The evidence is still indirect and requires several steps of inference to get to the conclusion that there really is a salty ocean. NASA plans to send a future probe to Europa, scheduled for launch in 2003. This would take more accurate measurements to ascertain any manifestations of Europa's tides. Scientists previously suspected that Europa may contain a liquid ocean. In some areas it appears as if the fissures have opened up and water has come to the surface and has immediately frozen solid.
Some pieces of ice appear as if they have broken up and then floated away.
An alternative explanation may be that water was present in a much earlier period but has been solidified for a long time. Scientists have speculated that warmth generated by tidal heating due to the enormous pressure from Jupiter's gravitational pull may have been sufficient to soften or even liquefy some portion of Europa's icy covering. Some scientists speculate that the movement of softened ice may be responsible for the complex ice patterns observed on the surface. Europa has now become a second likely candidate after Mars for finding life in the solar system. Recent studies on Earth have located living things in the most extreme environments where it was previously thought it would be impossible for anything to live.