Changes in the frequency, phase, and amplitude of the Mariner IV radio signal, caused by passage through the atmosphere and ionosphere of Mars, were observed immediately before and after occultation by the planet. Preliminary analysis of these effects has yielded estimates of the refractivity and density of the atmosphere near the surface, the scale height in the atmosphere, and the electron density profile of the Martian ionosphere. The atmospheric density, temperature, and scale height are lower than previously predicted, as are the maximum density, temperature, scale height, and altitude of the ionosphere.
The question of the existence of intelligent life elsewhere in space has long fascinated people, but, until recently, has been properly left to the science-fiction writers. This is simply because our technology has not been capable of detecting any reasonable manifestation that might be expected from other civilized communities in space. Lately, however, astrophysical knowledge of the universe and our technology have advanced to a stage where these questions can no longer be ignored by scientists. I would like to describe briefly the astronomical picture connected with the development of life, and to follow this with some anthropomorphic arguments which help us in our search for other abodes of life. Finally, there will be given a brief description of some instruments that one might apply to this problem.
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