The Sentinel Part 15

The full force of the Sun...He smiled wryly, remembering all his attempts to explain solar sailing to those lecture audiences back on Earth. That had been the only way he could raise money, in those early days. He might be Chief Designer of Cosmodyne Corporation, with a whole string of successful s.p.a.ces.h.i.+ps to his credit, but his firm had not been exactly enthusiastic about his hobby.

"Hold your hands out to the Sun," he'd said. "What do you feel? Heat, of course. But there's pressure as well-though you've never noticed it, because it's so tiny. Over the area of your hands, it comes to only about a millionth of an ounce.

"But out in s.p.a.ce, even a pressure as small as that can be important, for it's acting all the time, hour after hour, day after day. Unlike rocket fuel, it's free and unlimited. If we want to, we can use it. We can build sails to catch the radiation blowing from the Sun."

At that point, he would pull out a few square yards of sail material and toss it toward the audience. The silvery film would coil and twist like smoke, then drift slowly to the ceiling in the hot-air currents.

"You can see how light it is," he'd continue. "A square mile weighs only a ton, and can collect five pounds of radiation pressure. So it will start moving-and we can let it tow us along, if we attach rigging to it.

"Of course, its acceleration will be tiny-about a thousandth of a g. That doesn't seem much, but let's see what it means.

"It means that in the first second, we'll move about a fifth of an inch. I suppose a healthy snail could do better than that. But after a minute, we've covered sixty feet, and will be doing just over a mile an hour. That's not bad, for something driven by pure sunlight! After an hour, we're forty miles from our starting point, and will be moving at eighty miles an hour. Please remember that in s.p.a.ce there's no friction; so once you start anything moving, it will keep going forever. You'll be surprised when I tell you what our thousandth-of-a-g sailboat will be doing at the end of a day's run: almost two thousand miles an hour! almost two thousand miles an hour! If it starts from orbit-as it has to, of course-it can reach escape velocity in a couple of days. And all without burning a single drop of fuell" If it starts from orbit-as it has to, of course-it can reach escape velocity in a couple of days. And all without burning a single drop of fuell"

Well, he'd convinced them, and in the end he'd even convinced Cosmodyne. Over the last twenty years, a new sport had come into being. It had been called the sport of billionaires, and that was true. But it was beginning to pay for itself in terms of publicity and TV coverage. The prestige of four continents and two worlds was riding on this race, and it had the biggest audience in history.

Diana had made a good start; time to take a look at the opposition. Moving very gently-though there were shock absorbers between the control capsule and the delicate rigging, he was determined to run no risks-Merton stationed himself at the periscope. had made a good start; time to take a look at the opposition. Moving very gently-though there were shock absorbers between the control capsule and the delicate rigging, he was determined to run no risks-Merton stationed himself at the periscope.

There they were, looking like strange silver flowers planted in the dark fields of s.p.a.ce. The nearest, South America's Santa Maria Santa Maria, was only fifty miles away; it bore a close resemblance to a boy's kite, but a kite more than a mile on a side. Farther away, the University of Astrograd's Lebedev Lebedev looked like a Maltese cross; the sails that formed the four arms could apparently be tilted for steering purposes. In contrast, the Federation of Australasia's looked like a Maltese cross; the sails that formed the four arms could apparently be tilted for steering purposes. In contrast, the Federation of Australasia's Woomera Woomera was a simple parachute, four miles in circ.u.mference. General s.p.a.cecraft's was a simple parachute, four miles in circ.u.mference. General s.p.a.cecraft's Arachne Arachne, as its name suggested, looked like a spider web, and had been built on the same principles, by robot shuttles spiraling out from a central point. Euros.p.a.ce Corporation's Gossamer Gossamer was an identical design, on a slightly smaller scale. And the Republic of Mars's was an identical design, on a slightly smaller scale. And the Republic of Mars's Sunbeam Sunbeam was a flat ring, with a half-mile-wide hole in the center, spinning slowly, so that centrifugal force gave it stiffness. That was an old idea, but no one had ever made it work; and Merton was fairly sure that the colonials would be in trouble when they started to turn. was a flat ring, with a half-mile-wide hole in the center, spinning slowly, so that centrifugal force gave it stiffness. That was an old idea, but no one had ever made it work; and Merton was fairly sure that the colonials would be in trouble when they started to turn.

That would not be for another six hours, when the yachts had moved along the first quarter of their slow and stately twenty-four-hour orbit. Here at the beginning of the race, they were all heading directly away from the Sun-running, as it were, before the solar wind. One had to make the most of this lap, before the boats swung around to the other side of Earth and then started to head back into the Sun.

