The West Ford payload

Waldron, P.; Maclellan, D. C.; Crocker, M.C.

doi:10.1109/proc.1964.2997

Cited by 5 publications

(4 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The purpose of this West Ford project was to establish an orbiting belt of dipole antennas, where messages could be sent coast to coast via the orbiting copper needles (Shapiro, 1964;Morrow, 1964;Waldron, 1964). The needles were each 1.78 cm long and 0.00178 cm in diameter.…”

Section: Introductionmentioning

confidence: 99%

Orbit perturbation analysis of West Ford needles clusters

Bowman

Barker²,

Schick³

2000

Astrodynamics Specialist Conference

View full text Add to dashboard Cite

Abstract. The West Ford package placed in orbit in 1963 contained almost 500 million copper dipoles. Due to a delay in releasing the needles in orbit a number of clusters of needles formed. Analysis of 34 years of mean orbital elements of 20 different clusters has revealed perturbations of 10 km or more in the semimajor axis due to direct solar radiation pressure, atmospheric drag, and Earth albedo pressure. The orbits have perigee heights ranging from 1500 km to 3600 km. A simplified Earth albedo model has been adopted to account for the long periodic perturbations observed in the semi-major axis. The periodic terms are a function of the sun and cluster nodal longitude angles. The atmospheric drag perturbation was modeled by extending the CIRA72 model atmosphere to heights above 2000 km. Cluster area-to-mass ratios were determined from fitting direct solar radiation pressure coefficients over 25 to 30 year data spans. Twenty to thirty year semi-major axis fits produced mean atmospheric density factors for hydrogen and helium for each cluster. These factors show a very high correlation with average perigee height. The results show that average hydrogen concentrations are from 3 to 5 times greater than given by the CIRA72 model. Helium concentrations also are from 1.5 to 4 times greater than predicted for these heights.

show abstract

Section: Introductionmentioning

confidence: 99%

Orbit perturbation analysis of West Ford needles clusters

Bowman

Barker²,

Schick³

2000

Astrodynamics Specialist Conference

View full text Add to dashboard Cite

show abstract

“…

In May 1963 a package containing 4.8 X I0 n copper dipoles, each 1.78 cm in length and 0.00178 em in diameter, was ejected from a parent satellite into a nearly circular, nearly polar orbit at a mean altitude of about 3650 km.These Project West Ford dipoles were subsequently dispensed individually such that each tumbled rapidly about its center of mass [Waldron et al, 1964;Shapiro et al, 1964]. Because of their extreme thinness, the dipoles are more susceptible to charge (i.e., Coulomb) drag perturbations than are any other satellites; they thus enable a stringent upper bound to be placed on the orbital effects of the drag [Shapiro, 1963a].As is well known, the main effect of a drag force is to decrease the period and the mean altitude of a satellite.

…”

mentioning

confidence: 99%

“…These Project West Ford dipoles were subsequently dispensed individually such that each tumbled rapidly about its center of mass [Waldron et al, 1964;Shapiro et al, 1964]. Because of their extreme thinness, the dipoles are more susceptible to charge (i.e., Coulomb) drag perturbations than are any other satellites; they thus enable a stringent upper bound to be placed on the orbital effects of the drag [Shapiro, 1963a].…”

mentioning

confidence: 99%

“…The nonzero reflectivity of the dipoles could then have caused the average direction of the sunlight force to differ from that of sunlight, which would have resulted in important changes in the orbital period of the dipole density peak when the orbit was partly in shadow [Shapiro, 1963b]. The dipole tumbling axes may have been preferentially oriented in the direction of the spin axis of the dispenser package; in view of the geometry of ejection [Waldron et al, 1964], such orientations could have led to an average increase in dipole orbital period during the first 360 revolutions when the orbit was partly in shadow. For the equivalent sphere, the corresponding net effect of sunlight pressure was to decrease the orbital period, but only slightly.…”

mentioning

confidence: 99%

See 1 more Smart Citation

Experimental bound on the orbital effects of charge drag

Shapiro¹

1964

J. Geophys. Res.

View full text Add to dashboard Cite

In May 1963 a package containing 4.8×10s copper dipoles, each 1.78 cm in length and 0.00178 cm in diameter, was ejected from a parent satellite into a nearly circular, nearly polar orbit at a mean altitude of about 3650 km. These Project West Ford dipoles were subsequently dispensed individually such that each tumbled rapidly about its center of mass [Waldron et al., 1964; Shapiro et al., 1964]. Because of their extreme thinness, the dipoles are more susceptible to charge (i.e., Coulomb) drag perturbations than are any other satellites; they thus enable a stringent upper bound to be placed on the orbital effects of the drag [Shapiro, 1963a]. As is well known, the main effect of a drag force is to decrease the period and the mean altitude of a satellite. Since orbital period can be measured more accurately, its variations are commonly used to study drag phenomena. But West Ford dipoles can neither be distinguished nor detected individually; it is therefore impossible to monitor the orbital period variations of any given dipole. Fortunately, the dipoles were dispensed in a manner such that their density along the orbit exhibited a logarithmic singularity [Shapiro et al., 1964]. For the first 80 days (i.e., for the first 700 orbital revolutions) the motion of this peak in the density represented essentially the group velocity of the dipole ensemble, and the changes in its orbital period contained the average effects of charge drag. After 80 days, the peak became asymmetrically ‘contaminated’ by dipoles that had lapped and been lapped by it; in addition the peak became far less pronounced and was therefore no longer useful for studying charge drag.

show abstract