group might have given up on the balloon if not for the spectacular successes of Explorer I on 31 January and Vanguard I on 17 March 1958. These American satellites proved not only that Americans could put an object in orbit but also that those objects, tiny as they were, could disclose great scientific discoveries such as the Van Allen radiation belts. Beyond that, satellites could be of tremendous economic and social benefit. They could make continuous worldwide observation of the weather possible, and the existence and the likely paths of hurricanes and other destructive storms would be accurately predicted. By studying the development of the world's weather patterns from space, humans might someday control the climate. In summary, satellites offered too many far-reaching benefits for researchers to allow a few launch vehicle failures to discourage them. Rockets were still....

[ 174 ]

In July 1959, William J. O'Sullivan (right, standing) and an unidentified engineer examine the capsule containing the tightly folded and packed 12-foot-diameter Beacon satellite (below). . L-59-4973 . L-59-2836

...in their infancy, in the "Model-T" stage of technical evolution. Failures were to be expected, Langley's team consoled itself. All the problems had been with the boosters, not with their own satellites. 44

According to O'Sullivan, he set an example of grit and determination for the rest of his people, many of whom were still quite young. As he told a magazine writer at the time, he was "mindful of his research associates who had labored so hard" to produce the experiments and who "looked to me as their leader." This was driven home to him, he told the writer, during the unsuccessful launch of the 12-foot satellite. Watching the Doppler velocity drop off rather than climb, he knew instantly the launching rocket had failed. Turning to his associates, he said, "The launching is a failure." Standing dumbfounded, staring at O'Sullivan, one of them asked, "What do we do now?" O'Sullivan immediately answered, "We pack up our instruments and equipment as quickly as we can. We haven't a moment to lose. We have to get back to the Laboratory and get the next satellite ready for launching." When his men started moving in a hurry, O'Sullivan informed the writer, he knew for sure that he "must never waiver or hesitate no matter how stunning the blow." 45

According to other key individuals involved with the project, however, O'Sullivan was not the leader he claimed to be. Walter Bressette remembers that "O'Sullivan never went to the satellite launch areas." In fact, he gave....

[ 175 ]

. . L-58-88a L-58-1063a

The genius of William J. O'Sullivan (left) rested in the theory stage of an engineering development; other Langley researchers took over the main responsibility during the design and deployment phases. Walter Bressette (right) played a major role in the Echo program from start to finish. Here he examines a scaled prototype of the satelloon in December 1958.

....up direction of the 12-foot satellite mission immediately after the Juno II failure, handing it over to Claude W. Coffee, Jr., and Bressette, who then made the 12-foot Scout proposals. O'Sullivan abandoned his project, leaving it to others to carry on. Those who did continue the work view O'Sullivan's self-publicized heroic role in the eventual success of the effort as egotistical and inaccurate. 46

Big Ideas Before Congress

Up to the point of the Juno II failure, Langley's interest in inflatable satellites had been limited to air-density experiments in the upper atmosphere and to orbiting an object large enough to be seen by the naked eye; the notion of deploying satellites for a worldwide telecommunications network like the one suggested by John Pierce and Arthur Clarke had not yet taken hold as an immediate possibility.

But the flight of the Sputniks emboldened conservative researchers. In the spring of 1958, as plans for NASA were being formulated in Washington, communications satellites or "comsats" became a moderately hot topic. Not surprisingly' even the NACA began to take a healthy interest in them. At [ 176 ] Langley, an advance planning committee recommended that the center begin a comprehensive study of radio-wave propagation and channel requirements, as well as the requirements for active relays. In a decision that would later come to haunt them, the planning committee resolved that the first flight experiment should involve only a simple passive reflector, one in which the satellite acted merely as a mirror and retransmitted only those signals it received. That sort of simple experimental communications satellite could be placed in orbit very soon, perhaps as early as fiscal year 1959, the Langley planners stated. The greater difficulties of building an active system were being tackled elsewhere. A passive flight experiment would demonstrate the feasibility of a space based system, and the new NASA could accomplish the task largely on its own, without extensive help from industrial contractors, notably Radio Corporation of America (RCA), American Telephone and Telegraph (AT&T), and General Electric (G.E.), who at that time were petitioning the federal government to invest in their own special comsat projects. 47

