This topic was also discussed here (regarding some previous missions): http://news.ycombinator.com/item?id=4356878 http://news.ycombinator.com/item?id=4356878

This topic was also discussed here (regarding some previous missions): http://news.ycombinator.com/item?id=4356878 http://news.ycombinator.com/item?id=4356878 They use a black and white CMOS to accurately measure the actual light hitting the lens (which may include non visible spectrum. To get a colour image they need to use filters and take multiple photos, where as consumer cameras have a fixed grid (Bayer pattern) of one filter per each pixel. That probably won't give you such an accurate picture. Also when they're using filters they're not interested in reproducing true colour but rather highlighting a difference in materials. The bandwidth constraints no doubt the reason they didn't change the sensor. Besides, when they combine three different images taken with filters to create one colour image it will essentially be 6MP anyway.