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Voyager 2 at Neptune: Imaging Science Results

Smith, B. A. and Banfield, D. and Danielson, G. E. and De Jong, E. and Howell, C. and Ingersoll, A. P. and Schwartz, J. (1989) Voyager 2 at Neptune: Imaging Science Results. Science, 246 (4936). pp. 1422-1449. ISSN 0036-8075. doi:10.1126/science.246.4936.1422.

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Voyager 2 images of Neptune reveal a windy planet characterized by bright clouds of methane ice suspended in an exceptionally clear atmosphere above a lower deck of hydrogen sulfide or ammonia ices. Neptune's atmosphere is dominated by a large anticyclonic storm system that has been named the Great Dark Spot (GDS). About the same size as Earth in extent, the GDS bears both many similarities and some differences to the Great Red Spot of Jupiter. Neptune's zonal wind profile is remarkably similar to that of Uranus. Neptune has three major rings at radii of 42,000, 53,000, and 63,000 kilometers. The outer ring contains three higher density arc-like segments that were apparently responsible for most of the ground-based occultation events observed during the current decade. Like the rings of Uranus, the Neptune rings are composed of very dark material; unlike that of Uranus, the Neptune system is very dusty. Six new regular satellites were found, with dark surfaces and radii ranging from 200 to 25 kilometers. All lie inside the orbit of Triton and the inner four are located within the ring system. Triton is seen to be a differentiated body, with a radius of 1350 kilometers and a density of 2.1 grams per cubic centimeter; it exhibits clear evidence of early episodes of surface melting. A now rigid crust of what is probably water ice is overlain with a brilliant coating of nitrogen frost, slightly darkened and reddened with organic polymer material. Streaks of organic polymer suggest seasonal winds strong enough to move particles of micrometer size or larger, once they become airborne. At least two active plumes were seen, carrying dark material 8 kilometers above the surface before being transported downstream by high level winds. The plumes may be driven by solar heating and the subsequent violent vaporization of subsurface nitrogen.

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Ingersoll, A. P.0000-0002-2035-9198
Additional Information:© 1989 American Association for the Advancement of Science. Received 6 November 1989; accepted 15 November 1989. We gratefully acknowledge the skill, hard work, and good cheer of all our colleagues who helped us during this final Voyager encounter, especially the Voyager Spacecraft Team, for providing us with a healthy, reliable, obedient, and stable spacecraft with which to perform our imaging experiments. Special thanks go to H. Marderness, G. Hanover, and E. Wahl for designing the image motion compensation; G. Masters, M. Urban, B. Cunningham, and D. Rice for extended exposure capability; and our own E. Simien for making every image available. We thank our fellow scientists J. Burns, C. Ferrari, D. M. Janes, F. Rocques, and the analysts at MIPL, coordinated and directed by C. Avis and S. Lavoie: G. Garneau, H. Mortensen, C. Stanley, L. Wynn, L. Wainio, G. Yagi, D. Alexander, C. Levine, E. Runkle, J. Yoshimizu, R. Mortensen, and D. Jensen. We thank those at the USGS in Flagstaff for their help: K. Edwards, E. Eliason, T. Becker, J. Swann, K. Hoyt, R. Batson, J. Inge, P. Bridges, and H. Morgan. We also thank P. Goldreich, P. Nicholson, D. Stevenson, and R. West for careful and thoughtful reviews of this manuscript.
Issue or Number:4936
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ID Code:37154
Deposited On:26 Feb 2013 22:39
Last Modified:09 Nov 2021 23:27

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