Throughout the spring and summer of 1958, Congress listened to arguments about the potential of space exploration and what should be done to ensure that the country's nascent "into space" enterprises would continue far beyond the end of the IGY. This testimony, in part, was the genesis of NASA. The NACA's director of research, Hugh Dryden, testified more than once on Capitol Hill. Before the House Select Committee on Science and Astronautics on 22 April, Dryden explained, among many other things, how large aluminized balloons could be inflated in orbit and used for communication tests. Accompanying him on this occasion was O'Sullivan, who took a full-size Beacon satellite into the Capitol and inflated it there "to demonstrate the structural, optical, and electronic principles involved." In his testimony, O'Sullivan delighted the congressmen by saying, quite emphatically, that Langley had been studying the problem of communications satellites for several months and that its staff was absolutely convinced that a very large inflatable reflecting sphere, at least 10 stories high, could be built quickly and launched into space. This big balloon "would reflect radio signals around the curvature of the earth using frequencies not otherwise usable for long range transmission, thus mostly increasing the range of frequencies for worldwide radio communications and, eventually, for television, thus creating vast new fields into which the communications and electronics industries could expand to the economic and sociological benefit of mankind." 48

The ideas of Pierce and Clarke were finding a home at, of all places, a government aeronautics laboratory. On 31 March 1958, some three weeks before Dryden and O'Sullivan testified in Washington, John W. "Gus" Crowley, Dryden's associate director, had visited Langley and told Floyd Thompson, O'Sullivan, Joseph Shortal, and others that Dryden had been having conversations with Dr. Pierce of Bell Telephone Labs and with members of President Eisenhower's Science Advisory Committee about [ 177 ] the potential of a global telecommunications system based on satellites. What NACA headquarters now wanted to know, Crowley said, was whether Langley was interested in constructing a larger 100-foot inflatable sphere, on a tight schedule, to be used as an orbital relay satellite like that envisioned by Pierce. 49

O'Sullivan assured Crowley a few days later that his Space Vehicle Group was "not only interested but enthusiastic about the possibility of placing such a satellite in orbit, and that the schedule could be met." On 3 April 1958, a follow-up meeting took place at Shortal's PARD office to consider designs for the big balloon. At this meeting, O'Sullivan, adopting Jesse Mitchell's scheme, suggested using the 100 foot sphere as a lunar probe. On 18 April, Langley submitted to NACA headquarters a proposed research authorization entitled, "A Large Inflatable Object for Use as an Earth Satellite or Lunar Probe." The NACA did not formally approve the proposal until 8 May, but work on the big sphere had actually started at Langley on a high-priority basis even before Crowley's visit. 50

In early February 1959, Project Echo, as O'Sullivan had begun to call it, cleared another major hurdle when NASA headquarters assured Langley that an allotment of space would be devoted to the large inflatable in a forthcoming "space shot." Following this authorization, on 19 February, Langley Assistant Director Draley approved the creation of a large interdisciplinary "task group" of approximately 200 people, assigned on a temporary basis without change of organization and initially under O'Sullivan's leadership. The Space Vehicle Group alone could not handle the entire work load, which at this point still involved the 30-inch Sub-Satellite and the 12-foot inflatable. Significantly, as befitting a project that had to succeed, Draley announced that the move was necessary to meet an "emergency." He informed the directorate that "for the duration of this emergency condition," O'Sullivan's Space Vehicle Group and Clarence L. Gillis's Aircraft Configuration Branch, both of PARD, "will merge and work as one unit" with O'Sullivan as head and Gillis as his deputy. To make room for the work load in this merged group, "it may be necessary to postpone, or transfer to other units, some of the work now in progress." In other words, Project Echo took priority over business-as-usual, and everyone at Langley would just have to adjust. 51

Assigning Responsibilities

The first planning meetings for Project Echo convened at NASA headquarters in the summer of 1959, not long before the first NASA inspection. At the second of these meetings, on 13 October 1959, Leonard Jaffe, chief of NASA's fledgling communications satellite program and director of one of the program offices in the Office of Space Sciences at NASA headquarters, surprised Langley representatives by announcing that the "primary responsibility'' for managing Echo was being given, not to Langley, but to Goddard, [ 178 ] which was still under construction in Greenbelt, Maryland. Various parties would contribute to the project through expanded in-house activities and some extensive contracting, Jaffe explained. The Douglas Aircraft Company plant in Tulsa (a converted B-24 factory) would provide the assembled booster, a three stage Thor-Delta (later it would be called just a Delta); Bell Telephone Laboratories, where comsat pioneer John Pierce worked as director of electronics research, would make available at Holmdel, New Jersey, a 20 x 20-foot horn-fed parabolic receiver, a 60-foot antenna, as well as amplifiers, demodulators, and other electronic and radar equipment; RCA would provide the radar beacon antenna for incorporation upon the Echo spheres; NRL would use its large 60-foot dish antenna at Stump Neck, Maryland, to receive the reflected signals from Echo; and JPL would employ its two 85-foot low-noise antennae at the Goldstone (California) Receiving Site to track the satellite. 52

