SP-4218 To See the Unseen


- Introduction -



[vii] Planetary radar astronomy has not attracted the same level of public attention as, say, the Apollo or shuttle programs. In fact, few individuals outside those scientific communities concerned with planetary studies are aware of its existence as an ongoing scientific endeavor. Yet, planetary radar has contributed fundamentally and significantly to our knowledge of the solar system.

As early as the 1940s, radar revealed that meteors are part of the solar system. After the first detections of Venus in 1961, radar astronomers refined the value of the astronomical unit, the basic yardstick for measuring the solar system, which the International Astronomical Union adopted in 1964, and they discovered the rotational rate and direction of Venus for the first time. Next, radar astronomers determined the correct orbital period of Mercury and calculated an accurate value for the radius of Venus, a measurement that Soviet and American spacecraft had failed to make reliably. Surprisingly, radar studies of Saturn revealed that its rings were not swarms of minute particles, but rather consisted of icy chunks several centimeters or more in diameter. Planetary radar also provided further proof of Albert Einstein's theory of General Relativity, as well as the "dirty snowball" theory of comets. The only images of Venus' surface available to researchers are those made from radar observations. The ability of planetary radar astronomy to characterize the surfaces of distant bodies has advanced our general knowledge of the topography and geology of the terrestrial planets, the Galilean moons of Jupiter, and the asteroids. The Viking project staff utilized radar data to select potential landing sites on Mars. More recently, radar revealed the surprising presence of ice on Mercury and furnished the first three-dimensional images of an asteroid.

Again, these achievements seldom have attracted the attention of the media. The initial American radar detections of the Moon in 1946 and of Venus in 1961 attracted notice in daily newspapers, weekly news magazines, news reels, and cartoons. Only in recent years have the accomplishments of radar astronomy returned to the front-page of the news. The images of Venus sent back by Magellan received full media coverage, and images of the asteroid Toutatis appeared on the front-page of the New York Times.

Planetary radar astronomy has shared its anonymity with other applications of radar to space research. The NASA radar-equipped SEASAT satellite provided unprecedented images of Earth's oceans; European, Canadian, end Japanese satellites, as well as a number of space shuttles, have imaged Earth with radar. The radars of NASA's Deep Space Network also have played a major role in tracking space launches and spacecraft on route to planets as distant as Saturn and Neptune. Among the more down-to-Earth, visible and even pervasive applications of radar are those for air traffic control and navigation, the surveillance of automobile traffic speeds, and the imaging of weather patterns reported daily on television and radio.

Planetary radar astronomy is part of the great wave of progress in solid-state and digital electronics that has marked the second half of the twentieth century. For instance, the earliest planetary radar experiment marked the first use of a maser (a solid-state microwave amplifying device) outside the laboratory. Although radio astronomy has long claimed the first maser application for itself, namely in April 1958 by Columbia University and the Naval Research Laboratory, two months earlier, MIT's Lincoln Laboratory used a maser in its first attempt to bounce radar waves off Venus. The same radar experiment also saw [viii] one of the first uses of a digital tape recorder, as well as the incorporation of a digital computer and other digital data processing equipment into a civilian radar system.

The origins of this solid-state and digital electronics progress, as well as of planetary radar astronomy, are rooted in electronic research and development that started as early as the 1930s. The first radar astronomy experiments, which were carried out on meteors and the Moon in the 1940s, relied on equipment designed and built for military defense during World War II and were based on research conducted during the 1930s.

Planetary radar astronomy, and so too radar itself, had its origins in Big Science. British war preparations during the 1930s concentrated large amounts of scientific, technological, financial, and human resources into a single effort. Part of that effort was a massive radar research and development program that produced an impressive range of defensive and offensive radars. In a secret mission known only at the highest levels of government, Britain gave the United States one of the key devices born of that large-scale radar effort, the magnetron. In turn, the magnetron formed the technological base for an American radar research and development effort on a scale equal to that of the Manhattan Project, which historians traditionally have recognized as the beginning of Big Science.

