title: MESSENGER observations of Mercury's exosphere: detection of magnesium and distribution of constituents.
abstract: Mercury is surrounded by a tenuous exosphere that is supplied primarily by the planet's surface materials and is known to contain sodium, potassium, and calcium. Observations by the Mercury Atmospheric and Surface Composition Spectrometer during MESSENGER's second Mercury flyby revealed the presence of neutral magnesium in the tail (anti-sunward) region of the exosphere, as well as differing spatial distributions of magnesium, calcium, and sodium atoms in both the tail and the nightside, near-planet exosphere. Analysis of these observations, supplemented by observations during the first Mercury flyby, as well as those by other MESSENGER instruments, suggests that the distinct spatial distributions arise from a combination of differences in source, transfer, and loss processes.
authors.affiliation: Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, CO 80303, USA. william.mcclintock@colorado.edu
authors.forename: William E
authors.initials: WE
authors.lastname: McClintock
authors.forename: Ronald J
authors.initials: RJ
authors.lastname: Vervack
authors.forename: E Todd
authors.initials: ET
authors.lastname: Bradley
authors.forename: Rosemary M
authors.initials: RM
authors.lastname: Killen
authors.forename: Nelly
authors.initials: N
authors.lastname: Mouawad
authors.forename: Ann L
authors.initials: AL
authors.lastname: Sprague
authors.forename: Matthew H
authors.initials: MH
authors.lastname: Burger
authors.forename: Sean C
authors.initials: SC
authors.lastname: Solomon
authors.forename: Noam R
authors.initials: NR
authors.lastname: Izenberg