Explanation:

Galileo was an American unmanned spacecraft that studied the planet Jupiter and its moons As per the observations made, Jupiter's moon Europa might be able to support life even if there's little or no volcanic activity under the satellite's icy shell.
A salty ocean of liquid water is believed to lie beneath Europa's icy exterior.
Scientists think this ocean could be habitable, if it harbors the required chemical building blocks and the right proportion of elements to provide energy for biological systems — the right ratio of oxygen to hydrogen, for example.
Recently NASA sent Juno to study Jupiter from its orbit.