October 4, 2008

MESSENGER Closes In On Mercury

If you look at our "Where Is MESSENGER?" page, which displays the spacecraft's trajectory status, you'll see that we're right on Mercury's doorstep. MESSENGER's mission design and navigation teams met today at the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Md., to discuss the spacecraft's current trajectory to determine if a last-minute trajectory-correction maneuver would be needed.

"Early this morning, the navigation team delivered the final ephemeris update for the spacecraft prior to the flyby," said APL's Eric Finnegan, the MESSENGER Mission Systems Engineer. "The data indicate that the last solar sailing attitude alternation implemented between Tuesday and Wednesday was a complete success. The current position estimate places the spacecraft within approximately 800 meters of the target! This is a phenomenal achievement for both the navigation and guidance and control teams."

"The operations team has confirmed that the core Mercury command load sequence was onboard the spacecraft, and all subsystems and instruments are operating nominally," Finnegan said. With less than two days to the flyby, MESSENGER is on target to encounter Mercury at an altitude of 200 kilometers (124 miles) on Monday, October 6, at approximately 4:41 a.m. EDT.

Over the next two days, the spacecraft will continue to gather optical navigation images approximately every eight hours, while the operations team monitors the spacecraft.

The entire operations and engineering teams will gather in the operations center at APL on Sunday to make one last assessment of the spacecraft before the core encounter sequence begins, rotating the probe away from the Earth to view once again the closest planet to the Sun, revealing terrain never before seen by spacecraft!

MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) is a NASA-sponsored scientific investigation of the planet Mercury and the first space mission designed to orbit the planet closest to the Sun. The MESSENGER spacecraft launched on August 3, 2004, and after flybys of Earth, Venus, and Mercury will start a yearlong study of its target planet in March 2011. Dr. Sean C. Solomon, of the Carnegie Institution of Washington, leads the mission as Principal Investigator. The Johns Hopkins University Applied Physics Laboratory built and operates the MESSENGER spacecraft and manages this Discovery-class mission for NASA.


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