Abstract
The hypothesis that significant deposits of water ice exist in cold
traps near lunar poles includes a supposition that acquired water is
concentrated in the traps by exospheric lateral transport. That
supposition, and by inference the trapped water hypothesis, are proven
to be false by the present analysis of data obtained in 2013-2014 by the
neutral mass spectrometer on the Lunar Atmosphere and Dust Environment
Explorer (LADEE) spacecraft. These data show no evidence of exospheric
water. The upper limit for exospheric water at the lunar surface,
$\sim3$ molecules cm$^{-3}$, is deficient by
several orders of magnitude in accounting for the deposition of the
chondritic influx of water in cold traps. The present hypothesis is that
the precursor of clay formation, cation exchange involving water
molecules and anorthite, is analogous to reversible chemi-sorption, and
that adsorbed water on the lunar surface is rapidly removed from the
moon by solar wind sputtering.