Time, Merton told himself, for the first check, while he had no navigational worries. With the periscope, he made a careful examination of the sail, concentrating on the points where the rigging was attached to it. The shroud lines-narrow bands of unsilvered plastic film-would have been completely invisible had they not been coated with fluorescent paint. Now they were taut lines of colored light, dwindling away for hundreds of yards toward that gigantic sail. Each had its own electric windla.s.s, not much bigger than a game fisherman's reel. The little windla.s.ses were continually turning, playing lines in or out as the autopilot kept the sail trimmed at the correct angle to the Sun.

The play of sunlight on the great flexible mirror was beautiful to watch. The sail was undulating in slow, stately oscillations, sending multiple images of the Sun marching across it, until they faded away at its edges. Such leisurely vibrations were to be expected in this vast and flimsy structure. They were usually quite harmless, but Merton watched them carefully. Sometimes they could build up to the catastrophic undulations known as the "wriggles," which could tear a sail to pieces.

When he was satisfied that everything was s.h.i.+pshape, he swept the periscope around the sky, rechecking the positions of his rivals. It was as he had hoped: the weeding-out process had begun, as the less efficient boats fell astern. But the real test would come when they pa.s.sed into the shadow of Earth. Then, maneuverability would count as much as speed.

It seemed a strange thing to do, what with the race having just started, but he thought it might be a good idea to get some sleep. The two-man crews on the other boats could take it in turns, but Merton had no one to relieve him. He must rely on his own physical resources, like that other solitary seaman, Joshua Sloc.u.m, in his tiny Spray Spray. The American skipper had sailed Spray Spray singlehanded around the world; he could never have dreamed that, two centuries later, a man would be sailing singlehanded from Earth to Moon-inspired, at least partly, by his example. singlehanded around the world; he could never have dreamed that, two centuries later, a man would be sailing singlehanded from Earth to Moon-inspired, at least partly, by his example.

Merton snapped the elastic bands of the cabin seat around his waist and legs, then placed the electrodes of the sleep-inducer on his forehead. He set the timer for three hours, and relaxed. Very gently, hypnotically, the electronic pulses throbbed in the frontal lobes of his brain. Colored spirals of light expanded beneath his closed eyelids, widening outward to infinity. Then nothing...

The brazen clamor of the alarm dragged him back from his dreamless sleep. He was instantly awake, his eyes scanning the instrument panel. Only two hours had pa.s.sed-but above the accelerometer, a red light was flas.h.i.+ng. Thrust was falling; Diana Diana was losing power. was losing power.

Merton's first thought was that something had happened to the sail; perhaps the antispin devices had failed, and the rigging had become twisted. Swiftly, he checked the meters that showed the tension of the shroud lines. Strange-on one side of the sail they were reading normally, but on the other the pull was dropping slowly, even as he watched.

In sudden understanding, Merton grabbed the periscope, switched to wide-angle vision, and started to scan the edge of the sail. Yes-there was the trouble, and it could have only one cause.

A huge, sharp-edged shadow had begun to slide across the gleaming silver of the sail. Darkness was falling upon Diana Diana, as if a cloud had pa.s.sed between her and the Sun. And in the dark, robbed of the rays that drove her, she would lose all thrust and drift helplessly through s.p.a.ce.

But, of course, there were no clouds here, more than twenty thousand miles above the Earth. If there was a shadow, it must be made by man.

Merton grinned as he swung the periscope toward the Sun, switching in the filters that would allow him to look full into its blazing face without being blinded.

"Maneuver 4a," he muttered to himself. "We'll see who can play best at that that game." game."

It looked as if a giant planet was crossing the face of the Sun; a great black disc had bitten deep into its edge. Twenty miles astern, Gossamer Gossamer was trying to arrange an artificial eclipse, specially for was trying to arrange an artificial eclipse, specially for Diana Diana's benefit.

The maneuver was a perfectly legitimate one. Back in the days of ocean racing, skippers had often tried to rob each other of the wind. With any luck, you could leave your rival becalmed, with his sails collapsing around him-and be well ahead before he could undo the damage.

Merton had no intention of being caught so easily. There was plenty of time to take evasive action; things happened very slowly when you were running a solar sailboat. It would be at least twenty minutes before Gossamer Gossamer could slide completely across the face of the Sun, and leave him in darkness. could slide completely across the face of the Sun, and leave him in darkness.