Naturally, Langley was quite disturbed over the assignment of the overall responsibility to Goddard. As one senior Langley researcher remembers, "Echo was considered to be but the first in a long series of large satellite experiments under the jurisdiction of Langley." If Langley lost Echo to Goddard, all the other large satellite experiments would probably go to Goddard as well. Whatever proved to be the case, however, Langley felt that Jaffe's instructions need not have any immediate effect on Echo. Langley, both through in-house work and the monitoring of contracts, would keep the responsibilities for the key research and development tasks. These tasks were not spelled out precisely by Jaffe at the planning meeting, and more than a year would pass before a working agreement satisfactory both to Goddard and Langley was finalized. Even after the agreement was reached in January 1961, relations between the two NASA centers were stressful. As we have seen, tensions already existed between them. Goddard staff wanted to exercise management authority over a project they felt was rightfully theirs; Goddard was the center for all NASA space projects. As the originators of the Echo concept, O'Sullivan and his associates saw Goddard as an intruder. Langley researchers, therefore, planned to ignore Goddard and continue working as before the reassignment. 53

Pending the final agreement over the division of responsibilities, Langley's Project Echo Task Group continued to do whatever it felt needed to be done to assure the success of the "satelloon." ****** This included doing virtually all [ 179 ] of the preliminary design for the payload, including the satellite itself; the satellite container with all its associated circuitry, hardware, and pyrotechnics; the container-separation or deployment mechanism; and the inflation system. The Langley group developed the techniques for fabricating, folding, packing, and inflating the rigidized sphere, and it carried out the systematic ground tests to make sure that everything worked properly. After completing the ground tests, Langley also assisted in all launches and test flights.

Nonetheless, as the Langley engineers involved would soon discover, the assignment of Project Echo to the Goddard Space Flight Center was the initial step in the demise of the development of any passive communications satellite system. The Goddard director had already heavily committed his resources to the development of an active system; his organization was thus reluctant to take on the added burden of the passive system, which many Goddard engineers, and probably Goddard Director Goett, believed would prove inferior.

Shotput

One of the responsibilities taken on by Langley in early 1959 was the management of a project essential to Echo's success: Shotput. The purpose of Shotput was "to ensure proper operation of the payload package at simulated orbital insertion"-in other words, to do thorough developmental testing of the techniques by which the folded Echo balloon would be ejected from its canister and inflated in space. The techniques conceived and refined for the Sub-Satellite and the 12-foot Beacon satellite were almost totally inapplicable to the giant Echo balloon, so new schemes had to be perfected. Only some of the critical tests could be made on the ground because a vacuum chamber large enough to simulate the complete dynamics of the balloon inflating in space was impractical to build. The only option was to do the testing in the actual environment of space, and that meant developmental flight tests. 54

The importance of Shotput to Project Echo's ultimate success bears witness to the need for thorough developmental testing prior to any spaceflight program. Before NASA researchers risked an expensive launch of a precious piece of space hardware, they made sure that the project would work from start to finish. Langley's plan was to flight-test suborbital Shotput vehicles from Wallops Island, then conduct as many orbital launches from Cape Canaveral as needed to put an Echo satellite in orbit successfully. For the most part, that plan was followed.

[ 180 ] One of the most difficult technical tasks facing Langley researchers working on Project Echo was designing a container that would open safely and effectively release the satelloon. After several weeks of examining potential solutions to this problem, the Langley engineers narrowed the field of ideas to five. They then built working models of these five container designs, and 12-foot-diameter models of the satellite for simulation studies. With help from Langley's Engineering Service and Mechanical Service divisions, the Echo group built a special 41-foot-diameter spherical vacuum chamber equipped with pressure-proof windows. There the dynamics of opening the container and inflating the satelloon could be studied as the satelloon fell to the bottom of the tank. To observe and photograph the explosive opening and inflation within the dark chamber, a special lighting rig had to be devised. Employing heavy bulbs enclosed in protective housings, the rig ensured that in the short time the test required, the bulbs would not overheat or be shattered by a shock wave. 55

The container-opening mechanism that eventually resulted from these vacuum tests was surely one of the oddest explosive devices ever contrived. The container was a sphere that opened at its equator into top and bottom hemispheres. The top half fit on the bottom half much like a lid fits snugly atop a kitchen pot. The joint between the two hemispheres, therefore, formed a sliding valve. The halves had to move apart an inch or two before the canister was actually open. It was in this joint between the hemispheres that the charge was placed.

