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Science 2 November 1984:
Vol. 226. no. 4674, pp. 512 - 516
DOI: 10.1126/science.226.4674.512
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Articles

Io's Sodium Cloud

Bruce A. Goldberg 1, Glenn W. Garneau 2, and Susan K. LaVoie 3

1 Senior scientist and member of the technical staff in the Atmospheric Sciences Section, Earth and Space Sciences Division., Jet Propulsion Laboratory, California Institute of Technology, Pasadena 91109.
2 Senior research analyst., Jet Propulsion Laboratory, California Institute of Technology, Pasadena 91109.
3 Group leader for flight projects in the Image Processing Laboratory, Observational Systems Division., Jet Propulsion Laboratory, California Institute of Technology, Pasadena 91109.

The first two-dimensional images of the source region of Io's neutral sodium cloud have been acquired by ground-based observation. Observed asymmetries in its spatial brightness distribution provide new evidence that the cloud is supplied by sodium that is ejected nonisotropically from Io or its atmosphere. Complementary, high-time-resolution, calibrated image sequences that give the first comprehensive picture of the variations of the fainter regions of the cloud extending more than 105 kilometers from Io were also obtained. These data demonstrate that the cloud exhibits a persistent systematic behavior coupled with Io's orbital position, a distinct "east-west orbital asymmetry," a variety of spatial morphologies, and true temporal changes. The geometric stability of the sodium source is also indicated. Isolation of the cloud's temporal changes constitutes an important milestone toward its utilization as a long-term probe of Io and the inner Jovian magnetosphere.

Submitted on June 14, 1984
Accepted on July 25, 1984


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
Molecular Origin of Io's Fast Sodium.
N. M. SCHNEIDER, J. T. TRAUGER, J. K. WILSON, D. I. BROWN, R. W. EVANS, and D. E. SHEMANSKY (1991)
Science 253, 1394-1397
   Abstract »    PDF »
Eclipse Measurements of Io's Sodium Atmosphere.
N. P. Schneider, N. M. SCHNEIDER, D. M. HUNTEN, W. K. WELLS, and L. M. TRAFTON (1987)
Science 238, 55-58
   Abstract »    PDF »


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