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The HiRISE camera on the Mars Reconnaissance Orbiter has 3 color sensors, red (440-850nm), blue-green (400-600nm), and near-infrared (800-1000nm). Why these particular channels? Why not standard visible colors?

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    $\begingroup$ The HiRISE camera did not chose, its designers did ;-) Good question ... $\endgroup$ – s-m-e Jul 21 '13 at 15:05
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Red because of the color of the planet - we need to be able to see the most red detail, as that's what most of the planet is colored. Blue-green because we don't really need to see blue and green individually. If it's not red, it's enough to know that it's blue or green.

Now, the near-infrared sensor. Why? It turns out that information on mineral groups can be effectively acquired with a near-infrared camera, and has been in use for years. For example, this article on this use of near-infrared cameras is quite informative:

Mineral analysis by near-infrared (NIR) analysis is not well known, even though spectral information on minerals has existed for years. This is primarily because NIR users typically have focused on the elemental minerals rather than geologic mineral species. Researchers using near-infrared for minerals have applied a remote sensing approach rather than a chemometric-based approach, and unfortunately these two groups seldom talk to one another. By bringing together NIR, software and chemometric modeling, advanced technology applications are being created for diverse industries, including mineral analysis in mining exploration and control ore processing.

It's a good read for anyone interested in the subject - and shows just how useful this camera is on the HiRISE orbiter.

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