The charge was incased in a soft metal tube that encircled the canister; in cross section, the tube had the shape of a sideways V. This shape concentrated the blast into a thin jet that shot out the mouth of the V. When the charge had been placed, Langley technicians fastened the hemispheres of the container together. Because even minimal pressure remaining inside the canister would be greater than that in space, the team had to take steps to prevent the canister from blowing apart too soon. The solution was to lace fishing line through eyelet holes in the hemispheres. When the explosive charge fired out, the resulting jet cut the lacing so that the container halves were free to separate. At the same time, pressure from the charge drove the hemispheres apart, releasing the balloon.

This ingenious arrangement proved successful despite its inelegance. So pleased were the Langley researchers with their invention that they were "somewhat taken aback" when visiting scientists and engineers, hearing descriptions of a container-opening mechanism involving such crazy things as a pot-lid sliding valve and a lacing made of fishing line, "thought we were joking." 56

As challenging as the opening of the satelloon container was, the problem of inflating the large satelloon without bursting it was even more vexing O'Sullivan once explained the crux of the matter: "When the satelloon container is opened to release the satelloon in the hard vacuum of space, any air inside the folded satelloon or outside of the satelloon between its....

[ 181 ]

A technician assigned to the Project Echo Task Group separates the two hemispheres of the Echo 1 container for inspection. The charge that freed the balloon was placed inside of a ring encircling the canister at its equator. L-64-6971

....folds tends to expand with explosive rapidity and rip the satelloon to pieces. But this understanding of the problem was not easily acquired, for there is no vacuum chamber on earth big enough and capable of attaining the hard vacuum of space, in which the ejection and complete inflation of the satelloon could be performed and the process photographed with high speed cameras to detect malfunctionings of the process." 57

Before risking the launch of a balloon into space, the Project Echo Task Group determined that it should first conduct a static inflation test on the ground to see whether the 100 foot-diameter satelloon would assume a spherical shape with surface conditions sufficient to serve as a passive communications relay satellite between two distant stations on the surface of the earth. To make the static inflation tests, Jesse Mitchell took a team of engineers to nearby Weeksville, North Carolina, off the north shore of the Albemarle Sound, where a cavernous navy blimp hangar big enough to inflate the Echo balloon to full size stood empty. The inflation process was slow, taking more than 12 hours, and thus did not offer a dynamic simulation of the explosive inflation that would take place in space; however, the results did reassure everyone that the balloon would work as a communication relay. As Norm Crabill, present at the Weeksville tests, explains, "It was another one of the tests we had to go through before we could trust the design." 58

These tests also demonstrated that the original balloon, manufactured by General Mills, was seriously defective. When the balloon was inflated in the hangar, the triangular panels, or gores, began coming apart at the seams.

[ 182 ]

L-58-3598 . L-B . . L-F L-58-3600 . Testing Echo 1's inflation (above) in the navy hangar at Weeksville took half the day but proved worth the trouble.

[ 183 ]

Langley engineers Edwin Kilgore (center), Norman Crabill (right), and an unidentified man take a peek inside the vast balloon during inflation tests. L-58-3603

The Echo 1 team stand in front of their balloon. William J. O'Sullivan is the tall man at center; Walter Bressette is to his left. L-61-4603

[ 184 ]

L-60-490 . L-60-485 . Langley technicians Will Taub and James Miller (left) prepare to spin-balance the final stage of the Shotput launch vehicle. The ABL X248 motor sits on the spin table; the balloon-containing canister is at the top. When the Shotput was fully prepared for launch (right), a pencil-shaped shroud was fitted over the payload.

Another manufacturer, the G. T. Schjeldahl Company of rural Northfield, Minnesota, had a glue perfect for sealing the seams, so General Mills hired the company to construct a second sphere. The proud Schjeldahl Company provided all subsequent inflatable spheres for NASA. 59

Although the ground testing proved critical, the only sure way to test the inflation process was to launch the sphere in its container up to satellite altitude. To do this, members of the Project Echo Task Group designed the special two-stage test rocket called "Shotput." This, they thought, was the perfect nickname for a vehicle that would essentially hurl a big ball out of the atmosphere.

