Dr Dave Stegman, a Centenary Research Fellow in the School of Earth Sciences at the University of Melbourne, led the study and says that part of the intrigue with Enceladus is that it was once presumed to be a lifeless, frozen ice ball until a water vapour plume was seen erupting from its surface in 2006.
“NASA’s Cassini spacecraft recently revealed Enceladus as a dynamic place, recording geological features such as geysers emerging from the ‘tiger stripes’ which are thought to be cracks caused by tectonic activity on the south pole of the moon’s surface,” says Dr Stegman.
The moon is also one of the brightest objects in our solar system because the ice covering its surface reflects almost 100 percent of the sunlight that strikes it. One of Saturn’s 53 moons (so far identified) Enceladus reflects so much of the sun’s energy that its surface temperature is about -201° C (-330° F).
Grappling with how an inaccessible small moon with a completely frozen interior was capable of displaying geological activity, Dr Stegman and colleagues used computer simulations to virtually explore it.
Ammonia, usually found on Earth as an odorous gas used to make fertilizers, has been indirectly observed to be present in Enceladus and formed the basis of the study which is the first to reveal the origins of the subsurface ocean.
The model reveals that Enceladus initially had a frozen shell composed of a mixture of ammonia and water ice surrounding a rocky core. Over time, as Enceladus interacted with other moons, a small amount of heat was generated above the silicate core which made the ice shell separate into chemically distinct layers. An ammonia-enriched liquid layer formed on top of the core while a thin layer of pure water ice formed above that. The work will be published in the August issue of the planetary science journal, Icarus.
“We found that if a layer of pure water ice formed near the core, it would have enough buoyancy to rise upwards, and such a redistribution of mass can generate large tectonic stresses at the surface,” says Dr Stegman. “However, the pure water ice rising up is also slightly warmer which causes the separation to occur again, this time forming an ammonia-enriched ocean just under the surface. The presence of ammonia, which acts as an anti-freeze, then helps keep the ocean in its liquid state.”
“These simulations are an important step in understanding how planets evolve and provide questions to focus future space exploration and observations. It will hopefully progress our understanding of how and why planets and moons are different to each other.”
Nerissa Hannink | EurekAlert!
Black hole spin cranks-up radio volume
15.01.2018 | National Institutes of Natural Sciences
The universe up close
15.01.2018 | Georg-August-Universität Göttingen
For the first time, scientists have precisely measured the effective electrical charge of a single molecule in solution. This fundamental insight of an SNSF Professor could also pave the way for future medical diagnostics.
Electrical charge is one of the key properties that allows molecules to interact. Life itself depends on this phenomenon: many biological processes involve...
At the JEC World Composite Show in Paris in March 2018, the Fraunhofer Institute for Laser Technology ILT will be focusing on the latest trends and innovations in laser machining of composites. Among other things, researchers at the booth shared with the Aachen Center for Integrative Lightweight Production (AZL) will demonstrate how lasers can be used for joining, structuring, cutting and drilling composite materials.
No other industry has attracted as much public attention to composite materials as the automotive industry, which along with the aerospace industry is a driver...
Scientists at Tokyo Institute of Technology (Tokyo Tech) and Tohoku University have developed high-quality GFO epitaxial films and systematically investigated their ferroelectric and ferromagnetic properties. They also demonstrated the room-temperature magnetocapacitance effects of these GFO thin films.
Multiferroic materials show magnetically driven ferroelectricity. They are attracting increasing attention because of their fascinating properties such as...
The oceans are the largest global heat reservoir. As a result of man-made global warming, the temperature in the global climate system increases; around 90% of...
Scientists at Helmholtz Zentrum München have discovered a mechanism that amplifies the autoimmune reaction in an early stage of pancreatic islet autoimmunity prior to the progression to clinical type 1 diabetes. If the researchers blocked the corresponding molecules, the immune system was significantly less active. The study was conducted under the auspices of the German Center for Diabetes Research (DZD) and was published in the journal ‘Science Translational Medicine’.
Type 1 diabetes is the most common metabolic disease in childhood and adolescence. In this disease, the body's own immune system attacks and destroys the...
15.01.2018 | Event News
08.01.2018 | Event News
11.12.2017 | Event News
15.01.2018 | Physics and Astronomy
15.01.2018 | Life Sciences
15.01.2018 | Life Sciences