Why Mars? New polls show that Mars is students' favorite planet. Why the fuss over our next-door neighbor? (Earth Science: Space Exploration * Planetary Science).

An alien spacecraft shaped like a massive dog dish hovers over a bustling city, flashing like holiday tree lights at warp speed. Baffled pedestrians freeze. Traffic stalls. The floating disc extends tripod legs, anchoring in a busy intersection. As a hatch slowly grinds open, a ramp unfurls. Out march green Martians to the drum of a flat voice: "Where's McDonald's?" Surprise! The aliens whip out garage door opener-like devices and zap slime at onlookers.

Scenario B: Earthlings land on a Martian landscape. Repeat above scenario but swap the cast of characters.

Maybe you've been bombarded by such over-the-top fantasies in comics and Hollywood sci-fi flicks. But now everywhere you look there's news about the real Mars, including NASA's latest probe Odyssey, which arrived October 23 to orbit 400 kilometers (250 miles) above the Red Planet. Why our endless fascination with the planet next door?

YO, NEIGHBOR?

At an average distance of 78.4 million km (48.7 million mi) from Earth, Mars shines like a red speck in the night sky. Its unusual fiery glow--from iron oxide (rust)-rich soil--inspired ancient Greeks and Romans to associate the planet with bloodshed, like Mars, the Roman god of war. And Martians hold a special place in Earthling imagination--perhaps because the real Mars is so alien, yet so Earthlike. "Humans are curious beings," says planetary scientist Pascal Lee of the SETI Institute and NASA Ames Research Center. "We wonder about the possibility of life elsewhere, mainly because we wonder about our own place in this universe." And Mars is a very promising place to look for possible extraterrestrial (not earth) life.

Mars--along with Mercury, Venus, and Earth--is one of four terrestrial (solid surface) planets in the inner solar system. And of all the terrestrial planets, Mars is most similar to Earth. "Its landscape even looks somewhat like our Southwest deserts," Lee says. The Red Planet is rocky, dented with craters (depressions caused by meteorites, or space rocks), and swept with fierce dust storms. Some distinguishing features: networks of valleys and canyons, hardly visible with Earth's telescopes. When early-model telescopes first saw fuzzy markings on the planet's surface, the images unleashed Earthlings' Martian fever.

In 1877, Italian astronomer Giovanni Schiaparelli reported seeing canali (channels) on Mars. But canali was mistranslated as "canals." And since the engineering marvel of that era was the Suez Canal, many assumed Martians were just as sophisticated in waterway design. In the early 20th century, U.S. astronomer Percival Lowell even mapped out the canals, boldly claiming they were irrigation systems used to transport water from the planet's polar ice caps to Martian civilizations. Thus the sci-fi fantasy of Martians and Earthlings exchanging (often hostile) visits was born.

LITTLE GREEN MEN?

When NASA probe Mariner 4 flew by Mars in 1965 and sent home the first grainy black-and-white close-ups of the planet, none showed canals or life forms. Since then, probes have flown by, landed on, or still orbit Mars, supplying Earth with a wealth of images and mapping the planet's terrain. Robotic instruments also give us up-close looks at some Martian rocks. "But these experiments aren't conclusive," says astrobiologist (extraterrestrial-life scientist) Pamela Conrad at NASA Jet Propulsion Laboratory. "We still can't prove if there was or still is life on Mars."

Mars is cold and dry. So Conrad travels to Antarctica, "essentially a cold desert--kind of like Mars," to study parallels between the two environments. In Antarctica's extreme environment, Conrad studies microbes (tiny organisms) that live inside rocks called endoliths. Life, as we know it, needs water to survive. "Those endoliths can live for a really long time with only a tiny amount of water," she says.

While the average surface temperature on Mars is a frigid -53 [degrees] C (-63 [degrees] F), too cold for liquid water to be stable on the rocky and rusty crust, "we know so far it looks like there has been water at or near the surface in the not-so-distant geological past," says Conrad. "So the notion that there might be some water on Mars, and the idea that microbes could live in rocks, suggests there is a possibility some form of life could exist."

NASA's Odyssey aims to search for water above and near ground. In addition, Odyssey will map out chemical elements and minerals to find out exactly what Mars is made of and measure radiation levels: information that will help NASA devise methods to protect future astronauts.

ARE WE THERE YET?

While getting humans to Mars may be a decade or two away, preparation isn't. Pascal Lee's NASA Haughton-Mars Project tests robots and human exploration methods in the rocky, desolate, Mars-like terrain of Devon Island in the Canadian Arctic. Last summer Lee even led scientists in a Mars living simulation: Groups took turns living in a "Martian" habitat (built by the Mars Society), and performed traverses (exploring trips) in spacesuits, as if working in Mars' lethal atmosphere.

"You don't plan a manned mission to Mars just on a drawing board," says Lee. Getting even the tiniest detail down right takes trial and error. For example? Unlike astronauts sharing a moon buggy, each person will need one. Why? "If one breaks down you can still find a way back to camp."

"Going to Mars is exciting not just as a destination, but as a journey," Lee says. "It will push the limit of what we know and can do." Maybe this journey will even shed light on the question: What on Earth are we doing in the universe?

READY TO PACK UP?

Mars is filled with geological wonders, including a crater that looks like a smiley face. It also boasts the largest volcano in the solar system: Olympus Mons is three times taller than Mount Everest--26 km (16 mi) high--and covers an area as large as Arizona! But it will be some time before the scientific know-how is ready to ship humans off to the Red Planet. Here's your chance to use your research skills and imagination to try and solve some of the real-life design problems scientists face.

Students are invited to participate in Space Day 2002 Design Challenge: Adventure to Mars! Team up and explore:

1. Create an invention that will make living or working on Mars easier for astronauts.

2. Design a rover to collect data on a planet or a moon.

3. Come up with an electronic newspaper to transmit Martian. life information back to Earth.

The deadline is March 1, 2002. All participating teams will receive a certificate signed by Astronaut John Glenn! Teams from grades 4 to 8 can qualify for national recognition. Check out www. spaceday.com.

TRAVEL MAP

With current technology, it will take lots of fuel to make a roundtrip between Earth and Mars. To keep the route fuel-efficient, good timing between the planets' orbital paths is necessary. The best time to launch:When Earth is at six o'clock and Mars is at four o'clock--an alignment that occurs once every 26 months.

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Cross-Curricular Connection

Social Studies: Watch a Mars-exploration movie. Site a concept that is pure science fiction. Then research and report on current scientific research that may make this fantasy a reality one day.

Did You Know?

* Mars has two small, oddly shaped, and cratered moons: Phobos and Deimos--meaning fear and panic, respectively, in Greek. They were named after the sons of Mars, Roman god of war. Scientists believe the moons are asteroids captured by Mars' gravitational pull.

* Researchers believe, in theory, that Mars' environmental conditions could be altered to resemble Earth (terraforming). How? By orbiting giant mirrors around Mars, sunlight could be reflected to warm the planet. Carbon dioxide now frozen in rocks and polar ice caps could be released, raising the planet's temperature and air pressure. This could eventually create an environment sufficient for plants to grow and humans to thrive--a process that could take many centuries.

National Science Education Standards 

Grades 5-8: structure of the Earth system * science and technology in society * science as a human endeavor * history of science

Grades 9-12: origin and the evolution of the universe * science as a human endeavor * science and technology in society * historical perspectives

Resources

"A Mars Never Dreamed Of," by Kathy Sawyer, National Geographic, February 2001

Visit the homepage of NASA's Odyssey: mars.jpl.nasa.gov/odyssey/

For more on the NASA Haughton-Mars project: www.arctic-mars.org

Directions: Read our story on Mars exploration, then write two essays using the words provided.

1. You're in a sci-fi flick. Portray a Martian who has to explain the planet to Earthlings. (iron oxide, meteorites, liquid water)

2. You're selected to go on a mission to Mars. Describe your preparation and agenda. (Odyssey, 26 months, spacesuits)