M2K4 Roaming the Red Planet -Explore Mars
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Olympus Mons
The largest volcano in the solar system, Olympus Mons is about the same size
(in area) as the state of Arizona. Olympus Mons is a shield volcano nearly 375
miles in diameter and 16 miles high. A caldera, or volcanic collapse crater,
50 miles wide sits atop the summit. To compare, the largest similar volcano
on Earth is Mauna Loa, a shield volcano more than 6 miles high and 75 miles
across that makes up much of the island of Hawaii. About 100 Mauna Loas would
fit inside Olympus Mons. Its flanks slope up at only 6 degrees, so that if you
climbed it you would not realize you are walking uphill.
Tharsis Montes
The largest volcanic region ("center") on Mars, Tharsis Montes is
approximately 2,400 miles across, 6 miles high and contains 12 large shield
volcanoes. The summits of Tharsis Montes summits are about the same elevation
as the summit of Olympus Mons, the largest of the Tharsis volcanoes. While not
the largest of the Tharsis volcanoes, Arsia Mons has the largest caldera, or
volcanic collapse crater, on Mars, having a diameter of 75 miles. The main difference
between the volcanoes on Mars and Earth is their size and fresh appearance.
Volcanoes in the Tharsis region are up to 100 times larger than those anywhere
on Earth.
Alba Patera
This is a unique volcanic center on Mars, and it appears different from nearby Tharsis montes. Alba Patera is a 'patera', a flattened volcanic feature with a larger summit collapse crater. It is clearly associated with a region of Mars' crust that behaves differently than that found in the Tharsis area. Alba may be the last of a family of giant, flatter volcanoes that have been replaced by the larger shield volcanoes of Tharsis.
Tharsis Tholus
This Viking 1 Orbiter image shows Tharsis Tholus, a partially buried shield
volcano. The exposed portion measures approximately 100 miles in diameter. The
wide bench in the lower left of the caldera, or volcanic collapse crater, may
be the remnants of an ancient lava lake.
Valles Marineris
Valles Marineris, or Mariner Valley, is a vast canyon system that runs along the Martian equator just east of the Tharsis region. Valles Marineris is 2,500 miles long and reaches depths of up to 4 miles. For comparison, the Grand Canyon in Arizona is about 500 miles long and typically less than 1 mile deep. In fact, the extent of Valles Marineris is as long as the United States and it spans about 20 percent of the entire circumference of Mars. The canyon extends from the Noctis Labyrinthus region in the west to the chaotic terrain in the east. Most researchers currently think that Valles Marineris is a large "crack" or rift in the Martian crust that formed as the planet's crust and interior cooled , affected by the more buoyant crust in the Tharsis region to the west, and subsequently widened by erosion. However, near the eastern flanks of the rift there appear to be some channels that may have been formed by the flow of liquid water.
Cydonia Mensae
On July 25, 1976, the Viking 1 Orbiter photographed the northern plains of Mars as it searched for a suitable landing site for the Viking 2 lander. Some of those images were of an area called Cydonia, which included a landform that some people felt resembled a gigantic human face and others that some thought might be pyramids or other artificial constructions. Images taken by currently operating spacecraft clearly show these formations are natural terrain. (The rectangular outlines in the left of this image show areas targeted for photographs by NASA's Mars Global Surveyor.)
Elysium Planitia
Elysium Planitia is the second largest volcanic region on Mars. It is about 1,000 miles by 1,440 miles in area and is believed to represent an uplifted region at a smaller scale than Tharsis. The three large volcanoes, Hecates Tholus, Albor Tholus, and Elysium Mons, are smaller than those found in Tharsis but are still quite large by terrestrial standards.. Elysium Mons is the largest volcano in this region, measuring about 420 miles across and rising about 8 miles above the surrounding plains. Like most of the named volcanoes on Mars, it resembles the large shield volcanoes of Hawaii.
Gusev Crater
The Mars Exploration Rover Spirit will land at Gusev Crater, named after the 19th-century Russian astronomer Matvei Gusev. Gusev is 15 degrees south of Mars' equator, near the transition between the planet's ancient highlands to the south and smoother/lower plains to the north. A meandering valley enters Gusev from the southeast. Long ago, flowing water may have eroded the valley by cutting through the crater's rim and creating a lake inside. The lake is gone now, but the floor of Gusev Crater may contain water-laid sediments to reveal whether Mars had a warmer, wetter past -- perhaps suitable for life. Gusev is 100 miles across and was probably 4-5 miles deep when it formed billions of years ago, but is presently filled with a thick deposit of sediments.
Meridiani Planum
The Mars Exploration Rover Opportunity will land in an area known as Meridiani Planum, which is near the martian equator and halfway around the planet from Gusev. The name comes from its position near the planet's prime meridian, or line of zero longitude, and the word "planum," meaning plains. One of the smoothest, flattest places on Mars, Meridiani Planum is apprarently characterized by local surfaces rich in an iron oxide mineral called gray hematite. On Earth, gray hematite usually forms in a wet environment, or at least in association with liquid water.