Spacecraft Charging at Geosynchronous Altitudes


Book Description

Spacecraft charging threatens to disable spacecraft components and adversely impact any satellite function. Electrostatic charge, and especially discharge, can hinder the proper operation of, or destroy, spacecraft components, thereby rendering the spacecraft ineffective or inoperative. The level of charging is dependent on the particle energy (speed) distribution. Current spacecraft design and material provide limited protection against the dangers of electrostatic discharge, and active measures such as beam emission are also employed.




High-Level Spacecraft Charging at Geosynchronous Altitudes: A Statistical Study


Book Description

We present the results of a statistical study on high-level spacecraft charging at geosynchronous altitudes. Below the critical temperature T ̂for a surface material, no spacecraft charging occurs. The spacecraft charging potential data are obtained from the ion line of the ion energy spectrum. If the ion line can not be clearly identified, the data point is flagged and not used in our analysis. Since T ̂depends on the surface material and since each satellite has its own surface material or materials, each satellite is expected to have its own critical temperature. The coordinated space environmental parameter data of the Los Alamos National Laboratory (LANL) include spacecraft charging data measured on several geosynchronous satellites in eclipses and in sunlight over years. We have obtained statistical results of T ̂for each satellite studied and found that, beyond T, ̂ the high-level spacecraft potential increases almost linearly with the ambient electron temperature. Amazingly, the critical temperature in sunlight remains the same as in eclipse, agreeing with the monopole-dipole differential charging model. This work offers a useful method not only for predicting the onset of spacecraft charging in eclipse and in sunlight but also for predicting high-level spacecraft charging potential with reasonable accuracy at any given ambient electron temperature in the geosynchronous environment.




High-level Spacecraft Charging Environments Near Geosynchronous Orbit


Book Description

High-level spacecraft charging events in sunlight are discussed and statistically analyzed to determine environmental parameters critical to charging and the region of space near geosynchronous altitude where charging occurs. Significant levels of spacecraft charging are shown to occur only between 1900 LT and 0900 LT at any altitude or latitude of the SCATHA satellite orbit. High-level charging is shown to occur only during periods when the magnetic activity index is 2+ or greater. Distribution functions of energetic electrons and ions are presented for 3 high-level charging periods on days 114, 241 and 363, 1979. Moments of the distribution functions are determined, and fitting techniques used to derive two-Maxwellian densities and temperatures are discussed. Results are provided in a format usable in satellite design specifications.




High-Level Spacecraft Charging in Eclipse at Geosynchronous Altitudes: A Statistical Study


Book Description

We present the results of a statistical study on high-level (above -200V in magnitude) negative-voltage spacecraft charging in eclipse at geosynchronous altitudes. Theoretically, there exists a critical temperature T* for a surface material. Below T*, no spacecraft charging occurs. Since T* depends on the surface material, which differs from satellite to satellite, each is expected to have its own critical temperature. The theoretical results are compared with the coordinated space-environmental parameter data obtained by the Los Alamos National Laboratory (LANL) geosynchronous satellites. The LANL data include spacecraft charging events measured on several geosynchronous satellites, in eclipse and in sunlight, over several years. We have found a nearly linear trend, or better described by a quadratic one, between the spacecraft potential and the ambient electron temperature for potentials below in magnitude of about -5kV. Extrapolation of the linear trend to zero volts shows an intercept at a finite temperature which agrees reasonably well with the critical temperature predicted by theory. The existence of a critical electron temperature is useful for informing decision and operational support of geosynchronous spacecraft with enhanced knowledge.




Spacecraft Charging at Geosynchronous Orbit


Book Description

Rapid variations in spacecraft potential are observed on entry and exit from the earth's shadow. Generalized equations, based on elementary plasma probe theory, are developed which make quantitative estimates of these potentials as a function of satellite position in the earth's penumbra, and are compared with data from the ATS-5 and ATS-6 geosynchronous satellites. The agreement between the observations and the predictions results from the approximate constancy of the ratio of the ambient ion to electron current during injection events. Due to the significant size and shape differences of the ATS-5 and ATS-6 satellites, the results are applicable in many space physics situations such as estimating the effects of electron beams on satellite potential and of spacecraft charging on very large space structures. (Author).




