The Mercury Surface, Space Environment, Geochemistry and Ranging (MESSENGER) mission, launched on 2004-08-03, was mainly designed to study the characteristics and environment of Mercury from orbit. After an Earth flyby July-August, 2005, Venus flybys October-November, 2006, and May-June, 2007, and Mercury flybys December 2007 - January 2008, September-October, 2008, and September-October, 2009,
MESSENGER entered Mercury orbit 2011-03-04. Much data of interest to
the heliospheric community was obtained during the cruise phases
between planetary encounters from a magnetometer and an energetic
particle and plasma spectrometer.