Encelascope Summary

Background We selected Enceladus as our initial target for study due to its apparent habitability, as discovered by the Cassini mission to Saturn. Enceladus has water geysers erupting from its surface, which emerge from the global ocean lying beneath its icy shell. After being ejected into space, the tiny water droplets flash freeze into ice grains and form plumes over 100 km high. Cassini flew through the plumes, and scientists back on Earth analyzed the contents of the ice grains via measurements taken by Cassini's onboard instruments. In addition to water, the ice grains were found to contain salt, silica, methane, complex organics, and nitrogen. The salt concentration appears to be in a range compatible with life, like the Earth's oceans. The silica indicates direct interaction between the subsurface ocean and the rocky mantle, likely at hydrothermal vents. This resembles processes known to take place on the Earth's ocean floor. The methane abundance is more consistent with biogenic sources than abiogenic sources. Nitrogen is a key element required by life on Earth, and the complex organics detected may have been formed by biological processes. In addition to the tantalizing clues indicating habitability and perhaps even habitation, the radiation environment at Enceladus is much less intense than the radiation environment at other potential mission destinations, such as Europa, an icy moon of Jupiter. This allows lower-cost electronics to be used for the mission because they don't need to be as resistant to the effects of radiation.