Fundamentals of Spacecraft Charging


Book Description

As commercial and military spacecraft become more important to the world's economy and defense, and as new scientific and exploratory missions are launched into space, the need for a single comprehensive resource on spacecraft charging becomes increasingly critical. Fundamentals of Spacecraft Charging is the first and only textbook to bring together all the necessary concepts and equations for a complete understanding of the subject. Written by one of the field's leading authorities, this essential reference enables readers to fully grasp the newest ideas and underlying physical mechanisms related to the electrostatic charging of spacecraft in the space environment. Assuming that readers may have little or no background in this area, this complete textbook covers all aspects of the field. The coverage is detailed and thorough, and topics range from secondary and backscattered electrons, spacecraft charging in Maxwellian plasmas, effective mitigation techniques, and potential wells and barriers to operational anomalies, meteors, and neutral gas release. Significant equations are derived from first principles, and abundant examples, exercises, figures, illustrations, and tables are furnished to facilitate comprehension. Fundamentals of Spacecraft Charging is the definitive reference on the physics of spacecraft charging and is suitable for advanced undergraduates, graduate-level students, and professional space researchers.




Proceedings of the Spacecraft Charging Technology Conference


Book Description

A Spacecraft Charging Technology Conference, sponsored by the USAF and NASA, was held in October 1976. The Proceedings contain over 50 papers dealing with subjects including: (1) the geosynchronous plasma environment, (2) spacecraft modeling, (3) spacecraft materials characterization, (4) spacecraft materials development, (5) satellite design and test. In addition, an executive summary and the transcript of a panel discussion are included. (Author).




Large Space Structure Charging During Eclipse Passage


Book Description

Much work has been developed to the study of the differential charging of geosynchronous spacecraft, primarily that charging caused by injection events and uneven illumination of isolated surfaces. However, as the lack of illumination in the penumbra eliminates the latter problem, little attention has been paid to charging during eclipse passage. For a sufficiently large structure (length greater than 1 km), the gradient of illumination in the penumbra is large enough to contribute significantly to differential charging. In this paper, three main subjects will be discussed: (1) the causes of charging at geosynchronous altitudes; (2) a simple model of the plasma from which the differential charging equations can be derived; and (3) the results of a computer program based on these equations, together with several theoretically fit sets of equations to approximate the results. (Author).




Physics of Satellite Surface Charging


Book Description

This book will explore the fundamentals of spacecraft charging: why it occurs, when it occurs, where it occurs, how to measure it, and its side effects. It will discuss state-of-the-art spacecraft charging technologies, which will be explained in detail and with pedagogical emphasis. Exercises for further learning will be included to facilitate a deeper understanding of the material. It will be of interest to advanced undergraduate and graduate students, in addition to researchers working in physics and engineering keen to understand more about spacecraft interactions with space plasmas. Key Features: Translates complex terminology into accessible language Authored by experts in the field Provides worked examples and exercises for further learning




Guide to Mitigating Spacecraft Charging Effects


Book Description

The definitive guide to the modern body of spacecraft charging knowledge—from first principles for the beginner to intermediate and advanced concepts The only book to blend the theoretical and practical aspects of spacecraft charging, Guide to Mitigating Spacecraft Charging Effects defines the environment that not only creates the aurora, but which also can have significant effects on spacecraft, such as disruption of science measurements and solar arrays from electrostatic discharge (ESD). It describes in detail the physics of the interaction phenomenon as well as how to construct spacecraft to enhance their survivability in the harsh environment of space. Combining the authors' extensive experience in spacecraft charging—and in their provision of design support to NASA, JPL, the commercial satellite market, and numerous other projects—this incredible book offers both a robust physics background and practical advice for neophytes in the field and experienced plasma physicists and spacecraft engineers. In addition to containing numerous equations, graphs, tables, references, and illustrations, Guide to Mitigating Spacecraft Charging Effects covers: Solar cell technology, especially higher voltage arrays, and the new design approaches that are appropriate for them Information about the space plasma environment New analytic computer codes to analyze spacecraft charging Spacecraft anomalies and failures which emphasized designs that are of greater importance than others