Flight directors, feeling more confident that they understand what jammed the camera platform aboard Voyager II as it passed Saturn Tuesday, today restarted one of the spacecraft's five blacked-out cameras.
Goaded in part by scientists who feel that Voyager soon will be too far beyond Saturn to get more good pictures, flight directors signaled the start-up of the wide-angle lens on the camera platform, and photographs of a rapidly receding Saturn were resumed tonight.
Moving at 26,000 mph on the first leg of a 4 1/2-year flight to Uranus, Voyager II was 2 million miles beyond Saturn late today.
Earlier today, flight directors were able to move the camera platform at just the speed they intended for the first time since the platform jammed as Voyager II crossed Saturn's rings. The platform responded today by rotating 40 degrees on command in exactly the expected time.
The platform responded a second time and swung around to aim its wide-angle lens at the rings of Saturn. At 8:50 p.m. (EDT) a photograph of the rings came back to Earth. It was somewhat underexposed but in perfect focus. Voyager II had taken its first photograph since Tuesday.
"The platform is getting better with use, but we haven't built up our confidence level to where we can go slewing all over the place," mission director Richard Laeser said. "We have not built ourselves up to where we can take photographic sequences that require a lot of movements of the camera platform."
Still fearful that direct or reflected sunlight from the tops of Saturn's clouds might blind the cameras, flight directors kept inactive the narrow-angle lens and the ultraviolet, infrared and polarimeter telescopes on the platform.
Laeser said the wide-angle lens would be used to photograph Saturn and its outermost moon, Phoebe, whose orbit Voyager II is to cross next Thursday.
Scientists have given high priority to Phoebe, presumed to be the burned-out nucleus of a comet captured eons ago by Saturn's gravity. Phoebe rotates in the opposite direction that Saturn's 16 other moons move, one reason scientists believe that Phoebe is not native to Saturn.
When Voyager approaches Phoebe, flight directors will fire tiny gas jets to rotate the entire spacecraft so that it faces Phoebe, eliminating the risk that moving the camera platform rapidly will jam it again. The maneuver will use some of the 155 pounds of gas left in Voyager's tanks but not enough to cause concern.
The directors are becoming convinced that tiny foreign bodies are stuck inside at least one of the platform's electrical gear boxes. Most scientists think the foreign bodies were left when microscopic dust particles from Saturn's rings sandblasted the spacecraft. The directors lean toward that theory because the platform moves more freely the more often it is used, perhaps because gears are grinding foreign bodies into small pieces that don't impede movement.