On June 28, the MESSENGER team successfully tested the spacecraft and instrument commands planned for the Aug. 2 flyby of Earth -- the gravity assist that starts the next leg of the spacecraft's journey toward Mercury. The Earth flyby will send the spacecraft toward Venus. The first of two Venus flybys is planned for October 2006.

The test involved a 180-degree rotation to turn MESSENGER's sunshade toward the Sun; then five hours and 40 minutes of activities involving three instruments -- the Magnetometer, the Mercury Atmospheric and Surface Composition Spectrometer, and the Mercury Dual Imaging System. Another 180-degree rotation returned the spacecraft back to the sunshade-away-from-Sun orientation.

On the basis of this rehearsal of spacecraft activities planned near the Earth flyby, mission controllers at the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Maryland, will make minor corrections to the final Earth flyby commands sent to the spacecraft. These corrections will maximize the quality of the science data collected for the flyby. In the coming weeks, the MESSENGER team will create the final Earth flyby command sequences, as well as perform additional simulations and reviews.