PASADENA, Calif. -- Voyager 1 found a new moon of Saturn, the 15th now known, before a rain storm in Spain wiped out five hours of pictures and science data from the spacecraft, Jet Propulsion Laboratory scientists said Saturday.
The new moon, only about 50 miles across, was sighted by Voyager cameras just outside the bright A-ring of the planet. Scientists were studying how the satellite influences particles in the outer part of the planet's ring.
'In the first of its programmed satellite searches,' said Brad Smith, imaging team leader. 'Voyager has discovered a 15th satellite of Saturn.'
He said it was the third moon of the ringed planet discovered by Voyager 1 in the past few days.
Scientists were still seeing the satellite as a point, he said, and could not determine an actual size, but it appeared a little more than 50 miles in diameter.
The five-hour loss of data included pictures of Saturn, now about 3.5 million miles away from Voyager, and the planet-sized moon Titan, a target of intensive scientific investigation in the Voyager mission.
Titan is the only moon in the solar system with an atmosphere.
'All of the humor has gone out of the rain in Spain,' project manager Ray Heacock said. 'We lost essentially the entire transmission, a little over five hours of data.'
He said some critical optical navigation data was also lost in transmission but it had been stored in the Voyager computers and was received later.
Rainstorms were expected to sweep across the Iberian Peninsula for another day, which could cause a further loss of information and pictures, he said.
Large fans are used on the receiving antenna at Madrid, Spain, but the rain was too heavy to be blown away.
As soon as data reception was transferred to the Goldstone receiving antenna in California the transmissions 'came in loud and clear,' a JPL spokesman said.
Madrid, Goldstone and a receiving antenna in Australia form a worldwide network for space data reception.
A recent picture of Titan, which appears as a glowing orange ball, discloses no surface features, project scientist Dr. Edward Stone said.
Stone said scientists assume Titan has a rocky core but its size is not known. It could extend to the surface of the satellite which is slightly larger than the planet Mercury.
The Titan atmosphere, which could be much thinner than Earth's or up to twice as thick, is mostly methane. If it is a dense and very cold atmosphere, Stone said, the surface could have lakes of liqid nitrogen or liquid methane.
'Its atmosphere is really quite remarkable,' he said. It may be subject to photo chemical changes, that is changes caused by sunlight, or it could be influenced by energetic particle chemistry, assiciated with impacting electrons.
Stone said Titan could have a constant rain of particles of acetylene and ethane forming a soft surface from several meters to possibly several kilometeres thick.
He described the Titan atmosphere as evolved and could be subjected to the same type of chemistry that occurred in the formative history of Earth.
Voyager 1 is to fly under the rings of Saturn for its closest approach at 77,174 miles Wednesday afternoon. On Tuesday, it will scan the hazy cloud tops of Titan at 2,500 miles.
