The Sentinel

by Arthur C. Clarke

  The Professor was standing with his back to us, staring morosely out of the window. Seemingly balanced on the horizon, the immense bulk of Jupiter nearly filled the sky.

  “We’ve got to convince her that we really do mean business,” he said. Then he turned abruptly to me.

  “Do you think she’s actually fond of this blackguard?”

  “Er—I shouldn’t be surprised. Yes, I really believe so.”

  The Professor looked very thoughtful. Then he said to Searle, “Come into my room. I want to talk something over.”

  They were gone quite a while. When they returned, they both had an indefinable air of gleeful anticipation, and the Professor was carrying a piece of paper covered with figures. He went to the radio, and called the “Henry Luce.”

  “Hello,” said Marianne, replying so promptly that she’d obviously been waiting for us. “Have you decided to call it off? I’m getting so bored.”

  The Professor looked at her gravely.

  “Miss Mitchell,” he replied. “It’s apparent that you have not been taking us seriously. I’m therefore arranging a somewhat—er—drastic little demonstration for your benefit. I’m going to place your employer in a position from which he’ll be only too anxious for you to retrieve him as quickly as possible.”

  “Indeed?” replied Marianne noncommittally—though I thought I could detect a trace of apprehension in her voice.

  “I don’t suppose,” continued the Professor smoothly, “that you know anything about celestial mechanics. No? Too bad, but your pilot will confirm everything I tell you. Won’t you, Hopkins?”

  “Go ahead,” came a painstakingly neutral voice from the background.

  “Then listen carefully, Miss Mitchell. I want to remind you of our curious—indeed our precarious—position on this satellite. You’ve only got to look out of the window to see how close to Jupiter we are, and I need hardly remind you that Jupiter has by far the most intense gravitational field of all the planets. You follow me?”

  “Yes,” replied Marianne, no longer quite so self-possessed. “Go on.”

  “Very well. This little world of ours goes round Jupiter in almost exactly twelve hours. Now there’s a well-known theorem stating that if a body falls from an orbit to the center of attraction, it will take point one seven seven of a period to make the drop. In other words, anything falling from here to Jupiter would reach the center of the planet in about two hours seven minutes. I’m sure Captain Hopkins can confirm this.”

  There was a long pause. Then we heard Hopkins say, “Well, of course I can’t confirm the exact figures, but they’re probably correct. It would be something like that, anyway.”

  “Good,” continued the Professor. “Now I’m sure you realize,” he went on with a hearty chuckle, “that a fall to the center of the planet is a very theoretical case. If anything really was dropped from here, it would reach the upper atmosphere of Jupiter in a considerably shorter time. I hope I’m not boring you?”

  “No,” said Marianne, rather faintly.

  “I’m so glad to hear it. Anyway, Captain Searle has worked out the actual time for me, and it’s one hour thirty-five minutes—with a few minutes either way. We can’t guarantee complete accuracy, ha, ha!

  “Now, it has doubtless not escaped your notice that this satellite of ours has an extremely weak gravitational field. It’s escape velocity is only about ten meters a second, and anything thrown away from it at that speed would never come back. Correct, Mr. Hopkins?”

  “Perfectly correct.”

  “Then, if I may come to the point, we propose to take Mr. Mays for a walk until he’s immediately under Jupiter, remove the reaction pistols from his suit, and—ah—launch him forth. We will be prepared to retrieve him with our ship as soon as you’ve handed over the property you’ve stolen. After what I’ve told you, I’m sure you’ll appreciate that time will be rather vital. An hour and thirty-five minutes is remarkably short, isn’t it?”

  “Professor!” I gasped, “You can’t possibly do this!”

  “Shut up!” he barked. “Well, Miss Mitchell, what about it?”

  Marianne was staring at him with mingled horror and disbelief.

  “You’re simply bluffing!” she cried. “I don’t believe you’d do anything of the kind! Your crew won’t let you!”

  The Professor sighed.

  “Too bad,” he said. “Captain Searle—Mr. Groves—will you take the prisoner and proceed as instructed.”

