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Promising discoveries about the potential for life on one of Saturn’s icy moons
Planetary scientists from Freie Universität Berlin have published two new studies in Science Advances with promising discoveries about the potential for life on one of Saturn’s icy moons. New evidence indicates that Enceladus might be more supportive of life than once assumed. In fact, spacecrafts already in planning could be used to identify evidence of life there much easier than previously thought, should it exist.
A photograph of the icy moon Enceladus taken by the space probe Cassini.Image Credit: NASA/JPL/Space Science Institute
What are the chances of finding extraterrestrial life in our solar system? Professor Frank Postberg, planetary scientist at Freie Universität Berlin, has just published a study in Science Advances with a team of international researchers, in which they present new evidence that it is easier to determine the constituents of the ocean hidden under Enceladus’s icy surface than previously assumed. Postberg was also part of a second study published on the same day, in which he and another planetary scientist from Freie Universität, Dr. Nozair Khawaja, contributed to research that reveals that certain microorganisms could actually tolerate the conditions in Enceladus’s ocean better than was previously thought. These results increase the probability of finding evidence of life on Saturn’s moon.
Enceladus is considered to be one of the most promising places to search for extraterrestrial life in our solar system. Researchers suspect that under the moon’s icy crust there is a global ocean of liquid water and a rocky core further below. Due to cryovolcanic activity, gigantic plumes break through cracks in the crust at the moon’s south pole, ejecting ice particles hundreds of kilometers into space.
NASA’s Cassini spacecraft passed through these plumes multiple times to analyze its composition. Enceladus’s ocean is the only extraterrestrial “body of water” from which scientists have been able to directly analyze samples. The samples revealed traces of various salts and organic compounds. Furthermore, previous analyses conducted by Cassini gave indications of hydrothermal processes on the seafloor and other conditions that are significant in supporting life.
Postberg’s study, “Cassini CDA Observes Compositional Segregation of Enceladus’ Ice Grains from Slow Freezing and Fragmentation of Oceanic Spray,” includes surprising findings about what happens to the ocean water on its way into space. The international team of scientists working on the study used Cassini data, long-term laboratory experiments, and theoretical models to reconstruct the process.
Droplets form at the ocean’s surface as bubbles filled with gas float up and pop. Water vapor then carries the droplets through cracks in the ice shell out into space. Until now, scientists believed that they froze instantaneously, however these new findings reveal that they freeze slowly. Due to this slow process, most components (including dissolved ones) separate from each other. Salts and organic materials are thus distributed at different locations inside each freezing droplet. Various types of previously dissolved salts also get segregated in the process; for example, sodium chloride (table salt) separates from sodium carbonate.
Enceladus ejects ice particles hundreds of kilometers into space. This results in salts and organic materials being separated and distributed at different locations inside each droplet.Image Credit: Professor Frank Postberg
On their way up, the frozen droplets are accelerated to speeds of up to 1,000 km/h. If they smash into the walls of the icy cracks, they break into fragments only a few micrometers in size before they shoot into space. This results in the ice particles often consisting of just one highly concentrated, previously segregated, substance.
“Enceladus actually does a lot of the work for us in preparing samples for analysis that usually take a lot of effort in chemical labs on Earth,” says Postberg, who led the