Short-range 'lunar hydrology'

Observations from NASA's Deep Impact mission of the moon's north pole June 2 and 9, 2009 revealed changes in the amounts of water and hydroxyl. In the week between these datasets, the moon rotated 90 degrees. A volcanic mare terrain (labeled 'M') is observed in the morning on June 2 and at local noon by June 9 and a highland unit ('H') begins at noon and rotates to evening by June 9. Deep Impact observed a significant change in the strength of a water and hydroxyl signature as the moon rotated around. The highland unit has a weaker signal near noon (red) and a stronger signal by evening (blue). Taken together the data show a "systematic" change in water loss from morning to noon, recovery in the afternoon and return to "steady state" by evening. This daytime cycle suggests that hydrogen ions in the solar wind may be a source for re-hydration. [NASA/JPL-Caltech/University of Maryland]