Thursday, February 19, 2004

Seeing red and feeling blue



Something has been nagging me about the recent Mars mission. There have been fantastic pictures coming back -- highly detailed, brilliant panoramas, deep color, but... the color, it's... wrong. And not just a little wrong, but a lot wrong, and not just in a few of the pictures but in ALL of them. They have too much red. "OK," you're saying, "Duh, Garrett, it's Mars, it's red." And, yes, the dirt is red on Mars, but the sky on Mars, unless there's a dust storm present, isn't red -- it should be kind of blue. You see, what makes our sky blue is Rayleigh scattering -- the light from the sun comes through the atmosphere and bounces off the air molecules, careening off them and then coming down to your eye from all directions. The shorter wavelengths, the blue light, gets scattered more than the larger wavelengths, so the light we see coming down from the sky is blue. This same process happens on Mars. The atmosphere there is thinner, so the blue isn't as deep, but it sure as hell shouldn't be red.

But ALL the color photos coming from NASA, on their website, look like this recent one, taken by Opportunity looking back at its landing chute:

Red. Bah. And these photos are described on NASA's site as "approximately true color," "as if you were standing on Mars." Bah!

The rovers are equipped with very high quality cameras as well as a color palette for excellent color calibration. Fortunately, since many images are made available, including some of this standard color palette, off the shelf image processing software can be used with the NASA data and the images properly color calibrated and corrected. If you're nerdy enough to do this (and this takes an order of magnitude less nerdiness than is possessed by your average JPL guy) you can process the images and see what Mars really looks like. Applied to the image above, it looks like this:

Ahh, a nice light blue sky. And the whole thing is less ruddy. (If you want to see more color correct images of Mars, you can look at this nerd's page, which is where the above image came from.)

So, to put it bluntly, what the fuck are NASA and JPL doing releasing images that consistently misrepresent what Mars looks like? It is not cool (understatement) in science to misrepresent data. Now, it is true that it's only being misrepresented to Joe public, since any decent scientist will be able to get at the truth and NASA can claim they are thus giving the correct data to anyone really interested, but it still remains that they are misrepresenting things to the press and to the general public. And it pisses me off. Many things like this can be attributed to laziness or stupidity, but this answer in this case is absurd given the resources JPL and NASA have available. Why they are doing it is up for speculation. It could be political: hard to justify the expense of the mission if the surface of Mars looks too much like the Mojave desert? Anyone have any other ideas why they'd do it? Conspiracy theories abound. Maybe our theocratic dictator in chief just likes the color red? Or it's better to give the taxpayers the red planet they expect? Who knows. In any case, it's just wrong. And I'm sure they know it. Right now, thousands of school kids are looking at pictures of the red Martian sky, and it's wrong. But, anyway, now you know the truth, and I've had my rant.

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gar@lisi.com