Lunar Prospector data support the contention that water ice reservoirs exist in the permanently shaded craters near the lunar poles. Yet the question remains whether the detected hydrogen abundance is actually water ice or is hydrogen in some other form. Present plans call for a controlled impact of Lunar Prospector into a polar crater at the end of July, 1999, in an attempt to liberate a small amount of water vapor that may be detected by ground- and space-based observatories. A positive spectral detection of water vapor or its photo-dissociated byproduct, OH, would be definite proof of the presence of water ice in the regolith. The following represents both an analysis of this method of searching for water ice as well as an announcement to the observing community of the event. ¿ 1999 American Geophysical Union