Ever wondered why many countries are competing to explore the Moon’s south pole? It all boils down to one of the most precious assets for future space exploration: water. Water on the Moon is not merely an interesting scientific discovery—it could revolutionize how human beings live and travel in space, from constructing lunar bases to powering missions to Mars.
The Quest for Water: A History
For centuries, people wondered what the dark spots on the Moon could be. Early scientists referred to them as “maria,” or seas, and pictured them as great oceans on the Moon. By the turn of the 1800s, scientists such as William Pickering had ruled out the possibility, deciding that the Moon was barren, with no atmosphere and no water. When the Apollo astronauts returned samples in the late 1960s and early 1970s, the proof appeared to support this—the rocks and dirt appeared bone dry.
But science progresses, and outdated assumptions are continually challenged with new instruments. In 2008, scientists at Brown University reexamined Apollo samples using new techniques and discovered something unexpected: hydrogen locked in Antarctic-sized volcanic glass beads. This was the initial indication that water had existed previously in Antarctic-sized regions deep within the Moon.
How Scientists Discovered Water on the Moon
The actual breakthroughs began in the late 1990s and early 2000s. In 1998, NASA’s Lunar Prospector measured high concentrations of hydrogen at the lunar poles, hinting at trapped ice. Ten years later, India’s Chandrayaan-1 probe found water on the surface of the Moon, and NASA’s LCROSS mission made it irrefutable by slamming a probe into a shadowed crater at the south pole, scattering water ice in the impact cloud.
Recently, NASA’s flying observatory SOFIA validated the existence of water molecules even in the sunlit regions of the Moon, in particular in the Clavius Crater. This finding shook the conviction that water could exist only in the Moon’s permanently shadowed, subfreezing craters.
Where Is the Water? Sunlit vs. Shadowed Regions
Now we know water on the Moon is present in various forms. In areas exposed to sunlight, it presents itself as small molecules locked in lunar regolith—SOFIA detected amounts equivalent to the volume of a small bottle of water per cubic meter. There is a different tale at the poles, and particularly the South Pole. There, in the permanently shadowed craters faring no sunlight, ice has been kept intact for billions of years in regions so cold they are comparable to Pluto.
The Origin of Lunar Water: Volcanic, Cometary, and Solar Wind Sources
So how did all this water appear? The explanation is not straightforward. Some of it might have originated from the volcanoes of the Moon itself billions of years ago. When those volcanoes erupted, they spewed out water vapor, which then likely condensed and froze at the poles. Models indicate that perhaps 40 percent of that water could have frozen as ice, particularly at the South Pole, which is more conducive to cold traps.
Other sources are comets and asteroids that brought water and dropped it in impacts, and the solar wind. When solar wind hydrogen strikes the surface of the Moon, it combines with lunar minerals’ oxygen to produce hydroxyl and water under the appropriate conditions.
Why the South Pole Is the Focus
The South Pole is the jackpot because it has the biggest and most easily reached reserves of water ice. Its craters and ridges, which are perpetually in shadow and therefore kept cold by their lack of sunlight, function as natural freezers. That’s why NASA, Indian, and Chinese missions are aimed at the area—it’s where the water has the best chance of existing in a usable quantity.
The Challenges of Accessing and Using Lunar Water
Reaching this resource is no easy feat. The surface of the south pole is harsh, covered with deep craters and steep slopes that render landing perilous. Russia’s Luna-25 mission recently fell short of landing there, a reminder of the challenge that entails. And even if a mission makes it, tapping water will not be simple. Some ice may be contaminated with lunar soil or impregnated with sulfur and other substances, making it difficult to convert it into drinking water or rocket fuel.
Nevertheless, the potential reward is immense. Water can be split into hydrogen and oxygen, providing astronauts with both breathable air and rocket fuel. This can turn the Moon into a refueling depot for deeper space travel, lowering the cost and complexity of traveling beyond the Earth.
The Future: Artemis and Beyond
NASA’s Artemis program is leading the charge. The goal isn’t simply to return astronauts to the Moon, but to establish a sustainable presence there, utilizing resources such as lunar water to sustain human life and exploration. New rovers and equipment are on the drawing board to map water deposits more accurately and determine how they can be accessed.
Every discovery takes us one step closer to the next big break in space travel. The Moon, previously regarded as an empty, desolate world, is proving to be full of possibilities. Water is the answer, and it has the potential to transform the Moon from a rock in the distance to a gateway to humans’ future in space.