Shotput's first stage was the Sergeant XM-33; its second stage was the ABL (Allegheny Ballistics Laboratory) X248. The latter also served as the third stage of the Douglas Thor-Delta, soon to be one of the United States' primary satellite launchers. Although the test program's main purpose was to check out the Echo satelloon, testing this part of the Thor-Delta became a critical secondary task. The ABL X248 stage included a solid-propellant rocket motor designed to achieve proper satellite velocity and altitude. The motor was spin-stabilized, so after it had burned out and the motor-satellite complex had entered orbit, the whole ensemble had to be de-spun before the satellite could be separated. To accomplish that, engineers fashioned a [ 185 ] weighted mechanism known as a "yo-yo," which stopped the spinning and allowed the container to separate safely. 60

Solving the problems of the launch vehicle was as difficult as solving the problems of the balloon. Norm Crabill traveled back and forth to Tulsa several times to understand the detailed design of the Delta third stage. (O'Sullivan once tried to remove Crabill from the project because he thought the young Langley engineer did not know enough to be in charge of the development of the Shotput test vehicle.) Crabill and his assistant Robert James intensely studied the forces and moments (i.e., the aerodynamic tendency to cause rotation about a point or axis) on the Shotput vehicle as it shot up and out of the atmosphere, spun its way to altitude, and despun for payload separation. The researchers had to assimilate in just a few months what amounted to an advanced course in aerodynamics and missile dynamics, but finally, after numerous analytical studies and simulations, Crabill and his helpers, one by one, solved the problems of launching Shotput 1.

A Burst Balloon

By the second Project Echo planning meeting, Langley had established a schedule for four Shotput tests. (Five Shotput launches would in fact occur; the last would take place on 31 May 1960.) Everyone inside NASA, including the interested parties at Goddard, agreed that the responsibility for managing Shotput and launching the vehicles from Wallops Island should remain in Langley's hands.

Unfortunately, keeping their brainchild at home did not assure total success. As described in this chapter's opening, the launch of Shotput 1 on 28 October 1959 started off well, but far above the "sensible" atmosphere, upon inflation, the big balloon blew Up. Instead of a respectable scientific experiment, Echo looked more like a Fourth of July skyrocket. 61

Despite the initial subterfuge of calling the test a success and omitting any mention of the balloon's explosion, the group's spokesmen finally confessed under pressure from the media and with great embarrassment, "that it was not supposed to work that way." For several weeks thereafter, everyone at Langley became an authority on inflatable satellites, telling O'Sullivan's associates (not daring to tell O'Sullivan himself, as he was known to have little charity for opinions contrary to his own) what had caused the explosion and how to fix it. Many of these "self-appointed experts" demanded to be heard. The Project Echo Task Group accommodated most of them, trying to keep in mind that "all of these people meant well and were trying to help." 62 Thereafter, NASA headquarters also announced the Shotput tests well ahead of time, so that everyone on the East Coast could watch and enjoy them. However, if everything went right with the balloon, the spectacular fireworks would not occur.

[ 186 ] A 500-inch focal-length photographic camera set up on the beach at Wallops Island had taken pictures of Shotput I as the balloon inflated and blew up, but even with these data a team from the Project Echo Task Group spent several weeks trying to confirm why the balloon had burst apart. Some researchers believed that the water used to help inflate the balloon had been the culprit. Like other volatile liquids, water will boil explosively in the zero pressure of space. It was "entirely conceivable that the elastic containers in which the water was carried inside the satellite might have leaked or ruptured during launch, and thus did not release the water at a slow and controlled rate as planned, to give a slow and gentle inflation." 63 Leaked water could easily have produced an explosion.

To ensure that the water inflation system would not malfunction in the future, the team, led by Walter Bressette, switched to benzoic acid, a solid material that underwent sublimation-that is, transformation from a solid state directly to a vapor. With such a material, conversion to a gas would be limited by the rate at which it would absorb heat from the sun. In essence, it would "gas off" slowly, not instantaneously.

Researchers worried that another contributor to the explosion may have been residual air, which the payload engineers had intentionally left inside the folds of the balloon as an inflation agent Langley's O'Sullivan once explained: "When the satelloon container is opened to release the satelloon in the hard vacuum of space, any air inside the folded satelloon or outside the satelloon between its folds tends to expand with explosive rapidity and rip the satelloon to pieces." 64 To remove all residual air from future deployments, the engineers made over 300 little holes in the balloon to allow the air to escape after the balloon was folded. Once the balloon was packed, the canister was placed, slightly open, in a vacuum tank. When its internal pressure had been reduced to near zero, the canister was closed, and an O-ring maintained the internal vacuum.

