Moon Mineralogy Mapper (M3 – NASA)
The Moon Mineralogy Mapper, from Brown University and NASA's Jet Propulsion Laboratory, was an imaging spectrometer designed to map the mineral composition of the entire lunar surface in the 430–3,000 nm range. It was activated on 17 December 2008.
M3 delivered the mission's most celebrated result: the detection of absorption features characteristic of hydroxyl (OH) and water (H2O) molecules across the lunar surface, strongest towards the poles — announced in September 2009 and published in Science. It also mapped iron-bearing minerals such as pyroxene in the Orientale Basin and identified new spinel-rich rock types.
In 2018, re-analysis of M3 data provided definitive evidence of exposed water ice in permanently shadowed regions of the lunar poles — a key motivation for today's south pole missions, including the upcoming ISRO–JAXA Chandrayaan-5/LUPEX rover.