Even now, life on our planet depends on water for nutrients, travel, recreation, and much more. Europa is one of the 16 moons of Jupiter and the focus of intense speculation from scientists. It was discovered by Simon Marius and Galileo Galilei in 1610. It orbits Jupiter in 3.55 days and is thought to have a rocky crust, similar to some of the terrestrial planets. Covering that rocky crust is a thick layer of ice with a heavily fractured surface.
Some scientists speculate that there is an ocean of liquid water lying beneath that ice layer.
Although the presence of water does not necessarily imply the emergence of life, it does indicate that the conditions for the development of life could exist elsewhere in the universe. The evidence for the existence of water on Europa starts with the lack of impact craters on its surface, unlike its sister moons. This lack of cratering suggests that the surface is less than 10 million years old. Scientists speculate that the surface is being continually resurfaced by either frost falling from liquid geysers or from continual thawing and refreezing of the surface ice. The Galileo space probe has identified salt deposits on the icy surface that also point to the existence of a hidden ocean.