By Patricia Daukantas

We know Mars as the Red Planet, but what color is its sky? Early Viking lander photos from 1976 seemed to show a light blue sky, but a recalibration—and subsequent images from the Mars Pathfinder mission in 1997—changed the atmosphere to a light pink and then to a butterscotch color.

Such calibration depends on having a handy color-reference target in the field of view of the lander camera. Viking used an American flag, a symbol of the U.S. bicentennial celebration in 1976 (remember that?) and a small color grid, all posted on the outside of the spacecraft. NASA’s Phoenix lander, which touched down successfully on May 25, uses two color-calibration targets specially designed for the mission by scientists at the University of Central Florida.

UCF physics and astronomy professor Dan Britt and two of his students made the color chips, which range from white to royal blue (but no red), to aid spectroscopists in figuring out the true colors and composition of the Martian soil. The targets have built-in magnets to help keep them free of dust buildup, which was a problem on earlier missions.

The UCF team collaborated with a University of Florida chemistry professor and a group from the University of Copenhagen in Denmark. For more information and a photo of the color-calibration target, check the UCF Web site.

2008-05 May, Astronomy, Imaging engineering, imaging, astronomy, camera, spectroscopy, color, calibration