Measured Velocities of Interplanetary Dust Particles

Nilsson, C. S.; Alexander, W. M.; Mccracken, C. W.; Berg, O. E.; Secretan, L.

doi:10.1038/208673a0

Cited by 9 publications

(7 citation statements)

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“…Troubles were encountered with both the spacecraft and the experiment, however, and only three probable dust-particle impacts were recorded. The probable orbits of these particles are described in this paper in greater detail than in an earlier report (Nilsson et al, 1965). The detector array consists of four tubular detectors aligned along the three body axes of the spacecraft.…”

Section: Discussionmentioning

confidence: 99%

Meteor orbits and dust; the proceedings of a symposium

Hawkins¹

1967

Smithsonian Contributions to Astrophysics

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The Proceedings of the Symposium on Meteor Orbit* and Dust is published simultaneously as a NASA Special Publication (SP-135) and as Volume 11 of the Smithsonian Contributions to Astrophysics. This single publication thus serves in a dual capacity to satisfy the requirements of both agencies for the published record of this international meeting.The NASA Special Publications series, begun in 1962, makes available information derived from or of value to NASA activities, and includes such publications as conference proceedings, monographs, data compilations, handbooks, Bourcebooks, and special bibliographies.The IntroductionWe recently completed a general analysis of the atmospheric trajectories of 413 precisely reduced Super-Schmidt photographic meteors (Jacchia, Verniani, and Briggs, 1965). We studied the dependence of heights, lengths, decelerations, and magnitudes on such basic parameters as velocity, angle of incidence, and mass, as well as on derived parameters such as the ablation coefficient and the fragmentation index; the latter were in turn related to the other geometrical and physical characteristics, including the phenomena of wake and terminal blending. The results of the analysis are mainly concerned with physical characteristics of meteors; in this paper we shall limit ourselves to only a few points related to problems of orbits and distribution, namely, physical differences dependent on the type of orbit, peculiarities of individual showers, and the mass scale for photographic meteors.Systematic differences between groups of meteors Systematic differences in some physical characteristics between meteors in short-period and long-period orbits were first pointed out by Jacchia (1958Jacchia ( , 1963. He found that the beginning heights of meteors with aphelion distances greater than 7 a.u. were higher than the corresponding heights of meteors with aphelion distances smaller than 7 a.u. All meteors were, of course, reduced to the same brightness.• Smithsonian Astrophysical Observatory and Harvard College Observatory, Cambridge, Massachusetts.'Smithsonian Astrophysical Observatory and Harvard College Observatory; on leave from Centra Nationals per la Fisica dell'Atmosfera c la Meteorologia del C.N.R., Rome, Italy. * Smithsonian Astrophysical Observatory, Cambridge, Massachusetts.The present general analysis has confirmed the effect found by Jacchia: meteors with aphelion distance smaller than 6 a.u. appear 1.8 km lower than meteors in long-period orbits, reduced to the same velocity, mass, and zenith angle. The maximum light and end heights are correspondingly lower ( fig. 1). This effect is related to the different densities that we find for the two groups: on the average, meteors in short-period orbits appear to be about 1.4 times as dense as meteors in long-period orbits. In addition, for short-period meteors, the density increases as the aphelion distance decreases ( fig. 2). These systematic differences in density could be ascribed to the different conditions in which the meteoroids were formed ...

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Section: Discussionmentioning

confidence: 99%

Meteor orbits and dust; the proceedings of a symposium

Hawkins¹

1967

Smithsonian Contributions to Astrophysics

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“…Later even larger arrays of thin film capacitors that discharge momentarily upon puncture were employed (D' AIuTOLO et al, 1965). Recently, coincidence techniques and time-of-flight detectors (NILSSON et al, 1965) have been introduced to obtain needed information on velocity and momentum.…”

Section: A Rocket and Spacecraft Datamentioning

confidence: 99%

“…The points, with order-of-magnitude accuracy, fall on or above the acoustic sensor curve. Note should be taken of a recent experiment measuring micrometeoroid velocities near Earth (NILSSON et aL, 1965). A directional, time-of-flight telescope involving two thin-film penetrations and a piezoelectric element was utilized to give velocity and mass.…”

Section: A Rocket and Spacecraft Datamentioning

confidence: 99%

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Minor objects in the solar system

Vedder

1966

Space Sci Rev

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The present status of theory and experiment relating to interplanetary bodies larger than molecules but smaller than asteroids is reviewed. The dynamics, nature, and origins of these objects are considered. The evidences from rocket and spacecraft measurements, meteor observations, terrestrial accretion and light-scattering phenomena are presented. The various lines of research are leading to a better understanding of these bodies, but there are many uncertainties to be resolved.

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“…The first attempts at in situ measurements of cosmic dust orbits (particle mass larger than 10 -12 gram) were performed in the 0go 1 satellite, and the data were reported by Nilsson et al [1965]. Unfortunately, their results are severely limited statistically.…”

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confidence: 99%

Orbital elements of micrometeorites derived from Pioneer 8 measurements

Berg¹,

Gerloff²

1970

J. Geophys. Res.

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Data from a cosmic dust experiment on Pioneer 8 have revealed the speed and radiant of six cosmic dust particles in 390 days of measurement. This gives a particle flux of 2×10−4/meter²/sec/2π ster. The probability of an extraneous velocity measurement during the 265 days is 2.6×10−7. Each of the six events has been analyzed for orbital elements, including true velocity, inclination, perihelion distance, and aphelion distance. Particle mass and energy have been derived on the basis of laboratory calibrations of the sensors using a two‐million‐volt electrostatic dust particle accelerator. The particle velocities range from 8.2 to 31.2 km/sec. The particle energies range from 6 to more than 80 ergs. Only one of the six particles exhibited retrograde orbital parameters.

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Measured Velocities of Interplanetary Dust Particles

Cited by 9 publications

References 1 publication

Meteor orbits and dust; the proceedings of a symposium

Meteor orbits and dust; the proceedings of a symposium

Minor objects in the solar system

Orbital elements of micrometeorites derived from Pioneer 8 measurements

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