Enceladus waters Titan

Recently, I wrote an entry noting news that sunlight can build up nitrogenated hydrocarbons on Titan. Now another building block of life – water – has found a way to settle on that cold world.

Enceladus is a pretty important moon of Saturn. The tiny satellite was initially known for its tiger stripes until the Cassini probe caught a glimpse of what was coming out of them – geysers of water. First detected by their influence on the magnetic field in the immediate vicinity, the spectacle was caught in silhouette, shining in the twilight of that alien place. New work suggests that the geysers are powered by gas created ultimately by the rain of charged particles striking the surface of the satellite. These cause damage to the molecules, making them more reactive, altering their chemistry. Over time, the churning of the ice brings them deeper into the interior, where they meet gases like ammonia, also very reactive, and together they create pockets of gas that increase the pressure inside the moon.

However it happens, the result is an irregular stream of water and other materials that creates the E ring. The stuff comes out as both charged ‘water group’ particles and neutral molecules. The neutral stuff languishes in orbit of Saturn while the charged stuff gets swept away by the forces within the magnetosphere. Some of them meet the largest moon of Saturn – Titan – and enter its upper atmosphere.

Another piece of work recently published describes how water in the upper atmosphere of Titan can be encased in a carbon cage called a fullerene. This allows the particles to be transported to the surface, reacting with carbon based molecules all the way. There are detections of signals that could belong to fullerenes in Titan’s atmosphere, but these are ambiguous at present and could be due to the presence of something else.

Whatever turns out to be the truth of the details of production and distribution mechanisms in the Saturn system, it is an illustration of how dynamic and complex the exchanges of particles and actions of chemistry are in the bleak darkness of space.


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