Technicians with The Johns Hopkins University Applied Physics Laboratory APL check one of two solar panels on the MESSENGER spacecraft.

At Astrotech in Titusville, Fla., technicians with The Johns Hopkins University Applied Physics Laboratory (APL) check one of two solar panels on the MESSENGER spacecraft after a deployment test. The other panel is at right, undeployed. The solar arrays will provide MESSENGER’s power on its journey to Mercury. MESSENGER is scheduled to launch Aug. 2 aboard a Boeing Delta II rocket from Pad 17-B, Cape Canaveral Air Force Station, Fla. It will return to Earth for a gravity boost in July 2005, then fly past Venus twice, in October 2006 and June 2007. The spacecraft uses the tug of Venus’ gravity to resize and rotate its trajectory closer to Mercury’s orbit. Three Mercury flybys, each followed about two months later by a course-correction maneuver, put MESSENGER in position to enter Mercury orbit in March 2011. During the flybys, MESSENGER will map nearly the entire planet in color, image most of the areas unseen by Mariner 10, and measure the composition of the surface, atmosphere and magnetosphere. It will be the first new data from Mercury in more than 30 years - and invaluable for planning MESSENGER’s year-long orbital mission. MESSENGER was built for NASA by APL in Laurel, Md.