Russian space experts are considering sending a manned space mission to Mars in 2010, a dream that U.S. space planners have put on hold for lack of money.

But if you could fly there now, here's what you would find, based on information gathered through telescopic observations and by unmanned spacecraft that have visited the planet.As you step out on the surface of Mars, make sure the backpack you're wearing is feeding a steady supply of oxygen into your space suit. Not only is the atmosphere on Mars much thinner than Earth's, it's mostly carbon dioxide. That's the gas that makes soft drinks fizz.

The good news: Mars, a planet about half the diameter of Earth, has a smaller mass and hence less of a gravitational tug. So the backpack that weighed 100 pounds on Earth feels like a 38-pound load on Mars.

As your eyes scan the Martian landscape, all the rocks and soil you see are red. Not fire-engine red, but an orange-brown red. The rusty covering comes not from flowing water, but from oxidation caused by the oxygen from carbon-dioxide affecting iron in the rocks and soil, said Eric Carlson, a Mars expert at Chicago's Adler Planetarium.

Mars is basically a very cold place, but you'll find temperature variations much greater than on Earth. At the equator on Mars, daily temperature fluctuations can range from about 70 degrees above at noon to 110 or more below in the night. Mars' thin air heats and cools more rapidly than Earth's.

You'll see some misty clouds, seasonal weather patterns and global winds that sometimes stir up giant dust storms. Blowing dust is responsible for most of the color variations once mistakenly thought to be a sign of life. The greenish tinges seen through telescopes are optical illusions.

But there are some spectacular sights on Mars. One of its mountains rises three times higher than Mount Everest; a huge canyon near the Martian equator dwarfs the Grand Canyon; and giant sand dunes in one area on Mars could bury the Great Pyramid, said Rodney Nerdahl of the Minneapolis Planetarium.

The polar ice caps are primarily dry ice - frozen carbon dioxide that melts into a vapor rather than a liquid. There's still some water ice in Mars' north polar cap, but during the Martian summer it, too, melts into vapor rather than liquid because of the planet's low atmospheric pressure.

For the same reason, you can forget looking for rivers, streams or even puddles of water on Mars, although you will see some dried-up river channels.

"Everybody agrees that water was once there - the only question is whether it flowed on the surface or below the surface," said Robert Pepin, a Mars expert at the University of Minnesota. If it was below the surface, the ground above caved in.

You'll also see two Martian moons, but both are midgets. The moons are smaller than the average American county.

And as you look back at Earth, it will look like a bright star.