The Search for Life in our Solar System leads seekers to strange places. From our Earthbound viewpoint, an ice-covered moon orbiting a gas giant far from the Sun can seem like a strange place to search for life. But underneath all that ice sits a vast ocean. Despite the huge distance between the moon and the Sun and despite the thick ice cap, the water is warm. <\/p>\n
Of course, we\u2019re talking about Enceladus, and its warm, salty ocean\u2014so similar to Earth\u2019s in some respects\u2014takes some of the strangeness away. <\/p>\n
<\/p>\n Enceladus is Saturn\u2019s sixth-largest moon, and the Cassini spacecraft observed it during its mission to the Saturn system. Scientists discovered that plumes of water originating from Enceladus\u2019 southern region are responsible for one of Saturn\u2019s rings. They also discovered that the water is salty. Any place we find warm, salty water attracts our immediate attention, even when it\u2019s covered by kilometres of ice and is 1.5 billion kilometres away from the life-giving Sun. <\/p>\n There\u2019s lots of talk about a future mission to Enceladus to explore the moon and its potentially life-supporting ocean in more detail. But until then, scientists are working with their current data, and using models and simulations to understand the moon better. <\/p>\n Enceladus\u2019 most defining surface features are its Tiger Stripes. They\u2019re four parallel, linear depressions on the moon\u2019s surface about 130 km long, 2 km wide, and 500 meters deep. They have higher temperatures than their surroundings, indicating that cryovolcanism is active. The stripes are the source of Enceladus\u2019 plumes.<\/p>\n New research suggests that strike-slip faults at the moon\u2019s prominent Tiger Stripe features allow plumes of water from Enceladus to escape into space. It\u2019s published in Nature Geoscience and titled \u201cJet activity on Enceladus linked to tidally driven strike-slip motion along tiger stripes.\u201d The lead author is Alexander Berne, a doctoral candidate in Geophysics at the California Institute of Technology. <\/p>\n The plumes above the Tiger Stripes aren\u2019t stable and continuous. They wax and wane as the moon follows its 33-hour orbit around Saturn. Tidal heating keeps the moon\u2019s water in liquid form, and according to the researchers, the same tidal forces are responsible for the intermittent plumes. Theory shows that tidal forces open and close faults at the Tiger Stripes like an elevator door, and that turns the plumes on and off. <\/p>\n However, those theories can\u2019t accurately predict the timing of the plumes\u2019 peak brightness. They also show that tidal forcing alone doesn\u2019t provide enough energy to open and close the faults. <\/p>\n This research digs deeper into the question and provides an answer. The authors say that rather than acting like an elevator door, strike-slip faults at the Tiger Stripes open and close to regulate plume activity. This is similar to what happens on Earth in places like the San Andreas Fault. It\u2019s a strike-slip fault where one side shears past the other, causing Earthquakes. The critical part of this is that strike-slip faults require less energy than the elevator opening and closing scenario. <\/p>\n Models are more effective as they\u2019re fed more detailed and accurate data. Berne and his co-researchers built a numerical model that simulates the strike-skip faults on Enceladus. They included friction, compressional forces and shear forces. The numerical model showed the faults acting in concert with the changing plumes. This strongly suggests that Enceladus\u2019 orbit and the tidal forces acting on the moon cause the strike-slip faults to open and close.<\/p>\n The Tiger Stripes have bent sections that pull apart under strain. Since they\u2019re bent, an opening appears as they slide. The plumes come from these openings.<\/p>\n The research team\u2019s work and previous research into the Tiger Stripes by NASA\u2019s Jet Propulsion Laboratory both support the idea that the plumes come from these strike-slip faults. <\/p>\n \u201cWe now appear to have both geologic and geophysical reasons to suspect that jet activity occurs at pull-aparts along Enceladus\u2019s tiger stripes,\u201d said lead author Berne.<\/p>\n Enceladus gets most of its attention because of its potential to support life. The plumes themselves aren\u2019t part of what life needs, but they\u2019re a window into the moon\u2019s potential habitability. <\/p>\n \u201cFor life to evolve, the conditions for habitability have to be right for a long time, not just an instant,\u201d said study co-author Mark Simons, Professor of Geophysics at Caltech. \u201cOn Enceladus, you need a long-lived ocean. Geophysical and geological observations can provide key constraints on the dynamics of the core and the crust as well as the extent to which these processes have been active over time.\u201d<\/p>\n There\u2019s a lot more work to be done to understand Enceladus. On Earth, satellites can monitor the movement at strike-slip faults and use it to better understand Earthquakes. Once we get a spacecraft to Enceladus, it could do the same. <\/p>\n \u201cDetailed measurements of motion along the tiger stripes are needed to confirm the hypotheses laid out in our work,\u201d Berne says. \u201cFor instance, we now have the capacity to image fault slip, such as earthquakes, on Earth using radar measurements from satellites in orbit. Applying these methods at Enceladus should allow us to better understand the transport of material from the ocean to the surface, the thickness of the ice crust, and the long-term conditions which may enable life to form and evolve on Enceladus.\u201d<\/p>\n When we get a spacecraft to Enceladus, it can monitor the faults and jets over multiple orbits. That will allow researchers to test their predictions. <\/p>\n \u201cThese observations could provide key constraints on the mechanical nature of the crust, tidal controls on jet activity and the evolution of the south polar terrain,\u201d the authors conclude. <\/p>\n![\"This](\"https:\/\/www.universetoday.com\/wp-content\/uploads\/2024\/05\/Enceladus-Strike-Slip-Fault.jpg\")
![\"This](\"https:\/\/www.universetoday.com\/wp-content\/uploads\/2024\/05\/Enceladus-Fault-Movement-1024x732.jpg\")
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