The solid's proportion was thought to be smaller

Dec 21, 2009 10:02 GMT  ·  By
Researchers have upped their estimates of the proportion of ice in Enceladus's plume
   Researchers have upped their estimates of the proportion of ice in Enceladus's plume

Recent investigations have determined that ice particles make up for more than half of contents inside the plumes that come out of Saturn's moon Enceladus. The discovery questions previous knowledge, which held that only about ten to 20 percent of the plumes were ice, with the rest being made of water vapor. According to the new results, it may be that the plumes are not the result of sublimation after all, as first thought, but that they rather stem from a sub-surface lake boiling off into space.

The study was conducted on photos collected by the NASA/ESA Cassini spacecraft in 2006. The investigation was led by California Institute of Technology (Caltech) planetary scientist Andrew Ingersoll, and its results were presented on Thursday, December 17, at the annual meeting of the American Geophysical Union (AGU), held in San Francisco. The photos on which these conclusions are based were taken during a very special time in Cassini's mission, the Pasadena-based team reveals.

Back in 2006, the probe was in Saturn's shadows, and managed to catch a glimpse of Enceladus, as it was backlit by the Sun. This allowed the spacecraft to look at the moon without having its very sensitive instruments blinded by looking directly into the Sun, Nature News reports.

According to recent reports, it may be that the thing keeping the liquid water and vapors on the icy Enceladus from freezing is nothing else than a natural form of antifreeze. The most important chemical in such a cocktail is ammonia, which has the ability to significantly alter the temperature points at which substances move from one of their states (solid, liquid, gaseous, etc.) to another. The find has been made using the Cassini space probe, which identified traces of the chemical compound last October, while analyzing emission plumes coming from the moon's surface.

“This is the first time Cassini has actually been able to ’smell’ ammonia. And because ammonia is an antifreeze, it probably ensures that there is liquid water in the interior of Enceladus,” University of Arizona planetary scientist Jonathan Lunine says. He is the co-author of a new study detailing the theory, published in the July issue of the prestigious scientific journal Nature.