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Next Stop: Mars

Sometime in November, a rocket will blast into the sky from its launch pad at the Kennedy Space Center in Florida. A month later, a second rocket will take off. Both will carry space probes that are headed on a journey millions of miles beyond our moon, all the way to the Red Planet: Mars.

The first probe is called Mars Global Surveyor. It will take about a year to reach the Red Planet. Once there, it will orbit Mars and take supersharp pictures of the Martian surface. The second probe, called Mars Pathfinder, will actually land on the surface. This will be the first time a space probe has touched Martian ground since one named Viking landed there more than 20 years ago.

Even more amazing, Pathfinder will be carrying a little six-wheeled robot named Sojourner. Moving at about two feet a minute (that's much slower than a turtle), the two-foot-long robot will go exploring. It will take close-up pictures of Martian dirt and rocks. It will also test the soil to see what Mars is made of.

Clues To A Watery Past
Scientists have lots of reasons to be interested in Mars. Although about half the size of our planet and pocked with craters as is our moon, Mars is similar to Earth in some ways. It has volcanoes and giant canyons. It also has areas that look like dry riverbeds. This means there was probably water on Mars ages ago, even though it's now dryer than a desert. And where there's water, there is always the possibility of life.

Scientists have thought the possibility of life on Mars was very slim--until this summer. In August, to everyone's amazement, a team of geologists and biologists announced they had found evidence that life may actually have existed on Mars long ago. They found it inside a Martian rock known as ALH84001.

The potato-size rock had been found on Earth, sitting on a sheet of ice in Antarctica. Scientists have found about a dozen rocks from Mars on Earth. They know the rocks are from Mars because they're made of minerals different from anything on Earth (or our moon, asteroids or comets, for that matter). The rocks probably were blasted into space when an asteroid smashed into Mars. After many years, they fell to Earth.

When scientists cracked this particular rock open, they found several interesting things. One was a group of chemicals called polycyclic aromatic hydrocarbons (polly-sik-lik, ah-row-ma-tik, high-dro-car-buns), or PAHS for short. PAHS are created when bacteria die and rot. Using a microscope, scientists also found objects that look like fossils of bacteria and even tiny worms. Best of all, the chemicals and objects were found deep inside the rock. If they had come from contact with the Earth, they would be near the surface. Another promising sign: ALH84001 dates back to between 3 billion and 4 billion years ago--exactly the time when Martian rivers were flowing.

There's Plenty Left To Prove
The scientists are being very careful, though. They admit this still doesn't prove life once existed on Mars. PAHS are sometimes found in ordinary lifeless meteorites, and the tiny objects inside ALH84001 could just look like worms and bacteria. If similar chemicals and objects can be found in other rocks on Mars, researchers may be a little more certain.

Unfortunately, the Pathfinder mission and other Mars missions that NASA has planned are one-way trips. There's no solid plan to bring back rocks from Mars. Also the probes that are going are not designed to test for signs of life.

Thanks to ALH84001, though, NASA may be making new plans. The space agency is already thinking about sending a probe on a round trip to Mars in the year 2005. If Congress okays some extra money, it could happen sooner. And if Congress is willing to spend a lot of money, there could even be a Mars trip with humans aboard.

Some scientists believe life may still exist on the Red Planet--not on the dry surface but deep underground, where water may be trapped. If so, astronauts with the right equipment could dig down and find it. This would certainly be one of the biggest discoveries ever.

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Did You Know?

MARS' day lasts 24 hours and 37 minutes. A year--the time it takes to orbit the sun--lasts 687 days.
MARS has less than half of the gravity on Earth. If you weigh 50 pounds on Earth, you would weigh only 19 pounds on Mars.
MARS' diameter is about 4,210 miles, making it about half the size of Earth and nearly twice as big as our moon.
MARS is the home of the largest mountain in the solar system. The volcano, Olympus Mons, stands about 17 miles high and has a crater 50 miles wide.
MARS was named after the Roman god of war because of its blood-red color. Iron-rich dust and rock give Mars a red surface and a pink sky. March, the month, is also named after the god Mars.
MARS' temperatures vary from minus 200°F to 80°F.

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