A team of Cassini mission researchers led by University of Colorado Boulder discovered microscopic grains of rocks on Enceladus’ surface. This suggests that there may be warm water. Scientists published their results in Nature, an academic journal. Citation below. The grains were the first evidence that Enceladus’ icy moon had hydrothermal activity. This is when heated water infiltrates the rock crust and creates a mineral-rich solution. Sean Hsu (Research Associate at CU-Boulder’s Laboratory for Atmospheric and Space Physics) is the lead author. He and his colleagues believe that Enceladus may contain suitable environments for living organisms. Enceladus’s tiny silica grains are a sign that hydrothermal activity in the ice-covered ocean is taking place. These extreme environments on Earth are considered suitable for living. Image: University of Colorado. The Cassini Huygens (Cassini), spacecraft, left Earth in 1997.. The spacecraft was designed to study Saturn’s many moons. The spacecraft, which was unmanned, arrived in 2004. This surprising result is the product of a four-year comprehensive analysis that included data from Cassini and computer simulations as well laboratory experiments. Grains are formed when hot and cold water meet. The authors think that the tiny grains were created when the hot seawater containing dissolved mineral travelled upwards, becoming in contact with cooler seawater near the bottom. These interactions, which form tiny rock grains, must occur at minimum 90degC (194degF. According to Mr. Hsu, “It’s exciting that we are able to use these small grains of rock, which have been spewed into the space by geysers to tell us about the conditions on–and beneath–the ocean floor of anicy moon.” 2004, Cassini has used his CDA (Cosmic dust Analyzer), instrument several times in order detect tiny silicon-rich rocks particles. The team determined that the particles were grains of silica. This mineral is often found in quartz and sand on Earth. Cassini observed most grains in the same size, with larger grains measuring 6 to 9 nanometers. This suggests that they had been formed by a particular process. There is evidence that hot springs are located on Enceladus’ floor, allowing jets to penetrate its frozen crust. Image: Nature. Hydrothermal activity is the most frequent way that silica grains this large are created on Earth. This involves specific conditions, such as slightly alkaline water, moderate salinity and silica super-saturated, with a substantial drop in temperature. Frank Postberg from Heidelberg University, Germany is co-author. He was a CDA scientist and was part of the team that discovered the silica grains. “We tried many theories, but none of them were convincing.” The detailed laboratory experiments at the University of Tokyo by Postberg, Hsu, and others validated the hypothesis of hydrothermal activity. NASA has confirmed that 62 Moons were discovered orbiting Saturn. 53 have been officially named. Image: NASA. Japanese scientists led by Yasuhito Skine confirmed that silica grains could be formed in conditions similar to those observed by Cassini. These conditions may exist on Enceladus’ seafloor where the hot water below meets the cold ocean floor. Assistant Professor Sascha Kempf from LASP, and CU-Boulder Prof Mihaly Horanyi were also co-authors. They are also both faculty members at CU-Boulder’s physics department as well as co-investigators in the Cassini CDA. Professor Kempf believes that the Enceladus plumes puzzle, first discovered in 2004, by Cassini’s arrival on Saturn, has been partially solved. It was not clear ten years ago why the nanograins contained silica, rather than water-ice. We now know that the observations are correct. Now we know the source of silica particles and their purpose. Professor Kempf said, “We learned something unexpected which is why we really like this research.” Researchers believe that very tiny silica particles move up quite quickly from their hydrothermal source to near-surface moon geysers. Scientists wrote that the silica particles travel from the seafloor up to the outer space (a distance of about 30 km), and then send back data on Enceladus’ active geology in 2005,. This included evidence of an icy rain in the South Polar region, along with higher than expected temperatures at the region’s icy surface. The towering plume. It was soon apparent that the plume contained water ice, vapor, organic material and salts. This plume is formed from warm fractures in the lunar surface. According to gravity measurements published in 2014, there is probably a 10-kilometer-deep (6-mile-deep) ocean beneath an ice shell about 30 to 40 kilometers (19 to 25 miles) thick. Cassini’s gravity measurements indicate that Cassini has a rock core which is very porous. This would permit its ocean water, as well as other fluids to penetrate the interior. It would allow water and rocks to interact on a vast surface. According to Mr. Hsu: “It is possible that much of the interesting hot water chemistry happens deep within the moon’s core.” Nature. Publication online 11 February, 2015. DOI: 10.1038/nature14262. Reuters Video – Hot water clue for life on Enceladus