Finally, to better identify deployment problems, the engineers put a red fluorescent powder into the folded-up balloon. If the balloon ruptured during ejection or inflation in subsequent tests, the powder would blow out and leave a trail that could be instantly seen around the satellite even from the earth.

Four Shotputs were launched before the Langley researchers were satisfied that Echo would work. The second shot, on 16 January 1960, failed because of a problem with Crabill's beloved launch vehicle. The yo-yo despin system of the Shotput second stage did not deploy properly, and the payload separated from the burned-out second stage still spinning at 250 rpm. When the red dye appeared in the sky, it was clear that the de Spin failure had caused the balloon to tear while inflating. Following this test, no more serious problems with the launch vehicle occurred; there were only problems with the test balloon. On the third shot five weeks later, on 27 February, the balloon tore and developed a hole, although not before Bell Labs was able to use the sphere to transmit voice signals from its headquarters in Holmdel, New Jersey, to Lincoln Labs in Round Hill, Massachusetts.

[ 187 ] A successful shot took place on 1 April, but the tests were still incomplete as the satellite did not yet carry any of the tracking beacons that the final version would have. 65 (Because Echo's orbit would not be geostationary- hovering over the same spot on earth 24 hours a day-such devices were required to enable ground crews to track the balloon.)

The Project Echo Task Group, however, believed that "they were over the hump" and that the next step was to move beyond Shotput, put the completely equipped 100-foot passive reflector balloon on the Thor-Delta, and attempt a launch. The scheduled launch date of "TD No. 1" from Cape Canaveral was 13 May 1960, just over a month away. Unlike the Shotput tests, whose ABL X248 carried the test balloons only to 200 to 250 miles above the surface, the much more powerful 92-foot-high Thor-Delta would ultimately take the balloon to an orbit 1000 miles above the earth. From there, the enormous Echo would be visible to people all around the world. 66

"Anything's Possible!"

The Echo balloon was perhaps the most beautiful object ever to be put into space. The big and brilliant sphere had a 31,416-square foot surface of Mylar plastic covered smoothly with a mere 4 pounds of vapor-deposited aluminum. All told, counting 30 pounds of inflating chemicals and two 11-ounce, 3/8-inch-thick radio tracking beacons (packed with 70 solar cells and 5 storage batteries), the sphere weighed only 132 pounds.

For those enamored with its aesthetics, folding the beautiful balloon into its small container for packing into the nose cone of a Thor-Delta rocket was somewhat like folding a large Rembrandt canvas into a tiny square and taking it home from an art sale in one's wallet. However, the folding of the balloon posed more than aesthetic problems. The structure not only had to fit inside the spherical canister but also had to unfold properly for inflation.

The technique for folding the 100 foot inflatable balloons evolved from a classic "Eureka" moment. One morning in 1960, Ed Kilgore, the man in the Engineering Service Division responsible for the Shotput test setups, received a call from Schjeldahl, the manufacturer of the Echo balloons. The company's technicians were having a terrible time: not only were they unable to fit the balloon into its canister, they couldn't even squeeze it into a small room.

Kilgore mulled over the problem all day and part of the night, but it wasn't until the next morning that he happened upon a possible solution. "It was raining," he recalls, "and as I started to leave for work, my wife Ann arrived at the door to go out as I did. She had her plastic rain hat m her hand. It was folded in a long narrow strip and unfolded to a perfect hemisphere to fit the head." Recognizing the importance of his accidental discovery, Kilgore told his wife that she "would have to use an umbrella or get wet because I needed that rain hat." 67

[ 188 ] At Langley, Kilgore gave the hat to Austin McHatton, a talented technician in the East Model Shop, who had full-size models of its fold patterns constructed. Kilgore remembers that a "remarkable improvement in folding resulted." The Project Echo Task Group got workmen to construct a makeshift "clean" room from two by-four wood frames covered with plastic sheeting. In this room, which was 150 feet long and located in the large airplane hangar in the West Area, a small group of Langley technicians practiced folding the balloons for hundreds of hours until they discovered just the right sequence of steps by which to neatly fold and pack the balloon. For the big Echo balloons, this method was proof-tested in the Langley 60-foot vacuum tank as well as in the Shotput flights. 68

Whether the packed balloon would have deployed properly on 13 May 1961, no one will ever know because once again the launch vehicle failed. The second stage of the Delta refused to fire, and the whole rocket dropped into the Atlantic. The vehicle's manufacturer, Douglas, blamed a malfunctioning accelerometer. 69

By this point, the program had experienced a total of seven failures including those of the two small pre Echo test satelloons. For a test conducted on 31 May, the team returned to using the Shotput launcher. With tracking beacons aboard, the balloon deployed successfully, which helped the NASA engineers rally from their recent setback.

