Moon's Water Mostly Chemically Bound in Deep Interior

For decades, scientists believed the Moon was essentially dry, based on analyses of lunar samples returned by the Apollo missions and subsequent studies. That consensus was upended in 2009 when NASA’s Lunar Crater Observation and Sensing Satellite (LCROSS) detected clear signatures of water ice in the Moon’s permanently shaded polar regions (PSRs). The spacecraft’s impact plume revealed hydroxyl and water molecules, confirming that the lunar surface harbors substantial ice deposits hidden in the coldest craters.

The LCROSS findings have reshaped our understanding of the Moon’s composition and its potential for future exploration. By demonstrating that water ice can survive in the extreme temperature gradients of the lunar poles, the mission opened new possibilities for in‑situ resource utilization, such as producing drinking water, breathable air, and rocket propellant for extended missions. The discovery also prompted a flurry of follow‑up observations, including NASA’s LCROSS Follow‑On mission and the Lunar Reconnaissance Orbiter’s radar studies, all aimed at mapping the extent and purity of these ice deposits.

These revelations underscore the Moon’s role as a stepping stone for deeper space exploration. As agencies plan crewed missions and lunar bases, the presence of accessible water ice will be a critical factor in logistics and sustainability. The 2009 LCROSS data thus marked a pivotal shift from viewing the Moon as a barren rock to recognizing it as a reservoir of essential resources for humanity’s next frontier.