Steady State Analysis of the Rectified Superconducting Alternator

Equations are derived to predict the electrical behavior of a three-phase superconducting alternator connected to a full-wave bridge rectifier. This is accomplished by expanding a previous analysis for conventional rectified alternators and adding computational impovements. The significance of the work is that it provides a means of calculating certain critical variables such as the ac current in the superconducting field winding and the ac voltage harmonics at the rectified output. A numerical example based on a machine designed for airborne applications is included.     

Computation of Optimal Earth-Mars and Earth-Venus Trajectories

Accurate solutions of minimal time Earth-Mars and Earth-Venus heliocentric trajectories are calculated with a shooting-Newton method. The flight times are less and the steering histories are diferent than those presented in [1], thus contradicting the optimality claims in [1].     

Planetary radio astronomy experiment for Voyager missions

The planetary radio astronomy experiment will measure radio spectra of planetary emissions in the range 1.2 kHz to 40.5 MHz. These emissions result from wave-particle-plasma interactions in the magnetospheres and ionospheres of the planets. At Jupiter, they are strongly modulated by the Galilean satellite Io.As the spacecraft leave the Earth's vicinity, we will observe terrestrial kilometric radiation, and for the first time, determine its polarization (RH and LH power separately). At the giant planets, the source of radio emission at low frequencies is not understood, but will be defined through comparison of the radio emission data with other particles and fields experiments aboard Voyager, as well as with optical data. Since, for Jupiter, as for the Earth, the radio data quite probably relate to particle precipitation, and to magnetic field strength and orientation in the polar ionosphere, we hope to be able to elucidate some characteristics of Jupiter auroras.Together with the plasma wave experiment, and possibly several optical experiments, our data can demonstrate the existence of lightning on the giant planets and on the satellite Titan, should it exist. Finally, the Voyager missions occur near maximum of the sunspot cycle. Solar outburst types can be identified through the radio measurements; when the spacecraft are on the opposite side of the Sun from the Earth we can identify solar flare-related events otherwise invisible on the Earth.     

Rocket measurements of mesospheric ionization irregularities

The Langmuir-probe technique for measurement of electron concentration in the mesosphere is capable of excellent altitude resolution, of order 1 m. Measurements from nine rocket flights frequently show small-scale ionization structures in the altitude region 60–90 km. These are believed to be identical with regions of strong coherent backscatter seem by VHF radars at Jicamarca, Peru and Urbana, Illinois. They are believed to represent intermittent turbulence attributable to nonlinear interaction of waves in the mesosphere. Parameters of the turbulent regions are estimated.     

Non-intrusive methods for temperature measurements in liquid zones in microgravity environments

Material Science and Life Science experiments in microgravity both have urgent needs of evaluating the temperature distribution within and on the surface of liquid zones. Non intrusive methods are available which measure the IR radiations emitted by the surface. The thermograph systems have a number of advantages since they supply a thermal picture of the surface with sufficient time, space and temperature accuracy. A computerized system has been designed for data acquisition and elaboration and used for ground experiments; the system can also be used for space experiments with some modifications. Non intrusive measurements of bulk temperature in two dimensional liquid flow fields can be made by means of optical methods which detect variations of the index of refraction. A method is proposed which is able to take with the same optical apparatus shadowgraph. Schlieren and differential interferometers pictures. A computerized system is proposed for data acquisition and elaboration.     

Maximum Theoretical Angular Accuracy of Planar and Linear Arrays of Sensors

A study has been made of the maximum theoretical accuracy in the angular location of a radiating object that is achievable by using a planar or linear array. The elements are assumed to have identical radiation patterns and the complex voltages observed at their ports are assumed to be subject to phase measurement errors, having normal probability density. An optimum scheme for the statistical extraction of the parameters defining the direction is established. It consists of combining the observed phases linearly with weights depending upon the element locations. It is shown that the presence of thermal noise, for sufficiently high signal-to-noise ratio, does not change the structure of the estimator. Comparison with conventional multiple interferometric techniques indicates the superiority of the proposed scheme. Finally, a limited numerical study on a small linear array vertically located on a reflecting terrain is performed. Although in such a situation the scheme proposed is not the theoretical optimum, it leads to errors that, for most directions of the target, are smaller than those found for the same array when using conventional multiple interferometer techniques.     

The Voyager mission Photopolarimeter Experiment

The Voyager Photopolarimeter Experiment is designed to determine the physical properties of particulate matter in the atmospheres of Jupiter, Saturn, and the Rings of Saturn by measuring the intensity and linear polarization of scattered sunlight at eight wavelengths in the 2350–7500 Å region of the spectrum. The experiment will also provide information on the texture and probable composition of the surfaces of the satellites of Jupiter and Saturn and the properties of the sodium cloud around Io. During the planetary encounters a search for optical evidence of electrical discharges (lightning) and auroral activity will also be conducted.     

Environment and Radar Operation Simulator

The environment and radar operation simulator (EROS) is a hardware system whose function is to produce realistic synthetic radar backscatter, incorporating both target and clutter. The simulator is electrically connected to a subject radar and responds in real time to the radar's antenna scan angle by producing the correct composite video signal.     

The role of magnetic field shear in solar flares

We present observational results and their physical implications garnered from the deliberations of the FBS Magnetic Shear Study Group on magnetic field shear in relation to flares. The observed character of magnetic shear and its involvement in the buildup and release of flare energy are reviewed and illustrated with emphasis on recent results from the Marshall Space Flight Center vector magnetograph. It is pointed out that the magnetic field in active regions can become sheared by several processes, including shear flow in the photosphere, flux emergence, magnetic reconnection, and flux submergence. Modeling studies of the buildup of stored magnetic energy by shearing are reported which show ample energy storage for flares. Observational evidence is presented that flares are triggered when the field shear reaches a critical degree, in qualitative agreement with some theoretical analyses of sheared force-free fields. Finally, a scenario is outlined for the class of flares resulting from large-scale magnetic shear; the overall instability driving the energy release results from positive feedback between reconnection and eruption of the sheared field.     

Cell morphological, ontogenic, and genetic reactions to 0-g simulation and hyper-g

Organisms use gravity for spatial orientation, and differentiation into species during evolution follows geological processes which are caused by gravity. On the other hand, the task of most organismic functions which have or may have a relation to gravity is to compensate gravity. Furthermore, today it is very obvious that organisms do not disintegrate under the conditions of weightlessness, at least for the currently tested durations. These previous statements indicate a large field of still unknown regulation and adaptation mechanisms. Experiments to simulate weightlessness on the fast clinostat and with hyper-g show a highly developed ability of the genetic chain and of differentiating cells in being autonomous against mechanical stresses caused by outer accelerations. Nevertheless, different strong and slight changes of different tested end points were found. The question remains if the cells react actively or only passively.