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General frequency equation is developed for both forward and backward precession of rigid rotors in undamped bearings on flexible foundations. As well as major critical speeds, nonsynchronous critical speeds that may result from bearing defects can be located.
Two body torque free gyrostat equations of rotational motion, relating rotational, spin and precession angular velocities
Apollo 11 lunar rock plagioclases crystallography, obtaining single crystal X ray diffraction patterns by Buerger precession method
Single crystal structure of shocked terrestrial and lunar ilmenite from X ray precession and Laue analyses
An estimated mean thickness of about 1 km of frost in the Martian north polar cap summer remnant, if vaporized, would yield about 1000 g/sq cm of atmosphere over the planet, higher global temperatures through the greenhouse effect, and a greatly increased likelihood of liquid water. Vaporization of such cap remnants may occur twice each equinoctial precession, and Martian organisms may now be in cryptobiotic repose awaiting the end of the long precessional winter. The Viking biology experiments can test this hypothesis.
Metric theories of gravity are presented, including the definition of metric theory, evidence for its existence, and response of matter to gravity with test body trajectories, gravitational red shift, and stressed matter responses. Parametrized post-Newtonian framework and interpretations are reviewed. Gamma, beta and gamma, and varied other parameters were measured. Deflection of electromagnetic waves, radar time delay, geodetic gyroscope precession, perihelion shifts, and periodic effects in orbits are among various studies carried out for metric theory experimentation.
Gyroscopes in motion about a massive body are found to have two main effects: (1) geodetic effect, solely due to motion of the gyroscope about the earth and (2) motional effect, due to earth rotation. An experiment is proposed to measure the precession rate of one or more gyroscopes, mounted either on earth or in a satellite, with respect to the axis of a telescope pointing at a suitable fixed star. The procedures and apparatus to be used in this experiment are outlined; the error analysis is summarized. The relation of error to size, speed, and mechanical properties of rotor is presented, along with the design requirements for accuracy of 10 to the -16th power rad/s.
Two perturbations, the earth's quadrupole moment and the earth's revolution around the sun, are discussed. Schiff's proposed gyroscope test of gravitation is analyzed, along with the capability of deciphering each separate contribution to the angular velocity of spin precession.
The objective of the relativity satellite mission is to perform an experiment in which a gyroscope in motion about the earth undergoes precession, presumably relativistic, with respect to the fixed stars. Performance of this experiment would clearly test the general theory of relativity and its various modifications. This is the only experiment suggested to date which would confirm the existence of motional drift as well. A mission is defined in which the measurement of the geodetic effect term to 0.2 arc sec/yr is achievable and the measurement of both geodetic and motional drift terms to an accuracy of 0.001 arc sec/yr may be possible. The design of the flying dewar satellite needed to maintain the experiment at cryogenic temperatures is discussed. The gyroscopes, magnetometer, and optical contacting method for dimensional stability of the experimental assembly are considered.
A gyroscope test of general relativity theory is proposed. The basic ideas and hardware concepts conceived by the investigators to implement the experiment are discussed. The goal is to measure the extremely small relativistic precession of gyroscopes in an earth-orbiting satellite. The experiment hardware (cryogenic gyroscopes, a telescope and superconducting circuits) is enclosed in a liquid helium dewar. The experiment will operate in orbit for about one year.
A stellar attitude reference system concept for satellites was studied which promises to permit continuous precision pointing of payloads with accuracies of 0.001 degree without the use of gyroscopes. It is accomplished with the use of a single, clustered star tracker assembly mounted on a non-orthogonal, two gimbal mechanism, driven so as to unwind satellite orbital and orbit precession rates. A set of eight stars was found which assures the presence of an adequate inertial reference on a continuous basis in an arbitrary orbit. Acquisition and operational considerations were investigated and inherent reference redundancy/reliability was established. Preliminary designs for the gimbal mechanism, its servo drive, and the star tracker cluster with its associated signal processing were developed for a baseline sun-synchronous, noon-midnight orbit. The functions required of the onboard computer were determined and the equations to be solved were found. In addition detailed error analyses were carried out, based on structural, thermal and other operational considerations.
