Hydrogen-implanted interplanetary dust grains: their role in hydrogen chemistry of the upper atmosphere

An evaluation of past measurements of submicron dust grains in the interplanetary medium, by means of zodiacal light observations, satellite-borne detectors and rocket-borne collectors, has been made to specify the earthward flux of the grains. Using laboratory data on ion-implantation, an estimate of the solar wind implanted hydrogen in the grains is then derived. A hypothesis is offered that the hydrogen is released in the upper atmosphere, probably as H2O, by chemical reactions accompanying impacts of atmospheric atomic oxygen on the grain surfaces. The resultant number density of H2O and the ionic H2O+ concentrations are then computed. The latter is compared with rocket-measured concentrations of these species. The fair corroboration appears to support the hypothesis. (author)