METAL-IONS IN THE ATMOSPHERE OF NEPTUNE

Microwave propagation experiments performed with Voyager 2 at Neptune revealed sharp layers of electrons in Neptune's lower ionosphere with densities of similar to 10(4) per cubic centimeter. These layers are r eminiscent of the sporadic-E layers in the Earth's ionosphere, and whe n taken together with data from the other giant planets, these data co nfirm the importance of the magnetic field in layer formation, A photo chemical model that incorporates species produced by meteoroid ablatio n predicts that singly ionized magnesium is the most likely metal to b e found in the layers, although laboratory data on the kinetics of met allic atoms and ions in a reducing environment are lacking. The metal chemistry discussed here is directly relevant to the abundant metals o bserved at the impact site of the G fragment of comet Shoemaker Levy 9 on Jupiter.