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The Camera Takes Aim

MESSENGER's camera takes over for the Webcam in this week's image, snapping the above photo during recent instrument alignment checks at NASA's Goddard Space Flight Center. Taken by the Mercury Dual Imaging System's wide-angle camera, the picture shows an engineer using a theodolite - an instrumented telescope used to measure angles - to check the camera's bore sight. This alignment test shows the team exactly where the camera is pointing in relation to the spacecraft's three directional axes.

The picture appears blurry because the wide-angle camera is designed to focus on objects at least 200 kilometers (124 miles) away. The theodolite projects an illuminated cruciform - the white crosshairs in the center of the image - and since its optics make the cruciform appear far away, the crosshairs are in focus when viewed by the wide-angle camera. (If you look closely you can also see a small-but-sharper image of the engineer in the telescope's eyepiece.)

Careful alignment of each MESSENGER instrument is crucial for planning future science observations, but operators will also use the camera for navigation during MESSENGER's flight. In particular, when MESSENGER prepares to enter orbit about Mercury, the navigation team will take distant images of the planet and starry background to refine the spacecraft's exact position in space - knowledge key to pointing the spacecraft correctly during critical engine burns.

Click here to see the image at full resolution.

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Last updated: February 11, 2004

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