Still, critics continued to doubt the overall Echo concept. Some swore that even if the satelloon ever got up into space and inflated properly, micrometeorites would puncture its skin, thus destroying the balloon within hours. Not so, the Langley engineers countered. The idea was to pressurize the balloon just enough to overstress the material slightly, thus causing it to take on a permanent set. Even after its internal pressure had dwindled to nothing, the balloon would retain its shape. Because the outer skin was not extremely rigid-it was in engineering slang "dead-soft"-it could be punctured by a small meteorite and still not shatter. Finally, a study by Bressette showed that micrometeorites would erode less than one-millionth of the surface area a day. If only a launching and deployment would go right, the satelloon's sublimating solid-pressurization system would work long enough to enable engineers to conduct their communications experiment. 70

The next time around, the launch finally did go right. At 5:39 a.m. on 12 August 1960, Thor-Delta No. 2 blasted into the sky from launchpad 17 at Cape Canaveral, taking its balloon into orbit. A few minutes later, the balloon inflated perfectly. At 7:41 a.m., still on its first orbit, Echo 1 relayed its first message, reflecting a radio signal shot aloft from California to Bell Labs in New Jersey. "This is President Eisenhower speaking," the voice from space said. "This is one more significant step in the United States' program of space research and exploration being carried forward for peaceful purposes. The satellite balloon, which has reflected these words, may be used freely by any nation for similar experiments in its own interest." 71 After the presidential message, NASA used the balloon to [ 189 ] transmit two way telephone conversations between the east and west coasts. Then a signal was transmitted from the United States to France and another was sent in the opposite direction. During the first two weeks, the strength of the signal bounced off Echo I remained within one decibel of Langley's theoretical calculations.

The newspapers sounded the trumpets of success: "U.S. Takes Big Jump in Space Race"; "U.S. Orbits World's First Communications Satellite: Could Lead to New Marvels of Radio and TV Projection"; "Bright Satellite Shines Tonight." So eager was the American public to get a glimpse of the balloon that NASA released daily schedules telling when and where the sphere could be seen overhead. 72

For the engineers from Langley who were lucky enough to be at Cape Canaveral for the launch, this was a heady time. Norm Crabill remembers hearing the report that "Australia's got the beacon," meaning that the tracking station on that far-off continent had picked up the satellite's beacon signal. To this day, Crabill "gets goose bumps just thinking about that moment." He remembers thinking, "Anything's possible!" 73 After all, the space age had arrived, and in a sense, anything was.

Reflections

Out of the seven failures, including the scintillating bits of Shotput 1, NASA built a successful communications satellite program, which entranced the public. After a fully operational Echo balloon was launched into orbit on 12 August 1960, the big silver satelloon continued to orbit for eight years, not falling back to earth until May 1968. For that entire period, the satelloon served as a significant propaganda weapon for the United States. It was a popular symbol of the peaceful and practical uses of space research, especially in the early 1960s when the country still seemed so far behind the Soviets.

During its long sojourn in space, Echo I proved to be an exceptionally useful tool. First and foremost, by enabling numerous radio transmissions to be made between distant ground stations, it demonstrated the feasibility of a global communications system based on satellites. The rapid and successful development of worldwide communications in the 1960s depended upon this demonstration. Echo I also proved wrong the experts who said that the satelloon, after losing internal pressure because of meteoroid punctures, would collapse from external pressure. Echo actually retained its sphericity far longer than expected, the external pressures (including solar radiation) doing more to change the orbit of the satelloon than to collapse it. 74 In addition, NASA researchers studied the long-term durability of the unique metallized plastic of the Echo balloons (an Echo 2 was launched m 1964) in order to evaluate similar materials proposed for components of other spacecraft, including early versions of a manned space station.

[ 190 ] Finally, Echo permitted scientists to demonstrate a triangulation technique for determining the distance between various points on the earth's surface, thus improving mapping precision. The satelloon also served as a test target for the alignment and calibration of a number of new radars.

