UPDATE: August 5, 2012: NASA's newest rover, Curiosity has just touched down safely on Mars. On board is a sundial made out of the color camera calibration target. See an NBC LA news segment on Dr. Nordgren's participation in its design.
In January 2004, NASA’s Spirit and Opportunity rovers landed on Mars carrying two sundials. Dr. Nordgren was part of a team of seven astronomers and artists chosen by Dr. Steve Squyers, the Principle Investigator for the rovers, to turn the color calibration targets into sundials. What’s a color calibration target? Here on Earth we know that trees should be green and the sky should be blue and we can adjust our images’ colors accordingly to bring out these true colors. But there are now color cues on Mars unless we bring them ourselves. Sitting on each rover is a target with red, green, blue, and yellow tabs as well as a post to cast shadows so we can see these colors in direct and indirect lighting. According to team member Bill Nye “The Science Guy,” that’s just a sundial. Under the direction of world-famous artist, Jon Lomberg, who worked on Carl Sagan’s Cosmos TV series as well as the NASA Pioneer and Voyager spacecraft plaques, the Mars rover targets are working sundials bearing the name “Mars” in 16 languages from all over the world and the slogan (a common feature of all sundials), “Two Worlds, One Sun.” These Marsdials are now the most photographed objects on the surface of Mars. In 2011, a third Marsdial was launched to Mars on board NASA’s newest rover, Curiosity. This third dial, continuing the tradition of the previous two, carries the slogan that speaks to anyone who has ever wondered what’s over the horizon or on other worlds: “To Mars, to Explore.”