The Sentinel Page 14

  Once we had passed that crisis, it was only a matter of time before we found the pyramid and forced it open. Now its signals have ceased, and those whose duty it is will be turning their minds upon Earth. Perhaps they wish to help our infant civilization. But they must be very, very old, and the old are often insanely jealous of the young.

  I can never look now at the Milky Way without wondering from which of those banked clouds of stars the emissaries are coming. If you will pardon so commonplace a simile, we have set off the fire-alarm and have nothing to do but to wait.

  I do not think we will have to wait for long.

  JUPITER V

  “Jupiter V,” written in June 1951, belongs to that typical and often despised category of science fiction, the “gimmick” story, in which some little-known fact or natural law forms an essential part of the plot. The genre may well have originated (like much else) with Edgar Allan Poe; his “A Descent into the Maelstrom” is a classic example.

  As I wrote on its first appearance in volume form (Reach for Tomorrow, 1956): “I am by no means sure that I could write ‘Jupiter V’ today; it involved twenty or thirty pages of orbital calculations and should by rights be dedicated to Professor G. C. McVittie, my erstwhile tutor in applied mathematics.” Twenty-seven years later I’m completely sure on this point.

  But during those years something has happened that, when I wrote the story, I would have dismissed as completely incredible. The photographer covering the satellites of Jupiter for a 2044 issue of Life Magazine (presumably a holographic, satellite-delivered edition) was sixty-five years too late. The Voyager spacecraft had already done the job, back in 1979 . . .

  Or at least the first part of it, for we will never finish unravelling the complexities of the mini-solar-system formed by Jupiter and his moons. And dated though this story has been by the astonishing speed of space exploration (it was written, please remember, when Sputnik I was still six years in the futurel), it may yet contain some elements of truth.

  Those fuzzy, long-range shots of little Jupiter V (now officially christened Amalthea) look very, very odd indeed . . .

  PROFESSOR FORSTER IS SUCH A SMALL MAN that a special space-suit had to be made for him. But what he lacked in physical size he more than made up—as in so often the case—in sheer drive and determination. When I met him, he’d spent twenty years pursuing a dream. What is more to the point, he had persuaded a whole succession of hard-headed business men, World Council Delegates and administrators of scientific trusts to underwrite his expenses and to fit out a ship for him. Despite everything that happened later, I still think that was his most remarkable achievement. . . .

  The “Arnold Toynbee” had a crew of six aboard when we left Earth. Besides the Professor and Charles Ashton, his chief assistant, there was the usual pilot—navigator—engineer triumvirate and two graduate students—Bill Hawkins and myself. Neither of us had ever gone into space before, and we were still so excited over the whole thing that we didn’t care in the least whether we got back to Earth before the next term started. We had a strong suspicion that our tutor had very similar views. The reference he had produced for us was a masterpiece of ambiguity, but as the number of people who could even begin to read Martian script could be counted, if I may coin a phrase, on the fingers of one hand, we’d got the job.

  As we were going to Jupiter, and not to Mars, the purpose of this particular qualification seemed a little obscure, though knowing something about the Professor’s theories we had some pretty shrewd suspicions. They were partly confirmed when we were ten days out from Earth.

  The Professor looked at us very thoughtfully when we answered his summons. Even under zero g he always managed to preserve his dignity, while the best we could do was to cling to the nearest handhold and float around like drifting seaweed. I got the impression—though I may of course be wrong—that he was thinking: What have I done to deserve this? as he looked from Bill to me and back again. Then he gave a sort of “It’s too late to do anything about it now” sigh and began to speak in that slow, patient way he always does when he has something to explain. At least, he always uses it when he’s speaking to us, but it’s just occurred to me—oh, never mind.

  “Since we left Earth,” he said, “I’ve not had much chance of telling you the purpose of this expedition. Perhaps you’ve guessed it already.”

  “I think I have,” said Bill.

