摘要 :
NASA's share of the project
will be the provision of the main spacecraft which will carry the ESA probe to Halley and the provision of the solar electric propulsion system (SEPS).
The lain spacecraft and the probe will be launched...
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NASA's share of the project
will be the provision of the main spacecraft which will carry the ESA probe to Halley and the provision of the solar electric propulsion system (SEPS).
The lain spacecraft and the probe will be launched together by the Shuttle Transportation System (STS)/ Shortly after separation from the IUS, the space craft attitude, is stabilized, the solar arrays are deployed and the electric thrusters are turned on. Ion propulsion thrust is applied almost continuously throughout the mission with brief periods of interruption during the ESA probe release, Halley encounter data acquisition and a few science instrument calibration sequences during cruise. The heliocentric trajectory is shown in Figure 1.
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[科技报告]共235页
摘要 :
This report discusses the techniques that may be applied to equipping six-degree-of-freedom vibration test facilities with hydraulic cylinders.
It 1s understood from a number of publications that similar test facilities have been ...
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This report discusses the techniques that may be applied to equipping six-degree-of-freedom vibration test facilities with hydraulic cylinders.
It 1s understood from a number of publications that similar test facilities have been constructed in the US, but none for simultaneous movement in all six degrees of freedom. IABG is operating a facility that is capable of moving in all degrees of freedom simultaneously, but was designed to use seismic signals in its tests and, consequently, has a relatively small usable frequency range.
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[科技报告]共59页
摘要 :
This document (volume III) descries the program ne structure of the three FORTRAN progrsmmes Written within optimal sstelltte man-oeuvres project.
Section 2,3 and 4 deal respectively with the main algorithm (ALG7)the back-up (ALGS...
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This document (volume III) descries the program ne structure of the three FORTRAN progrsmmes Written within optimal sstelltte man-oeuvres project.
Section 2,3 and 4 deal respectively with the main algorithm (ALG7)the back-up (ALGS)and the path curvatures program(CRVI).
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[科技报告]共63页
摘要 :
This report contains the results of a study of attitude maneuvers of spin-stabilised satellites, with emphasis on maneuvers controlled by Earth sensors. The original objective of the study was to determine what fuel savings could ...
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This report contains the results of a study of attitude maneuvers of spin-stabilised satellites, with emphasis on maneuvers controlled by Earth sensors. The original objective of the study was to determine what fuel savings could be achieved by appropriate choice of sensors. It is concluded in general that possible savings are limited, because the maneuvers which occur most frequently (between two attitudes each approximately orthogonal to the Sun line) are fairly efficient when executed using Sun sensors. On the other hand, the use of Earth sensors would also give efficient maneuvers in such cases, provided that the start were timed suitably.
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[科技报告]共67页
摘要 :
The first programme determines the delay angle necessary to achieve a desired mgnoeuvre, the second determines maneuvers for input values of the delay angle and fee third determines manoeuvre path curvatures. The programmes are ca...
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The first programme determines the delay angle necessary to achieve a desired mgnoeuvre, the second determines maneuvers for input values of the delay angle and fee third determines manoeuvre path curvatures. The programmes are called ALG 7, ALG 8 and CSV 1 respectively.
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[科技报告]共134页
摘要 :
Communications satellite systems for mobile applications involving single global beam coverage are inefficient in the use of power. Significant power savings can be made if the required coverage is achieved by a number of higher g...
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Communications satellite systems for mobile applications involving single global beam coverage are inefficient in the use of power. Significant power savings can be made if the required coverage is achieved by a number of higher gain spot beams. The traffic capacity of a multibeam system, having its channels dedicated to individual beams, is lower than that of a global beam Rvstem having the same number of channels. The traffic capacity can be improved by providing channel to beam interconnectivity by using switchable channels, beam over laps etc. The report describes mathematical models and associated software which allow the traffic capacity of multibeam systems with various types and degrees of interconnectivity to be calculated;the models include idealized versions and a simulation. Is a practical system the traffic capacity must be balanced against the complexity of the hardware associated with the interconnectivity. The report discusses hardware aspects of the methods of interconnectivity. Three examples of multibeam systems are analysed in detail using the mathe matical models developed.
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摘要 :
This catalogue contains observations carried out by the S2/68 Ultraviolet Sky Survey Telescope (UVSST) aboard the ESRO Satellite, TD-1. The data presented here were obtained during the first observation period, which lasted from 1...
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This catalogue contains observations carried out by the S2/68 Ultraviolet Sky Survey Telescope (UVSST) aboard the ESRO Satellite, TD-1. The data presented here were obtained during the first observation period, which lasted from 19 March 1972 to 31 October 1972.
The catalogue is limited to the brightest objects, for which the signal is good enough to give valuable spectrophotometric information. A Faint Star Catalogue will contain the photometric data of the stars up to the limit of detectability of the instrument.
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摘要 :
A computer program is described by which the sequence of launches can be simulated that is required for the installation and maintenance of a satellite-based communication system. A 'Monte Carlo' method is used for the generation ...
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A computer program is described by which the sequence of launches can be simulated that is required for the installation and maintenance of a satellite-based communication system. A 'Monte Carlo' method is used for the generation of random events. Details of the satellite functional model, reliability model, allocation of resources to requirements, and decision rules are given.
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摘要 :
The objective of the study is to define a payload compatible with the requirements of a second genes rat ton maritime and aeronautical system.
[科技报告]共47页
摘要 :
A detailed survey of the effects of hrdrothermal degradation on carbon fibre resin matrix composites has been carried out. It was noted that exposure to water or high relative humilities caused a fall-oil is mochantoal properties,...
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A detailed survey of the effects of hrdrothermal degradation on carbon fibre resin matrix composites has been carried out. It was noted that exposure to water or high relative humilities caused a fall-oil is mochantoal properties, and this was enhanced by Increasing temperature. The reversibility of the effects, on drying out, depended on the property measured;the effects on fibre dominated properties tended to be reversible, but those on matrix dominated ones were not. Degradation is believed to be caused by enter swelling the resin and causing cracking, end disruption of the fibre/matrix bond. In the experimental work undertaken it was found that flexural modulus, strength, and interlaminar shear strength decreased after exposure to temperature, or temperature and water, but that complete drying restored properties to their initial, pro-exposure, values. The transverse flexural strength, which is matrix dominated, was not however restored on drying ou, indicating that the resin, or bond, or both, did suffer permanent environmentally-induced damage. Generally the effect of temperature alone was more severe than that of temperature plus water, and it is suggested that in the latter case the presence of the water eased ＇in built＇ stresses. The unreinforced reｓin proved difficult to make into bulk specimens and thus it was not possible to deduce trends in the effects of environmental exposure on this material.
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