The planned May launch of NASA's MESSENGER spacecraft - the first designed to orbit the planet Mercury - has been rescheduled for no earlier than July 30.

The new launch period extends from July 30-August 13, 2004. Several factors led to NASA's decision to move the launch from its original date, including a desire to perform more testing of MESSENGER's fault-protection system software. This allows the spacecraft to check its own health and, when necessary, switch between alternative backup systems. This will also create some additional time for the test team to complete final assembly and checkout, affording a more comfortable spacecraft-processing schedule.

MESSENGER will launch aboard a Boeing Delta II rocket from Cape Canaveral Air Force Station, FL. Under a new mission profile, the spacecraft will return to Earth for a gravity assist a year after liftoff; swing past Venus twice, then fly by Mercury three times before starting a yearlong orbit of the innermost planet in March 2011. MESSENGER's science plans - to provide the first ../../../images of the entire planet and collect detailed information on the composition and structure of Mercury's crust, its geologic history, the nature of its thin atmosphere and active magnetosphere, and the makeup of its core and polar materials - remain intact.

MESSENGER recently completed a successful three-month series of space-environment tests at NASA's Goddard Space Flight Center, MD, demonstrating that it could withstand the rigors of launch and the wide range of hot and cold temperatures it will face on its journey to and orbit around Mercury. On March 10, the spacecraft arrived in Florida, where technicians and engineers have been processing it for launch at the Astrotech Space Operations facility outside Kennedy Space Center. The spacecraft will continue its processing activities at Astrotech, and the team is developing a new schedule for the work leading up to the summer launch opportunity.

Visit the Mission Design Web pages for more information on MESSENGER's path to Mercury.

MESSENGER Mission Events
Launch period: July 30 - August 13, 2004
Earth flyby: July 2005
Venus flybys (2): October 2006, June 2007
Mercury flybys (3): January 2008, October 2008, September 2009
Mercury orbit begins: March 2011

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