Cosmic Connection by Carl Sagan Page A

a relatively fragile spacecraft, which was crushed by the weight of the Venus atmosphere far above the surface–much as a submarine, not designed for great depths, will be crushed at the ocean bottoms.
    At the 1968 Tokyo meeting of COSPAR, the Committee on Space Research of the International Council of Scientific Unions, I proposed that the Venera 4 spacecraft had ceased operating some fifteen miles above the surface. My colleague, Professor A. D. Kuzmin, of the Lebedev Physical Institute, in Moscow, argued that it had landed on the surface. When I noted that the radio and radar data did not put the surface at the altitude deduced for the Venera 4 touchdown, Dr. Kuzmin proposed that Venera 4 had landed atop a high mountain. I argued that ground-based radar studies of Venus had shown mountains a mile high, at most, and that it was exceptionally unlikely Venera 4 would land on the only fifteen-mile-high mountain on Venus, even if such a mountain were possible. Professor Kuzmin replied by asking me what I thought was the probability that the first German bomb to fall on Leningrad in World War II would kill the only elephant in the Leningrad zoo. I admitted that the chance was very small, indeed. He responded, triumphantly, with the information that such was indeed the fate of the Leningrad elephant.
    The designers of subsequent Soviet entry probes were, despite the Leningrad zoo, cautious enough to increase the structural strength of the spacecraft in each successive mission. Venera 7 was able to withstand pressures of 180 times that at the surface of the Earth, a quite adequate margin for the actual Venus surface conditions. It transmitted twenty minutes’ worth of data from the Venus surface before being fried. Venera 8, in 1972, transmitted more than twice as long. The surface pressure is not at twenty atmospheres, and the spectacular Mount Kuzmin does not exist.
    The principal conclusion about the scientific method that I draw from this history is this: While theory is useful in the design of experiments, only direct experiments will convince everyone. Based only on my indirect conclusions, there would today still be many people who did not believe in a hot Venus. As a result of the Venera observations, everyone acknowledges a Venus of crushing pressures, stifling heat, dim illumination, and strange optical effects.
    That our sister planet should be so different from Earth is a major scientific problem, and studies of Venus are of the greatest interest in understanding the earliest history of Earth. In addition, it helps to calibrate the reliability of astral projection and spirit travel of the sorts popularized by Emanuel Swedenborg, Annie Besant, and innumerable present-day imitators, none of whom caught a glimmering of the true nature of Venus.



13. Venus Is Hell
    T he planet Venus floats, serene and lovely, in the sky of Earth, a bright pinpoint of yellowish-white light. Seen or photographed through a telescope, a featureless disc is discerned; a vast unbroken and enigmatic cloud layer shields the surface from our view. No human eye has seen the ground of our nearest planetary neighbor.
    But we now know a great deal about Venus. From radio telescope and spacevehicle observations, we know that the surface temperature is about 900 degrees Fahrenheit. The atmospheric pressure at the surface of Venus is about ninety times that which we experience at the surface of the Earth. Since the planet’s gravity is about as strong as the Earth’s, there are about ninety times more molecules in the atmosphere of Venus as in the atmosphere of Earth. This dense atmosphere acts as a kind of insulating blanket, keeping the surface hot through the greenhouse effect and smoothing out temperature differences from place to place. The pole of Venus is probably not significantly colder than its equator, and on Venus it is as hot at midnight as at noon.
    Forty miles above the surface is the thick cloud layer that we see from Earth. At least