A steady state analysis of the shaft and the bearing housing motion was made by assuming synchronous precession of the system. The conditions under which the support system would act as a dynamic vibration absorber at the rotor critical speed were studied; plots of the rotor and support amplitudes, phase angles, and forces transmitted were evaluated by the computer, and the performance curves were automatically plotted by a CalComp plotter unit. Curves are presented on the optimization of the support housing characteristics to attenuate the rotor unbalance response over the entire rotor speed range. The complete transient motion including rotor unbalance was examined by integrating the equations of motion numerically using a modified fourth order Runge-Kutta procedure, and the resulting whirl orbits were plotted by the CalComp plotter unit. The results of the transient analysis are discussed with regards to the design optimization procedure derived from the steady-state analysis.
The design, construction, and preliminary testing of a new high accuracy star tracking telescope for the laboratory model of the Stanford gyro relativity experiment are described. The function of the telescope in the final flight experiment is to define (by reference to a suitable star) a direction in space for comparison with the relativistic precession of a group of gyroscopes. The design of the telescope has been strongly affected by designs for other portions of the overall experiments, for example the gyroscopes, the attitude control system of the satellite, and the instrumentation system used in processing relativity data. Main goals for the star tracker are: (1) independent readout of angular position in two planes; (2) absolute null stability over a one year period of mechanical parts; (3) readout linear to 0.001 arc-seconds over + or - 0.05 arc-second; (4) noise performance leading to a resolution of 0.05 arc-second in 0.1 second observation time of the chosen reference star; and (5) provision for automatic gain control capable of matching the gains of the gyroscopes and telescope readouts to 1% or better.
A zonal geopotential is presented to degree 21 from evaluation of mean elements for 21 satellites including 2 of low inclination. Each satellite is represented by an arc of at least one apsidal rotation. The lengths range from 200 to 800 days. Differential correction of the initial elements in all of the arcs, together with radiation pressure and atmospheric drag coefficients, was accomplished simultaneously with the correction for the zonal harmonics. The satellite orbits and their variations are generated by numerical integration of the Lagrange equations for mean elements. Disturbances due to precession and nutation of the earth's pole, atmospheric drag, radiation pressure and luni-solar gravity are added at from 1- to 8-day intervals in the integrated orbits. The results agree well with recent solutions from other authors using different methods and different satellite sets.
A temporal microenvironment model is proposed for Martian biology that is based on an estimated mean thickness of nearly 1 km of frost in the Martian north polar cap summer remnant. If vaporized, this frost could yield not only 1 kg per sq cm of atmosphere, but also higher global temperatures through the greenhouse effect and a greatly increased likelihood of liquid water. Vaporization of such cap remnants may occur twice each equinoctial precession, and Martian organisms may now be in cryptobiotic repose awaiting the end of the long precessional winter. The Viking biology experiments might test this hypothesis.
The concept of characteristics thrust is introduced herein as a means of classifying propulsion system tasks related particularly to geosynchronous communications spacecraft. Approximate analytical models are developed to permit estimation of characteristic thrust for injection error corrections, orbit angle re-location, north-south station keeping, east-west station keeping, spin axis precession control, attitude rate damping, and orbit raising applications. Performance assessment factors are then outlined in terms of characteristic power, characteristic weight, and characteristic volume envelope, which are related to the characteristic thrust. Finally, selected performance curves are shown for power as a function of spacecraft weight, including the influence of duty cycle on north-south station keeping, a 90 degree orbit angle re-location in 14 days, and finally comparison of orbit raising tasks from low and intermediate orbits to a final geosynchronous station. Power requirements range from less than 75 watts for north-south station keeping on small payloads up to greater than 15 KW for a 180 day orbit raising mission including a 28.5 degree plane change.
A synoptic study is presented of field-aligned precipitation events observed during a 16-month period, representing a full 4 pi precession of the satellite orbital plane in magnetic local time. The morphology of this type of precipitation, its nature, and relationships between this phenomenon and other geophysical events are discussed in the context of the 16-month data base.
The Belinfante-Swihart (BS) theory is reformulated in a representation in which uncharged matter responds to gravity in the same way as in metric theories. The BS gravitationally modified Maxwell equations are also put into metric form to first order in the deviations of the physical metric from flat space, but not to second order; consequently the theory is nonmetric except in first order. Also shown is that the theory violates the high precision Eotvos-Dicke experiment, but cannot be ruled out by the gravitational precession of gyroscopes.