Printer Friendly

Jupiter's gossamer ring: a refined look.

It was only a single photo among the thousands taken by the Voyager 1 spacecraft in 1979 that unexpectedly revealed the presence of the faint ring system of Jupiter (SN: 3/17/79, p. 172). So subtle is it that even in a series of photos deliberately taken by Voyager 2 a few months later, a major portion of the system went undetected until refined computer processing suggested its presence four years later (SN: 11/5/83, p. 295). This was Jupiter's "gossamer" ring, the outermost portion of the system, and now a group of researchers has published a version of the photo that most clearly confirms its presence.

The gossamer ring at first went unnoticed because of its faintness in early versions of images made with Voyager's vidicon camera system. With a vidicon, even a photo of the plain dark sky -- or one made with the camera's shutter completely closed -- never produces an evenly black image, because of variations in the vidicon's response. A standard part of the processing of spacecraft vidicon images is therefore to subtract this variation, called a "dark current." The change is often a small one, making little difference except to images of extremely faint features. And Jupiter's gossamer ring, says Mark Showalter of Cornell University, is about 95 percent fainter than the also rarefied "bright" ring just inside it.

Using a refined dark-current value, however, makes the gossamer ring readily apparent, Showalter and his colleagues report in the Aug. 8 NATURE. From the outer edge of the "bright" ring, about 129,000 kilometers from Jupiter's center, the gossamer ring extends to about 210,000 km, though its outer edge is unclear.

The clarified view of the gossamer ring has already affected NASA's next Jupiter mission, called Galileo, which will not arrive until 1988. Galileo will send a probe into the Jovian atmosphere, but the possibility of damage to the probe's heat shield has prompted officials to double the distance from Jupiter at which it penetrates the plane of the rings.
COPYRIGHT 1985 Science Service, Inc.
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 1985, Gale Group. All rights reserved. Gale Group is a Thomson Corporation Company.

Article Details
Printer friendly Cite/link Email Feedback
Author:Eberhart, Jonathan
Publication:Science News
Date:Aug 31, 1985
Words:336
Previous Article:Dial-a-spacecraft during comet mission.
Next Article:The ICE plan cometh.
Topics:


Related Articles
Mooning over the dust rings of Jupiter.
Incumbent Hall, newcomer McCown capture LCC seats.
LIVING THE HIGH LIFE SETH ROGEN DISHES ON WHAT IT'S LIKE TO BE A DUDE IN L.A.
FOR LOYOLA, THE EIGHTH IS MORE THAN ENOUGH.
KUWAIT - The Kuwaiti Oil Refining Sector.
KUWAIT - Upgrades.
Maryland high court expands economic loss exception.
Beat the summer heat: cool looks for warm days.
Putting community in forests: a look back at the evolution of American Forests' policy niche and toward recommendations for expanding the role of...
How the human "network" collided with the environment.

Terms of use | Copyright © 2017 Farlex, Inc. | Feedback | For webmasters