Here's another press release on the Martian sundial, from the University of
Washington's point of view. Go to the cited URL at the end for the 2
illustrations. It's been a fun project to work on (and it's still got a
long ways to go!)
- Woody Sullivan
*
FOR IMMEDIATE RELEASE
DATE: April 21, 1999
Sundial will mark passage of days, seasons on Mars -
You could call it Martian Standard Time. The new time zone takes
effect in January 2002 when a sundial designed and assembled at the
University of Washington lands on the red planet aboard NASA's 2001
Mars Surveyor. The sundial project was announced today during a news
conference at Cornell University in Ithaca, N.Y., which is creating
the experiment that will contain the sundial. Once the sundial is in
place, the public will be able to monitor the passage of Martian days
and seasons via the Internet.
The idea for the sundial originated with Bill Nye, host of public
television's Bill Nye the Science Guy. It will be contained in a
package of four instruments that make up the Athena Precursor
Experiment, or APEX, on the Mars Surveyor mission scheduled for
launch in 2001.
Nye, a Cornell graduate, noticed a small square and post used as a
kind of test pattern to calibrate the spacecraft's color panoramic
camera, and suggested it could be a sundial.
He sent an e-mail asking me if I wanted to help design the first
sundial on Mars, recalls UW astronomy professor Woodruff Sullivan,
and I sent one back asking, 'Does it rain in Seattle?'
Sullivan and Nye for eight months have been part of a design team
that includes artists Jon Lomberg and Tyler Nordgren, Cornell
planetary scientists Steven Squyres and Jim Bell, and Louis Friedman,
executive director of the Planetary Society.
Inscribed with the motto Two Worlds, One Sun, this sundial will travel to
Mars aboard NASA's 2001 Mars Surveyor lander. Four gold side panels around
the sundial's base contain etched characters and the following message:
People launched this spacecraft from Earth in our year 2001. It arrived on
Mars in 2002. We built its instruments to study the Martian environment
and to look for signs of life. We used this post and these patterns to
adjust our cameras and as a sundial to reckon the passage of time. The
drawings and words represent the people of Earth. We sent this craft in
peace to learn about Mars' past and about our future. To those who visit
here, we wish a safe journey and the joy of discovery.
With the team's design, Larry Stark, who makes scientific instruments in
the UW physics department, devised detailed drawings for making the
sundial. Much of the fabrication is being done at Arizona State University
in Tempe. The parts will be returned to the UW for final assembly, and the
sundial is to be delivered to NASA's Jet Propulsion Laboratory in Pasadena,
Calif., late this summer.
Sullivan, a sundial expert, has designed numerous instruments for reckoning
time using the sun's shadow, including a large one on an outside wall of
the Physics-Astronomy Building on the UW's Seattle campus. Designs must
account for the Earth's orbit and the site latitude if the shadow cast by
the post is to give accurate time. For the first sundial away from Earth,
some factors differ. For one thing, a year is nearly twice as long on Mars.
In addition, while Mars has seasons as Earth does, the seasonality is
exaggerated because the planet's orbit is far more elliptical. But there
are similarities, too. Earth tilts about 23.5 degrees on its axis, while
Mars tilts 25 degrees, and a Martian day is only 37 minutes longer.
It's not as different as you might think, Sullivan said. It's the same
basic principle, you just have to feed in different parameters. It's like
the difference between making a map of Los Angeles and a map of London.
The Martian sundial will be located near the planet's equator, though a
final landing site for the Surveyor mission hasn't been chosen. Uncertainty
about the location, and the fact that the sundial could be tilted by
surrounding terrain, limits the features that can be designed into it,
Sullivan said. Once the spacecraft has landed, the panoramic camera will
monitor the sundial's shadow, allowing Sullivan and other scientists to
calculate its exact orientation. The appropriate sundial lines then will be
superimposed over the sundial's image on the World Wide Web.
The sundial, made from anodized aluminum, is just 3 inches square and
weighs slightly more than 2 ounces. Black, gray and white rings in the
center and color tiles in the corners will be used to adjust the brightness
and tint of pictures taken by the panoramic camera. The rings are arranged
to represent the orbits of Mars and Earth, with red and blue dots showing
the planets' positions
