To See the Unseen; A History of Planetary Radar Astronomy, NASA SP-4218
Washington DC: National Aeronautics and Space Administration, NASA History Office, 1996. Presumed First Edition, First printing. Hardcover. [4], xiii, [1], 301, [3] pages. Illustrations. Footnotes. Planetary Radar Astronomy Publications. A Note on Sources. Interviews. Technical Essay: Planetary Radar Astronomy. Abbreviations. For Further Reading. Index. About the Author. This is one of the NASA History Series. Dr. Butrica received his doctorate from the Iowa State University's History of Science and Technology program. He is a professional research historian and the author of numerous books and articles. He has been an invited lecturer at prestigious academic institutions and is a member of a number of professional bodies. The past 50 years prior to the publication of this work had brought forward a unique capability to conduct research and expand scientific knowledge of the Solar System through the use of radar to conduct planetary astronomy. This technology involves the aiming of a carefully controlled radio signal at a planet (or some other Solar System target, such as a planetary satellite, asteroid, or a ring system), detecting its echo, and analyzing the information that the echo carries. This capability has contributed to the scientific knowledge of the Solar System in two fundamental ways. Most directly, planetary radars can produce images of target surfaces otherwise hidden from sight and can furnish other kinds of information about target surface features. Radar also can provide highly accurate measurements of a target's rotational and orbital motions. Such measurements are obviously invaluable for the navigation of Solar System exploratory spacecraft, a principal activity of NASA since its inception in 1958. Planetary radar astronomy has not attracted the same level of public attention as, say, the Apollo or shuttle programs. 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. 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 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. 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. Condition: Very good / Very good.
Keywords: Radio Astronomy, Planetary Science, Arecibo Observatory, Deep Space Network, Donald Campbell, Richard Goldstein, Jodrell Bank, Gordon Pettengill, Radar, NASA, Spacecraft, Space Instrumentation
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