Ocean on Europa. Cutaway computer artwork showing the thick ice layer (across centre) that is thought to cover the surface of Europa. Between the ice and the rocky bedrock (bottom), there is thought to be an ocean of liquid water. Europa is one of the moons of Jupiter (upper right). The bright band of the Milky Way is at upper left. There are plans to send a probe to Europa to melt through the ice and sample the ocean below. It is possible that life may be found here, surviving around underwater volcanic vents. The probe would have to use transmitter relays to communicate through the thick ice. It is thought that the tides produced by Jupiter, largest of the planets, provides the heat source to keep the ocean liquid.