While approaching the planet for the third flyby of its mission, the MESSENGER spacecraft took this photo of Mercury, crescent-lit by the sun and showing terrain that has never been imaged before.
The region along the planet’s limb, the brightest area seen here, had yet to be mapped by the spacecraft’s cameras. It contains many unnamed features, such as a 160-mile-wide double-walled crater, visible above on the right side of the photo.
Although now officially the smallest planet, Mercury is also the densest and contains an enigmatic and surprisingly strong magnetic field. The mission will investigate these aspects of the planet, as well as continue mapping the surface. MESSENGER will become the first spacecraft to enter orbit around Mercury in March of 2011. The flyby, executed yesterday, was the final such maneuver before orbit insertion.
Image: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington