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.     

Minimal-Order Models for False-Alarm Calculations on Sliding Windows

A procedure is developed to obtain practical numerical results in connection with the m-out-of-n sliding-window detection problem. This effort was motivated by difficulties with previous approaches involving approximation, Markov models, and Monte Carlo simulation. Generating-function methods were found to be unsatisfactory for window lengths greater than 6 due to their complexity. Instead, a Markov model is described that is then constructively reduced to the minimum number of state variables. The results are derived for binary strings with intersymbol correlation. Computational aids are discussed for obtaining design information, such as quantiles, from the minimal-order Markov models. Numerical results are given comparing the methods of the paper with a "jumping" window approximation for an 8/10 problem.     

A more accurate modeling of the effects of actuators in large space structures

The present paper deals with finite actuators. A nonspinning three-axis stabilized space vehicle having a two-dimensional large structure and a rigid body at the center is chosen for analysis. The torquers acting on the vehicle are modeled as antisymmetric forces distributed in a small but finite area. In the limit they represent point torquers which also are treated as a special case of surface distribution of dipoles. Ordinary and partial differential equations governing the forced vibrations of the vehicle are derived by using the Hamilton's principle. Associated modal inputs are obtained for both the distributed moments and the distributed forces. We show that the finite torquers excite the higher modes less than the point torquers. Modal Cost Analysis proves to be a suitable methodology to this end.     

Zener Diodes as Vehicular and Aircraft Transient Suppressors

The prime purpose of this paper is to describe the characteristics and application of high powered Zener diodes as transient suppressors for transients emanating in ground vehicle and aircraft power supplies. Information is presented on voltage transients as specified in MIL-STD-704 for aircraft and MIL-STD-1275(AT) for military ground vehicles and the ability of advanced high power Zener diodes in suppressing the levels of voltages specified therein. A complete transient suppressor capable of operating externally to the equipment intended for protection is also described.     

Implications of an Engineering Manpower Shortage

Many competent sources have been predicting an increasing shortage of graduate engineers to perform needed research and development work in the United States. Consequently, many industrialists, educators, and government officials have been advocating an increased enrollment of students in the engineering curriculum in college in a greater effort to produce more engineers. This paper examines the assumptions behind the projected manpower shortage, and proposes some rather unique and occasionally radical alternatives to the solution of a manpower deficit. The paper, and the solutions, may produce violent controversy, but at least the material is not the usual dull rehash so often seen of late.     

Range Dependent Waveform of an Active Weighted Pulse Compression Receiver

This paper presents the output waveform of a correlation techniquewhich incorporates time domain amplitude weighting and matchedfiltering. This scheme may be used in pulse compression radars wherefine target detail is desired over an increment of range, the rangewindow. Analytic expressions describing the amplitude, phase, andfrequency modulation of the output waveform are obtained for thecosine-squared weighted spectrum, truncated Taylor weighted spectrum,and cosine-cubed weighted spectrum with weighting mismatchas a parameter. The effects of such mismatches on the amplitude,phase, and frequency modulation of the compressed waveform areplotted. However, the methods used to obtain these results are generalenough to obtain output waveforms of other weighting functions similarlymismatched.     

Physical characteristics of the upper layers of Saturn's atmosphere

Analysis of polarimetric observations of Saturn was carried out. In the long wave-length spectral range (λ > 0.5μm) polarimetric observations do not contradict the model of spherical or irregular randomly oriented particles. In the short wave-length spectral interval (λ < 0.5μm) it is necessary to take into account the scattering by oriented particles.     

Stable mid-latitude red arcs: Observations and theory

Summary The observational features of the arc are fairly well established. At present, the thermal conduction model appears to explain the red arc features most consistently, but it must be noted that a soft electron flux would give very similar results. Ion temperature measurements in the vicinity of an arc, which should be forthcoming in the very near future, can establish conclusively whether transverse electric fields play any important role in the formation of the arcs. Accepting the assumption that the arcs are the result of energy flowing down from the plasmasphere, the major remaining question is: where does the energy come from and how does it get into the plasmasphere? The various proposed mechanisms discussed in the previous chapter appear feasible, but much work needs to be done before this problem is completely resolved.On leave from the Department of Electrical Engineering, The University of Michigan, Ann Arbor.The National Center for Atmospheric Research is sponsored by the National Science Foundation.     

The Goddard Experiment Package?An Automated Space Telescope

The Goddard Experiment Package will measure the ultraviolet spectral emittance of stars and nebulae. It has a spectral resolution of 2 ? in the 1050-? to 4000-? band. The telescope has a 38-inch clear aperture and automatically reduces the spectral data to digital form. Guidance accuracy is 1 of second arc.     

Spectral computation of Tandem mirror equilibria with Finite Larmor Radius effects

A direct iterative method of solving for Tandem equilibria by moving magnetic field lines in a manner to satisfy the linearized equilibrium equations converges much more rapidly than standard relaxation techniques, typically in under a fifty iterations. At the highest 's the number of iterations increase, but is still far less than other methods. In quadrupole tandem mirror equilibrium, octupole and higher distortions of the flux surfaces are important which forces us to abandon finite differences in the angle-like flux variable and resort to a spectral decomposition to solve the equilibrium equations. We display equilibria at the high expected for MFTF-B and show how Finite Larmor Radius (FLR) effects strongly suppress these azimuthal distortions.