MARS STATS MARS STATISTICS
Mass (kg) . . . . . . . . 6.421e23 ATMOSPHERE
Carbon Dioxide . . . . . . . 95.3% Scientists think that long ago the Martian surface had running water. They infer this from features that look like stream-lined islands in river channels and the presence of canyons. Today, however, the atmosphere on Mars contains very little water and the conditions on Mars are far too dry for extensive water clouds to form, but even this little amount can condense, forming high, thin, wispy clouds. Early morning fog may collect in valleys and frost may form on the ground, but these rapidly disipate as the morning temperature rises. Since Mars is so cold, the water is in the form of ice crystals in the clouds, fog and frost. The Martian atmosphere is too thin for the carbon dioxide to hold in any infrared radiant energy and so it does not have any heating effect like the greenhouse effect on Earth. Mars is heated only by the incoming solar radiation. With the lack of Martian cloud cover there is nothing to prevent the little bit of incoming heat from escaping. There is no ozone layer in the upper atmosphere to block out ultra-violet rays. Storms on Mars are not water rain storms as they are on Earth. They are dust storms. These occur when the southern hemisphere on Mars is having summer. The dust particles in the clouds trap the infrared energy and keeps it from escaping back into space. The dust helps to make Mars' atmosphere a little warmer. POLAR ICE CAPSMars can get so cold that even the carbon dioxide gas freezes. This freezing occurs alternately at each pole, forming a large polar cap, made of mostly carbon dioxide ice. Some water ice also forms over the frozen carbon dioxide. Mars polar ice caps constantly change. During the long summer hemisphere summer most of the polar ice shrinks as it sublimates (changes from a solid to a gas) and refoms at the northern pole. The opposite change occurs during northern hemisphere summer. More ice accumlates at the northern polar cap because southern hemisphere summers are longer and hotter. OLYMPUS MONSOlympus Mons is the largest known volcano in the entire solar system! It is a shield volcano, similar to the Hawaiian volcanoes on Earth. Olympus Mons rises 24 km (about 15 miles) above the surrounding plains and stretches for 480 km (300 miles) across . High clouds of water ice frequently can be found around this huge volcano. The picture in the newspaper shows ripple patterns in the distant clouds. These were caused by wind flowing over some unseen obstacle. VIKING 2 SPACE CRAFT VIEWYou can see the dark reddish surface. The trenches were dug by the spacecraft to collect samples for chemical and biological experiments. SOILThe surface of Mars is covered with red rock and soil. This color is due to the oxidation (rusting) of iron in the rocks and soil. The overall red color or Mars is due to this oxidized iron. The pink color of the sky is caused by fine red dust that is suspended in the Martian atmosphere. SEASONSSeasons on Mars occur the same way they do on Earth. Mars' axis is tilted about 25 degrees. When the northern hemisphere is facing the sun it is summer in the north. This occurs when Mars is at its farthest from the sun in its orbit. Summer in the southern hemisphere occurs when Mars is at the closest to the sun in its orbit. This is called the perihelion. Mars is 128 million miles from the sun at this point. The orbit of Mars is very elliptical compared to Earth's , and is 36 million miles closer to the sun at perihelion than at its farthest point from the sun, at aphelion. By comparison, there is only a 4 million mile difference between perihelion and aphelion for Earth. When Mars is at perihelion, there is greater solar radiation and a greater temperature difference between the lower and upper arts of the atmosphere. This causes convection to occur. When rising and falling air currents are rotated winds can result, which create storms that often blanket the planet with dust. The dust absorbs sunlight, further warming the atmosphere. This results in two distinct summer seasons: a warm, dusty southern summer and a cold, dust-free northern summer. The orbit of Mars is not nearly circular as is Earth's. In fact, it is quite elliptical and the sun is not in the center of the ellipse. Information retrieved from the ill-fated Mars Observer Mission in l993 reveals that the eccentricity (lack of being circular) of Mars orbits results in seasons that are not of equal length. The distance from the sun (becuase of this ecentricity of orbit) as well as the tilt of the axis are factors in the seasons. The chart below shows the seasons and their lengths in earth days.
