Man-Made Satellites

The successful launching of a man-made satellite has an intrinsic excitement aside from its scientific meaning. Merely to place an object in the heavens — to create, in short, a new celestial body revolving about the earth like a small moon and obeying the laws of celestial mechanics—is an event without precedent.

The scientific significance of the satellite is several-fold. Until recent years, the important events and processes in the upper atmosphere have had to be observed indirectly. Life-giving and protective though it is, the earth’s atmosphere masks events high above us. Indirect observations, often involving ingenious ground-based instruments and balloons, and deduction have been the sources of our knowledge. Satellites will permit man to project his senses far beyond the earth.

The currently planned set of experiments suggests the nature of the results to be expected from satellites. These experiments include cosmic rays, ultraviolet radiation, meteors, the earth’s magnetic field in space, heat radiation balance, cloud cover, and electron density at satellite altitudes. Engineering studies of the satellite itself will also be carried by measuring such quantities as the temperature at various points and the erosion of the skin. In addition, radio and optical observations of the satellite from ground stations will permit the calculation of its orbit. Precise orbit determinations may yield information about the shape and structure of the earth itself — its oblateness, mass distribution in the crust, and the determination of positions of points on the surface of the earth.

The studies of heat radiation balance and cloud cover are basic to a better understanding of weather and climate. The first experiment contemplates a measure of total heat radiation to the earth and the total reradiation into outer space. Knowledge of this “heat budget” is essential to our fuller understanding of trends in weather and climate. Satellites also provide a means of observing cloud cover over the earth and following cloud formations. Information of this kind is invaluable for studying short-range weather trends and may permit accurate prediction of hurricanes and typhoons.