History of the Search of Life on Mars.
The belief that we are not alone in the universe is a long held belief and one that has fascinated humankind through the ages. It is not inconceivable to imagine that our earliest pre-historic ancestors living somewhere in the savannahs of Africa probably in modern day Kenya or Ethiopia peering up towards the heavens and musing that somewhere up there in the heavens yonder there existed a kind of being just like themselves.
In modern times, at least since the late 1870's when the famed Italian astronomer Giovanni Schiparelli peered at the heavens using his telescope and he reported seeing canali or channels on the red planet, mars, the red planet has thrown hints at us that maybe just maybe after all we are not alone in the universe. Some years later the American businessman Percival Lowell made similar observations via his telescope and he became utterly convinced that the canals were actually a creation of some alien civilization.
As a matter of fact in 1922 and 1924 the US government asked for complete radio silence, they asked radio stations to go quiet so that radio astronomers could listen in on radio communications/signals from the planet mars. This was due to the fact that the red planet was making two of its closet/nearest passage to our planet. Prior to that, Sci-Fi authors had thought of beaming images using gigantic mirrors to the planet mars in a bid to detect whether there is any life form there. Images returned from our nearest celestial neighbor in the 1960's showed a desolate world riddled with craters.
Further experiments were carried out by the Viking Landers in 1976 to search for chemical signs of life. In the summer of 1996 a team from NASA's Johnson Space Centre and Stanford University alerted the White House and announced that they had a chunk of rock from mars which had been blasted off the red planet by cataclysmic asteroid or meteor impacts some 17 million years ago and landed in Antarctica, contained microscopic fossils and other signs of life.
What seems to make the planet hospitable to life according to astrobiologists is the presence of liquid water billions of years ago. The planets canyons wind thousands of miles downhill to the planets Northern plains. They look like they were formed by running water; plenty of it at that, some look like they were created by water running with the force of 10,000 Mississippi Rivers in flood.
The mars orbiter camera sent back images which showed a 500 mile long channel named Nanedi Vallis its sinuous shape suggest it was created by groundwater. In that case liquid water may still be present underneath the Martian surface. Even though the planet today is too cold and the atmosphere too thin to keep water liquid at the surface (in such thin air water boils instantly). Liquid water is necessary, though not sufficient for life, that is according to geologist Michael Carr of the United States Geological survey.