  “Well, go on,” replied the Professor, a peculiar gleam in his eye. I did my best to stop Bill, but have you ever tried to kick anyone when you’re in free fall?

  “You want to find some proof—I mean, some more proof—of your diffusion theory of extraterrestrial culture.”

  “And have you any idea why I’m going to Jupiter to look for it?”

  “Well, not exactly. I suppose you hope to find something on one of the moons.”

  “Brilliant, Bill, brilliant. There are fifteen known satellites, and their total area is about half that of Earth. Where would you start looking if you had a couple of weeks to spare? I’d rather like to know.”

  Bill glanced doubtfully at the Professor, as if he almost suspected him of sarcasm.

  “I don’t know much about astronomy,” he said. “But there are four big moons, aren’t there? I’d start on those.”

  “For your information, Io, Europa, Ganymede and Callisto are each about as big as Africa. Would you work through them in alphabetical order?”

  “No,” Bill replied promptly. “I’d start on the one nearest Jupiter and go outward.”

  “I don’t think we’ll waste any more time pursuing your logical processes,” sighed the Professor. He was obviously impatient to begin his set speech. “Anyway, you’re quite wrong. We’re not going to the big moons at all. They’ve been photographically surveyed from space and large areas have been explored on the surface. They’ve got nothing of archaeological interest. We’re going to a place that’s never been visited before.”

  “Not to Jupiter!” I gasped.

  “Heavens no, nothing as drastic as that! But we’re going nearer to him than anyone else has ever been.”

  He paused thoughtfully.

  “It’s a curious thing, you know—or you probably don’t—that it’s nearly as difficult to travel between Jupiter’s satellites as it is to go between the planets, although the distances are so much smaller. This is because Jupiter’s got such a terrific gravitational field and his moons are traveling so quickly. The innermost moon’s moving almost as fast as Earth, and the journey to it from Ganymede costs almost as much fuel as the trip from Earth to Venus, even though it takes only a day and a half.

  “And it’s that journey which we’re going to make. No one’s ever done it before because nobody could think of any good reason for the expense. Jupiter Five is only thirty kilometers in diameter, so it couldn’t possibly be of much interest. Even some of the outer satellites, which are far easier to reach, haven’t been visited because it hardly seemed worth while to waste the rocket fuel.”

  “Then why are we going to waste it?” I asked impatiently. The whole thing sounded like a complete wild-goose chase, though as long as it proved interesting, and involved no actual danger, I didn’t greatly mind.

  Perhaps I ought to confess—though I’m tempted to say nothing, as a good many others have done—that at this time I didn’t believe a word of Professor Forster’s theories. Of course I realized that he was a very brilliant man in his field, but I did draw the line at some of his more fantastic ideas. After all, the evidence was so slight and the conclusions so revolutionary that one could hardly help being skeptical.

  Perhaps you can still remember the astonishment when the first Martian expedition found the remains not of one ancient civilization, but of two. Both had been highly advanced, but both had perished more than five million years ago. The reason was unknown (and still is). It did not seem to be warfare, as the two cultures appear to have lived amicably together. One of the races had been insect-like, the other vaguely rept
ilian. The insects seem to have been the genuine, original Martians. The reptile-people—usually referred to as “Culture X”—had arrived on the scene later.

  So, at least, Professor Forster maintained. They had certainly possessed the secret of space travel, because the ruins of their peculiar cruciform cities had been found on—of all places—Mercury. Forster believed that they had tried to colonize all the smaller planets—Earth and Venus having been ruled out because of their excessive gravity. It was a source of some disappointment to the Professor that no traces of Culture X had ever been found on the Moon, though he was certain that such a discovery was only a matter of time.

  The “conventional” theory of Culture X was that it had originally come from one of the smaller planets or satellites, had made peaceful contact with the Martians—the only other intelligent race in the known history of the System—and had died out at the same time as the Martian civilization. But Professor Forster had more ambitious ideas: he was convinced that Culture X had entered the Solar System from interstellar space. The fact that no one else believed this annoyed him, though not very much, for he is one of those people who are happy only when in a minority.

