Moffett Field, Calif.

PICTURE a habitat atop a hill in warm sunlight on the edge of a crater near the south pole of the Moon. There are metal ores in the rocks nearby and ice in the shadows of the crater below. Solar arrays are set up on the regolith that covers the Moon’s surface. Humans live in sealed, cave-like lava tubes, protected from solar flares and sustained by large surface greenhouses. Imagine the Moon as the first self-sustainable human settlement away from Earth and a high-speed transportation hub for the solar system.

We can finally begin to think seriously about establishing such a self-sufficient home on the Moon because last week, NASA announced that it had discovered large quantities of water there.

While we have known for decades that the Moon had all the raw chemicals necessary for sustaining life, we believed they were trapped in rocks and thus difficult to extract. The discovery of plentiful lunar water is of tremendous importance to humanity and our long-term survival.

There have been 73 missions, manned and unmanned, to the Moon, and understanding its chemical composition, particularly finding water, has always been a priority. So why haven’t we seen significant amounts of water until now?