Learn about the missions to the planet Mars. Also learn about how the images of Mars helped scientists mapping out Mars.
Read the full transcript »
The Beginning of Missions to Mars Mars, known as the “Red Planet” and home to Olympus Mons, the largest known volcano in the solar system, its scarp and ever-changing surface has baffled astronomers for hundreds of years. Of all the planets in the solar system, Earth and Mars the third and fourth planets from the sun are the most similar. But despite the similarities, Mars is essentially like no other planet. It’s a unique world with two tiny irregularly shaped moons, Phobos and Deimos, caught in its gravitational pull. To early telescopes, Mars appeared to be a small, red sphere and later it was estimated to be about half the size of the Earth. One of the earliest known representations of the planet drawn in the 1659 indicated markings on the surface and by the movement of this dark patches across the disks, it was shown that Mars rotated on its axis in a period just slightly longer than Earth about 24 ½ hours. It is observed too that the tilt of its axis like the Earth’s exposes its polar regions alternately to the sunlight. Thus, its hemisphere has a summer and a winter period. And since Mars orbits the sun in 687 Earth day’s, one Martian year and each of its seasons is almost twice as long as our own. Lighter mappings of the planet displayed light and dark region identified incorrectly as continents and oceans. The land masses as red as the sandstone areas on Earth and the water a greenish blue. In 1877, Italian astronomer Giovanni Schiaparelli discovered what he called "canali" or canals resembling he said the finest threads of a spider’s web drawn across the disks. In America, Percival Lowell found on a observatory to study these Martian features. Massive irrigation systems he called them designed to carry water from the melting ice caps to the major centers of a dying civilization. Science fiction writers populated the city with terrible creatures of enormous size and skills beyond Earthmen’s dreams. In the 1960’s, three mariner spacecraft flew by Mars and photographed about 10% of the surface. Gone with the canals, gone with the cities and gone with the brilliant but sinister Martians. The photographs revealed a cratered landscape much like the moon, waterless and apparently hostile to life. But in 1971, the Mariner 9 spacecraft orbited Mars and transmitted more than 7000 photographs of the planet to Earth. The extensive mapping revealed a new and unexpected world. The southern hemisphere seen by early spacecraft was flattened and gauge by the impact of media rights while the northern hemisphere was a vast plain with few craters and rising format, a great dome called Tharsis topped by giant volcanoes. The plateau that joins the two hemispheres is cut by a vast and deep canyon and by channels with a characteristic pattern of streambeds on Earth. Some of the channels suggested that water may have once flowed on Mars and vast life might have evolved and possibly adapted to Mars changing conditions. And then in 1975, two Vikings spacecraft were launched. Each of which was programmed to land a robot on the Martian surface. One of its principal objectives was to test for the presence or absence of living organisms. A communication system linked the spacecraft to the mission controlling and computing center in Pasadena, California. On June 19, 1976, the first Viking arrived in the vicinity of Mars after a yearlong journey of more than 400 million miles. Once in orbit, its cameras began a detailed examination in order to locate a landing area. Imaging teams on Earth scan some 800 photographs covering a territory about the size of Texas. The chosen landing site was a flat expanse with a few impact craters, one of the lowest regions on the surface. On July 20, 1976, flight control has ordered to land and to separate from the orbit. Because of the great distance from Earth, the signal traveling at a speed of light 186,000 per second took 19 minutes to reach the spacecraft. This necessitated a completely automated onboard system f
Copyright © 2005 - 2014 Healthline Networks, Inc. All rights reserved for Healthline.