A worker at Astrotech Space Operations looks over the fuel supply to be loaded in the MESSENGER spacecraft.

A suited worker at Astrotech Space Operations in Titusville, Fla., looks over the fuel supply to be loaded in the MESSENGER (Mercury Surface, Space Environment, Geochemistry and Ranging) spacecraft. Liftoff of MESSENGER aboard a Boeing Delta II Heavy rocket, bound for Mercury, is scheduled for Aug. 2. The spacecraft is expected to reach orbit around the planet in March 2011. MESSENGER was built for NASA by the Johns Hopkins University Applied Physics Laboratory in Laurel, Md.