The Foundations of Paradise - Arthur C. Clarke [75]
V
Ascension
38
A Place of
Silent Storms
Extract from Professor Martin Sessui’s address, on receiving the Nobel Prize for Physics, Stockholm, 16 December 2154:
“Between heaven and Earth lies an invisible region of which the old philosophers never dreamed. Not until the dawn of the twentieth century—to be precise, on 12 December 1901—did it make its first impact upon human affairs.
“On that day, Guglielmo Marconi radioed the three dots of the Morse letter s across the Atlantic. Many experts had declared this to be impossible, because electromagnetic waves could travel only in straight lines, and would be unable to bend around the curve of the globe. Marconi’s feat not only heralded the age of world-wide communications, but also proved that, high up in the atmosphere, there exists an electrified mirror capable of reflecting radio waves back to earth.
“. . . The Kennelly-Heaviside layer, as it was originally named, was soon found to be a region of great complexity, containing at least three main layers, all subject to major variations in height and intensity. At their upper limit they merge into the Van Allen radiation belt, whose discovery was the first triumph of the early Space Age.
“This vast region, beginning at a height of approximately fifty kilometers and extending outward for several radii of the Earth, is now known as the ionosphere. Its exploration by rockets, satellites, and radio waves has been a continuing process for more than two centuries. I would like to pay a tribute to my precursors in this enterprise—the Americans M. A. Tuve and G. Breit, the Englishman E. V. Appleton, the Norwegian F. C. M. Størmer, and, especially, the man who, in 1970, won the very award I am now so honored to accept, your countryman Hannes Alfvén. . . .
“The ionosphere is the wayward child of the sun; even now, its behavior is not always predictable. In the days when long-range radio depended upon its idiosyncrasies, it saved many lives—but more men than we shall ever know of were doomed when it swallowed their despairing signals without trace.
“For less than one century, before the communications satellites took over, it was our invaluable but erratic servant—a previously unsuspected natural phenomenon, worth countless billions of dollars to the three generations who exploited it.
“Only for a brief moment in history was it of direct concern to mankind. And yet, if it had never existed, we would not be here! In one sense, therefore, it was of vital importance even to pretechnological humanity, right back to the first ape man—indeed, right back to the first living creatures on this planet. For the ionosphere is part of the shield that protects us from the sun’s deadly X-ray and ultraviolet radiations. If they had penetrated to sea level, perhaps some kind of life might still have arisen on earth; but it would never have evolved into anything remotely resembling us.
“. . . Because the ionosphere, like the atmosphere below it, is ultimately controlled by the sun, it, too, has its weather. During times of solar disturbance, it is blasted by planet-wide gales of charged particles, and twisted into loops and whirls by the Earth’s magnetic field. On such occasions, it is no longer invisible. It reveals itself in the glowing curtains of the aurora—one of Nature’s most awesome spectacles, illuminating the cold polar nights with its eerie radiance. . . .
“Even now, we do not understand all the processes occurring in the ionosphere. One reason why it has proved difficult to study is that all our rocket and satellite-borne instruments race through it at thousands of kilometers an hour. We have never been able to stand still to make observations. Now, for the first time, the construction of the proposed Orbital Tower gives us a chance of establishing fixed observatories in the ionosphere. It is also possible that the Tower may itself modify the characteristics of the ionosphere—though it will certainly not, as Dr. Bickerstaff has suggested, short-circuit it!
“Why should we study this region, now that