MarsDial: The Movie!

Watch time pass on Mars in new movies of a Mars-based sundial, a MarsDial, made from still images captured over a 10 day period by the Spirit rover. The movies were created by The Planetary Society's Student Astronauts, teenaged members of the Mars Exploration Rover team.

The Student Astronauts - 16 young people from 12 different countries - are part of The Planetary Society and LEGO Company Red Rover Goes to Mars Project, the first educational experiment selected by NASA for a planetary mission. They work at JPL in teams of two, each pair remaining one week, processing MarsDial images taken by NASA's twin rovers on Mars. This is the final week in which a team of Student Astronauts will work at JPL.

The Planetary Society selected the students as part of the Red Rover Goes to Mars education activity. Red Rover Goes to Mars is privately funded by The Planetary Society and the LEGO Company.

Each rover, Spirit and Opportunity, carries an identical MarsDial, approximately three inches square. While ordinary sundials are fixed in place, the MarsDials move with the rovers. So, the MarsDials have no hour lines because the rovers' changing positions would render such markings useless. Instead, the Student Astronauts add hour marks electronically to the images, using software developed by students Alex Hayes and Christopher Wong at Cornell University in collaboration with Professor Woodruff "Woody" Sullivan, an astronomer and sundial expert at the University of Washington.

To produce each movie, the Student Astronauts selected a set of images taken through the same color filter, calibrated the images to match their brightness, aligned the images to each other, and then animated them. The black-and-white movie, composed of 17 frames, shows the motion of the central post's shadow across the MarsDial from about 10 am to about 5 pm local solar time. The background flickers between the lander petal and the rocky surface of Mars because the images were captured both before and after Spirit stood up from the lander.

The color movie contains fewer frames because, in order to produce a color image of the MarsDial, the rover has to capture three images at nearly the same time through its red, green, and blue filters, and only seven image sets through all three colored filters were available at the time the animation was created. Additional MarsDial movies will be made as more image sets become available

The Student Astronauts have also been asked to participate in a scientific investigation that uses the Panoramic Camera. Jim Bell of Cornell University, Pancam Payload Element Lead, has recently asked the students to analyze the MarsDial images, recording the brightness of the surface of the MarsDial in the areas lit directly by the Sun and the areas within the shadow cast by the post on the MarsDial. The brightness of the shadowed portion of the MarsDial is directly related to how much light is scattered by dust in the Martian atmosphere. By measuring the level of brightness over time, the students will be able to draw conclusions about the changing amount of dust in the Martian atmosphere.

The Student Astronauts will compare their results with measurements of the same phenomenon performed through a different method by scientist Geoffrey Landis of NASA's Glenn Research Center. Landis is studying the response of the rovers' solar panels to light in the Martian atmosphere.

The MarsDial resulted from a brainstorm of Bill Nye the Science Guy, a Planetary Society Board Member. Nye worked with Bell, Sullivan, and Steve Squyres, the principal investigator for the rover missions, and a team of three others -- Louis Friedman, Executive Director of The Planetary Society; Tyler Nordgren, University of Redlands in California; and Jon Lomberg, Mauna Kea Center for Astronomy Education,University of Hawaii at Hilo -- to develop the MarsDial for flight. The dial serves as the "Pancam Calibration Target." Its primary role is as the image calibration fixture for the rover cameras, used like a television test pattern or photographer's color balance chart.

The Jet Propulsion Laboratory in Pasadena, a division of the California Institute of Technology, manages NASA's Mars Exploration Rover project; Cornell University in Ithaca, N.Y., manages the science instruments carried by the two rovers.