Solar System Exploration: Planet Selector: Mars

PLANET SELECTOR

ABOUT MARS

Mars is a cold desert world. It is half the diameter of Earth, but both planets have the same amount of dry land. Like Earth, Mars has seasons, polar ice caps, volcanoes, canyons and weather. There are signs of ancient floods on Mars, but evidence for water now exists mainly in icy soil and thin clouds.
Read More About Mars >>

Featured Mission: Opportunity
Opportunity was the second of two robot geologists to land on the Red Planet in January 2004. The rovers are seeking evidence of past water on Mars.
Read More About Spirit >>

VITAL STATISTICS

Average Distance from Sun:	227,936,640 km (141,633,330 miles)
Diameter:	6,780 km (4,213 miles)
Volume:	0.149 x Earth's
Mass:	641,850,000,000,000,000,000,000 kg (0.107 x Earth's)
Length of Day:	24.62 hours
Length of Year:	24.62 hours
Known Moons:	2

SIZE & DISTANCE

If the Sun was as tall as a typical front door, Earth would be the size of a nickel - and Mars would be about as big as an aspirin tablet.

Average Distance from the Sun: 227,936,640 km (1.52 A.U.)

EXTREME SPACE

Slam Dunk
With gravity only one-third of Earth's, there's a good chance just about anyone could dunk a basketball in an NBA-regulation goal on Mars. Unfortunately, the required spacesuit might cut down on your edge.

The Real Grand Canyon
Mars' Valles Marineris is long enough to stretch from California to New York - more than 4,800 km (3,000 miles). The Martian canyon is 7 kilometers (4.3 miles) deep and 320 kilometers (200 miles) wide. America's Grand Canyon is 'only' 446 kilometers (277 miles) long, 30 kilometers (18 miles) wide and its deepest point is 1,600 meters (5,250 feet).

Ring Around the Red Planet
Phobos, the larger of Mars' two moons, is slowly sliding toward Mars. In about 50,000,000 million years it will either smash into the planet or break up - creating a dusty ring around the Red Planet.

Into (Really) Thin Air
Towering above the planet at 27,000 meters (88,000 feet), Olympus Mons is three times as tall as Mt. Everest, the highest point on Earth. The long dormant volcano is so enormous its base could cover the entire state of New Mexico.

Are We There Yet?
If you could drive the minimum distance to Mars at an average highway speed - say 100 kph (62 mph) - it would still take more than 66 years to reach the Red Planet. A spacecraft takes about six months to get to Mars. It takes sunlight about 4 1/3 minutes longer to get to Mars than to get to Earth.

Speed Brakes
To survive a landing on Mars, a spacecraft must shave three zeroes off its speed in only six minutes - from about 19,000 kph (12,000 mph) in space to less than 19 kph (12 mph) at the surface.

TIMELINE

1576 - Using keen eyesight and careful record keeping, Danish astronomer Tycho Brahe makes surprisingly accurate calculations of Mars' orbit.

1877 - Asaph Hall discovers Martian moons Phobos and Deimos. The existence of the moons was predicted 150 years earlier in Jonathan Swift's ''Gulliver's Travels.

1965 - NASA's Mariner 4 sends back 22 photos of Mars - the world's first close-up photos of the Red Planet.

1976 - NASA's Viking 1 Lander touches down onto the surface of Mars on July 20th. This was the first successful landing onto the Red Planet.

1997 - NASA's Mars Pathfinder lands and dispatches Sojourner - the first wheeled rover to explore the surface of another planet.

2004-now - NASA's Opportunity rover discovered that bedrock in Gusev Crater suggests that Mars once had water flowing on its surface. The Mars Odyssey also discovered carbon dioxide jets that erupt during Martian spring in South Polar region.

SLIDE SHOW

First Mars Close-up (1965)
Viking 1 on Martian Surface
Valles Marineris
Olympus Mons
Mars Pathfinder Landing Site
Sojourner Rover on Mars
Martian Moon Phobos
Happy Face Crater
Gullies on Mars
Sunset on Mars

MOONS

Mars has two small moons: Phobos and Deimos. Phobos (fear) and Deimos (terrified flight) are named for the mythological sons of Ares, the Greek counterpart of the Roman god, Mars. Scientists believe the oddly shaped moons, discovered in 1877, may be captured asteroids.