Diana's tiny computer-the size of a matchbox, but the equivalent of a thousand human mathematicians-considered the problem for a full second and then flashed the answer. He'd have to open control panels three and four, until the sail had developed an extra twenty degrees of tilt; then the radiation pressure would blow him out of Gossamer Gossamer's dangerous shadow, back into the full blast of the Sun. It was a pity to interfere with the autopilot, which had been carefully programmed to give the fastest possible run-but that, after all, was why he was here. This was what made solar yachting a sport, rather than a battle between computers.

Out went control lines one and six, slowly undulating like sleepy snakes as they momentarily lost their tension. Two miles away, the triangular panels began to open lazily, spilling sunlight through the sail. Yet, for a long time, nothing seemed to happen. It was hard to grow accustomed to this slow-motion world, where it took minutes for the effects of any action to become visible to the eye. Then Merton saw that the sail was indeed tipping toward the Sun-and that Gossamer Gossamer's shadow was sliding harmlessly away, its cone of darkness lost in the deeper night of s.p.a.ce.

Long before the shadow had vanished, and the disc of the Sun had cleared again, he reversed the tilt and brought Diana Diana back on course. Her new momentum would carry her clear of the danger; no need to overdo it, and upset his calculations by side-stepping too far. That was another rule that was hard to learn: the very moment you had started something happening in s.p.a.ce, it was already time to think about stopping it. back on course. Her new momentum would carry her clear of the danger; no need to overdo it, and upset his calculations by side-stepping too far. That was another rule that was hard to learn: the very moment you had started something happening in s.p.a.ce, it was already time to think about stopping it.

He reset the alarm, ready for the next natural or man-made emergency. Perhaps Gossamer Gossamer, or one of the other contestants, would try the same trick again. Meanwhile, it was time to eat, though he did not feel particularly hungry. One used little physical energy in s.p.a.ce, and it was easy to forget about food. Easy-and dangerous; for when an emergency arose, you might not have the reserves needed to deal with it.

He broke open the first of the meal packets, and inspected it without enthusiasm. The name on the label-s.p.a.cETASTIES-was enough to put him off. And he had grave doubts about the promise printed underneath: "Guaranteed crumbless." It had been said that crumbs were a greater danger to s.p.a.ce vehicles than meteorites; they could drift into the most unlikely places, causing short circuits, blocking vital jets, and getting into instruments that were supposed to be hermetically sealed.

Still, the liverwurst went down pleasantly enough; so did the chocolate and the pineapple puree. The plastic coffee bulb was warming on the electric heater when the outside world broke in upon his solitude, as the radio operator on the Commodore's launch routed a call to him.

"Dr. Merton? If you can spare the time, Jeremy Blair would like a few words with you." Blair was one of the more responsible news commentators, and Merton had been on his program many times. He could refuse to be interviewed, of course, but he liked Blair, and at the moment he could certainly not claim to be too busy. "I'll take it," he answered.

"h.e.l.lo, Dr. Merton," said the commentator immediately. "Glad you can spare a few minutes. And congratulations-you seem to be ahead of the field."

"Too early in the game to be sure of that that," Merton answered cautiously.

"Tell me, Doctor, why did you decide to sail Diana Diana by yourself? Just because it's never been done before?" by yourself? Just because it's never been done before?"

"Well, isn't that a good reason? But it wasn't the only one, of course." He paused, choosing his words carefully. "You know how critically the performance of a sun yacht depends on its ma.s.s. A second man, with all his supplies, would mean another five hundred pounds. That could easily be the difference between winning and losing."

"And you're quite certain that you can handle Diana Diana alone?" alone?"

"Reasonably sure, thanks to the automatic controls I've designed. My main job is to supervise and make decisions."

"But-two square miles of sail! It just doesn't seem possible for one man to cope with all that."

Merton laughed. "Why not? Those two square miles produce a maximum pull of just ten pounds. I can exert more force with my little finger."

"Well, thank you, Doctor. And good luck. I'll be calling you again."

As the commentator signed off, Merton felt a little ashamed of himself. For his answer had been only part of the truth; and he was sure that Blair was shrewd enough to know it.

There was just one reason why he was here, alone in s.p.a.ce. For almost forty years he had worked with teams of hundreds or even thousands of men, helping to design the most complex vehicles that the world had ever seen. For the last twenty years he had led one of those teams, and watched his creations go soaring to the stars. (Sometimes...There were were failures, which he could never forget, even though the fault had not been his.) He was famous, with a successful career behind him. Yet he had never done anything by himself; always he had been one of an army. failures, which he could never forget, even though the fault had not been his.) He was famous, with a successful career behind him. Yet he had never done anything by himself; always he had been one of an army.

