A recent survey by NASA’s Cassini probe leads researchers to believe that there may be water below the surface of one of Saturn’s moons according to Wired.com.
The probe detected ammonia on the moon and sodium salts in Saturn’s rings during its survey on the planet last year. Both elements are strong indicators that liquid water could be under the surface of Enceladus.
“This is the first time Cassini has actually been able to ’smell’ ammonia,” said planetary scientist Jonathan Lunine of the University of Arizona, co-author of the study in ‘Nature’ on Wednesday. “And because ammonia is an antifreeze, it probably ensures that there is liquid water in the interior of Enceladus.”
Researchers studies jets of ice from cracks near the south pole, which generally generate plumes of gas and particles of water and carbon dioxide. A special instrument on the Cassini probe detected trace amounts of ammonia in the plumes, suggesting the source of gas could be liquid water beneath the surface.
“I’m pretty convinced,” Lunine said. “By itself, the findings we have are strong. But they’re made even stronger by the article in Nature last month that found, using a different instrument on Cassini, that there are sodium and ice particles on the E-ring.”
However, some scientists are not convinced the evidence leads to liquid water. Space scientist Susan Kieffer of the University of Illinois developed a model that doesn’t require liquid water for the creation of gas plumes, and the finding of ammonia hasn’t changed her skepticism.
“The argument in this paper hinges on an early announcement by NASA that temperatures in excess of 180 Kelvin have been reported,” Kieffer wrote in an e-mail. However, later measurements near the plume cracks reported temperatures closer to 167 Kelvin, she said.
“It sounds like a small difference, but it’s huge in terms of the ammonia-water system,” Kieffer wrote. If the temperature is above 173 Kelvin, there can be liquid water, but below there would likely be a system of frozen solids.
Despite the lower temperatures, Lunine says he stands by his group’s conclusions. Because the Cassini temperature instrument samples a fairly large region around the gas plumes, the temperature it reports is an average of hotter and colder regions of the moon.
“These temps are lower limit temperatures for what’s in the crack,” Lunine said. “Given fact that ammonia and water can melt at 176 Kelvin, we’re really in the range that liquid water could exist.”
“I’d love to have a situation where we actually dipped our toes into the water, although I’m not sure I’d want to do it barefoot,” Lunine said. “But we’re not going to be able to do that. Just the fact that we can sample the water — smell it if you will — by studying the gas in the plumes, is pretty great.”
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