Enceladus is believed to have a solid core, which would generate friction as the moon moves its orbit around Saturn. This in turn would create energy, which may be what heats the sub–surface ocean. NASA's Cassini mission observed jets of water erupting from its surface, which may be connected to active hydrothermal vents at the floor of the subsurface ocean.
In 2018, scientists reported that the Cassini orbiter had detected complex organic compounds, including what could be the 'building blocks' for life, in Enceladus's jet plumes.
© Haydn Thompson 2021