If you want to send astronauts to the moon, a place with water would be a good destination.
Obviously, humans need to drink water to survive, and water molecules can be split into hydrogen and oxygen. Oxygen provides air to breathe, and hydrogen and oxygen can also be used as rocket propellants to get back home to Earth, or somewhere else in the solar system.
But water is heavy, and lugging it from Earth is expensive and inconvenient.
The rocks brought back by NASA’s Apollo astronauts from 1969 through 1972 suggested that the moon was completely dry. But then planetary scientists started seeing hints of water ice at the bottom of craters in the polar regions where the sun never shines. India’s first lunar orbiter, Chandrayaan-1, collected some of the data that confirmed the presence of water.
The armada of missions now headed to the south pole aim to measure how much water is contained in the shadowed craters and how difficult it would be to extract the water. (It could be very difficult if the water molecules are trapped within minerals and not as ice mixed in with the soil.)
Layers of ice in the craters could also provide a history book of the solar system, much like how ice cores in Greenland and Antarctica provide a record of Earth’s climate.
