The mission began with launch from Cape Canaveral Air Force Station, Fla., on August 3, 2004. After returning to Earth for a gravity assist on August 2, 2005, MESSENGER headed toward the first of two Venus flybys. The first occurred on October 24, 2006, when the spacecraft approached the planet from its dayside. MESSENGER again flies past a mostly sunlit Venus on June 5, 2007.

The Mercury flybys on January 14, 2008, October 6, 2008, and September 29, 2009, will provide the first close-up look at Mercury in more than 30 years. On all three flybys, the spacecraft departs with sunlit views of the planet, taking pictures of the regions not seen by the first spacecraft to visit Mercury - Mariner 10. This early science return will be invaluable in planning observation strategies for MESSENGER's historic yearlong orbit mission, which begins in March 2011.

On the way, MESSENGER will also perform several trajectory correction maneuvers, thruster burns that adjust its path to Mercury.