The water vapour found coming from active asteroids (comets) and larger active asteroids (dwarf planets like Ceres and Pluto) would appear to be electrochemical in nature.
It is also found on the moons surface. A new study has suggested it is slightly more concentrated in certain locations on the moon. Could this be due to the shadows, the fact that they are in craters, the latitude on the moon
Recent observations by NASA's Lunar Reconnaissance Orbiter (LRO) spacecraft indicate these deposits may be slightly more abundant on crater slopes in the southern hemisphere that face the lunar South Pole.
Slopes closer to the South Pole show a larger hydrogen concentration difference. Also, hydrogen was detected in greater concentrations on the larger PFS, about 45 ppmw near the poles. Spatially broader slopes provide more detectable signals than smaller slopes. The result indicates that PFS have greater hydrogen concentrations than their surrounding regions. Also, the LEND measurements over the larger EFS don't contrast with their surrounding regions, which indicates EFS have hydrogen concentrations that are equal to their surroundings, according to McClanahan. The team thinks more hydrogen may be found on PFS in northern hemisphere craters as well, but they are still gathering and analyzing LEND data for this region.
Hydrogen retention on pole-facing slopes