At Astrotech Space Operations facilities near KSC, workers help while an overhead crane lowers the Mercury Surface, Space Environment, Geochemistry and Ranging (MESSENGER) spacecraft onto a turnover fixture. Workers will perform the propulsion system phasing test - firing gas through the thrusters in order to verify that the right thrusters fire when expected - as part of prelaunch testing at the site. Launch is scheduled for May 11 from Pad 17-B, Cape Canaveral Air Force Station. The spacecraft will fly past Venus three times and Mercury twice before starting a year-long orbital study of Mercury in July 2009.