Louise Prockter describes why there is ice in the moons of Jupiter and beyond.

Ice and Ganymede

Has ice ever been discovered on the earth’s moon? What are the benefits of finding water on other planets? 

It’s hard to underestimate the importance of water given it covers 70% of the Earth's surface, and makes up well over 50% of the human body but how common is it on other celestial bodies?
The question of whether other planets contain ice and water remains one of the most important lines of inquiry for many scientists working in that field because  water can shield us  against radiation, in its component forms of hydrogen and oxygen it’s the most powerful chemical rocket propellant known and of course water can sustain life.

The following 4 films examine how much water if any has been discovered on Moons in our Solar System and its implications for science