We and Space Exploration
It is difficult in a few short paragraphs to do justice to the drama, excitement, and intellectual achievements of the space program. We have all become somewhat blase about its accomplishments. But we should remember that only about 50 years have elapsed between the discovery of Pluto and Voyager 1 and 2's close-up views of jupiter and Saturn. It has been a little more than 20 years since the first Venus probes by the Soviet Union in 1961 and the United States in 1962 propelled astronomy into the realm of physical exploration of the planets. Spacecraft have now visited ailS naked-eye planets and one is on its way to the first of the "discovered" planets (Uranus). Also we have landed spacecraft on Mars and Venus and carried out experiments on their surfaces. We have brought back samples from the moon and could do so from Mars, asteroids, and comets. We have photographed and mapped the surface of Mars and with an orbiting radar system have mapped the surface of Venus through its veiling clouds. Although there are no immediate plans to do so, we could build and orbit about the earth a permanently man ned space station from which to explore the solar system.
But what were the reasons that propelled the United States into space exploration? Of course the pursuit of knowledge was one. Unfortunately, to many people knowledge for its own sake is not a sufficient rationale for the expenditu res that have been made in the space program. Basically, there are four dominant reasons2: knowledge, vision, applications, and national prestige.
The growth of knowledge concerning the solar system has been overwhelming, leading many observers of science to refer to the last 20 years of solar-system astronomy as its golden age. (The next three chapters will cover many of the new-in some cases startlingly new-findings.)
