Mars Essay, Research Paper
I. INTRODUCTION Mars, fourth planet from the sun and sixth largest planet, revolves in an orbit lying between those of Earth, the third, and Jupiter, the fifth planet. It named for the Roman god of war. Mars has two small moons, Phobos and Deimos. Their diameters are so small that measurements of their angular diameters is entirely beyond the reach of present- day giants telescopes. The closer satellite, Phodos, approximately 10 miles in diameter, is unique in he entire solar system in that rotates around its planet Mars about three times each day, and rises in the West. Deimos revolves around Mars in 30 hours and 18 minutes. Its diameter is believed to be about half that of Phodos, or about 5 miles. (Knopf,140)II. Appearance from Earth Viewed without a telescope Mars is reddish and varies in brightness. When closest to Earth, Mars is the second-brightest planet in the night sky, after Venus. A telescope shows Mars to have bright orange regions and darker, less red areas. The reddish color results from its rusted surface. The brighter areas seem to contain more dust-sized particles than do the dark regions. Yellow dust clouds are often extensive.Bright caps mark the planet’s Polar Regions. Each autumn, clouds form over the cooling pole. Carbon Dioxide frost is deposited during autumn and winter. By late winter, the cap may extend down to latitudes of 45.. In spring the clouds scatter, and the cap recedes poleward as sunlight evaporates the frost. Some frost and ice, believed to be mostly frozen water, lasts through the summer.III. Atmosphere The Martian atmosphere consists of carbon dioxide (95 percent), nitrogen (2.7 percent), argon (1.6 percent), oxygen (0.2 percent), and trace amounts of other gases. Because the atmosphere is thin, daily temperature variations of 100. C (180. F) are common. Average temperatures do not exceed 240 K (-27. F). (Glasstone,80)The amount of water vapor present in the atmosphere is slight. Mars is like a very cold, high-altitude desert. Temperatures are mostly too cold and pressures too low for liquid water, but liquid water may exist just below the surface in a few places.IV. Surface and Interior The southern half of the Martian surface is cratered terrain dating from earliest times, when Mars and the other planets were subjected to intense meteoroidal bombardment. The northern half is younger terrain, believed to be ancient volcanic flows. Some of the largest volcanoes in the solar system are on Mars. Olympus Mons is more than 25 km (15.5 mi.) high and more than 600 km (370 mi.) across its base (Glasstone,101). Evidence of plane tectonics seems lacking, and Mars may have a thicker crust and a cooler history than Earth.The most spectacular geologic features on Mars are channels resembling the valleys of dried-up rivers. Two major types are known. Large outflow channels may have been formed by the sudden release of vast amounts of liquid water. The cause remains uncertain, but these features probably date from the planet’s first billion years or so. Numerous small features show less compelling but possible evidence for erosion by liquid water.The low average density of Mars indicates that it cannot have an extensive metallic core. Any core that may be present is probably not fluid, because Mars does not have a measurable magnetic field. The crust of Mars may be as thick as 200 km (125 mi.) Five or six times as thick as earth’s crust.
V. The Search for Life In 1877 Italian astronomer Giovanni Schiaparelli claimed to have seen a planetwide system of channels on Mars. American astronomer Percival Lowell maintained that these were canals built by intelligent beings to irrigate a dry planet. Spacecraft observations have shown that there are no canals on Mars. The strongest evidence against the presence of life is the thin atmosphere and the fact that the surface of the planet is exposed not only to lethal doses of utralviolent but also too highly reactive substances (such as hydrogen peroxide) produced by photochemistry. The Viking landers of 1976 found no organic material in the soil. In 1996, however, scientists announced the discovery of possible evidence of primitive life on Mars inside a meteorite that collided with Earth about 13,000 years ago. Organic compounds and minerals composing the meteorite suggest that microbial life may have existed on Mars more than three billion years ago. In 1997 the Mars Pathfinder spacecraft landed on the planet. The mission produced large volumes of data, including more than 16,000 pictures, and allowed scientists to further analyze Martian soil, rocks, and weather. VI. THE POSSIBILITE OF LIFE ON MARS The newly developing subject of exobiology is largely concerned with the study of various aspects of the existence, characteristics, and evolution of life on bodies other than Earth. The problem of immediate interest is, of course related to the occurrence of life on Mars. So, What are the prospects of finding living organisms on Mars? (Glasstone, 209). There are several conceivable situations in connection with life on Mars. One extreme in the possibility that there never has been and never will be any indigeneous life forms, whereas the other extreme is that advanced and complex organisms now exist on the planet. The truth may well lie somewhere between. Life may have developed in the past in more favorable circumstances but may have become extinct as a result of changes in the environment. On the other hand, more complex forms of life may have died out, leaving simpler organisms that have become adapted to the present Martian conditions. There is now no life on Mars, regardless of whether or not it has existed in the past, it is possible that life can develop in the future. In view of the physical characteristics of the planet, this would not appear to be probable although it is by no-means possible. Even if indigenous life forms could not arise, there are reasons for believing that some terrestrial organisms would probably survive if introduced on Mars. This raise a highly interesting question: Could man live on Mars? Any attempts to supply an answer are highly speculative at present .(Glasstone, 211). I think, right now it is really difficult for humans to live on Mars, but it is not impossible. In the future we will be able to know all the deep secrets of Mars. It will not be hard to design the first community of humans in a different planet