Beyond the Atmosphere: Early Years of Space Science

[327] The breadth of the field as it evolved was impressive. Among the disciplines to which space techniques were making important contributions were geodesy, meteorology, atmospheric and ionospheric physics, magnetospheric research, lunar and planetary science, solar studies, galactic astronomy, relativity and cosmology, and a number of the life sciences. [328] The assured role of space science in so many disciplines in the late 1960s was a source of considerable satisfaction to those who had pioneered the field, an ample justification of their early expectations.
But more significant was the strong coherence that had begun to develop among certain groups of space science disciplines. Perhaps the most profound impact of space science in its first decade was that exerted upon the earth sciences. Sounding rockets made it possible to measure atmospheric parameters and incident solar radiations at hitherto inaccessible altitudes and thus to solve problems of the atmosphere and ionosphere not previously tractable. Satellites added a perspective and a precision to geodesy not attainable with purely ground-based techniques. The improved precision laid a foundation for establishing a single worldwide geodetic network essential to cartographers who wished to position different geographic features accurately relative to each other. The new perspective gave clearer insights into the structure and gravitational field of the earth. These examples illustrate one of several ways in which space science was affecting the earth sciences; that is, making it possible to solve a number of previously insoluble problems.
Following James Van Allen's discovery of the earth's radiation belts one and the growing realization over the ensuing years that these were but aspect of a tremendously complex magnetosphere surrounding the earth, magnetospheric research blossomed into a vigorous new phase of geophysical research. This was a second way in which space science contributed to the earth sciences, opening up new areas of research.
But probably the most significant impact of space methods on geoscience was to exert a powerful integrating influence by breaking the field loose from a preoccupation with a single planet. When spacecraft made it possible to explore and investigate the moon and planets close at hand, among the most applicable techniques were those of the earth sciences, particularly those of geology, geophysics, and geochemistry on the one hand and of meteorology and upper atmospheric research on the other. No longer restricted to only one body of the solar system, scientists could begin to develop comparative planetology. Insights acquired from centuries of terrestrial research could be brought to bear on the investigation of the moon and planets, while new insights acquired from the study of the other planets could be turned back on the earth. Delving more deeply into the subject, one could hope to discern how the evolution of the planets and their satellites from the original solar nebula-it being generally accepted as and that the bodies of the solar system did originate in the cloud of gas and dust left over from the formation of the sun-could account for their similarities and differences.
The wide range of problems served to draw together workers from a number of disciplines. Astronomers found themselves working with geoscientists who came to dominate the field of planetary studies that had [329] once been the sole purview of the astronomers. Physicists found in the interplanetary medium and planetary magnetospheres a tremendous natural laboratory in which they could study magnetohydrodynamics free from the constraints encountered in the ground-based laboratory. Also known as hydromagnetics, this field was an extension of the discipline of hydrodynamics to fluids that were electrically charged (plasmas), particularly their interactions with embedded and external magnetic fields. The scientific importance of the field stemmed from the realization that immeasurably more of the matter in the universe was in the plasma state than in the solid, liquid, and gaseous states of our everyday experience. An outstanding practical value lay in the fact that magnetohydrodynamics was central to all schemes to develop nuclear fusion as a power source. Physicists also found the opportunity to conduct experiments on the scale of the solar system attractive for the study of relativity, and many of them began to devise definitive tests of the esoteric theories that were in existence. It is safe to say that this interdisciplinary partnership was a valuable stimulation to science in general.
The expanding perspective derived from space science was, in the author's view, the most important contribution of space methods to science in the first decade and a half of NASA's existence. While it was natural for individual scientists to concentrate attention on their individual problems, to those who took the time to assess progress across the board, the growing perspective was clearly evident even in the early years of the program. In a talk before the American Physical Society in April 1965, the author addressed himself to the growing impact of space on geophysics, which even then appeared much as described above.3 NASA managers in their presentations to the Congress began to emphasize the important perspectives afforded by space science. As a case in point, the spring 1967 defense of the NASA authorization request for fiscal 1968 described space science as embracing (1) exploration of the solar system and (2) investigation of the universe.4 Gathering the different space science disciplines into these two areas was not simply a matter of convenience. Rather it reflected a growing recognition of the broadening perspective of the subject, a point that was further developed by Leonard Jaffe and the author in a paper published in Science the following July.5 At the time it was much easier to treat of the impact of space science on the earth sciences, which already offered many examples. While it would probably take a number of decades to achieve a thorough development of the field of comparative planetology, with an appreciable number of missions to the moon and planets behind and more in prospect, the powerful new perspectives available to the geoscientists were quite clear.