  From where I was sitting, I could see Jupiter through the cabin porthole as Professor Forster unfolded his plan. It was a beautiful sight: I could just make out the equatorial could belts, and three of the satellites were visible as little stars close to the planet. I wondered which was Ganymede, our first port of call.

  “If Jack will condescend to pay attention,” the Professor continued, “I’ll tell you why we’re going such a long way from home. You know that last year I spent a good deal of time poking among the ruins in the twilight belt of Mercury. Perhaps you read the paper I gave on the subject at the London School of Economics. You may even have been there—I do remember a disturbance at the back of the hall.

  “What I didn’t tell anyone then was that while I was on Mercury I discovered an important clue to the origin of Culture X. I’ve kept quiet about it, although I’ve been sorely tempted when fools like Dr. Haughton have tried to be funny at my expense. But I wasn’t going to risk letting someone else get here before I could organize this expedition.

  “One of the things I found on Mercury was a rather well preserved bas-relief of the Solar System. It’s not the first that’s been discovered—as you know, astronomical motifs are common in true Martian and Culture X art. But there were certain peculiar symbols against various planets, including Mars and Mercury. I think the pattern had some historic significance, and the most curious thing about it is that little Jupiter Five—one of the least important of all the satellites—seemed to have the most attention drawn to it. I’m convinced that there’s something on Five which is the key to the whole problem of Culture X, and I’m going there to discover what it is.”

  As far as I can remember now, neither Bill nor I was particularly impressed by the Professor’s story. Maybe the people of Culture X had left some artifacts on Five for obscure reasons of their own. It would be interesting to unearth them, but hardly likely that they would be as important as the Professor thought. I guess he was rather disappointed at our lack of enthusiasm. If so it was his fault since, as we discovered later, he was still holding out on us.

  We landed on Ganymede, the largest moon, about a week later. Ganymede is the only one of the satellites with a permanent base on it; there’s an observatory and a geophysical station with a staff of about fifty scientists. They were rather glad to see visitors, but we didn’t stay long as the Professor was anxious to refuel and set off again. The fact that we were heading for Five naturally aroused a good deal of interest, but the Professor wouldn’t talk and we couldn’t; he kept too close an eye on us.

  Ganymede, by the way, is quite an interesting place and we managed to see rather more of it on the return journey. But as I’ve promised to write an article for another magazine about that, I’d better not say anything else here. (You might like to keep your eyes on the National Astrographic Magazine next Spring.)

  The hop from Ganymede to Five took just over a day and a half, and it gave us an uncomfortable feeling to see Jupiter expanding hour by hour until it seemed as if he was going to fill the sky. I don’t know much about astronomy, but I couldn’t help thinking of the tremendous gravity field into which we were falling. All sorts of things could go wrong so easily. If we ran out of fuel we’d never be able to get back to Ganymede, and we might even drop into Jupiter himself.

  I wish I could describe what it was like seeing that colossal globe, with its raging storm belts spinning in the sky ahead of us. As a matter of fact I did make the attempt, but some literary friends who have read this MS advised me to cut out the result. (They also gave me a lot of other advice which I don’t think they could have meant seriously, because if I’d followed it there would have been no story at all.)

  Luckily there have been so many color close-ups of Jupiter published by now that you’re bound to have seen some of them. You may even have seen the one which, as I’ll explain later, was the cause of all our trouble.

  At last Jupiter stopped growing: we’d swung into the orbit of Five and would soon catch up with the tiny moon as it raced around the planet. We were all squeezed in the control room waiting for our first glimpse of our target. At least, all of us who could get in were doing so. Bill and I were crowded out into the corridor and could only crane over other people’s shoulders. Kingsley Searle, our pilot, was in the control seat looking as unruffled as ever: Eric Fulton, the engineer, was thoughtfully chewing his mustache and watching the fuel gauges, and Tony Groves was doing complicated things with his navigation tables.

