The Sentinel

  Falcon’s pocket communicator beeped. The copilot was calling from the bridge.

  “O.K. for rendezvous, Captain? We’ve got all the data we need from this run, and the TV people are getting impatient.”

  Falcon glanced at the camera platform, now matching his speed a tenth of a mile away.

  “O.K.,” he replied. “Proceed as arranged. I’ll watch from here.”

  He walked back through the busy chaos of the Observation Deck so that he could have a better view amidships. As he did so, he could feel the change of vibration underfoot; by the time he had reached the rear of the lounge, the ship had come to rest. Using his master key, he let himself out onto the small external platform flaring from the end of the deck; half a dozen people could stand here, with only low guardrails separating them from the vast sweep of the envelope—and from the ground, thousands of feet below. It was an exciting place to be, and perfectly safe even when the ship was traveling at speed, for it was in the dead air behind the huge dorsal blister of the Observation Deck. Nevertheless, it was not intended that the passengers would have access to it; the view was a little too vertiginous.

  The covers of the forward cargo hatch had already opened like giant trap doors, and the camera platform was hovering above them, preparing to descend. Along this route, in the years to come, would travel thousands of passengers and tons of supplies. Only on rare occasions would the Queen drop down to sea level and dock with her floating base.

  A sudden gust of cross wind slapped Falcon’s cheek, and he tightened his grip on the guardrail. The Grand Canyon was a bad place for turbulence, though he did not expect much at this altitude. Without any real anxiety, he focused his attention on the descending platform, now about a hundred and fifty feet above the ship. He knew that the highly skilled operator who was flying the remotely controlled vehicle had performed this simple maneuver a dozen times already; it was inconceivable that he would have any difficulties.

  Yet he seemed to be reacting rather sluggishly. That last gust had drifted the platform almost to the edge of the open hatchway. Surely the pilot could have corrected before this . . . Did he have a control problem? It was very unlikely; these remotes had multiple-redundancy, fail-safe takeovers, and any number of backup systems. Accidents were almost unheard of.

  But there he went again, off to the left. Could the pilot be drunk? Improbable though that seemed, Falcon considered it seriously for a moment. Then he reached for his microphone switch.

  Once again, without warning, he was slapped violently in the face. He hardly felt it, for he was staring in horror at the camera platform. The distant operator was fighting for control, trying to balance the craft on its jets—but he was only making matters worse. The oscillations increased—twenty degrees, forty, sixty, ninety . . .

  “Switch to automatic, you fool!” Falcon shouted uselessly into his microphone. “Your manual control’s not working!”

  The platform flipped over on its back. The jets no longer supported it, but drove it swiftly downward. They had suddenly become allies of the gravity they had fought until this moment.

  Falcon never heard the crash, though he felt it; he was already inside the Observation Deck, racing for the elevator that would take him down to the bridge. Workmen shouted at him anxiously, asking what had happened. It would be many months before he knew the answer to that question.

  Just as he was stepping into the elevator cage, he changed his mind. What if there was a power failure? Better be on the safe side, even if it took longer and time was the essence. He began to run down the spiral stairway enclosing the shaft.

  Halfway down he paused for a second to inspect the damage. That damned platform had gone clear through the ship, rupturing two of the gas cells as it did so. They were still collapsing slowly, in great falling veils of plastic. He was not worried about the loss of lift—the ballast could easily take care of that, as long as eight cells remained intact. Far more serious was the possibility of structural damage. Already he could hear the great latticework around him groaning and protesting under its abnormal loads. It was not enough to have sufficient lift; unless it was properly distributed, the ship would break her back.

  He was just resuming his descent when a superchimp, shrieking with fright, came racing down the elevator shaft, moving with incredible speed, hand over hand, along the outside of the latticework. In its terror, the poor beast had torn off its company uniform, perhaps in an unconscious attempt to regain the freedom of its ancestors.

  Falcon, still descending as swiftly as he could, watched its approach with some alarm. A distraught simp was a powerful and potentially dangerous animal, especially if fear overcame its conditioning. As it overtook him, it started to call out a string of words, but they were all jumbled together, and the only one he could recognize was a plaintive, frequently repeated “boss.” Even now, Falcon realized, it looked toward humans for guidance. He felt sorry for the creature, involved in a man-made disaster beyond its comprehension, and for which it bore no responsibility.

  It stopped opposite him, on the other side of the lattice; there was nothing to prevent it from coming through the open framework if it wished. Now its face was only inches from his, and he was looking straight into the terrified eyes. Never before had he been so close to a simp, and able to study its features in such detail. He felt that strange mingling of kinship and discomfort that all men experience when they gaze thus into the mirror of time.

  His presence seemed to have calmed the creature. Falcon pointed up the shaft, back toward the Observation Deck, and said very clearly and precisely: “Boss—boss—go.” To his relief, the simp understood; it gave him a grimace that might have been a smile, and at once started to race back the way it had come. Falcon had given it the best advice he could. If any safety remained aboard the Queen, it was in that direction. But his duty lay in the other.

