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561.
The imaging capabilities of the Exosat and Einstein satellites at soft X-ray wavelengths have begun to show that suitable Galactic X-ray sources have extended ( 10 arcmin) haloes due to scattering of soft X-rays by interstellar dust. A simple argument suggests that similar haloes, due to scattering by intergalactic dust, should exist around distant (z 1) quasars and detailed analysis confirms this conclusion. A search for such haloes around suitable X-ray quasars could provide valuable, model-independent, constraints on the amount and origin of intergalactic dust. 相似文献
562.
This paper presents an overview of the identification and selection process of experiments and payloads for manned space flight missions, emphasizing the scope and magnitude of the problem of doing activity planning and the need for a methodology to assure timely flight and appropriate spacecraft design. Conclusions and results derived from the past several years are presented together with an analysis of the current procedure for defining activity for the space station. 相似文献
563.
Salinger S.N. Brandstatter J.J. 《IEEE transactions on aerospace and electronic systems》1970,(4):585-592
The techniques of recursive estimation and Kalman filtering are applied to the problem of estimation of space vehicle orbits and trajectories using only measurements of the Doppler shifts in radio signals transmitted by or reflected from the target. Two approaches are described. One is a global fit technique in which the parameters of an assumed trajectory model are estimated. The second is a pointwise mapping technique in which the trajectory estimate is extrapolated as the target tracking data is received. The paper provides a tutorial illustration of the direct application of recursive optimization techniques to a class of engineering problems. 相似文献
564.
565.
R.Z. Sagdeev G.G. Managadze A.A. Martinson Yu.A. Romanovsky R.I. Moisya W.K. Riedler M.F. Friedrich T.G. Adeishvily S.B. Lyakhov L.S. Novikov N.A. Leonov T.I. Gagua I.I. Slyusarenko 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1981,1(2):129-140
This paper describes two rocket experiments “Aelita” with high power lithium plasma injection. The results of onboard magnetometer, massspectrometer, photometer, plasma, corpuscular and ground radar measurements are given. Dynamics and structure of plasma formation are discussed. 相似文献
566.
A space diversity method of receiving and processing ILS localizer information has been developed and flight tested. Multiple lateral ly separated antennas are used which sense the ILS signal on and around the approach path. Combining these signals suppresses ILS beam distortion produced by multipath signal interference and provides much improved guidance information to the landing aircraft control system. 相似文献
567.
Kerwin JP 《Acta Astronautica》1975,2(1-2):85-87
The facts presented represent, for convenience, a composite clinical picture of the three crewmen aboard Skylab II as observed by me. 相似文献
568.
Koivo A.J. Kahne S.J. Koivo H.N. 《IEEE transactions on aerospace and electronic systems》1970,(3):306-312
The effect of bounded deterministic disturbances (external and/or internal) on a chosen performance index (PI) is investigated. Upper and lower bounds of the PI about a nominal value are determined by the application of the optimum control theory. A computational procedure is also proposed to determine an approximately optimal feedback controller for time-lag systems. Such a controller is designed here on the basis of min-max criteria. Numerical examples illustrate the proposed approach. 相似文献
569.
J. C. Kosik 《Space Science Reviews》1978,22(4):481-497
Two different utilisations of magnetospheric models are described in this paper. In the first one very crude analytical expressions are used to describe the motion of energetic particles and the evolution of fluxes along a given orbit. In the second one, the exact internal and external fields are used for field line tracing and the determination of conjugate points. Applications to the calculation of synchronous fluxes and the Geos conjugate points are given. 相似文献
570.
Ruoff CF 《Aerospace America》1989,27(8):38-41, 46
This article describes the use of robots to perform work in space. In particular, telerobotics, which uses human operators to control the movement and operation of the robots, are explored. The relationship between the human operator and the robot is very complex but these systems are being used to explore planetary surfaces and will also be used in the construction of the space station. Research being conducted at NASA facilities is described, providing a picture of the future of space robotics. 相似文献