What colour is Mars?



Sounds like a silly question, doesn’t it? Except that the photo above, taken by Viking 2 in the late 1970s, is Mars. So is Mars red (HST image) or cream-coloured (some Mars orbiter)? Viking 2 shows it less red, Viking 1 more red, and that silly robot they got there now makes it pretty red. Thing is those cameras are all digital and anybody who has a digital camera knows about colour-balance issues. And those scientific cameras usually record images in black and white, with colour being added afterwards.

PS (18 Jan 2004): This entry needs a little clarification. It’s about the calibration of the digital cameras used by the various scientific instruments mentioned above. It’s not about conspiracy theories that claim that NASA is systematically hiding information about life on Mars. To make it very clear, I think those “theories” are utter nonsense. My interest in the calibration problem originates from an article in New Yorker magazine that wrote “The digital images radioed home by the Viking lander in 1976 were notoriously ‘over-pinked’; if you actually stood on Mars, you would see a landscape whose color resembled not cotton candy, but butterscotch.” (The New Yorker, January 5, 2004, p.27)