Word: saturns
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Zeroing in on Saturn's moons, Voyager 2 discovered surprising contrasts between those icy little worlds. Hyperion, for example, is a small, distant moon shaped like a battered Idaho potato (or, as NASA scientists variously had it, a "hamburger patty" or a mouse-gnawed "hockey puck"). Tethys, closer in, is scarred by a huge crater more than a third as wide as the satellite's own 670-mile diameter, and by a canyon that extends at least two-thirds of the way around it. Apparently the moon was struck by a huge object and badly cracked...
...earthbound viewers, and even for scientists at the Jet Propulsion Laboratory outside Pasadena, which masterminds Voyager's progress, the show-stopper was, once again, Saturn's rings. Better illuminated than they were during Voyager 1's flyby, they showed up in greater detail and in far greater number: literally by the thousands. Before Voyager 2's visit, scientists had a ready hypothesis to explain why the icy materials of the rings-fragments ranging in size from dust specks to boulders-follow only certain orbits and not others, leaving gaps of hundreds of miles. The gaps...
...alternate theory holds that the rings and the gaps between them are in effect peaks and troughs in Saturn's own gravitational field, like the concentric ripples created by a rock dropped into the surface of a still pond. Another line of speculation attributes the formation of at least some of the rings to a periodic gravitational attraction, or "resonance," between the ring particles and Saturn's passing moons...
Voyager came closest to Saturn just before the 1½-hour period when the spacecraft was behind the planet, totally cut off from the earth. But the semi-intelligent machine continued operations under the command of its preprogrammed computers, taking pictures, performing experiments and storing the information on tape. Not until Voyager 2 emerged from behind Saturn and again began radioing back data did scientists learn that something had gone wrong. As Voyager 2 crossed the rings, the playback showed, the cameras began missing their targets. Somehow the spacecraft's movable "scan platform," which acts as an aiming mechanism...
...week's end, it appeared that they may well have succeeded. With a swivel that jubilant controllers described as "right on the money," the platform brought fading Saturn back onto their TV monitors again. This week they hope to aim the cameras at Phoebe, the planet's outermost moon. Even if the problem recurs, though, it should not spoil the photographic reconnaissance of Uranus or Neptune. The controllers can simply "pan" the cameras by rolling the entire spacecraft with blasts from its small thrusters...