The history of planetary radar astronomy in the United States is the history of Big Science. Without Big Science, planetary radar astronomy would be impossible and unthinkable. That is one of the main contentions of this book. The radar astronomy experiments of the 1940s and 1950s, as well as much of pre-war radar development, were intimately linked to ionospheric research, which was then undergoing a rapid publication rate typical of Big Science.

Also, the evolutions of planetary radar and radio astronomy converged. The search for research instruments free of military constraints brought planetary radar astronomers closer to radio astronomy during the 1960s, a time when radio astronomy was undergoing a rapid growth that transformed it into Big Science. Planetary radar and radio astronomy shared instruments and a common interest in electronic hardware and techniques, though ironically the instrumentation needs of the two communities ultimately provided little basis for cohabitation.

In the end, military Big Science was far more important than either radio astronomy or ionospheric science. Planetary radar astronomy emerged in the late 1950s thanks to Cold War defense research that furnished the essential instruments of planetary radar experimentation. The vulnerability of the United States to aircraft and ICBM attacks with nuclear explosives necessitated the creation of a network of ever more powerful and sensitive defensive radars. What President Dwight D. Eisenhower called the military-industrial complex, and what historian Stuart Leslie calls the military-industrial-academic complex,1 provided the radar instrument for the first attempts at Venus. The military-industrial or military-industrial-academic complex served as the social matrix which nurtured military and other Big Science research. Planetary radar astronomy eventually found itself part of a different, though at times interlocking, complex centered on the civilian enterprise to explore space, that is, what one might call the NASA-industrial-academic complex.

[ix] The emergence of space as Big Science under the financial and institutional aegis of NASA, and the design and construction of a worldwide network of antennas to track launches and communicate with spacecraft, furnished instruments for planetary radar research as early as 1961. Within a decade, NASA became the de facto underwriter of all planetary radar astronomy. Data on the nature of planetary surface features and precise reckoning of both the astronomical unit and planetary orbits were highly valuable to an institution whose primary goal was (and whose budgetary bulk paid for) the designing, building, and launching of vessels for the exploration of the solar system. Association with NASA Big Science enhanced the tendency of radar astronomers to emphasize the utility of their research and promoted mission-oriented, as opposed to basic, research.

The history of planetary radar astronomy is intrinsically interesting and forms the framework of this book. It also says something about Big Science. Defining Big Science, or even Little Science, is not easy though. After all, how true are the images of the Little Scientist as "the lone, long-haired genius, moldering in an attic or basement workshop, despised by society as a nonconformist, existing in a state of near poverty, motivated by the flame burning within him," and the Big Scientist as "honored in Washington, sought after by all the research corporations of the 'Boston ring road,' part of an elite intellectual brotherhood of co-workers, arbiters of political as well as technological destiny"?2

Since the publication in 1963 of Derek J. De Solla Price's ground-breaking Little Science, Big Science, historians have attempted to define Big Science.3 Their considerable efforts have clarified the meaning of the term, though without producing a universally authoritative definition. If large-scale expensive research instruments are the measure, then one might count the island observatory of Tycho Brahe in the sixteenth century, or the giant electrical machines built in eighteenth-century Holland. If Big Science is a large grouping of investigators from several disciplines working together on a common project, then the gathering of mathematicians, chemists, and physicists at Thomas Edison's West Orange laboratory was Big Science. A long-term research project, such as the quest for an AIDS cure, or one that entails elaborate organization, such as the Manhattan Project, might be termed Big Science too.

