Mariner 10 images: 1974-1975. MESSENGER flyby 1 images: January 14, 2008
Narrow Angle Camera (NAC) of the Mercury Dual Imaging System (MDIS)
Mercury's diameter is 4880 kilometers (3030 miles)
Mariner 10, the only spacecraft to visit Mercury prior to the MESSENGER mission, imaged about 45% of the planet's surface. On January 14 of this year, MESSENGER successfully completed its first of three planned flybys of Mercury, and during that encounter MDIS snapped the first images from spacecraft of an additional 21% of Mercury's surface. On October 6, 2008, one week from today, MESSENGER will again fly by Mercury, and this time the 1287 planned MDIS images will cover much of the remaining portion of Mercury's surface not yet seen by spacecraft. This figure shows a map of Mercury's surface with images from Mariner 10 overlaid by NAC mosaics (outlined in white) acquired during MESSENGER's first Mercury flyby. The map is shown using the planetocentric positive-east convention that has been adopted by the MESSENGER project. MESSENGER's first flyby of Mercury covered two general areas of Mercury surface: the crescent view of Mercury seen as the spacecraft approached the planet
and the fuller view of Mercury acquired as the spacecraft departed
. Similarly, Mercury will appear as a thin crescent during the inbound portion of MESSENGER's second Mercury flyby and as a nearly full disk during the outbound portion of the encounter, and the areas of the surface that will be imaged by the NAC are shaded in purple. As seen in this figure, MESSENGER's second flyby will result in nearly global spacecraft imaging coverage of Mercury's surface for the first time.
Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington
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