One of seven instruments in Messenger's science payload, the multispectral MDIS has wide- and narrow-angle imagers, both based on charge-coupled devices (CCDs) found in common digital cameras. MDIS has taken nearly 400 test shots since Messenger launched from Cape Canaveral Air Force Station last August, but all were of star fields, dark space or a calibration target on Messenger's lower deck.
The photo session was just part of the preparations for an August 2 Earth flyby, the first major adjustment to Messenger's flight path toward Mercury. While MDIS took its pictures, the Mercury laser altimeter team at NASA's Goddard Space Flight Center in Maryland checked its instrument's alignment by firing a high-powered laser at it from a ground-based Goddard telescope.
The mission operations and science teams are also finalizing plans to calibrate several instruments -- including the magnetometer, energetic particle and plasma spectrometer, and Mercury atmospheric and surface composition spectrometer -- during approach and departure observations of Earth and the Moon. During a 4.9-billion mile (7.9-billion kilometer) journey that includes 15 trips around the Sun, Messenger will fly past Earth once, Venus twice and Mercury three times before easing into orbit around its target planet.
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