  “Aye-aye, sir,” replied Searle with great solemnity.

  Mays looked frightened but stubborn.

  “What are you going to do now?” he said, as his suit was handed back to him.

  Searle unholstered his reaction pistols. “Just climb in,” he said. “We’re going for a walk.”

  I realized then what the Professor hoped to do. The whole thing was a colossal bluff: of course he wouldn’t really have Mays thrown into Jupiter; and in any case Searle and Groves wouldn’t do it. Yet surely Marianne would see through the bluff, and then we’d be left looking mighty foolish.

  Mays couldn’t run away; without his reaction pistols he was quite helpless. Grasping his arms and towing him along like a captive balloon, his escorts set off toward the horizon—and towards Jupiter.

  I could see, looking across the space to the other ship, that Marianne was staring out through the observation windows at the departing trio. Professor Forster noticed it too.

  “I hope you’re convinced, Miss Mitchell, that my men aren’t carrying along an empty space-suit. Might I suggest that you follow the proceedings with a telescope? They’ll be over the horizon in a minute, but you’ll be able to see Mr. Mays when he starts to—er—ascend.”

  There was a stubborn silence from the loudspeaker. The period of suspense seemed to last for a very long time. Was Marianne waiting to see how far the Professor really would go?

  By this time I had got hold of a pair of binoculars and was sweeping the sky beyond the ridiculously close horizon. Suddenly I saw it—a tiny flare of light against the vast yellow back-cloth of Jupiter. I focused quickly, and could just make out the three figures rising into space. As I watched, they separated: two of them decelerated with their pistols and started to fall back toward Five. The other went on ascending helplessly toward the ominous bulk of Jupiter.

  I turned on the Professor in horror and disbelief.

  “They’ve really done it!” I cried. “I thought you were only bluffing!”

  “So did Miss Mitchell, I’ve no doubt,” said the Professor calmly, for the benefit of the listening microphone. “I hope I don’t need to impress upon you the urgency of the situation. As I’ve remarked once or twice before, the time of fall from our orbit to Jupiter’s surface is ninety-five minutes. But, of course, if one waited even half that time, it would be much too late . . . ”

  He let that sink in. There was no reply from the other ship.

  “And now,” he continued, “I’m going to switch off our receiver so we can’t have any more arguments. We’ll wait until you’ve unloaded that statue—and the other items Mr. Mays was careless enough to mention—before we’ll talk to you again. Goodbye.”

  It was a very uncomfortable ten minutes. I’d lost track of Mays, and was seriously wondering if we’d better overpower the Professor and go after him before we had a murder on our hands. But the people who could fly the ship were the ones who had actually carried out the crime. I didn’t know what to think.

  Then the airlock of the “Henry Luce” slowly opened. A couple of space-suited figures emerged, floating the cause of all the trouble between them.

  “Unconditional surrender,” murmured the Professor with a sigh of satisfaction. “Get it into our ship,” he called over the radio. “I’ll open up the airlock for you.”

  He seemed in no hurry at all. I kept looking anxiously at the clock; fifteen minutes had already gone by. Presently there was a clanking and banging in the airlock, the inner door opened, and Captain Hopkins entered. He w
as followed by Marianne, who only needed a bloodstained axe to make her look like Clytaemnestra. I did my best to avoid her eye, but the Professor seemed to be quite without shame. He walked into the airlock, checked that his property was back, and emerged rubbing his hands.

  “Well, that’s that,” he said cheerfully. “Now let’s sit down and have a drink to forget all this unpleasantness, shall we?”

  I pointed indignantly at the clock.

  “Have you gone crazy!” I yelled. “He’s already halfway to Jupiter!”

  Professor Forster looked at me disapprovingly.

  “Impatience,” he said, “is a common failing in the young. I see no cause at all for hasty action.”

  Marianne spoke for the first time; she now looked really scared.

  “But you promised,” she whispered.

  The Professor suddenly capitulated. He had had his little joke, and didn’t want to prolong the agony.

  “I can tell you at once, Miss Mitchell—and you too, Jack—that Mays is in no more danger than we are. We can go and collect him whenever we like.”

