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Yes. MESSENGER and Mariner 10 are both Mercury Space missions.
No, not yet. The MESSENGER mission has flown by Mercury three times,
and is planned to land on the surface during 2010.
You likely mean NASA's MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) program of 2007.
"Messenger".
Messenger was a mission of the space program to reach Mercury. It took 3 years and 4 months to reach the destination.