As for astronomy-the investigation of the universe-the deeper significance of the impact of space science on the discipline appeared to be unfolding more slowly. To be sure, the most obvious benefit-that of [330] making it possible for the astronomer to observe all wavelengths that reached the top of the atmosphere, instead of being limited to only those that could reach the ground-began to accrue with the earliest sounding rockets that photographed the sun's spectrum in the hitherto hidden ultraviolet wavelengths. This benefit grew steadily with each additional sounding rocket or satellite providing observations of the sun and galaxy in ultraviolet, x-ray, and gamma-ray wavelengths. The value of these previously unobtainable data was inestimable. But in the long run, a deeper, more significant impact of space methods on astronomy could be expected, as Prof. Leo Goldberg and others pointed out: the advent of a much more powerful means of working between theory and experiment than had ever existed before.
At one time the author tried to persuade the House Subcommittee on Space Science and Applications that, as far as the origin and evolution of natural objects were concerned, the scientist knew more about the stars than about the earth. The statement was intentionally phrased in a provocative fashion to get attention, which it did. The Congressmen reacted immediately in disbelief, and it took quite a bit of discussion to develop the point, which went as follows.
Certainly men living on the earth, as they do, had been able to amass volumes and volumes of data on the earth's atmosphere, oceans, rocks, and minerals of a kind and in a detail that could not be assembled for a remote star. But, when it came to the question of just when, where, and how the earth formed and began to evolve many billions of years ago, the scientist was limited to a study of just one planet-the earth itself. From an investigation of that one body and whatever he could decipher of its origin and evolution, he had to try to discern the general processes that entered into the birth and evolution of planets in general. Only in such a broad context could the scientist feel satisfied that he really understood any individual case. Having only the earth to study, he was greatly hampered.
For the stars, however, the astronomer had the galaxy containing 100 billion stars to observe, and billions of other galaxies of comparable size. In that vast array the astronomer could find, for any object he might want to study, examples at any stage of evolution from birth to demise. With such a display before him in the heavens, the astronomer could proceed to develop a theory of stellar formation and evolution and test the theory against what he observed. In such an interplay between theory and observation the theorists did develop a remarkable explanation of the birth, evolution, and demise of stars.6 So, in this sense, the astronomer could claim to understand more about the stars than the earth scientist did about the earth.
But there was a shortcoming in this theoretical process. The theory was based on observations of those wavelengths that could reach the [331] ground-mostly visible, with a little in the ultraviolet and infrared, and after World War II critical observations in some radio wavelengths. Yet hat very theory predicted that vitally important stellar phenomena would be manifested in the emission of wavelengths that the astronomer could not yet see. The early formation of a star from a cloud of gas and dust that was beginning to aggregate into a ball would be revealed primarily in the infrared as gravitational pressures caused the material to heat up. At the other end of the spectrum very hot stars would be emitting mostly in wavelengths shorter than the visible, presumably mostly in the ultraviolet. Little attention was paid to x-rays or gamma rays, yet among the most important discoveries of space science have been x-ray emissions from the sun and more than a hundred stellar sources.7 Here is where the most profound impact of space science upon astronomy could be expected in the decades ahead. just as the new-found ability to study other planetary bodies than the earth immeasurably broadened the perspectives of the earth sciences, so the ability of the astronomer to observe in all the wavelengths that reached the vicinity of the earth could be expected to strengthen the interplay between theory and experiment in the field of astronomy. By the 1970s the process had already begun, but the full power would doubtless have to wait until astronomers had the benefit of a variety of satellites more powerful than the solar and astronomical satellites of the first decade. In addition to large, precise optical telescopes, which one naturally thought of in the 1950s and early 1960s, there would also have to be specially instrumented spacecraft to pursue the new field of "high-energy astronomy" which leapt into prominence with the early discovery of x-ray sources. One would also need both infrared and radio telescopes in orbit. In short, to make the most of the opportunity that had burst upon the astronomical community, there would have to be established in orbit a rather complete facility consisting not just of a single instrument, but of a set of instruments ranging across the whole observable spectrum.
As for the life sciences, space appeared able to contribute in a variety of ways. One could expose biological specimens-including the crews of manned spacecraft-to the environment of space and observe what happened. But the biologists agreed that the most significant contribution of space science to their discipline could well be in exobiology-the study of extraterrestrial life and the chemical evolution of planets.8 This subject was subsumed under the study of the solar system, since the evolutional histories of the planets, the kinds of conditions they developed on their surfaces and in their atmospheres, would have much to do with whether life formed on the planet, or with how far a lifeless planet moved toward the formation of life.
Thus, as one moved into the 1970s, although space scientists could take much satisfaction in the wide variety of individual disciplines to [332] which they had been able to contribute, it was the new perspective that brought groups of disciplines together in a common endeavor that was most important.