Regional map of molecular water at high southern latitudes on the Moon
using 6 µm data from the Stratospheric Observatory For Infrared
Astronomy
Abstract
A map of surface molecular water was derived from long slit spectroscopy
of the south polar region of the Moon using the Faint Object infraRed
CAmera for the SOFIA Telescope (FORCAST) spectrometer on the
Stratospheric Observatory for Infrared Astronomy (SOFIA). Mean water
abundances detected are about 250 µg/g over that of a mare reference
surface at Mare Fecunditatis. Water abundances are locally
anticorrelated with temperature and latitude. The distribution of water
is consistent with derivation of water from pre-existing hydroxyl
subsequently trapped in impact glass, provided hydroxyl increases with
latitude as some models and measurements suggest. The detected water
cannot be in equilibrium with the exosphere because insufficient water
is present to maintain the surface abundance. The data are also
consistent with a high latitude water-bearing mineral host that may be a
precursor to recently detected high latitude hematite.