THE APOLLO LUNAR-SURFACE WATER-VAPOR EVENT REVISITED

On March 7, 1971, the first sunrise following the Apollo 14 mission, the Suprathermal Ion Detector Experiment (SIDE) deployed at the Apollo 14 site reported an intense flux of ions whose mass per charge was consistent with water vapor. We examine the amount of water and discuss the various acceleration processes responsible for accelerating ions into the SIDE. We conclude that during most of the event the observed water vapor ions were accelerated by the negative lunar surface electric potential and secondly that this event was probably the result of mission associated water vapor, either from the LM ascent and descent stage rockets or from residual water in the descent stage tanks.