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Subsurface Ocean on Saturn Moon Enceladus: Discovery by Heidelberg Scientists

Press Release No. 1/2009
25 06 2009
Article in Nature—Sodium salts found in ice plumes emitted by Enceladus
Since 2004 the Cassini space probe launched in 1997 has been touring the Saturnian system to study the “lord of the rings” and its moons. After the spectacular landing of the Huygens spacecraft on Titan in 2005, another of Saturn’s moons has now moved into the forefront of interest: Enceladus. Flybys have indicated that this moon’s geological activity is surprisingly intensive, with plumes of water vapour and ice particles being hurled out into space from vents in the ice crust near the south pole. A cosmic dust analyser (CDA) on the Cassini spacecraft has now provided evidence that many ice particles in the Enceladus geysers contain sodium salts. The CDA was developed by Heidelberg scientists.

According to a study published today in Nature this makes it probable that there is a huge subsurface ocean on this moon (“Sodium Salts in E Ring Ice Grains from an Ocean below the Surface of Enceladus” in: Nature, 25 June 2009, Vol. 459, Issue 7250, pp. 1098-1101). At present Dr. Frank Postberg, first-named author of the article and physicist at Heidelberg University’s Institute of Earth Sciences and the Max Planck Institute of Nuclear Physics, is a member of a cooperative research team working on the acceleration of tiny dust particles. The team’s objective is to investigate impacts by ultra-high-velocity dust particles. The project is financed by the FRONTIER fund, part of Heidelberg University’s Institutional Strategy in the framework of the Initiative for Excellence.

“Our observations indicate that there is liquid water beneath the ice crust,” says Heidelberg physicist Frank Postberg. “The ice particles are basically shock-frozen salt-water droplets. Water vapour and other gases rise up from the surface of the water reservoir and drag the ice particles along with them before being hurled out into space at great speed through vents in the ice crust.” As the salts must have been leached out of rock at the core of the moon, it is probable that a huge water ocean still exists below the surface. This would make Enceladus “one of the few candidates worth searching for signs of primitive life forms” in our solar system.

Dr. Frank Postberg has been on the Heidelberg Cassini team since his doctoral dissertation. The investigation of ultra-high-velocity dust-particle impacts in the framework of his ongoing project makes it possible to achieve an even more precise reconstruction of the particles’ original chemical and mineralogical composition. Studies like these are essential for the interpretation of the measuring results. According to privatdozent Dr. Mario Trieloff and Dr. Ralf Srama, project leaders at the Institute of Earth Sciences and Heidelberg’s Max Planck Institute of Nuclear Physics, they are also evidence “not only of the exemplary cooperation between university and non-university institutions, but also of the successes achieved with the help of systematic research funding from the Initiative for Excellence”.

Dr. Frank Postberg
Institute of Earth Sciences
Heidelberg University
Im Neuenheimer Feld 234-236
D-69120 Heidelberg

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