  “Do you mean that you lied to me?”

  “Certainly not. Everything I told you was perfectly true. You simply jumped to the wrong conclusions. When I said that a body would take ninety-five minutes to fall from here to Jupiter, I omitted—not, I must confess, accidentally—a rather important phrase. I should have added “a body at rest with respect to Jupiter.” Your friend Mr. Mays was sharing the orbital speed of this satellite, and he’s still got it. A little matter of twenty-six kilometers a second, Miss Mitchell.

  “Oh yes, we threw him completely off Five and toward Jupiter. But the velocity we gave him then was trivial. He’s still moving in practically the same orbit as before. The most he can do—I’ve got Captain Searle to work out the figures—is to drift about a hundred kilometers inward. And in one revolution—twelve hours—he’ll be right back where he started, without us bothering to do anything at all.”

  There was a long, long silence. Marianne’s face was a study in frustration, relief, and annoyance at having been fooled. Then she turned on Captain Hopkins.

  “You must have known all the time! Why didn’t you tell me?”

  Hopkins gave her a wounded expression.

  “You didn’t ask me,” he said.

  We hauled Mays down about an hour later. He was only twenty kilometers up, and we located him quickly enough by the flashing light on his suit. His radio had been disconnected, for a reason that hadn’t occurred to me. He was intelligent enough to realize that he was in no danger, and if his set had been working he could have called his ship and exposed our bluff. That is, if he wanted to. Personally, I think I’d have been glad enough to call the whole thing off even if I had known that I was perfectly safe. It must have been awfully lonely up there.

  To my great surprise, Mays wasn’t as mad as I’d expected. Perhaps he was too relieved to be back in our snug little cabin when we drifted up to him on the merest fizzle of rockets and yanked him in. Or perhaps he felt that he’d been worsted in fair fight and didn’t bear any grudge. I really think it was the latter.

  There isn’t much more to tell, except that we did play one other trick on him before we left Five. He had a good deal more fuel in his tanks than he really needed, now that his payload was substantially reduced. By keeping the excess ourselves, we were able to carry The Ambassador back to Ganymede after all. Oh, yes, the Professor gave him a check for the fuel we’d borrowed. Everything was perfectly legal.

  There’s one amusing sequel I must tell you, though. The day after the new gallery was opened at the British Museum I went along to see The Ambassador, partly to discover if his impact was still as great in these changed surroundings. (For the record, it wasn’t—though it’s still considerable and Bloomsbury will never be quite the same to me again.) A huge crowd was milling around the gallery, and there in the middle of it were Mays and Marianne.

  It ended up with us having a very pleasant lunch together in Holborn. I’ll say this about Mays—he doesn’t bear any grudges. But I’m still rather sore about Marianne.

  And, frankly, I can’t imagine what she sees in him.

  REFUGEE

  Doubtless to the great confusion of anthologists, this story has been published under three other titles: “Royal Prerogative,” “This Earth of Majesty” and “?”. (Now, how do you index that?)

  It was written in 1954, and I cannot pretend that no resemblance was intended to any living character. Indeed, I have since met the prototype of “Prince Henry” on three occasions, and on the last—here in Colombo, only a few months ago—we had a conversation uncannily appropriate to this story.

  Our first meeting, I mentioned, had been at an exhibition circa 1958 optimistically called “Britain Enters The Space Age.” His Royal Highness laughed and answered wryly: “We never did, did we?”

  Not quite true, of course, since there are many British satellites in orbit, and there will soon be a few Britons (courtesy the U.S. Space Shuttle) as well. But that isn’t exactly what I had in mind.

  Well, Sir Isaac Newton invented gravity. Perhaps one day we British may be lucky enough to disinvent it.

  “WHEN HE COMES ABOARD,” said Captain Saunders, as he waited for the landing ramp to extrude itself, “what the devil shall I call him?” There was a thoughtful silence while the navigation officer and the assistant pilot considered this problem in etiquette. Then Mitchell locked the main control panel, and the ship’s multitudinous mechanisms lapsed into unconsciousness as power was withdrawn from them.