However, the Echo satelloon demonstrated some critical limitations. As it turned out, the balloon's shape was a poor passive reflector. When hit with a plane wave (a wave in which the wave fronts lay in a fixed line parallel to the direction of the propagation), the sphere tended to propagate the wave outward and reflect it as a divergent wave. Echo did an adequate job reflecting radio signals transmitted from the ground, but it did a poor job of focusing them. As a result, everybody received some of the reflected signal, but nobody received very much of it.

Thus, the Echo balloon served primarily as a demonstration model, showing how a simple passive comsat might work. For actual operations, a better concept, which NASA and the companies involved in the development of commercially viable satellites were already working on, was satellites that could communicate with active electronics. Because the force or intensity of a radio wave is weakened or attenuated by the square of the distance it must travel through space, an active communications system has a distinct advantage over the passive system: the active system receives the signal at one frequency and retransmits it at another. In effect, the signal travels the earth-to satellite distance only once; the signal in a passive system must travel the distance twice, and thus is more seriously attenuated, as the fourth power of the distance. 75

The demise of the passive satellite communication system and the emergence of the active communication system, however, also need to be explained in the context of broader economic, political, and institutional realities. In the beginning, satellite communications research was funded by the U.S. government because the military required worldwide instantaneous communications for national defense. The military was interested in the passive system because it could not be electronically jammed. On the other hand, the private telecommunications companies were not yet interested in a satellite communications system, partly because they were investing heavily in ground relay stations and under-the-ocean cable systems and partly because their engineers strongly suspected that radio signals passing through the earth's ionosphere would be seriously weakened in intensity.

In an ironic twist of fate, given the history that was to follow, the Echo balloon actually changed this thinking about the potential of a communications system in space. When Echo 1 demonstrated that the ionosphere was not going to be a problem in satellite communications, the private sector jumped on the bandwagon and demanded their own geosynchronous satellite system, but the private sector wanted an active rather than a passive system. Many of the companies involved had the technical knowledge to develop an active system, but this was not the sole reason for their interest; money was another factor. Individual companies could charge for sending a message [ 191 ] through the system since they would own the frequency channels located in the particular satellites. As Bressette comments, "The active communications people used the capitalistic approach for the success of a project: 'Does it make money?' On the other hand, the few people [like Bressette] who were promoting the passive system were thinking more democratically. Just think how inexpensive satellite communications would be today, if it were possible to replace all the active communications satellites with just three nonmaintenance passive satellites." 76

To overcome the problem of radio-wave attenuation from geosynchronous orbit, the Echo satelloon would need to be many times larger. Since the technology did not exist in the early 1960s to put such a large satelloon in orbit, even the military began to opt for the active system. Given the logistical difficulties and tremendous costs of flying high-altitude radio-relay stations over the oceans inside giant aircraft such as the B-52, the DOD was excited by the promise of a space-based geosynchronous system, which could move the high-altitude radar-relay flights into a backup position.

For its part, NASA Langley did not easily give up on the passive system. Between 1963 and 1965, in conjunction with Goodyear Aerospace Corporation, a team of Langley researchers performed a study showing that as little as a 10° segment cut from a very large sphere in geosynchronous orbit would be satisfactory for passive communications between two remote stations on earth. 77

William J. O'Sullivan's original concept for the inflatable satellite, which was to serve as an air-density experiment, was not forgotten. The long-term orbiting of the satelloon allowed scientists to measure accurately, for the first time, the density of the air in the far upper atmosphere. With the data came some important insights into the effects of solar pressure on the motion of satellites, information that was helpful in predicting the behavior and lifetime of future satellites. Several versions of the basic experiment were carried out at a high altitude over both low and high latitudes of the earth's surface as part of four Explorer missions: Explorer 9 in February 1961, Explorer 19 in December 1963, Explorer 24 in November 1964, and Explorer 39 in August 1968. NASA launched these satellites at regular intervals to provide continual coverage of density variation throughout a solar cycle. With the findings from these worthwhile missions, scientists were able to improve their measurements of atmospheric density, better understand variations in density caused by variations in the solar cycle, and study the MPD-related phenomena of geomagnetically trapped particles and their down-flux into the atmosphere. 78

O'Sullivan's 1956 concept led to not just a single experiment but an entire program of inflatable satellites, all of which involved Langley in some central way This program included, in addition to the Echo satelloons and the air-density Explorers, a Langley-managed passive geodetic satellite known as ''Pageos" (Passive Geodetic Earth-Orbiting Satellite)