LUNAR ICE - CAN ITS ORIGIN BE DETERMINED

The comet hypothesis of the origin of lunar ice, which was recently di scovered in the polar regions of the moon by Lunar Prospector, is exam ined. It is shown that a comet impact produces a temporary atmosphere whose volatile component accumulates essentially completely in cold tr aps - the permanently shadowed regions of the Moon. The condensation o f volatile compounds leads to the formation of ice with a definite che mical and isotopic composition, which contains important information a bout the composition of the comet. This hypothesis can be checked duri ng the next lunar missions, and if confirmed, definite progress will h ave been made in understanding the nature of comets. (C) 1998 American Institute of Physics.