Perspectives of auroral X-ray measurements in the 1980s

The measurement of auroral X-rays with balloon-borne instruments is an efficient means to study the behaviour of electrons with energies above about 30 keV in the magnetosphere during disturbed periods. Possibilities will be discussed to continue such measurements in the 1980's. It will be pointed out, what kind of investigations may be performed. Recently developed payloads will be described that can be used as a basis for further technical developments. Satellite projects scheduled for the 1980's will be presented that are suited for coordinated X-ray measurements.     

Comparative neutral composition instrumentation and new results

Composition and gas density measurement at all altitudes in the atmospheres of earth and other planets are made by mass spectrometers. Because of the impartiality and large dynamic range they are particularly favored for exploratory missions. Measurements of trace constituents, inert gases and height profiles, especially below clouds, are objectives where mass spectrometry is most useful. Significant advances have been made in recent years in development of light weight automated instruments. Experiments conducted in rarified atmospheres have been more successful or results were less controversial than in attempts to analyze high pressure atmospheres. Gas sampling and conditioning techniques are highly specific because of measurement environments and engineering constraints on the mission, and are usually the most critical elements in the experiment. Chemical sample enrichment and scrubbing for noble gas enhancement are additional sample conditioning techniques now employed. Dynamic range of more than 10⁸ is achievable. Reliable measurements of complex organic or chemically active trace constituents with mixing ratios of less than 10^?9 still require significant instrument development particularly where weight, power and sampling time are severely restricted. Adaptation of familiar and proven laboratory techniques for flight instruments is usually not straightforward and practical.     

Analysis of Detection Probability for the Acoustooptic Receiver

A numerical method is described for analyzing the performance of an acoustooptic receiver. The method provides output waveforms, probability density functions for samples of the output, and detection probabilities for output samples. The approach is general in that input pulse envelope shapes, pulse offset frequencies, and output rilter magnitude responses are arbitrary. The basic analysis is also independent of the shape of the optical beam and of the photodiode windows.     

Radio aurora magnetic and streaming aspect sensitivities on 6 simultaneous links at 50 MHz

During August 1981, a 50 MHz c.w. radar system was operated in central Canada to measure auroral scatter amplitudes and Doppler spectra from a scattering region centered near 66° magnetic invariant latitude (L ≈ 6.0). Narrow beams from 3 transmitters, differing in frequency by 1 KHz, were directed to cover a common volume of the ionosphere over a ground location at 56.3°N, 103.5°W. The scattered signals were received on narrow beam antennas at two receiving sites, and recorded in analog form on magnetic tape under the control of an AIM65 microcomputer. The analog tapes were digitized later and FFT-processed to obtain Doppler spectra and amplitudes.The 6 transmission paths were designed to provide several magnetic aspect angles varying by 1.5°-7° from perpendicularity with the earth's field B and two streaming aspect angles differing by ～38°. The objective was to employ controlled geometric factors to study the functional dependency of signal amplitudes and Doppler shifts on magnetic and streaming aspect angles. Several hundred hours of excellent data were obtained in continuous operation during the month of August 1981. Preliminary results will be reported.     

Perspectives for Strategic Analysis in Advancing Ocean Technology

There is a growing need for the scientist, engineer, and administrator to better understand the kinds of overall, across-the-board planning problems involved in the development of off-shore coastal areas. A recommended approach is to use systems analysis techniques. Principles will be set forth on maintaining and improving the quality of the ocean environment, with considerations of cost in so doing. Each proponent of an aspect of ocean technology usually believes that his field must be greatly enlarged in the near future. Along with these advances there is the likelihood of unnecessary social costs emanating from undesirable modifications of the environment. In making the analysis, an early step is to identify specific needs and appropriate roles. A next step is to lay out alternatives for achieving objectives both within a given organization and external to it. The alternatives may be appraised through their costs and benefits. But how do you make choices between goals when resources are limited? How can we gather the data, accomplish the evaluation, and do the planning that will make rational choices possible? This paper elucidates the problems involved in these kinds of questions and suggests methodology that might lead toward solutions.     

Latitudinal structure of the solar wind and interplanetary magnetic field

A review is given of both observational and theoretical results concerning the latitudinal structure of the solar wind and interplanetary magnetic field. Observations are reported on the solar wind plasma and magnetic fields, obtained both from direct satellite measurements and indirect methods, such as the observation of comet tails, radio scintillations, the study of the polar geomagnetic field and the semi-annual variation of geomagnetic activity. Results of theoretical work, both on three-dimensional modelling of the solar wind and on gas-magnetic field interactions in the solar corona are summarized. Finally, an attempt is made to compare available observations and theories. This points to the open questions which, to be settled, will need direct observations of plasma and magnetic field at high heliographic latitudes.     

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.