UW News

August 29, 2012

From UW to Mars, sundial has an important role

News and Information

            The recent landing of NASA’s Curiosity rover on Mars means that a timepiece put together at the University of Washington once again has found a home on the Red Planet.

A sundial aboard the NASA Mars rover Curiosity.

This image of a sundial assembled at UW was taken Aug. 12 on Mars by the Mastcam on board NASA’s Mars rover Curiosity.NASA/JPL-Caltech/Malin Space Science Systems

Two previous Mars missions, the Spirit and Opportunity rovers that landed in 2004, each carried a sundial – or Marsdial – about 3 inches square that had been largely fabricated in a UW Physics Department shop.

In all, seven of the small instruments (they weigh slightly more than 2 ounces) were assembled here, said Larry Stark, a scientific instrument maker in the physics shop who did the work in 1999. Five of the sundials were held as backups, and one of those was adapted for Curiosity.

“A lot of the writing changed, but one of the nicest things on the original is still there, the name for the planet Mars in many, many different languages,” Stark said.

A sundial might sound like a fanciful piece of equipment for a serious, and expensive, space mission, but it has a very down-to-Earth function – it is used to calibrate the mast camera, one of four science cameras (eight cameras total) aboard Curiosity.

The original sundials bore the title “Mars 2002” and the inscription “Two Worlds One Sun.” When the mission the sundial was intended for was cancelled and the experiment it was part of became incorporated in two later missions, Stark fashioned a slip cover that corrected the year to 2004.

Inscriptions on the four sides of the latest Marsdial paint a history of how humans have viewed the Red Planet:

  • For millennia, Mars has stimulated our imaginations. First we saw Mars as a wandering Red Star, a bringer of war from the abode of the gods.
  • In recent centuries, the planet’s changing appearance in telescopes caused us to think that Mars had a climate like the Earth’s.
  • Our first space age views revealed only a cratered, Moon-like world but later missions showed that Mars once had abundant liquid water.
  • Through it all, we have wondered: Has there been life on Mars? To those taking the next steps to find out, we wish a safe journey and the joy of discovery.

Similar changes went into the current version, including an altered inscription: “To Mars To Explore.” Stark also created new plates for each side of the Marsdial’s base, with inscriptions and images depicting the history of how humans view Mars (see info box).

One other significant change placed small magnets beneath the aluminum base of the sundial. Stark explained that previous sundials became coated with iron oxide – or rust – particles from Martian soil and made them less effective for calibrating the cameras. It is expected that the magnets will keep the metallic dust from settling in a way that defeats the calibration function.

A number of people and institutions helped design the Marsdials, including Woodruff Sullivan, a UW astronomy professor, and Bill Nye “The Science Guy.”

The original experiment that used the sundials for camera calibration was run by Cornell University. Cornell, Arizona State University, the University of Hawaii and The Planetary Society made significant contributions in fabricating the instruments.

Stark noted that the first sundial he ever worked on was with Sullivan, one that graces the south exterior wall of the Physics-Astronomy Building, visible from the Burke-Gilman Trail and Northeast Pacific Street.

But there is one thing that beats being able to see a sundial that he assembled sitting on Mars.

“The most fun is to take out-of-town friends to the Museum of Flight and see one of these on display there,” he said. “It’s not often you can go to a museum and see a piece of yours there.”


 For additional information, see “Sundial will mark passage of days, seasons on Mars” and “The MarsDial: A Sundial for the Red Planet.”