Defining Big Science is the intellectual equivalent of trying to nail Jell-O to the wall. For the purposes of this book, we shall call Big Science the large-scale organization of science and scientists, underwritten by an imposing pledge of (usually) public funds and centered around a complex scientific instrument. In his search to understand Big Science, Derek Price decided to "turn the tools of science on itself," charting the historical growth of science by means of a variety of statistical indicators obtained from the Institute for Scientific Information in Philadelphia. Price concluded that scientific activity (as measured by the amount of literature published) has grown exponentially over the last three hundred years, doubling in size about every fifteen years.4 We also shall define a rapid growth in scientific literature greater than the Price rate (doubling every fifteen years) as indicating [x] an emerging Big Science field. Whatever it is, Big Science has become the dominant form of contemporary American science. Moreover, because of its scale and scope, the conduct of Big Science necessarily intrudes into many areas of society, and in turn, society, through political, economic, and other activity, shapes the conduct of Big Science.

The interdependency of institutional factors, funding patterns, science, technology, and techniques found in Big Science has been the subject of extensive study by historians and sociologists of science and technology. Scholars traditionally have concerned themselves with both science and technology and their interactions. Such studies came to be termed "internalist," meaning that they dealt solely with the inner workings of science and technology. In contrast stood the so-called "externalist" approaches, which emphasized the social, economic, political, and other factors neglected by the "internalists."

Starting around 1980, sociologists of science, such as Michel Callon, developed new approaches, which were introduced into the history of technology by Thomas P. Hughes. These new approaches came to be called generically the "social construction of technology." The "technosocial networks" of Callon and the "systems" of Hughes consider the "internalist" and "externalist" aspects of technology as constituting a single continuum or "seamless web". Inventors, scientists, instruments, financing, institutions, politics, laws, and so forth are all equally part of the "technosocial network" or "system".5

The chief advantage of replacing the "internalist" and "externalist" dualism with the unitarian approach of the social construction school is the more sophisticated and certainly more complex view of the scientific, technical, economic, political, institutional, legal, and other aspects of Big Science that it offers. Moreover, by stressing that all components of a technosocial network are equal and necessary, the social construction approach dissuades us from emphasizing any one factor, "internal" or "external", over all others.

The social construction approach is useful for creating a taxonomy of the factors that shape Big Science. Nonetheless, although they served as a guiding principle in the writing of this book, social construction case studies do not go far enough; they fail to address the question that is, after chronicling the achievements of radar astronomy, central to this book-namely the conduct of Little Science in the context of Big Science. Furthermore, in all the discussions of Big Science, with few exceptions, the symbiotic relationship between Big Science and Little Science has been overlooked. This relationship is especially relevant to the organization of science within NASA space missions. The scientists who conduct experiments from those spacecraft typify Little Science: they work individually or in small collaborative groups, often with graduate assistants, and have relatively small budgets and limited laboratory equipment. Participation in NASA spacecraft missions induces these Little Scientists to function as part of a Big Science endeavor. The scientists are organized into both working groups around a single scientific instrument and disciplinary groups. They participate in the design of experiments and in [xi] the decisions to drop or modify certain experiments, as well as in the design of the instruments themselves. The overall scale of operation and budget is beyond that normally encountered by Little Scientists.

One noteworthy exception to the lack of literature dealing with the relationship between Big Science and Little Science is historian John Krige's study of British nuclear physics research in the period immediately following World War II. The Labor Government of Clement Attlee set out to equip the universities of Birmingham, Glasgow, Liverpool, Cambridge, and Oxford with particle accelerators for conducting high-energy nuclear physics research. The accelerator program involved the kinds of large-scale budgets and instruments that typify Big Science; however, research was conducted in a manner more typical of Little Science. Large multidisciplinary teams, in which physicists and engineers rubbed shoulders, did not form; rather the physicists remained individual academic researchers.6

Krige's case of "Big Equipment but not Big Science" finds its parallel in planetary radar astronomy. Big Science was the sine qua non of planetary radar astronomy, but planetary radar astronomy was not Big Science. It was, and remains, Little Science in terms of manpower, instruments, budget, and publications. Planetary radar astronomy took root within the interstices of Big Science, but rather than expand over time, it actually shrank.

