Science Debates Aesthetics

What is the color of Mars?

You would think that after all the money and time spent on Mars, that we would have this basic question answered. It turns out, we don't, and we haven't really bothered to find out.

Discover magazine had another great article, this one by Barry E. Di Gregorio titled "The Color of Mars". It turns out that many of the photos taken of Mars since the mid 1970s are not as "accurate" as we thought (at least in terms of how the human eye sees things). Discover notes:

"NASA imaging experts have been trying to get the color of Mars right for more than a quarter of a century. In 1976 the first Viking Lander color image released by the Jet Propulsion Laboratory showed brownish-colored soil and rocks with a blue sky. Within two hours, technicians issued an updated version in which the sky had transformed to a startling deep orange and the surface had turned red. This time, however, the colors on the Viking Lander color-calibration target no longer matched up; also, the American flag insignia on the side of the Viking Lander showed purple stripes instead of red, and the white stripes appeared pink. NASA scientists maintained that the ruddy surface and sky were correct, the result of atmospheric dust particles that scatter light toward the red end of the spectrum and tint the landscape. Subsequent Viking images continued in this vein, establishing the misconception that Mars is red."


View of the West Candor Chasma, part of a huge canyon system 5,000 km long, up to 240 km wide, and 6.5 km deep.

It's another one of those things that teaches us that what we see isn't always what we get. The reality is that the telescopes we send are not trying to take photos of the planets, at least not as we understand them. The article continues:

Early images from the Mars Pathfinder Lander released in 1997 likewise depict a ruddy landscape and a mud-orange sky. Images from the Hubble Space Telescope taken during 1996 and 1997 show a fire-engine red planet too. Jim Bell, now the lead scientist of the Mars Exploration rover panoramic camera and part of the Hubble team for the Mars imaging project since 1996, notes that getting the color balance right on these pictures was not a high priority at the time. “They are false-color composites and should not be interpreted as true color,” he says. “To the best of my knowledge, no attempt was made to correctly color-balance them.”

So why this great deception? Is the space industry a bunch of red Communists?

Not really. One chief purpose of the photos being taken was to learn about the geology of the planet, therefore the cameras used infrared and ultraviolet filters for various technical reasons.

For the laymen, however, it was just confusing. For most scientists, there were larger issues to worry about.

Too bad.


Links of Interest:

NASA Mars Exploration website

Mars Exploration Rover Mission

The European Space Agency

The ESA Mars site.

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