I was flown in a spacecraft one night and the next day I landed on an entirely unfamiliar land. Little people, as they called themselves inhabited the region. Many of them were running around aimlessly like little children, while the others were busy working on miniature machines resembling computers. I was taken by surprise when one of them transformed into an orb-like blob of light and traversed a considerable distance within microseconds! I could not believe my ears when one of those unfamiliar little women came to me and said, "Are you an earthling? I welcome you to Mars." I soon learned that Martians had already begun to establish contact with the Earth; in fact, they were trying to communicate with the people on Earth, through those miniature machines! I was further amused when I saw a few of those little people singing for me a welcome song! They called it the 'Martian melody'. I looked around to suddenly find that my tour to Mars was just a dream! I woke up and began with my daily routine. But I still wonder... will my dream come true?
Mars, as most of us know, is the fourth planet from the Sun. It derives its name from Mars, the Roman God of war. Being reddish in color, it is also known as the 'Red Planet'. The geographical features of this planet, as also its rotational speed and seasonal cycles, are similar to those on Earth. Among all the planets of the solar system, Mars has the highest probability to harbor water. Research, to some extent, has revealed the presence of water ice at the poles and mid-latitudes of Mars.
Owing to its similarities with the geographical and geological features of the planet Earth, scientists have always speculated about the existence of life on Mars. One of the striking similarities between the features of these planets, is that the length of a day on Mars is same as that on Earth. Also, owing to the similarity between the axial tilts of Earth and Mars, both the planets experience the same seasons. William Whewell from Trinity College, Cambridge proposed that Mars had seas, land and perhaps harbored life. Telescopic observations of the supposed Martian channels in the 19th century strengthened the belief that life could prevail on Mars. However, the observations were later found to be mere optical illusions. Later, in 1894, William Campbell, an astronomer from the US proved that neither water nor oxygen were present in the atmosphere of Mars. By 1909, it was proved that the presence of canals on Mars was only a myth.
Later, in 1964, the spacecraft Mariner 4 performed a flyby on planet Mars and managed to capture images of the Martian surface. The photographs taken by Mariner 4 revealed the presence of craters on Mars as also the absence of a global magnetic field around the planet. The craters brought out the fact that the Martian surface lacked plate tectonics and weathering. The absence of any global magnetic field made it apparent that Mars had no protection against the harmful cosmic rays. Moreover, the value of the atmospheric pressure on Mars which was 0.6 kPa as calculated by Mariner 4, proved that liquid water could not exist on the Martian surface. However, the search for existence of life on Mars did not end here. It rather transformed into a search for bacteria-like living organisms.
Another noteworthy mission aimed at the exploration of Mars was the Viking program by NASA that consisted of two probes, Viking 1 and Viking 2 and was regarded as the most expensive and ambitious endeavors towards the discovery of life on the planet. Each of the space probes were equipped with an orbiter that was meant to photograph the Martian surface, and a lander designed to study the surface of the planet. The mission did not detect the presence of any kind of organic molecules.
Meteorites that have reached the Earth's surface have given evidences of the presence of single-celled life on Mars. Some of them have led scientists to speculate the presence of methane, formaldehyde, and silica in trace amounts. Some of NASA's recent experiments have concluded that hematite is found on Mars. Since hematite is a mineral that forms only in presence of water, researchers have suspected the presence of liquid water on Mars.
Despite several facts and speculations about the existence of life on Mars, there is no conclusive evidence supporting the proposition that it harbors life. Perhaps, the Martians, if at all they exist, will have to come on Earth to prove their existence. How I wish, they invite me to their planet, for that tour of my dreams!