  He had almost completed his descent when, with a sound of rending metal, the vessel pitched nose down, and the lights went out. But he could still see quite well, for a shaft of sunlight streamed through the open hatch and the huge tear in the envelope. Many years ago he had stood in a great cathedral nave watching the light pouring through the stained-glass windows and forming pools of multicolored radiance on the ancient flagstones. The dazzling shaft of sunlight through the ruined fabric high above reminded him of that moment. He was in a cathedral of metal, falling down the sky.

  When he reached the bridge, and was able for the first time to look outside, he was horrified to see how close the ship was to the ground. Only three thousand feet below were the beautiful and deadly pinnacles of rock and the red rivers of mud that were still carving their way down into the past. There was no level area anywhere in sight where a ship as large as the Queen could come to rest on an even keel.

  A glance at the display board told him that all the ballast had gone. However, rate of descent had been reduced to a few yards a second; they still had a fighting chance.

  Without a word, Falcon eased himself into the pilot’s seat and took over such control as still remained. The instrument board showed him everything he wished to know; speech was superfluous. In the background, he could hear the Communications Officer giving a running report over the radio. By this time, all the news channels of Earth would have been preempted, and he could imagine the utter frustration of the program controllers. One of the most spectacular wrecks in history was occurring—without a single camera to record it. The last moments of the Queen would never fill millions with awe and terror, as had those of the Hindenburg, a century and a half before.

  Now the ground was only about seventeen hundred feet away, still coming up slowly. Though he had full thrust, he had not dared to use it, lest the weakened structure collapse; but now he realized that he had no choice. The wind was taking them toward a fork in the canyon, where the river was split by a wedge of rock like the prow of some gigantic, fossilized ship of stone. If she continued on her present course, the Queen would straddle that triangular
plateau and come to rest with at least a third of her length jutting out over nothingness; she would snap like a rotten stick.

  Far away, above the sound of straining metal and escaping gas, came the familiar whistle of the jets as Falcon opened up the lateral thrusters. The ship staggered, and began to slew to port. The shriek of tearing metal was now almost continuous—and the rate of descent had started to increase ominously. A glance at the damage-control board showed that cell number five had just gone.

  The ground was only yards away. Even now, he could not tell whether his maneuver would succeed or fail. He switched the thrust vectors over to vertical, giving maximum lift to reduce the force of impact.

  The crash seemed to last forever. It was not violent—merely prolonged, and irresistible. It seemed that the whole universe was falling about them.

  The sound of crunching metal came nearer, as if some great beast were eating its way through the dying ship.

  Then floor and ceiling closed upon him like a vise.

  2. “Because it’s there”

  “Why do you want to go to Jupiter?”

  “As Springer said when he lifted for Pluto—‘because it’s there.’ ”

  “Thanks. Now we’ve got that out of the way—the real reason.”

  Howard Falcon smiled, though only those who knew him well could have interpreted the slight, leathery grimace. Webster was one of them; for more than twenty years they had shared triumphs and disasters—including the greatest disaster of all.

  “Well, Springer’s cliché is still valid. We’ve landed on all the terrestrial planets, but none of the gas giants. They are the only real challenge left in the solar system.”

  “An expensive one. Have you worked out the cost?”

  “As well as I can; here are the estimates. Remember, though—this isn’t a one-shot mission, but a transportation system. Once it’s proved out, it can be used over and over again. And it will open up not merely Jupiter, but all the giants.”

  Webster looked at the figures, and whistled.

  “Why not start with an easier planet—Uranus, for example? Half the gravity, and less than half the escape velocity. Quieter weather, too—if that’s the right word for it.”

  Webster had certainly done his homework. But that, of course, was why he was head of Long-Range Planning.

  “There’s very little saving—when you allow for the extra distance and the logistics problems. For Jupiter, we can use the facilities of Ganymede. Beyond Saturn, we’d have to establish a new supply base.”

  Logical, thought Webster; but he was sure that it was not the important reason. Jupiter was lord of the solar system; Falcon would be interested in no lesser challenge.

  “Besides,” Falcon continued, “Jupiter is a major scientific scandal. It’s more than a hundred years since its radio storms were discovered, but we still don’t know what causes them—and the Great Red Spot is as big a mystery as ever. That’s why I can get matching funds from the Bureau of Astronautics. Do you know how many probes they have dropped into that atmosphere?”

  “A couple of hundred, I believe.”

  “Three hundred and twenty-six, over the last fifty years—about a quarter of them total failures. Of course, they’ve learned a hell of a lot, but they’ve barely scratched the planet. Do you realize how big it is?”

  “More than ten times the size of Earth.”

  “Yes, yes—but do you know what that really means?”

  Falcon pointed to the large globe in the corner of Webster’s office.

  “Look at India—how small it seems. Well, if you skinned Earth and spread it out on the surface of Jupiter, it would look about as big as India does here.”

  There was a long silence while Webster contemplated the equation: Jupiter is to Earth as Earth is to India. Falcon had—deliberately, of course—chosen the best possible example . . .

