Enceladus Science

Enceladus capured by Cassini. NASA/JPL/Space Science Institute

Enceladus, also known as Saturn Ⅱ, is one of the 82 known moons of Saturn. Compared with Saturn’s other moons, it’s with a mass of 1,08022 × 10 20 kg and a diameter of 504,2 km on place six and with an orbit radius of 237.948 km on place 14. It is also one of the 20 icy moons of our solar system and gained first popularity for its cryovolcanic activity.

This activity is located on the southern hemisphere of Enceladus. Due to the water particles that are extracted by this phenomenon, Enceladus owns a low-density atmosphere over its southern hemisphere. These geysers, also known as “plumes”, are erupting as high as 500km and are a main origin of Saturn’s E-Ring.

The cryoactivity seems to be an effect by higher temperatures than averagely expected within a “full-ice-moon”. Thus, the southern surface is approximately between 20 and 25 K warmer that the northern surface. Previous studies found that Enceladus is too small for any significant temperature differences caused by any kind of radioactive decay. Even though Enceladus is suffering of heating by tidal forces originating from Saturn’s gravitational forces, these too are not enough to evoke the melting of ice. So, the origin of this temperature difference is yet to be discovered.

When Cassini registered hints to liquid water located under the ice of Enceladus’ surface, the moon grew in scientific popularity. Further measurements showed that the liquid water was located only on the southern hemisphere, but instead hint to the existence of a global extraterrestrial, subsurface ocean. Cassini’s analysis of a plume further showed a higher concentration of Water vapor, carbon dioxide and carbon monoxide than expected. The concentration of organic material was also higher than previous spectroscopic analysis indicated. The total composition resembled the one of comets. But Enceladus origin of heat seems to be located on its inside, which stands in contrast to a comet.

These findings lead to the assumption of hydrothermal activity and pre-conditions for microbial life on Enceladus.

Artist rendering of a cutaway of Enceladus | NASA/JPL-Caltech

To further study the cryovolcanic activity and to find more answers to the question of the existence of life on Enceladus, the German Aerospace Center (DLR) called out the Enceladus Explorer Initiative to find concepts and technologies for a possible explorative mission to Enceladus. As a carrier of the initiative, the FH Aachen developed the “IceMole” – an ice melting heat probe, capable of navigating through thick, solid ice and gather samples. The goal is, to drill into the surface of Enceladus and analyze the inside water. A mission could be possible by the 2050’s.