The field attained its largest size, in terms of personnel, instruments, and publications, during the 1960s. Although one can count five active instruments between 1961 and 1964, the greatest number to ever carry out planetary radar experiments, only three subsequently sustained active research programs. That number fell to two instruments after 1975. For much of the period between 1978 and 1986, only one instrument, indeed the only instrument to have an established and secure planetary radar astronomy research program, the Arecibo Observatory, was steadily active.

The number of active planetary radar astronomers has declined since the 1960s too. As a group, they tend not to reproduce as easily or as abundantly as other scientists, and many practitioners in the long run find something else to do. Two paths-artifacts of the field's evolution-lead to a career in planetary radar astronomy. Many follow the traditional university path-doctoral research on a planetary radar topic, followed by a research position that permits them to perform planetary radar experiments. Of the current practitioners, the most recent Ph.D. was granted in 1994, the second most recent in 1978. The path more followed: practitioners were hired to conduct planetary radar experiments.

The declining instrument and manpower numbers are reflected in the planetary radar astronomy publication record (see Appendix: Planetary Radar Astronomy Publications). Price has shown that science publications have doubled about every fifteen years over the last three centuries. The planetary radar publication curve differs markedly from that normal growth pattern, suggesting a ceiling condition that has limited growth. The nature of that ceiling condition, as well as the causal factors for the declining size of the planetary radar enterprise, are part of the story of how planetary radar Little Science has been conducted within the framework of American Big Science. The association of planetary radar [xii] Little Science with NASA Big Science ultimately affected the conduct of planetary radar astronomy. Radar astronomers always had argued the utility of their efforts for space research; NASA mission-oriented support of planetary radar astronomy only reinforced that utilitarian inclination. As the story unfolds, other factors that shaped and amplified the utilitarian tendency of radar astronomers will rise to the surface.

Its relationship with NASA Big Science also transformed planetary radar astronomy from an exclusively ground-based scientific activity to one that was conducted in space as well. During the 1960s, planetary radar astronomers distinguished their ground-based research from that conducted from spacecraft, which they characterized as space exploration as opposed to astronomy. Starting in the following decade, when NASA became its sole underwriter, planetary radar astronomy began to engage the planetary geology community largely through its ability to image and otherwise characterize planetary surfaces. NASA funded specific radar imaging projects. At the same time, NASA began planning two missions to Venus, Pioneer Venus and Magellan, in order to capture in radar images the features of that planet's surface. Its opaque atmosphere keeps Venus's surface hidden from sight and bars exploration with optical methods.

Pioneer Venus and Magellan ultimately had a profound impact on the practice of planetary radar astronomy. In addition to enlarging the community of scientists using radar imagery and other data to encompass both geologists and astronomers, those two NASA missions erased the turf boundary between space exploration and ground-based planetary radar astronomy. Although Magellan in particular also gave radar astronomers a taste of Big Science, planetary radar astronomy did not permanently shift from Little to Big Science. Radar imaging from a spacecraft had limited prospects. Ultimately, the greatest consequence of Magellan for planetary radar astronomy was that it effectively ended ground-based radar observations of Venus, the chief object of radar research.

The plan of this book is to relate the history of planetary radar astronomy from its origins in radar to the present day and secondarily to bring to light that history as a case of "Big Equipment but not Big Science". Chapter One sketches the emergence of radar astronomy as an ongoing scientific activity at Jodrell Bank, where radar research revealed that meteors were part of the solar system. The chief Big Science driving early radar astronomy experiments was ionospheric research. Chapter Two links the Cold War and the Space Race to the first radar experiments attempted on planetary targets, while recounting the initial achievements of planetary radar, namely, the refinement of the astronomical unit and the rotational rate and direction of Venus.

