The fixed ground stations used for experiments by government, academic, and commercial entities used reflector-based offset-fed antenna systems with antennas ranging in size from 0.35 to 3.4 m in diameter. Gateway Earth stations included two systems referred to as the NASA Ground Station (NGS) and the Link Evaluation Terminal (LET).
Radiometric Tracking Techniques for Deep-Space Navigation focuses on a broad array of technologies and concepts developed over the last four decades to support radio navigation on interplanetary spacecraft. In addition to an overview of Earth-based radio navigation techniques, the book includes a simplified conceptual presentation of each radiometric measurement type, its information content, and the expected measeurement accuracy. The methods described for both aquiring and calibrating radiometric measurements also provide a robust system to support guidance and navigation for future robotic space exploration.
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The challenge of communication in planetary exploration has been unusual. The guidance and control of spacecraft depend on reliable communication. Scientific data returned to earth are irreplaceable, or replaceable only at the cost of another mission. In deep space, communications propagation is good, relative to terrestrial communications, and there is an opportunity to press toward the mathematical limit of microwave communication. Yet the limits must be approached warily, with reliability as well as channel capacity in mind. Further, the effects of small changes in the earth's atmosphere and the interplanetary plasma have small but important effects on propagation time and hence on the measurement of distance. Advances are almost incredible. Communication capability measured in 18 bits per second at a given range rose by a factor of 10 in the 19 years from Explorer I of 1958 to Voyager of 1977. This improvement was attained through ingenious design based on the sort of penetrating analysis set forth in this book by engineers who took part in a highly detailed and amazingly successful pro gram. Careful observation and analysis have told us much about limitations on the accurate measurement of distance. It is not easy to get busy people to tell others clearly and in detail how they have solved important problems. Joseph H. Yuen and the other contribu tors to this book are to be commended for the time and care they have devoted to explicating one vital aspect of a great adventure of mankind.
An important historical look at the space program's evolvingtelecommunications systems Large Antennas of the Deep Space Network traces the development ofthe antennas of NASA's Deep Space Network (DSN) from the network'sinception in 1958 to the present. It details the evolution of thelarge parabolic dish antennas, from the initial 26-m operation atL-band (960 MHz) through the current Ka-band (32 GHz) systems.Primarily used for telecommunications, these antennas also supportradar and radio astronomy observations in the exploration of thesolar system and the universe. In addition, the author also offersthorough treatment of the analytical and measurement techniquesused in design and performance assessment. Large Antennas of the Deep Space Network represents a vitaladdition to the literature in that it includes NASA-funded researchthat significantly impacts on deep space telecommunications. Partof the prestigious JPL Deep Space Communications and NavigationSeries, it captures fundamental principles and practices developedduring decades of deep space exploration, providing informationthat will enable antenna professionals to replicate radiofrequencies and optics designs. Designed as an introduction for students in the field as well as areference for advanced practitioners, the text assumes a basicfamiliarity with engineering and mathematical concepts andtechnical terms. The Deep Space Communications and Navigation Series is authored byscientists and engineers with extensive experience in astronautics,communications, and related fields. It lays the foundation forinnovation in the areas of deep space navigation and communicationsby disseminating state-of-the-art knowledge in key technologies.