  “The correct address,” he drawled slowly, “is ‘Your Royal Highness.’”

  “Huh!” snorted the captain. “I’ll be damned if I’ll call anyone that!”

  “In these progressive days,” put in Chambers helpfully, “I believe that ‘Sir’ is quite sufficient. But there’s no need to worry if your forget: it’s been a long time since anyone went to the Tower. Besides, this Henry isn’t as tough a proposition as the one who had all the wives.”

  “From all accounts,” added Mitchell, “he’s a very pleasant young man. Quite intelligent, too. He’s often been known to ask people technical questions that they couldn’t answer.”

  Captain Saunders ignored the implications of this remark, beyond resolving that if Prince Henry wanted to know how a Field Compensation Drive Generator worked, then Mitchell could do the explaining. He got gingerly to his feet—they’d been operating on half a gravity during flight, and now they were on Earth, he felt like a ton of bricks—and started to make his way along the corridors that led to the lower air lock. With an oily purring, the great curving door side-stepped out of his way. Adjusting his smile, he walked out to meet the television cameras and the heir to the British throne.

  The man who would, presumably, one day be Henry IX of England was still in his early twenties. He was slightly below average height, and had fine-drawn, regular features that really lived up to all the genealogical clichés. Captain Saunders, who came from Dallas and had no intention of being impressed by any prince, found himself unexpectedly moved by the wide, sad eyes. They were eyes that had seen too many receptions and parades, that had had to watch countless totally uninteresting things, that had never been allowed to stray far from the carefully planned official routes. Looking at that proud but weary face, Captain Saunders glimpsed for the first time the ultimate loneliness of royalty. All his dislike of that institution became suddenly trivial against its real defect: what was wrong with the Crown was the unfairness of inflicting such a burden on any human being . . .

  The passageways of the Centaurus were too narrow to allow for general sight-seeing, and it was soon clear that it suited Prince Henry very well to leave his entourage behind. Once they had begun moving through the ship, Saunders lost all his stiffness and reserve, and within a few minutes was treating the prince exactly like any other visitor. He did not realize that one of the earliest lessons royalty has to learn is that of putting people at their ease.


  “You know, Captain,” said the prince wistfully, “this is a big day for us. I’ve always hoped that one day it would be possible for spaceships to operate from England. But it still seems strange to have a port of our own here, after all these years. Tell me—did you ever have much to do with rockets?”

  “Well, I had some training on them, but they were already on the way out before I graduated. I was lucky: some older men had to go back to school and start all over again—or else abandon space completely if they couldn’t convert to the new ships.”

  “It made as much difference as that?”

  “Oh yes—when the rocket went, it was as big as the change from sail to steam. That’s an analogy you’ll often hear, by the way. There was a glamour about the old rockets, just as there was about the old windjammers, which these modern ships haven’t got. When the Centaurus takes off, she goes up as quietly as a balloon—and as slowly, if she wants to. But a rocket blast-off shook the ground for miles, and you’d be deaf for days if you were too near the launching apron. Still, you’ll know all that from the old news recordings.”

  The prince smiled.

  “Yes,” he said. “I’ve often run through them at the Palace. I think I’ve watched every incident in all the pioneering expeditions. I was sorry to see the end of the rockets, too. But we could never have had a spaceport here on Salisbury Plain—the vibration would have shaken down Stonehenge!”

  “Stonehenge?” queried Saunders as he held open a hatch and let the prince through into Hold Number 3.

  “Ancient monument—one of the most famous stone circles in the world. It’s really impressive, and about three thousand years old. See it if you can—it’s only ten miles from here.”

  Captain Saunders had some difficulty in suppressing a smile. What an odd country this was: where else, he wondered, would you find contrasts like this? It made him feel very young and raw when he remembered that back home Billy the Kid was ancient history, and there was hardly anything in the whole of Texas as much as five hundred years old. For the first time he began to realize what tradition meant: it gave Prince Henry something that he could never possess. Poise—self-confidence, yes, that was it. And a pride that was somehow free from arrogance because it took itself so much for granted that it never had to be asserted.