Title
MESSENGER observations of the composition of Mercury's ionized exosphere and plasma environment
Document Type
Article
Publication Date
2008
Department/School
Physics and Astronomy
Abstract
The region around Mercury is filled with ions that originate from interactions of the solar wind with Mercury's space environment and through ionization of its exosphere. The MESSENGER spacecraft's observations of Mercury's ionized exosphere during its first flyby yielded Na(+), O(+), and K(+) abundances, consistent with expectations from observations of neutral species. There are increases in ions at a mass per charge (m/q) = 32 to 35, which we interpret to be S(+) and H(2)S(+), with ( S(+) + H(2)S(+))/( Na(+) + Mg(+)) = 0.67 +/- 0.06, and from water- group ions around m/ q = 18, at an abundance of 0.20 +/- 0.03 relative to Na(+) plus Mg(+). The fluxes of Na(+), O(+), and heavier ions are largest near the planet, but these Mercury- derived ions fill the magnetosphere. Doubly ionized ions originating from Mercury imply that electrons with energies less than 1 kiloelectron volt are substantially energized in Mercury's magnetosphere.
Link to Published Version
Recommended Citation
Zurbuchen, T. H., Raines, J. M., Gloeckler, G., Krimigis, S. M., Slavin, J. A., Koehn, P. L., … Solomon, S. C. (2008). MESSENGER observations of the composition of Mercury’s ionized exosphere and plasma environment. Science, 321(5885), 90–92. doi:10.1126/science.1159314