National Geographic : 1957 Dec
The National Geographic Magazine things we now only dream of, such as pre dicting the weather accurately, perhaps even controlling it. And since new basic knowledge gleaned through satellites will range literally from the inside of the earth to the sun and beyond, we can expect to be led to achieve ments we cannot even dream of now, any more than the telephone was dreamed of be fore the use of electricity. To enlarge on this outline with more specific answers is the purpose of this article, but first let me project a picture of a typical IGY satellite at work. Dust from Space in Deep-sea Sludge Scientists eagerly await the recording of the satellite's signals on magnetic tape. The tape, in turn, can produce jagged patterns on a cathode-ray oscilloscope-similar to a TV pic ture tube-or on 35-mm film. The film moves five feet a second and re cords patterns that can reveal as many as 48 categories of information. Some of this in formation concerns the operation of a satellite itself, say the changing strength of its bat teries. But the rest reveals things scientists have long wanted to know. For example, how dense is the meteoric dust in the upper atmosphere? These bits of stone and metal have been estimated to float to the earth at the rate of a thousand tons a day; they can be identified as part of the sludge at the bottom of the oceans. Whenever a meteoric particle hits the satel lite, a microphone notifies its transmitter; a radioed response then shows up in the pattern on the film. That microphone will record particles so small that if one flew into your eye you would hardly notice it. Not only will we know the number of par ticles hitting the satellite during its circuit of the earth; one of the jagged lines on the film will enable us to time their impacts within one ten-thousandth of a second. The more recording stations we have, the better we'll be able to pinpoint areas where the count of particles drops or rises significantly. And so we will learn to what degree the tiny meteors come in showers or spread out more or less evenly in space. These clues will interest not only the astronomer; they may at last yield evidence for the meteorologist, who would like to know whether meteor showers in the upper atmosphere affect rainfall. By now we know a lot about our earth's surface, but a lot of what we know is not quite accurate. We have only a rough idea of the shape of the earth, for instance: it's like a ball flattened at top and bottom, but there is a bulge around the middle, and the entire curva ture is somewhat irregular. This bedevils the geodesist. He can map a country and even a continent with consid erable accuracy, by building up a network of triangles through painstaking surveying, and then orienting the entire network on a single marker known as the geodetic datum point. For France this point is in the Pantheon in Paris, and for the U. S., Mexico, and Canada it's in a meadow near Lucas, Kansas. This triangulation technique, however, can not be applied over water, and therefore can not link continents to one another. Nor can it yield precise positions for islands in the ocean, relative to continents or to one an other. Thus intercontinental distances now are believed to err by as much as 2,000 feet and, some scientists say, even more. The posi tions of some Pacific islands are in error as much as a mile, and that can cause trouble. Travel across the Pacific, for example, de pends heavily on the U. S. Coast Guard's elec tronic loran system, which helps ships and planes locate themselves on their charts. But loran itself depends on maps, and if its base stations are off a mile, the guiding patterns they send may be off five miles. This can mean the difference between life and death in rescue operations. A satellite can help us do away with these errors by giving us a reference point in the sky. Telescope-cameras to Track Spheres First we must compute the satellite's orbit, with the help of ingenious antennas and radio receivers which will record its signals. Then observing stations around the world, equipped with powerful telescope-cameras, will refine the orbit calculations; their photographs, pre cisely timed and linked with the radio data, will reveal the satellite's elliptical path around the earth. From that we will calculate the location of the earth's center. From then on, radio signals from the satel lite, together with the orbit calculations, will let us locate the positions of the antennas precisely. The U. S. Army Map Service, which is sending teams to Kwajalein, Luzon, Wake, Guam, and American Samoa, hopes to establish reference points on these islands accurate within 100 feet in respect to each other and to the center of the earth.