The Moon is generally anhydrous, yet the Deep Impact

• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: North Pole
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.602.5754; http://sciences.blogs.liberation.fr/files/sunshine-09-25-09-3.pdf

spacecraft found the entire surface to be hydrated during some portions of the day. OH and H2O absorptions in the near infrared were strongest near the North Pole and are consistent with <0.5 wt % H2O. Hydration varied with temperature, rather than cumulative solar radiation, but no inherent absorptivity differences with composition were observed. However, comparisons between data collected one week (a quarter lunar day) apart show a dynamic process with diurnal changes in hydration that were greater for mare basalts (~70%) than for highlands (~50%). This hydration loss and return to steady state occurred entirely between local morning and evening, requiring a ready daytime source of water group ions, which is consistent with a solar wind origin. EPOXI, NASA’s extended mission for the Deep Impact