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Space: Data From Saturn Probe Making Previous Theories About Planet Ring False

  • Jan Jun

The first data transmitted from Saturn by the joint U.S.-European Cassini-Huygens spacecraft is prompting scientists to consider abandoning existing theories about the ringed planet and its many moons. The spacecraft is now in orbit around the planet after a voyage of seven years and 3 billion kilometers.

London, 6 July 2004 (RFE/RL) -- Doctor Andrew Coates of the Mullard Space Science Laboratory at University College in London is one of the scientists participating in the Cassini-Huygens mission.

"It is fantastic, the data that is coming back from Cassini-Huygens and the first fly-past of the moon Titan," Coates says. "To provide such tantalizing but inexplicable results is actually very interesting."

Photographs taken by the spacecraft show hundreds of strange symmetrical waves in Saturn's rings, probably caused by the planet's magnetic field. The rings are shown in unprecedented detail and reveal interesting braid-like structures.

Measurements show the rings are made of water ice boulders and smaller particles, while the gaps between them contain mostly dust similar to that covering the moon Phoebe. This, say scientists, indicates that the rings may be remnants of a disintegrated moon.

There also is a surprisingly large quantity of oxygen at the edges of the rings.

Professor Stan Cawley of Britain's Leicester University, who is involved with the spacecraft's magnetic field measurements, says Saturn is a huge ball of gas with no rocky surface. The processes taking place there, including the source of its inner heat and its magnetic phenomena, are still unexplained.

"We have been looking particularly at the magnetic field which is present very close to the planet,” Cawley says. “This is the closest any spacecraft has ever been to the planet to measure the magnetic field. There are some unexpected features in that data that we are not quite sure what they mean, and we're working hard to try to understand at the moment."

Further surprises were revealed in the spacecraft's photographs of a hazy orange Titan -- the largest of Saturn's 31 moons, about the size of the planet Mercury. They show a methane cloud "the size of Italy," several crisscrossing linear features, and a huge circular area that could be a crater the size of Western Europe. Another image of the moon's atmosphere shows storms at different latitudes and moving in different directions.

Coates points out that the thick atmosphere of Titan makes it difficult for even the largest telescopes on Earth to see anything clearly. He says earlier theories about the surface are now being rewritten.

"In fact, the dark parts of the images turn out to be water ice probably, where the light parts of the images seem to be water ice with the mixture of hydrocarbons. There is evidence for methane clouds, perhaps tantalizing evidence that there may well be methane rain there, as well," Coates says.

Coates says Titan's nitrogen-rich atmosphere appears to be composed of chemical compounds similar to those that existed in Earth's distant past, so the spacecraft may be able to help scientists learn how our own planet formed: "It's something like the early Earth, at about 4 billion years ago, so this makes it a very exciting environment to try and look at, because it could be the start of something where life could perhaps evolve later on."

Professor Cawley adds that there will be more and better opportunities to study Titan during future Cassini fly-pasts, some at distances of just hundreds of kilometers from the surface. The next one is due to take place in October.

"The fly-by that took place of Titan was not a very close one. There will be a targeted encounter on the next orbit in which we undoubtedly will see major effects, and that is what we are looking to do," Cawley says.

Speaking to Reuters, Doctor Carolyn Porco of the U.S. space agency NASA sums up the enthusiasm of her colleagues about the success of Cassini-Huygens: "As you could imagine, life is good right now on the Cassini project. The imaging team scientists and our friends on the other teams are all in a whirl over what we're seeing from the images and all the other data."

And it's only going to get better.

On 14 January, the Huygens probe that is attached to Cassini is expected to land on the surface of Titan and reveal still more.

More information can be found at http://saturn.jpl.nasa.gov/home/index.cfm
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