Chapter Three discusses early attempts to organize radar astronomy and the efforts at MIT's Lincoln Laboratory, in conjunction with Harvard radio astronomers, to acquire antenna time unfettered by military priorities. Here, the chief Big Science influencing the development of planetary radar astronomy was radio astronomy. Chapter Four spotlights the evolution of planetary radar astronomy at the Jet Propulsion Laboratory, a NASA facility, at Cornell University's Arecibo Observatory, and at Jodrell Bank. A congeries of funding from the military, the National Science Foundation, and finally NASA marked that evolution, which culminated in planetary radar astronomy finding a single Big Science patron, NASA.

Chapter Five analyzes planetary radar astronomy as a science using the theoretical framework provided by philosopher of science Thomas Kuhn. Chapter Six explores the shift in [xiii] planetary radar astronomy beginning in the 1970s that resulted from its financial and institutional relationship with NASA Big Science. This shift saw the field 1) transform from an exclusively ground-based scientific activity to one conducted in space, as well as on Earth, and 2) capture the interest of planetary scientists from both the astronomy and geology communities. Chapter Seven relates how the Magellan mission was the culmination of this evolution. Chapters Eight and Nine discuss the research carried out at ground-based facilities by this transformed planetary radar astronomy, as well as the upgrading of the Arecibo and Goldstone radars.

The conclusion serves a dual purpose. It responds to the concern for the future of planetary radar astronomy expressed by many of the practitioners interviewed for this book, as well as to the author's wish to provide a slice of applied history that might be of value to both radar astronomers and policy makers. The conclusion also appraises planetary radar as a case of "Big Equipment but not Big Science". It considers the factors that have limited the size of planetary radar, its utilitarian nature, and its dependency on large-scale technological enterprises.

A technical essay appended to this book provides an overview of planetary radar techniques, especially range-Doppler mapping, for the general reader. Furthermore, the text itself explains certain, though not all, technical aspects of radar astronomy. The author assumed that the reader would have a familiarity with general technical and scientific terminology or would have access to a scientific dictionary or encyclopedia. For those readers seeking additional, and especially more technically-oriented, information on planetary radar astronomy, the technical essay includes a list of articles on the topic written by radar practitioners.



1. Stuart W. Leslie, The Cold War and American Science: The Military-lndustrial-Academic Complex at MIT and Stanford (New York: Columbia University Press, 1993).

2. Derek J. DeSolla Price, Little Science, Big Science... and Beyond (New York: Columbia University Press, 1986), p. 2.

3. Price, Little Science Big, Science... and Beyond, p. 15.

4. Price, Little Science, Big Science (New York: Columbia University Press, 1963). This discussion of Big Science draws on Peter Galison and Bruce Hevly, eds., Big Science: The Growth of Large-Scale Research (Stanford: Stanford University Press, 1992); James H. Capshaw and Karen A. Rader, "Big Science: Price to the Present," Osiris, ser. 2, vol. 7 ( 1992): 3-25; and Joel Genuth, "Microwave Radar, the Atomic Bomb, and the Background to U.S. Research Priorities in World War II," Science, Technology, and Human Values 13 (1988): 276-289.

5. For a discussion of this evolution, see John M. Staudenmaier, "Recent Trends in the History of Technology," The American Historical Review 95 (1990): 715-725, as well as Hughes, "The Seamless Web: Technology, Science, Etcetera, Etcetera," Social Studies of Science 16 (1986): 281-292. The primary social construction works are Wiebe E. Bijker, Hughes, and Trevor Pinch, eds., The Social Construction of Technological Systems: New Directions in the Sociology and History of Technology (Cambridge: MIT Press, 1987), and Bijker and John Law, eds., Shaping Technology/Building Society: Studies in Sociotechnical Change (Cambridge: MIT Press, 1992).

6. John Krige, "The Installation of High-Energy Accelerators in Britain after the War: Big Equipment but not 'Big Science,'" in Michelangelo De Maria, Mario Grilli, and Fabio Sebastiani, eds., The Restructuring of Physical Sciences in Europe and the United States, 1945-1960 (Teaneck, NJ: World Scientific, 1989), pp. 488-501.