Effects due to an artificial earth satellite in rapid motion through the ionosphere or the interplanetary medium

Conclusion In this paper we have been concerned with the results of theoretical calculations of the interaction between a fast moving body and a tenuous plasma. Particular attention was paid to the case where the velocity of the body is much smaller than the velocity of neutral particles and ions, while the dimensions of the body are sufficiently large in comparison with the Debye radius. Such conditions are realized during the motion of artificial satellites or space rockets through the ionosphere, or through the interplanetary medium in the immediate neighborhood of the earth. Although this case has, on the whole, been investigated quite extensively, there are still a number of problems which require further analysis. Firstly, it is necessary to take into account the effect of the electric field on the motion of ions in the near zone at the rear of the body. Another important problem is that of magnetic disturbances. In the case of scattering of radio waves by the trail of the body, it would be interesting indeed to know the increase in the effective cross-section in the resonance region in which 0. A number of other research problems which arise in the analysis of phenomena in the neighborhood of a moving body have been noted in the Introduction.In the lower layers of the ionosphere it is important to allow for the fact that the dimensions of the body are comparable with the mean free path. Under these conditions there is the further interesting problem of the heating and additional ionization of the plasma, the disintegration of the surface, and the emission of waves. At large distances from the surface of the earth, the dimensions of the body may become comparable with the Debye radius, and the velocity of the body in the given region may become smaller than the thermal velocity of the particles. The character of the various disturbances introduced by the body under these conditions will also require a special investigation.Thus, the interaction of a moving body with plasma leads to special and exceptionally varied effects. Disturbances due to the body are very considerable, so that the physical state of the region surrounding the body is very different from the state of the undisturbed medium.The above results indicate that the phenomena in the neighborhood of satellites and space rockets in the ionosphere, or the interplanetary medium, must be taken into account, in the processing of experimental data when it is required to deduce information about the state of the undisturbed medium. This is particularly important in the analysis of the results of measurements obtained with various types of probes. Considerable errors may be introduced if these effects are not allowed for.Further extensive experimental and theoretical studies of the structure of the disturbed region in the neighborhood of moving bodies in plasma are clearly necessary. Such investigations will, in particular, lead to the development of the most effective methods of studying the properties of the media through which satellites and space rockets travel.Translated from the Russian: Ob effektah vyzyvaemyh iskusstvennym sputnikom bystro dviimsja v ionosfere ili meplanetnoj srede (Uspehi fizieskih nauk 79, 23–80) by Express Translation Service.     

Wide angle X-ray optics for use in astronomy

Recently there was a suggestion in the literature to apply the principle of the lobster-eye to X-ray astronomy imaging (J.R.P. Angel, Ap. J. 233, 364, 1979). Our own suggestion for a wide angle X-ray telescope made earlier (W.K.H. Schmidt, Nucl. Instr. Meth.127, 285, 1975) is very similar to the above one. It consists of one or two sets of plane mirrors used in a grazing incidence configuration. The advantages of this type of X-ray optics over other systems for particular astronomical observations will be discussed.     

Hydrodynamic forces resulting from liquid motion in capillary tubes

The wetting kinetics of model tubes of different geometrical shape has been investigated theoretically and experimentally under conditions of simulated zero-gravity (earthbound laboratory experiments) and low gravity (sounding rocket experiments within the TEXUS-programme). The present note deals with the hydrodynamic forces (capillary-, friction-, inertia forces, etc.) resulting from capillary rise in cylindrical, conical and sinusoidal tubes. The rôle of these forces is studied numerically in some detail.     

A Nutation Damper for a Dual-Spin Spacecraft

This paper is concerned with a high-performance nutation damper for use in dual-spin spacecraft. The damper described here makes use of a wheel of uniform mass distribution. The wheel experiences torques which are produced by inertial forces. Damping and restoring (spring) torques are provided by means of a torsional arrangement built around the center of the wheel. The performance characteristics of the above nutation damper are evaluated by considering the small astronomy satellite (SAS-A) spacecraft parameters, and the results for an optimum design of the damper are presented. Finally, the result for the optimum performance is checked with the help of an approximate analysis.     

Enhanced Power Generation of GSS4PS by Optical Solar Reflectors

A novel arrangement is proposed to enhance the power generation capabilities of a gravitationally stabilized solid-state-satellite solar-power station (GSS4PS) spherical solar collector. The unilluminated portion of a GSS4PS is illuminated by employing optical solar reflectors. The different mechanisms required for implementation of this arrangement are already space proven. The detailed study of this arrangement made by the authors reveals that practical realization of this concept will enhance the power generation capability of the GSS4PS and simultaneously reduce the weight per unit power and cost per unit power in GSS4PS spherical solar collectors.     

Human dimensions in space development

Space exploration is now moving beyond the stage when technical development dominated research. As thinking shifts towards the problems of long-term colonization of the Solar System, the biological and behavioural sciences must make major contributions. This article outlines some of the issues which must be addressed, such as group behaviour and dynamics in space flight, the environment created at space stations and other outposts, recruitment and training of suitable spacefarers, and the planning and governing of space settlements. Ten dimensions of the human aspect of space habitation are described and an indication given of how they may form the basis for a new taxonomy of space planning, operations and management.