Arthur Clarke: Earthlight

“Some of mine, however, was unique. Not even a man in my own field would have guessed what it did. I suppose your people were looking for concealed radio transmitters, and that sort of thing?”

“Yes; we had monitors on the lookout, but they never spotted anything.”

Molton was obviously beginning to enjoy himself. Perhaps he too, thought Sadler, had been frustrated for the last thirty years, unable to say how he had fooled the security forces of Earth.

“The beauty of it was,” Molten continued, “my transmitter was in full sight all the time. In fact, it was about the most obvious thing in the Observatory. You see, it was the thousand-centimeter telescope.”

Sadler stared at him incredulously.

“I don’t understand you.”

“Consider,” said Molton, becoming once more the college professor he had been after leaving the Observatory, “exactly what it is a telescope does. It gathers light from a tiny portion of the sky, and brings it accurately to a focus on a photographic plate or the slit of a spectroscope. But don’t you see— A telescope can work both ways.”

“I’m beginning to follow.”

“My observing program involved using the thousand centimeter for studying faint stars. I worked in the far ultra-violet —which of course is quite invisible to the eye. I’d only to replace my usual instruments by an ultra-violet lamp, and the telescope immediately became a searchlight of immense power and accuracy, sending out a beam so narrow that it could only be detected in the exact portion of the sky I’d aimed it at. Interrupting the beam for signaling purposes was, of course, a trivial problem. I can’t send Morse, but I built an automatic modulator to do it for me.”

Sadler slowly absorbed this revelation. Once explained, the idea was ridiculously simple. Yes, any telescope, now he came to think of it, must be capable of working both ways—of gathering light from the stars, or of sending an almost perfectly parallel beam back at them, if one shone a light into the eyepiece end. Molton had turned the thousand-centimeter reflector into the largest electric torch ever built.

“Where did you aim your signals?” he asked.

“The Federation had a small ship about ten million kilometers out. Even at that distance, my beam was still pretty narrow and it needed good navigation to keep in it. The arrangement was that the ship would always keep dead in line between me and a faint northern star that was always visible above my horizon. When I wanted to send a signal—they knew when I would be operating, of course—I merely had to feed the co-ordinates into the telescope, and I’d be sure that they’d receive me. They had a small telescope aboard, with an ultra-violet detector. They kept in contact with Mars by ordinary radio. I often thought it must have been very dull out there, just listening for me. Sometimes I didn’t send anything for days.”

“That’s another point,” Sadler remarked. “How did the information get to you, anyway?”

“Oh, there were two methods. We got copies of all the astronomical journals, of course. There were agreed pages in certain journals— The Observatory, I recall, was one of them— that I kept my eye on. Some of the letters were fluorescent under far ultra-violet. No one could have spotted it; ordinary u.v. was no use.”

“And the other method?”

“I used to go to the gym in Central City every weekend. You leave your clothes in locked cubicles when you undress, but there’s enough clearance at the top of the doors for anything to be slipped in. Sometimes I used to find an ordinary tabulating-machine card on top of my things, with a set of holes punched in it. Perfectly commonplace and innocent, of course—you’ll find them all over the Observatory, and not only in the Computing section. I always made a point of having a few genuine ones in my pockets. When I got back, I’d decipher the card and send the message out on my next transmission. I never knew what I was sending—it was always in code. And I never discovered who dropped the cards in my locker.”

Molton paused, and looked quizzically at Sadler.

“On the whole,” he concluded, “I really don’t think you had much chance. My only danger was that you might catch my contacts and find they were passing information to me. Even if that happened, I thought I could get away with it. Every piece of apparatus I used had some perfectly genuine astronomical function. Even the modulator was part of an unsuccessful spectrum analyzer I’d never bothered to dismantle. And my transmissions only lasted for a few minutes; I could send a lot in that time, and then get on with my regular program.”

Sadler looked at the old astronomer with undisguised admiration. He was beginning to feel a good deal better: an ancient inferiority complex had been exorcised. There was no need for self-reproach; he doubted if anyone could have detected Molton’s activities, while they were confined to the Observatory end alone. The people to blame were the counter-agents in Central City and Project Thor, who should have stopped the leak further up the line.

There was still one question that Sadler wished to ask, but could not bring himself to do so; it was, after all, no real concern of his. How was no longer a mystery; why still remained.

He could think of many answers. His studies of the past had shown him that a man like Molton would not become a spy for money, or power, or any such trivial reason. Some emotional impulse must have driven him on the path he followed, and he would have acted from a profound inner conviction that what he did was right. Logic might have told him that the Federation should be supported against Earth, but in a case like this, logic was never enough.

Here was one secret that would remain with Molton. Perhaps he was aware of Sadler’s thoughts, for abruptly he walked over to the wide bookcase and slid aside a section of the paneling.

“I came across a quotation once,” he said, “that’s been a considerable comfort to me. I’m not sure whether it was sup posed to be cynical or not, but there’s a great deal of truth in it. It was made, I believe, by a French statesman named Talleyrand, about four hundred years ago. And he said this: ‘What is treason? Merely a matter of dates.’ You might care to think that over, Mr. Sadler.”

He walked back from the bookcase, carrying two glasses and a large decanter.

“A hobby of mine,” he informed Sadler. “The last vintage from Hesperus. The French make fun of it, but I’d match it against anything from Earth.”

They touched glasses.

“To peace among the planets,” said Professor Molton, “and may no men ever again have to play the parts we did.”

Against a landscape four hundred thousand kilometers away in space and two centuries ago in time, spy and counterspy drank the toast together. Each was full of memories, but those memories held no bitterness now. There was nothing more to say: for both of them, the story was ended.

Molton took Sadler down the corridor, past the quiet fountains, and saw him safely on the rolling floor that led to the main concourse. As he walked back to the house, lingering by the fragrant little garden, he was almost bowled over by a troop of laughing children racing across to the playground in Sector Nine. The corridor echoed briefly with their shrill voices; then they were gone like a sudden gust of wind.

Professor Molton smiled as he watched them racing toward their bright, untroubled future—the future he had helped to make. He had many consolations, and that was the greatest of them. Never again, as far ahead as imagination could roam, would the human race be divided against itself. For above him beyond the roof of Central City, the inexhaustible wealth of the Moon was flowing outward across space, to all the planets Man now called his own.