Magnetic Damping of Rotation of Satellite 1958β2

Wilson, Raymond H.

doi:10.1126/science.130.3378.791

Cited by 15 publications

(6 citation statements)

References 1 publication

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Thus, the model's moments of inertia in the three principal axes are 5 × 10 3 , 4 × 10 3 , and 1 × 10 3 kg·m 2 , and the elements M 1 -M 3 of the diagonalizable eddy current tensor are −2 × 10 5 , −3 × 10 5 , and −4 × 10 5 N·m 2 ·s/T 2 . Thus, the decay rate of the angular velocity in the simulation is about 2 yr −1 , which is consistent with actual observational data (Wilson 1959(Wilson , 1977Meeus 1974). The orbit chosen in the simulation is the nearearth orbit and the eccentricity is near 0.…”

Section: Variation Of Angular Velocitysupporting

confidence: 84%

“…The phenomenon that the angular velocity decays exponentially has been confirmed by observational data (Meeus 1971(Meeus , 1974. Wilson (1959Wilson ( , 1977 fits the variations of the angular velocities of satellites to the inverse of the magnitude of the magnetic field, which is in good agreement with that of the geomagnetic field. Based on observational data, Williams and Meadows (1978) verified that eddy current torque is the primary factor in spin decay.…”

Section: Introductionsupporting

confidence: 67%

“…The angular velocity of the space debris would decay exponentially under the effect of eddy current torque (Wilson 1959;Smith 1965), i.e., ω(t) = ω 0 e −λt , where ω 0 is the initial angular velocity, λ is the exponential decay rate, and t is the decay time. The rate of the exponential decay is associated with the magnitude of the magnetic field, shape of the space debris, conductivity, and moment of inertia, which are specific to the item of space debris.…”

Section: Variation Of Angular Velocitymentioning

confidence: 99%

See 2 more Smart Citations

Evolution of the rotational motion of space debris acted upon by eddy current torque

Lin

Zhao

2015

Astrophys Space Sci

View full text Add to dashboard Cite

Finding analytical solutions to the eddy current torque produced by a conducting body rotating within a magnetic field is arduous. In this paper, the finite difference method is adopted to solve numerically the boundary problem regarding the distributions of eddy currents in determining eddy current torque. Through analysis of the solutions, this paper presents the expression of eddy current torque that applies to a model of arbitrary shape rotating around an arbitrary axis. The parameters of the physical properties of the rigid body are integrated into the eddy current torque tensor, the features of which are analogous to the inertia tensor. The elements in the tensor are constants for a specific rigid body; thus, in the expression, the torque is associated only with the relative angular velocity and magnetic field. The expression is used to investigate the evolution of the rotation of space debris subjected to eddy current torque, through numerical integration with the angular velocity of the variation of the geomagnetic field, which is assumed a dipole. The results explain the observed phenomenon of change in the spin decay rate. Moreover, the effects of gravity-gradient torque and orbit precession cause the self-spin of the space debris to resonate with the orbital motion and ultimately, to reach a steady state.

show abstract

Section: Variation Of Angular Velocitysupporting

confidence: 84%

Section: Introductionsupporting

confidence: 67%

Section: Variation Of Angular Velocitymentioning

confidence: 99%

See 1 more Smart Citation

Evolution of the rotational motion of space debris acted upon by eddy current torque

Lin

Zhao

2015

Astrophys Space Sci

View full text Add to dashboard Cite

show abstract

“…Therefore, this satellite can be used to study the geomagnetic retardation of the spin rate predicted by D. P. Vinti's eddy current theory (18) and applied experimentally by R. H. Wilson Jr. (19). Vinti's study assumes that the dominant factors of the spin decay are the electromagnetic forces derived from the movement of a conductive body through the electric and magnetic fields of Earth.…”

Section: Im$^mi0mw^w(mimi Iife^mentioning

confidence: 98%

Anomalies of the Geomagnetic Retardation of the Spin of Satellite Vanguard I (1958 Beta)

Arendt

1961

ARS Journal

View full text Add to dashboard Cite

Continuous observations of the spin rate decay of satellite Vanguard I (Beta 1958) have indicated anomalies that do not fit into the picture developed from the theory of exponential magnetic damping by eddy currents. The first anomaly was detected in December 1958; the decay changed to a very low rate; a rate similar to the previous decay was observed early in 1959. Other anomalies were found later in 1959 and in 1960. Some of the anomalous low decay rates might be related to the movement of the Earth around the sun. During the 2| years of observation the spin changed from 1 revolution in J sec to 1 revolution in 20 sec. The slope of the decay curve varied between 0.19 and 7.6 arbitrary log units during fall 1960; initially the slope varied between 4.1 and 5.0 units. The slope during first anomaly was 2.2 units. Spin FadingT HE METHOD of obtaining the spin rate of an artificial satellite by the counting of maxima or minima in a satellite's CW signal is well known. These "spin fades" are produced by the lobes or zeros in the pattern of the satellite's transmitting antenna. The effects of various types of satellite antennas (such as dipoles, turnstile or slot antennas) have to be considered as well as the influence of the receiver antenna, the polarization of that antenna, and the geometry of and the ionization along the propagation path. For these reasons, the spin fading observations are easily disturbed by other fading phenomena such as multiple path reception or Faraday fading. For example, Sputnik I showed a spin fading period of about 4.6 sec. The period of Faraday fading observed was 4.4 sec at 20 mc and 15.0 sec at 40 mc. Thus, it is sometimes difficult to differentiate both phenomena. However, with frequencies in the order of 100 mc the periods of Faraday fading are in the order of minutes and will not divert spin fading observation. Further, multiple path reception is much less probable with such higher frequencies than in the 20-and 40-mc range. Therefore, the observations of Vanguard I on 108 mc are rather free from errors due to other types of fading.When a satellite is placed into orbit, the effects of gravity are greatly reduced in the sense that the satellite can be considered a free gyroscope and under no constraint. Therefore, small forces become effective. Torques acting at the spin axis produce a decay of the spin rate. Other small torques not aligned along the spin axis cause precession and lead to tumbling. Such tumbling or precession period causes a complicated rotation of the antenna pattern with respect to the observer on Earth. The resulting ambiguity in the interpretation of the data is demonstrated by Fig. 1, which shows the spin and precession fades during the early life of Vanguard I. The ambiguity was solved in this case by independent telemetry signals measuring the initial spin before third-state separation during the launching operation. 2 The author is indebted to R. I. Easton and M. J. Votav for this communication.Many authors have described the relationship between the radiation...

show abstract

“…Any ordinary sexual population, if allowed to reproduce maximally, would soon give rise to a vast array of variant individuals (1 ) . Even the descendants of only one pair, under similar conditions, would give rise to a great number of variant individuals.…”

Section: Potential Genetic Variability Of Wild Pairs Of Drosophilamentioning

confidence: 99%

Geomagnetic Rotational Retardation of Satellite 1959α1 (Vanguard II)

Wilson

1960

Science

Self Cite

View full text Add to dashboard Cite

show abstract

Magnetic Damping of Rotation of Satellite 1958β2

Cited by 15 publications

References 1 publication

Evolution of the rotational motion of space debris acted upon by eddy current torque

Evolution of the rotational motion of space debris acted upon by eddy current torque

Anomalies of the Geomagnetic Retardation of the Spin of Satellite Vanguard I (1958 Beta)

Geomagnetic Rotational Retardation of Satellite 1959α1 (Vanguard II)

Contact Info

Product

Resources

About