What was the first spacecraft to detect lunar water molecules from orbit?

The first spacecraft to detect lunar water molecules from orbit was Chandrayaan-1.

India’s Chandrayaan-1 entered lunar orbit in November 2008 and carried 11 scientific instruments from India, NASA, the European Space Agency, Bulgaria, and the United Kingdom. NASA’s Moon Mineralogy Mapper, or M3, identified an absorption signature near 2.8–3.0 micrometres, indicating hydroxyl and water-bearing molecules on the lunar surface. The signal was strongest at cooler, higher latitudes.

Chandrayaan-1 also carried the Moon Impact Probe. During its descent near the lunar south pole, the probe’s CHACE instrument recorded evidence of water in the thin lunar exosphere and soil. These findings helped transform the view of the Moon from a completely dry world into one with small, mobile quantities of water and hydroxyl.

The wording matters: Chandrayaan-1 detected molecules and related signatures, not lakes or broad oceans. Later missions, including NASA’s LCROSS and Lunar Reconnaissance Orbiter, added evidence about water ice and permanently shadowed polar regions. The spacecraft operated for about 10 months, ending in August 2009.