Destination Mars
Mars. The Red Planet. If interplanetary travel is your cup of tea, Mars is probably your best bet. Venus is closer, but its blistering surface temperature and crushing atmospheric pressure make it a poor prospect for tourism.
A Distant Desert
Though it is generally colder than most places on Earth, Mars offers a desert experience, punctuated by majestic mountains, many of them of volcanic origin, and dramatic valleys that make the Grand Canyon look like a humble ditch.
The distance between Mars and Earth varies as these two neighbors orbit the Sun. They can be as distant as 400 million kilometers (250 million miles) or as close as 57 million kilometers (35 million miles). Even at its closest, though, no one would
say Mars is a stone's throw away. Your trip to Mars, following an elliptical orbit and traveling at an average cruising speed of 80,000 kilometers per hour (50,000 miles per hour), should take between 7 and 10 months.
The Canyonlands
The best word to describe the Martian landscape is "awesome." The valleys are deeper and the mountains are higher than anything you'll find on Earth. The Mariner Valleys (Valles Marineris) cut a 4,000 kilometer (2,500 mile) long scar just south of the Martian equator.
Named after Mariner 4, the American spacecraft that was the first to take close up pictures of Mars when it flew by in 1965, the Mariner Valleys are really a system of canyons almost ten times longer than the Grand Canyon and twice as deep. These canyonlands are works in progress, holding the history of the planet within their steep walls. The huge rift probably started out as a long crack in the surface as forces within the planet's interior stretched the Martian crust. Fierce winds carrying dust and sand
have carved out the valleys over billions of years, and rockslides have shifted the landscape, filling in some places and leaving sharp cliffs in others.
In Search of Water
Giovanni Schiaparelli, a nineteenth-century Italian astronomer who studied Mars through a telescope, interpreted dark areas of the planet as seas. He called them maria, the plural form of mare, the Latin word for "sea." But don't expect to find bodies of water of any size on the planet today. Although scientists have evidence there was once liquid water on Mars, not a drop can be found on the surface now. The atmosphere is too thin to permit surface water to exist in a liquid state.
The Viking spacecraft observed many features on Mars that look like dry riverbeds, with meandering banks. There are also "islands" shaped like tear drops, perhaps formed by giant floods long ago on Mars.
Windy Weather
Although it is frequently overcast on Mars, the clouds do not hold much water. One type of gloomy weather can last for weeks during the summer and fall. That's when cyclones sweep out from the poles, churning up the fine rust-colored dust on the surface and producing yellowish clouds that sometimes cover the entire planet.
At other times, wispy white morning clouds drift over the landscape, then disappear as the day grows warmer. This "Martian mist" consists of crystals of frozen carbon dioxide, otherwise known as "dry ice."
From Pole to Pole
A trip to the poles should be on any visitor's list. As on Earth, the warmest temperatures in the northern hemisphere occur during the summer months, when the north pole tilts toward the sun. During those months, it is winter in the southern hemisphere. The biggest seasonal change takes place at the poles, where the vast ice caps shrink and expand with the passage of months. There's another reason to go in summer, though. You might see the water ice uncovered as the layer of dry ice
above it evaporates.
If it is true that Mars was once a warmer place, this water ice may be the remnant of a time, perhaps as long as 4 billion years ago, when Mars was a watery planet and living things may have thrived.
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