  And the Professor appeared to be rigidly attached to the eyepiece of the teleperiscope. Suddenly he gave a start and we heard a whistle of indrawn breath. After a minute, without a word, he beckoned to Searle, who took his place at the eyepiece. Exactly the same thing happened, and then Searle handed over to Fulton. It got a bit monotonous by the time Groves had reacted identically, so we wormed our way in and took over after a bit of opposition.

  I don’t know quite what I’d expected to see, so that’s probably why I was disappointed. Hanging there in space was a tiny gibbous moon, its “night” sector lit up faintly by the reflected glory of Jupiter. And that seemed to be all.

  Then I began to make out additional markings, in the way that you do if you look through a telescope for long enough. There were faint crisscrossing lines on the surface of the satellite, and suddenly my eye grasped their full pattern. For it was a pattern: those lines covered Five with the same geometrical accuracy as the lines of latitude and longitude divide up a globe of the Earth. I suppose I gave my whistle of amazement, for then Bill pushed me out of the way and had his turn to look.

  The next thing I remember is Professor Forster looking very smug while we bombarded him with questions.

  “Of course,” he explained, “this isn’t as much a surprise to me as it is to you. Besides the evidence I’d found on Mercury, there were other clues. I’ve a friend at the Ganymede Observatory whom I’ve sworn to secrecy and who’s been under quite a strain this last few weeks. It’s rather surprising to anyone who’s not an astronomer that the Observatory has never bothered much about the satellites. The big instruments are all used on extra-galactic nebulae, and the little ones spend all their time looking at Jupiter.

  “The only thing the Observatory had ever done to Five was to measure its diameter and take a few photographs. They weren’t quite good enough to show the markings we’ve just observed, otherwise there would have been an investigation before. But my friend Lawton detected them through the hundred-centimeter reflector when I asked him to look, and he also noticed something else that should have been spotted before. Five is only thirty kilometers in diameter, but it’s much brighter than it should be for its size. When you compare its reflecting power—its aldeb—its—”

  “Its albedo.”

  “Thanks, Tony—it’s albedo with that of the other Moons,
you find that it’s a much better reflector than it should be. In fact, it behaves more like polished metal than rock.”

  “So that explains it!” I said. “The people of Culture X must have covered Five with an outer shell—like the domes they built on Mercury, but on a bigger scale.”

  The Professor looked at me rather pityingly.

  “So you still haven’t guessed!” he said.

  I don’t think this was quite fair. Frankly, would you have done any better in the same circumstances?

  We landed three hours later on an enormous metal plain. As I looked through the portholes, I felt completely dwarfed by my surroundings. An ant crawling on the top of an oil-storage tank might have had much the same feelings—and the looming bulk of Jupiter up there in the sky didn’t help. Even the Professor’s usual cockiness now seemed to be overlaid by a kind of reverent awe.

  The plain wasn’t quite devoid of features. Running across it in various directions were broad bands where the stupendous metal plates had been joined together. These bands, or the crisscross pattern they formed, were what we had seen from space.

  About a quarter of a kilometer away was a low hill—at least, what would have been a hill on a natural world. We had spotted it on our way in after making a careful survey of the little satellite from space. It was one of six such projections, four arranged equidistantly around the equator and the other two at the Poles. The assumption was pretty obvious that they would be entrances to the world below the metal shell.

  I know that some people think it must be very entertaining to walk around on an airless, low-gravity planet in space-suits. Well, it isn’t. There are so many points to think about, so many checks to make and precautions to observe, that the mental strain outweighs the glamor—at least as far as I’m concerned. But I must admit that this time, as we climbed out of the airlock, I was so excited that for once these things didn’t worry me.