This vast region, beginning at a height of approximately fifty kilometres and extending outwards 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 should like to pay a tribute to my precursors in this enterprise – the Americans Tuve and Breit, the Englishman Appleton, the Norwegian Stшrmer – and, especially, the man who, in 1970, won the very award I am now so honoured to accept, your countryman Hannes Alfvйn…

The ionosphere is the wayward child of the sun; even now, its behaviour 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 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 should not be here! In one sense, therefore, it was of vital importance even to pre-technological 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 ultra-violet 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, for 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 because all our rocket and satellite-borne instruments race through it at thousands of kilometres an hour; we have never been able to stand still to make observations! Now, for the very 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 it is no longer important to the communications engineer? Well, apart from its beauty, its strangeness and its scientific interest, its behaviour is closely linked with that of the sun – the master of our destiny. We know now that the sun is not the steady, well-behaved star that our ancestors believed; it undergoes both long and short-period fluctuations. At the present time it is still emerging from the so-called “Maunder Minimum” of 1645 to 1715; as a result, the climate now is milder than at any time since the Early Middle Ages. But how long will this upswing last? Even more important, when will the inevitable downturn begin, and what effect will this have upon climate, weather and every aspect of human civilization – not only on this planet, but on the others as well? For they are all children of the sun…

Some very speculative theories suggest that the sun is now entering a period of instability which may produce a new Ice Age, more universal than any in the past. If this is true, we need every scrap of information we can get to prepare for it. Even a century's warning might not be long enough.

The ionosphere helped to create us; it launched the communications revolution; it may yet determine much of our future. That is why we must continue the study of this vast, turbulent arena of solar and electric forces – this mysterious place of silent storms.

39. The Wounded Sun

The last time that Morgan had seen Dev, his nephew had been a child. Now he was a boy in his early teens; and at their next meeting, at this rate, he would be a man.

The engineer felt only a mild sense of guilt. Family ties had been weakening for the last two centuries: he and his sister had little in common except the accident of genetics. Though they exchanged greetings and small talk perhaps half-a-dozen times a year, and were on the best of terms, he was not even sure when and where they had last met.

Yet when he greeted the eager, intelligent boy (not in the least overawed, it seemed, by his famous uncle) Morgan was aware of a certain bitter-sweet wistfulness. He had no son to continue the family name; long ago, he had made that choice between Work and Life which can seldom be avoided at the highest levels of human endeavour. On three occasions – not including the liaison with Ingrid – he might have taken a different path; but accident or ambition had deflected him.

He knew the terms of the bargain he had made, and he accepted them; it was too late now to grumble about the small print. Any fool could shuffle genes, and most did. But whether or not History gave him credit, few men could have achieved what he had done – and was about to do.

In the last three hours, Dev had seen far more of Earth Terminus than any of the usual run of VIPs. He had entered the mountain at ground level, along the almost completed approach to the South Station, and had been given the quick tour of the passenger and baggage handling facilities, the control centre, and the switching yard where capsules would be routed from the East and West DOWN tracks to the North and South up ones. He had stared up the five-kilometre-long shaft – like a giant gun barrel aimed at the stars, as several hundred reporters had already remarked in hushed voices – along which the lines of traffic would rise and descend. And his questions had exhausted three guides before the last one had thankfully handed him over to his uncle.

“Here he is, Van,” said Warren Kingsley as they arrived via the high-speed elevator at the truncated summit of the mountain. “Take him away before he grabs my job.”

“I didn't know you were so keen on engineering, Dev.”

The boy looked hurt, and a little surprised. “Don't you remember, Uncle – that No 12 Meccamax you gave me on my tenth birthday?”

“Of course – of course. I was only joking.” (And, to tell the truth, he had not really forgotten the construction set; it had merely slipped his mind for the moment.) “You're not cold up here?” Unlike the well-protected adults, the boy had disdained the usual light thermocoat.

“No – I'm fine. What kind of jet is that? When are you going to open up the shaft? Can I touch the tapes?”

“See what I mean?” chuckled Kingsley.

“One: that's Sheik Abdullah's Special – his son Feisal is visiting. Two: we'll keep this lid on until the Tower reaches the mountain and enters the shaft – we need it as a working platform, and it keeps out the rain. Three: you can touch the tapes if you want to – don't run – it's bad for you at this altitude!”

“If you're twelve, I doubt it,” said Kingsley towards Dev's rapidly receding back. Taking their time, they caught up with him at the East Face anchor.

The boy was staring, as so many thousands of others had already done, at the narrow band of dull grey that rose straight out of the ground and soared vertically into the sky. Dev's gaze followed it up – up – up – until his head was tilted as far back as it would go. Morgan and Kingsley did not follow suit, though the temptation, after all these years, was still strong. Nor did they warn him that some visitors got so giddy that they collapsed and were unable to walk away without assistance.