For many years Europa, one of the major satellites of Jupiter, was considered one of the most important candidates as a life forms host after the discovery of an ocean of liquid water beneath its ice crust. Lately, however, the findings about Enceladus, a moon of Saturn, are suggesting that there’s a second candidate.
In some ways, Enceladus is a smaller version of Europa because it too has an ocean of liquid water beneath a crust of ice. We knew little about this satellite of Saturn but in the early 80’s Voyager probes started sending us information about it.
However, it was only in 2005 that the Cassini space probe allowed scientists to analyze in detail the characteristics of the surface of Enceladus. A remarkable discovery was that jets of water and ice rose from the south pole of this satellite rising from cracks in the ice.
Liquid water is present in the subsurface probably due to the heat generated by tidal forces from Saturn, which literally deforms Enceladus. It’s possible that in the past the orbit of this satellite was more eccentric so it was deformed even more. In fact, in that case the gravitational pull exerted by Saturn varied more because Enceladus approached and receded from the planet more than today.
Enceladus is large enough to have stored the heat generated in the past releasing it slowly. This also means that this satellite is slowly cooling down but it’s possible that its orbit will become more eccentric in the future causing a new heating cycle.
On March 27, 2012, the Cassini space proble passed at a height of just 74 km (46 miles) from the south pole of Enceladus. In this way, the probe has been able to use its Ion and Neutral Mass Spectrometer (INMS) and its Plasma Spectrometer (CAPS) to analyze the particles of the jets coming from this satellite. It was found that these jets contain organic materials and salts with a salinity level very similar to the Earth’s oceans.
It’s too early to say that on Enceladus there are life forms, however there are conditions for an ecosystem similar to the deep seas of Earth. In fact, thermal springs are considered among the possible candidates as the cradle of life on Earth. Definitely, Enceladus deserves further investigation.