MESSENGER Observations of the Spatial Distribution of Planetary Ions Near Mercury

The polar regions of Mercury are important sources of material for its ionized exosphere. Global measurements by MESSENGER of the fluxes of heavy ions at Mercury, particularly sodium (Na+) and oxygen (O+), exhibit distinct maxima in the northern magnetic-cusp region, indicating that polar regions are important sources of Mercury’s ionized exosphere, presumably through solar-wind sputtering near the poles. The observed fluxes of helium (He+) are more evenly distributed, indicating a more uniform source such as that expected from evaporation from a helium-saturated surface. In some regions near Mercury, especially the nightside equatorial region, the Na+ pressure can be a substantial fraction of the proton pressure.

[1]  L. Frank Plasma in the Earth's polar magnetosphere , 1971 .

[2]  Barry H. Mauk,et al.  The Energetic Particle and Plasma Spectrometer Instrument on the MESSENGER Spacecraft , 2007 .

[3]  Richard D. Starr,et al.  Mercury's Magnetosphere After MESSENGER's First Flyby , 2008, Science.

[4]  F. Leblanc,et al.  Ion energization during substorms at Mercury , 2007 .

[5]  S. Solomon,et al.  MESSENGER Observations of Transient Bursts of Energetic Electrons in Mercury’s Magnetosphere , 2011, Science.

[6]  R. Kallenbach,et al.  Synopsis of the interstellar He parameters from combined neutral gas, pickup ion and UV scattering observations and related consequences , 2004 .

[7]  S. Solomon,et al.  The space environment of Mercury at the times of the second and third MESSENGER flybys , 2011 .

[8]  T. Hill,et al.  A Bx-interconnected magnetosphere model for Mercury , 2001 .

[9]  Haje Korth,et al.  The Global Magnetic Field of Mercury from MESSENGER Orbital Observations , 2011, Science.

[10]  Maxim L. Khodachenko,et al.  Processes that Promote and Deplete the Exosphere of Mercury , 2007 .

[11]  G. Thomas,et al.  Mercury's helium exosphere , 1975 .

[12]  Kenneth G. Powell,et al.  Interaction of Mercury with the Solar Wind , 1998 .

[13]  G. Gloeckler,et al.  MESSENGER Observations of the Composition of Mercury's Ionized Exosphere and Plasma Environment , 2008, Science.

[14]  G. Paschmann,et al.  The frontside boundary layer of the magnetosphere and the problem of reconnection , 1977 .

[15]  Helmut Lammer,et al.  Self-consistent modelling of Mercury's exosphere by sputtering, micro- meteorite impact and photon-stimulated desorption , 2010 .

[16]  S. Barabash,et al.  Energetic neutral atom imaging at Mercury , 2004 .

[17]  Mehdi Benna,et al.  MESSENGER Observations of Extreme Loading and Unloading of Mercury’s Magnetic Tail , 2010, Science.

[18]  D. Baker,et al.  MESSENGER observations of the plasma environment near Mercury , 2009 .