Mars

Early man thought that Mars was a distant, bloody battlefeild. The Greeks and Romans named it Aries and Mars for their respective Gods of war. Iron oxide (rust) in Mars' soil gives is a ruddy complexion.

At the end of the ninteenth century Giovanni Schiaparelli in Italy and Percival Lowell in the United States mapped what they thought to be 'canals' constructed by Martians to bring water from the ice caps to irrigate feilds. In the twentieth century many people still thought that a civilisation might exist on Mars.

Mars is similar to Earth in many ways. Although is has a much smaller diameter compared to Earth (6739 kilometers), Mars has polar ice caps very similar to Earth's. The Martian year is 687 Earth days, but a Martian day is 24.6 hours, is amazingly close to Earth's. Mars has an atmosphere consisting of more than 95% carbon dioxide, but oxygen and water vapour are known to be present, and the Martian equatorial zone can reach temperatures of 20 degrees C, although the average temperature on Mars is -63 degrees C. At the Viking 2 landing site, a thin layer of water frost covered the ground each winter.

In 1965 the Mariner 4 spacecraft transmitted 22 close-up pictures of the planet. The images taken depicted a barren and rocky world, not capable of sustaining life. There was, however, evidence that water did once flow there. The Martian south polar ice cap was found to be half frozen carbon dioxide (dry ice), but the north polar icecap was found to be almost entirely water.

One of Mars' distinguishing features is Mount Olympus. Mount Olympus is a dormant volcanoe 25 kilometers higher than Mount Everest. The 'canals' that Percival Lowell thought were manmade, actually turned out to be a giant fracture zone that was 4800 kilometers across the Martian equater. Now called Mariner valley, the fracture zone is 200 kilometers wide and four times deeper than the Grand Canyon.

In 1976 two American Viking spacecraft became the first craft to survive landing on mars. The Viking landers answered many questions about Mars, especially whether there was life on Mars. The answer was 'probably no'. The landers conducted a great deal of experiments to ascertain whether there was life on Mars, called the 'Gas Exchange Experiment'.

Mars has a mass of 6.421E23 and has a mean density of 3.94g/cm cubed. It orbits the Sun at a distance of 227,940,000 kilometers (1.5237AU)