  Was it already ten years ago? Yes, it must have been. The crash lay seven years in the past (that date was engraved on his heart), and those initial tests had taken place three years before the first and last flight of the Queen Elizabeth.

  Ten years ago, then, Commander (no, Lieutenant) Falcon had invited him to a preview—a three-day drift across the northern plains of India, within sight of the Himalayas. “Perfectly safe,” he had promised. “It will get you away from the office—and will teach you what this whole thing is about.”

  Webster had not been disappointed. Next to his first journey to the Moon, it had been the most memorable experience of his life. And yet, as Falcon had assured him, it had been perfectly safe, and quite uneventful.

  They had taken off from Srinagar just before dawn, with the huge silver bubble of the balloon already catching the first light of the Sun. The ascent had been made in total silence; there were none of the roaring propane burners that had lifted the hot-air balloons of an earlier age. All the heat they needed came from the little pulsed-fusion reactor, weighing only about two hundred and twenty pounds, hanging in the open mouth of the envelope. While they were climbing, its laser was zapping ten times a second, igniting the merest whiff of deuterium fuel. Once they had reached altitude, it would fire only a few times a minute, making up for the heat lost through the great gasbag overhead.

  And so, even while they were almost a mile above the ground, they could hear dogs barking, people shouting, bells ringing. Slowly the vast, Sun-smitten landscape expanded around them. Two hours later, they had leveled out at three miles and were taking frequent draughts of oxygen. They could relax and admire the scenery; the on-board instrumentation was doing all the work—gathering the information that would be required by the designers of the still-unnamed liner of the skies.

  It was a perfect day. The southwest monsoon would not break for another month, and there was hardly a cloud in the sky. Time seemed to have come to a stop; they resented the hourly radio reports which interrupted their reverie. And all around, to the horizon and far beyond, was that infinite, ancient landscape, drenched with history—a patchwork of villages, fields, temples, lakes, irrigation canals . . .

  With a real effort, Webster broke the hypnotic spell of that ten-year-old memory. It had converted him to lighter-than-air flight—and it had made him realize the enormous size of India, even in a world that could be circled within ninety minutes. And yet, he repeated to himself, Jupiter is to Earth as Earth is to India . . .

  “Granted your argument,” he said, “and supposing the funds are available, there’s another question you have to answer. Why should you do better than the—what is it—three hundred and twenty-six robot probes that have already made the trip?”

  “I am better qualified then they were—as an observer, and as a pilot. Especially as a pilot. Don’t forget—I’ve more experience of lighter-than-air flight than anyone in the world.”

  “You could still serve as controller, and sit safely on Ganymede.”

  “But that’s just the point! They’ve already done that. Don’t you remember what killed the Queen?”

  Webster knew perfectly well; but he merely answered: “Go on.”

  “Time lag—time lag! That idiot of a platform controller thought he was using a local radio circuit. But he’d been accidentally switched through a satellite—oh, maybe it wasn’t his fault, but he should have noticed. That’s a half-second time lag for the round trip. Even then it wouldn’t have mattered flying in calm air. It was the turbulence over the Grand Canyon that did it. When the platform tipped, and he corrected for that—it had already tipped the other way. Ever tried to drive a car over a bumpy road with a half-second delay in the steering?”

  “No, and I don’t intend to try. But I can imagine it.”

  “Well, Ganymede is a million kilometers from Jupiter. That means a round-trip delay of six seconds. No, you need a controller on the spot—to handle emergencies in real time. Let me show you something. Mind if I use this?”

  “Go ahead.”

  Falcon picked up a postcard that was lying on Webster’s desk; they wer
e almost obsolete on Earth, but this one showed a 3-D view of a Martian landscape, and was decorated with exotic and expensive stamps. He held it so that it dangled vertically.

  “This is an old trick, but helps to make my point. Place your thumb and finger on either side, not quite touching. That’s right.”

  Webster put out his hand, almost but not quite gripping the card.

  “Now catch it.”

  Falcon waited for a few seconds; then, without warning, he let go of the card. Webster’s thumb and finger closed on empty air.

  “I’ll do it again, just to show there’s no deception. You see?”

  Once again, the falling card had slipped through Webster’s fingers.

  “Now you try it on me.”

  This time, Webster grasped the card and dropped it without warning. It had scarcely moved before Falcon had caught it. Webster almost imagined he could hear a click, so swift was the other’s reaction.

  “When they put me together again,” Falcon remarked in an expressionless voice, “the surgeons made some improvements. This is one of them—and there are others. I want to make the most of them. Jupiter is the place where I can do it.”

  Webster stared for long seconds at the fallen card, absorbing the improbable colors of the Trivium Charontis Escarpment. Then he said quietly: “I understand. How long do you think it will take?”

  “With your help, plus the Bureau, plus all the science foundation we can drag in—oh, three years. Then a year for trials—we’ll have to send in at least two test models. So, with luck—five years.”

  “That’s about what I thought. I hope you get your luck; you’ve earned it. But there’s one thing I won’t do.”