NASA Out of Cassini Spacecraft Radio Contact Before Final Ring Dives and Death Plunge –“Will Gather Amazing New Data About This Huge World” (VIDEO)




Controllers and scientists must wait until Thursday to hear from the Cassini spacecraft that was due early on Wednesday to make the first of 22 dives in between Saturn's cloud tops and the inner edge of its spectacular rings designed to gather pictures and other science data of unprecedented resolution and science data that finally unlocks puzzles about the make-up and history of this huge world.

"We're going to top off this mission with a lot of new measurements – some amazing new data," said Athena Coustenis from the Paris Observatory in Meudon, France. "We're expecting to get the composition, structure and dynamics of the atmosphere, and fantastic information about the rings," she told the BBC.


The earliest that Cassini is expected to radio home is 07:00 GMT (08:00 BST) on Thursday. Contact should come through NASA's 70m-wide Deep Space Network antenna at Goldstone, California, andpictures and other data ought to start coming down about half an hour later.

Because the probe was moving at over 110,000 km/h (70,000mph) there's risk attached to flying through the ring plane where impact with even a tiny ice or rock particle at that velocity could do a lot of damage, so the decision was made to point Cassini's big antenna in the direction of travel, to act as a shield blanking out radio contact with Earth.




Twenty one similar dives will be made overthe next five months to determine the mass and therefore the age of the rings before the probe plunges into the atmosphere of Saturn. The more massive the ring, the older they are likely to be, some could be as old as Saturn itself. NASA's Scientists will do this by studying how the velocity of the probe is altered as it flies through the gravity field generated by the planet and the huge encircling bands of ice.



"In the past, we were not able to determine the mass of the rings because Cassini was flying outside them," explained Luciano Iess of the Sapienza University of Rome, Italy told the BBC. "Essentially, the contribution of the rings to the gravity field was mixed up with the oblateness of Saturn. It was impossible. But by flying between the rings and the planet, Cassini will be able to disentangle the two effects. We're able to tell the velocity of Cassini to an accuracy of a few microns per second. This is indeed fantastic when you think Cassini is more than one billion kilometres away from the Earth."

"We still need to understand the rings' composition," said Nicolas Altobelli, who is project scientist for Nasa's Cassini mission partner, the European Space Agency told the BBC. "They are made of very nearly pure water-ice. If they're very old, formed at the same time as Saturn, how come they still look so fresh when they're constantly bombarded with meteorite material?"

One possibility is that the rings are actually very young, perhaps the remains of a giant comet that got too close to Saturn and broke apart into innumerable fragments.

The Daily Galaxy via BBC Science, NASA, and ESA


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