MESSENGER's third flyby of Mercury occurs today, with closest approach to the planet at 5:55 pm EDT. This NAC image of a sunlit crescent Mercury was taken 44 hours before the spacecraft's closest pass to the surface. Visit the interactive visualization tool to examine in detail the instrument observations planned for the flyby. Starting at 3:45 pm EDT today, the visualization tool can be run in real-time, showing the planned observations on the website at the same time that the MESSENGER spacecraft will be performing the actual observations. The images and other measurements collected by MESSENGER during the flyby will begin to be transmitted to Earth just before midnight tonight.

Date Acquired: September 28, 2009
Image Mission Elapsed Time (MET): 162589824
Instrument: Narrow Angle Camera (NAC) of the Mercury Dual Imaging System (MDIS)
Resolution: 14 kilometers/pixel (8.7 miles/pixel)
Scale: Mercury's diameter is 4880 kilometers (3030 miles)
Spacecraft Altitude: 542,000 kilometers (337,000 miles)

These images are from MESSENGER, a NASA Discovery mission to conduct the first orbital study of the innermost planet, Mercury. For information regarding the use of images, see the MESSENGER image use policy.