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8 magnificent images of Mercury

astronauts working on MESSENGER

Photo: NASA

5 of 9

MESSENGER before flight

In 2004, NASA launched MESSENGER (MErcury Surface, Space ENvironment, GEochemistry and Ranging) on the space agency's second mission to Mercury. The purpose of MESSENGER was to pick up where Mariner 10 left off. NASA has since learned the planet's magnetic field might be produced from the planet's core. MESSENGER is mapping Mercury and is due to enter an elliptical orbit with the planet in 2011.