For more information on Mars' seasons, click here. CLIMATEIf you think the weather on Earth is unpredictable, try living on Mars. One week, the sky is pink and cloudless, filled with windblown dust raised from the rusty Martian surface. By Martian standards, it's warm, about minus 40 degrees Fahrenheit. Then, in a matter of days, the dust is swept from the atmosphere, temperatures plummet 40 degrees, and brilliant water ice cloudsappear against a dark blue sky. Dramatic weather changes like these may not seem very different from a batch of severe thunderstorms passing through your home town, but for Mars these changes can sweep over the entire planet every week. It appears that Mars' roller coaster-like weather is more chaotic and unpredictable than scientists first thought. Observations by the Hubble Space Telescope and the National Radio Astronomy Observatory (NRAO) radio telescope at Kitt Peak, Ariz., show that the atmosphere of Mars is more complex and variable than the picture revealed by the Viking and Mariner 9 orbiters. These spacecraft collected information from the planet in the 1970's and painted a fairly one-dimensional picture of Mars' climate. Images snapped by the orbiters revealed huge dust storms spreading throughout the entire atmosphere when Mars was closest to the sun (perihelion). These dusty conditions continued to dominate the planet's climate when it was farthest from the sun (aphelion). (Perihelion and aphelion occur every Mars year, which equals two Earth years. Aphelion occurs in northern summer, perihelion in southern summer.) But information captured by Hubble and NRAO show that Mars is more
often cloudy than dusty, experiencing abrupt planet-wide swings between
dusty and hot and cloudy and cold. A state of emergency would be declared
on Earth if an ice or dust storm blanketed the entire planet. Mars' elliptical orbit leads to planet-wide changes in atmospheric and surface temperatures over the course of a Mars year. During perihelion, when Mars is closest to the sun (summer in the southern hemisphere), the planet receives 40 percent more sunlight than during aphelion, when it is farthest from the sun (summer in the northern hemisphere). This annual variation in sunlight causes 35-degree Fahrenheit increases during southern summer (perihelion), forcing continental-scale dust storms at the planet's surface. The dust is swept aloft to altitudes of tens of miles, where it spreads globally, absorbs light from the sun, and heats the entire atmosphere by another 30 to 50 degrees Fahrenheit. This dusty perihelion climate was observed by Viking and Mariner 9 and by NRAO in 1992, 1994, and 1996. But what the 1970's orbiters did not identify was the very distinctive Mars aphelion climate, with its planet-wide belts of water ice clouds. These clouds are as striking as the perihelion global dust storms. During the aphelion climate, surface dust raised by low dust storms is confined to low altitudes (about 10 km or 6 miles), and is eventually swept to the ground by water ice clouds. These clouds surround the planet at altitudes of 3 to 10 km (2 to 6 miles). It is the cold atmospheric conditions of Mars during aphelion, when the sun is much weaker, that stimulate the formation of these water ice clouds. The clouds further reduce atmospheric temperatures by forming around the dust. Without sunlight, the dust freezes and falls to the ground. This strong competition between dust heating and cloud cooling drives sweeping annual and short-term regional changes in Mars' climate. (from the Hubble Telescope Site)
LIFETests of Martian soil, done by Vikings 1 and 2, showed no signs of living microorganisms. Scientists think that the dry soil and oxidizing nature of the soil prevents any formation of life. Though tests were inconclusive, generally scientists determined that the chances for life were negative. The lack of oxygen and water, high levels of ultra-violet radiation, dust storms in the southern hemisphere, and extreme temperatures make very poor conditions for life. Recently scientists studied a meteorite from Mars which contained microscopic features which may represent a primitive bacterial life form. Scientists think this meteorite may have come from an area of Mars where water is thought to have been present. Signs of Life in Merdiani Planum - What Might Opportunity See (or Miss)? Terrestrial Life in Extreme Environments
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