The University Record, February 6, 1995

February skywatchers can see Mars best on Feb. 12, Teske says

The red planet Mars is shining more brightly in the Michigan night sky than it has in the past two years, according to astronomer Richard Teske. "Mars is visible to starwatchers all night long, and is especially prominent now because it comes closest to Earth on Feb. 12, when it is only 63 million miles away," Teske said.

Close approaches between Earth and Mars occur every two years and two months when our faster-moving planet catches up with Mars and passes between it and the sun. The red planet is easy to spot on winter nights in the forequarters of the constellation Leo, the Lion, according to Teske. It rises in the northeast shortly after dark and is almost overhead around midnight.

"Observers who view Mars through a telescope can see patterns of lighter and darker shadings on its rust-colored surface. The northern polar cap, made of frozen carbon dioxide or "dry ice," gleams brilliantly in reflected sunlight," Teske said. "Mars has seasons just as Earth does and for the same reason. Its axis of rotation tilts at almost the same angle as does Earth's axis. Right now it is summer in Mars' northern hemisphere and the slowly melting northern polar cap tilts toward the sun and toward us as well, making it easily visible."

Mars has been a favorite subject for space scientists. Spacecraft orbiting around Mars have photographed its surface, and its landforms and atmosphere have been thoroughly scrutinized. Two U.S. Viking spacecraft landed on Mars in 1976 and spent almost 400 Mars-days examining the local surroundings. According to Teske, the first weather report from these unmanned spacecraft read as follows: "Light afternoon winds. Temperature a chilly -122 degrees F at dawn, warming to -22 degrees F by noon."

One of the Viking landers' tasks was to collect and analyze samples of Martian soil. "They performed three separate tests on soil samples to look for signs of organic material that might reveal the presence of life on Mars, but found none. Exactly the same tests done on samples from Earth's deserts fairly fizzed over with clear evidence of life on our planet," Teske said.

The Viking spacecraft reported that the chemical and mineral content of Mars is similar to that of Earth. The spacecraft also reported that Mars is desert dry. "Soil samples contained only about 1percent water, far less than on Earth." Teske said. "Almost all the water is chemically bonded with soil minerals and so is not in a readily usable form."

Indirect observations made from Earth and from orbiting spacecraft, however, indicate that water is abundant as ice frozen into both polar caps. Scientists believe some water may also exist in a kind of planet-wide, subsurface permafrost like that found in Earth's arctic regions.

In addition to their own water, explorers planning a trip to Mars should take along their own air supply, Teske said. "The atmosphere is nearly pure carbon dioxide, and it is very thin. The surface air pressure is only l/150th of Earth's. Airplane wings won't lift an airplane there at all; you shouldn't plan on playing Frisbee."

According to Teske, the most spectacular tourist attraction on Mars would be its volcanoes. Although none is now erupting, a half dozen of them are larger than anything on Earth. The biggest, Mount Olympus, is 80,000 feet high and covers an area larger than France. It is the largest volcano in our solar system.

"The most exciting and mysterious discovery was the finding of river-like channels on Mars' surface that almost surely were carved by running water," Teske said. "Since liquid water cannot now exist there, scientists conjecture that in some ancient, long-ago time, Mars had to be warmer, with a denser atmosphere. They are eager to continue the exploration of the red planet in voyages planned for 1996 and 1998 to learn more about its past and why it might have changed so dramatically."