Arthur Clarke - Earthlight

The unique feature of the lunar plants, however, was their ingenious mechanism for collecting air. An elaborate system of flaps and valves, not unlike that by which some sea creatures pump water through their bodies, acted as kind of compressor. The plants were patient; they would wait for years along the great crevasses which occasionally gush forth feeble clouds of carbon or sulphur dioxides from the Moon’s interior. Then the flaps would go frantically to work, and the strange plants would suck into their pores every molecule that drifted by, before the transient lunar mist dispersed into the hungry near-vacuum which was all the atmosphere remaining to the Moon.

Such was the strange world which was now home to some thousands of human beings. For all its harshness, they loved it and would not return to Earth, where life was easy and therefore offered little scope for enterprise or initiative. Indeed, the lunar colony, bound though it was to Earth by economic ties, had more in common with the planets of the Federation. On Mars, Venus, Mercury and the satellites of Jupiter and Saturn, men were fighting a frontier war against Nature, very like that which had won the Moon. Mars was already completely conquered; it was the only world outside Earth where a man could walk in the open without the use of artificial aids. On Venus, victory was in sight, and a land surface three times as great as Earth’s would be the prize. Elsewhere, only outposts existed: burning Mercury and the frozen outer worlds were a challenge for future centuries.

So Earth considered. But the Federation could not wait, and Professor Phillips, in complete innocence, had brought its impatience to the breaking point. It was not the first time that a scientific paper had changed the course of history, and it would not be the last.

Sadler had never seen the pages of mathematics that had caused all the trouble, but he knew the conclusions to which they led. He had been taught many things in the six months that had been abstracted from his life. Some he had learned in a small, bare classroom with six other men whose names he had never been told, but much knowledge had come to him in sleep or in the dreamy trance-state of hypnosis. One day, perhaps, it would be withdrawn from him by the same techniques. The face of the Moon, Sadler had been told, consists of two distinct kinds of terrain—the dark areas of the so-called Seas, and the bright regions which are usually higher in elevation and much more mountainous. It is the bright areas which are pitted with the countless lunar craters, and appear to have been torn and blasted by eons of volcanic fury. The Seas, by contrast, are flat and relatively smooth. They contain occasional craters and many pits and crevasses, but they are incomparably more irregular than the rugged highlands.

They were formed, it seems, much later than the mountains and crater chains of the Moon’s fiery youth. Somehow, long after the older formations had congealed, the crust melted again in a few areas to form the dark, smooth plains that are the Seas. They contain the wrecks of many older craters and mountains that have been melted down like wax, and their coasts are fringed with half-destroyed cliffs and ringed plains that barely escaped total obliteration.

The problem which had long engaged scientists, and which Professor Phillips had solved, was this: Why did the internal heat of the Moon break out only in the selected areas of the Seas, leaving the ancient highlands untouched?

A planet’s internal heat is produced by radioactivity. It seemed to Professor Phillips, therefore, that under the great Seas must be rich deposits of uranium and its associated elements. The ebb and flow of tides in the Moon’s molten interior had somehow produced these local concentrations, and the heat they had generated through millennia of radioactivity had melted the surface features far above them to form the Seas.

For two centuries, men had gone over the face of the Moon with every conceivable measuring instrument. They had set its interior trembling with artificial earthquakes; they had probed it with magnetic and electric fields. Thanks to these observations, Professor Phillips had been able to put his theory on a sound mathematical basis.

Vast lodes of uranium existed far below the Seas. Uranium itself was no longer of the vital importance that it had been in the twentieth and twenty-first centuries, for the old fission piles had long since given way to the hydrogen reactor. But where there was uranium, the heavy metals would be found as well.

Professor Phillips had been quite sure that his theory had no practical applications. All these great deposits, he had carefully pointed out, were at such depths that any form of mining would be totally out of the question. They were at least a hundred kilometers down—and the pressure in the rock at that depth was so great that the toughest metal would flow like a liquid, so that no shaft or bore-hole could stay open even for an instant.

It seemed a great pity. These tantalizing treasures, Professor Phillips had concluded, must remain forever beyond the reach of the men who needed them so badly.

A scientist, thought Sadler, should really have known better than that. One day Professor Phillips was going to have a big surprise.

Sadler lay in his bunk and tried to focus his mind on the past week. It was very hard to believe that he had arrived from Earth only eight of its days ago, but the calendar clock on the wall confirmed the notes he had made in his diary. And if he doubted both these witnesses, he had merely to go up to the surface and enter one of the observation domes. There he could look up at the unmoving Earth, now just past full and beginning to wane. When he had arrived on the Moon, it had been at its first quarter.

It was midnight over the Mare Imbrium. Dawn and sunset were both equally remote, but the lunar landscape was ablaze with light. Challenging the Earth itself was Nova Draconis, already brighter than any star in history. Even Sadler, who found most astronomical events too remote and impersonal to touch his emotions, would occasionally make the trip “upstairs” to look at this new invader of the modern skies. Was he looking at the funeral pyre of worlds older and wiser than the Earth ? It was strange that such an awe-inspiring event should take place at a moment of human crisis. It could only be coincidence, of course. N. Draconis was a close star, yet the signal of its death had been traveling for twenty centuries. One had to be not only superstitious but also very geocentric to imagine that this event had been planned as a warning for Earth. For what of all the other planets of other suns in whose skies the nova blazed with equal or even greater brilliance?

Sadler called home his wandering thoughts, and concentrated on his proper business. What had he left undone? He had visited every section of the Observatory, and met everyone of importance, with the single exception of the director. Professor Mac-laurin was due back from Earth in a day or so, and his absence had, if anything, simplified Sadler’s task. When the Boss returned, so everybody had warned him, life would not be quite so free and easy, and everything would have to be done through the Proper Channels. Sadler was used to that, but did not enjoy it any the better.

There was a discreet purr from the speaker in the wall over the bed. Sadler reached out one foot and kicked a switch with the toe of his sandal. He could do this the first time now, but faint scars on the wall were a still-visible memento of his apprenticeship.

“Yes,” he said. “Who’s that?”

“Transport Section here. I’m closing the list for tomorrow. There are still a couple of seats left—you want to come along?”