This was his last chance to try for individual achievement, and he would share it with no one. There would be no more solar yachting for at least five years, as the period of the Quiet Sun ended and the cycle of bad weather began, with radiation storms bursting through the solar system. When it was safe again for these frail, uns.h.i.+elded craft to venture aloft, he would be too old. If, indeed, he was not too old already...

He dropped the empty food containers into the waste disposal and turned once more to the periscope. At first he could find only five of the other yachts; there was no sign of Woomera Woomera. It took him several minutes to locate her-a dim, star-eclipsing phantom, neatly caught in the shadow of Lebedev Lebedev. He could imagine the frantic efforts the Australasians were making to extricate themselves, and wondered how they had fallen into the trap. It suggested that Lebedev Lebedev was unusually maneuverable. She would bear watching, though she was too far away to menace was unusually maneuverable. She would bear watching, though she was too far away to menace Diana Diana at the moment. at the moment.

Now the Earth had almost vanished; it had waned to a narrow, brilliant bow of light that was moving steadily toward the Sun. Dimly outlined within that burning bow was the night side of the planet, with the phosph.o.r.escent gleams of great cities showing here and there through gaps in the clouds. The disc of darkness had already blanked out a huge section of the Milky Way. In a few minutes, it would start to encroach upon the Sun.

The light was fading; a purple, twilight hue-the glow of many sunsets, thousands of miles below-was falling across the sail as Diana Diana slipped silently into the shadow of Earth. The Sun plummeted below that invisible horizon; within minutes, it was night. slipped silently into the shadow of Earth. The Sun plummeted below that invisible horizon; within minutes, it was night.

Merton looked back along the orbit he had traced, now a quarter of the way around the world. One by one he saw the brilliant stars of the other yachts wink out, as they joined him in the brief night. It would be an hour before the Sun emerged from that enormous black s.h.i.+eld, and through all that time they would be completely helpless, coasting without power.

He switched on the external spotlight, and started to search the now-darkened sail with its beam. Already the thousands of acres of film were beginning to wrinkle and become flaccid. The shroud lines were slackening, and must be wound in lest they become entangled. But all this was expected; everything was going as planned.

Fifty miles astern, Arachne Arachne and and Santa Maria Santa Maria were not so lucky. Merton learned of their troubles when the radio burst into life on the emergency circuit. were not so lucky. Merton learned of their troubles when the radio burst into life on the emergency circuit.

"Number Two and Number Six, this is Control. You are on a collision course; your orbits will intersect in sixty-five minutes! Do you require a.s.sistance?"

There was a long pause while the two skippers digested this bad news. Merton wondered who was to blame. Perhaps one yacht had been trying to shadow the other, and had not completed the maneuver before they were both caught in darkness. Now there was nothing that either could do. They were slowly but inexorably converging, unable to change course by a fraction of a degree.

Yet-sixty-five minutes! That would just bring them out into sunlight again, as they emerged from the shadow of the Earth. They had a slim chance, if their sails could s.n.a.t.c.h enough power to avoid a crash. There must be some frantic calculations going on aboard Arachne Arachne and and Santa Maria Santa Maria.

Arachne answered first. Her reply was just what Merton had expected. answered first. Her reply was just what Merton had expected.

"Number Six calling Control. We don't need a.s.sistance, thank you. We'll work this out for ourselves."

I wonder, thought Merton; but at least it will be interesting to watch. The first real drama of the race was approaching, exactly above the line of midnight on the sleeping Earth.

For the next hour, Merton's own sail kept him too busy to worry about Arachne Arachne and and Santa Maria Santa Maria. It was hard to keep a good watch on that fifty million square feet of dim plastic out there in the darkness, illuminated only by his narrow spotlight and the rays of the still-distant Moon. From now on, for almost half his...o...b..t around the Earth, he must keep the whole of this immense area edge-on to the Sun. During the next twelve or fourteen hours, the sail would be a useless enc.u.mbrance; for he would be heading into into the Sun, and its rays could only drive him backward along his...o...b..t. It was a pity that he could not furl the sail completely, until he was ready to use it again; but no one had yet found a practical way of doing this. the Sun, and its rays could only drive him backward along his...o...b..t. It was a pity that he could not furl the sail completely, until he was ready to use it again; but no one had yet found a practical way of doing this.

Far below, there was the first hint of dawn along the edge of the Earth. In ten minutes the Sun would emerge from its eclipse. The coasting yachts would come to life again as the blast of radiation struck their sails. That would be the moment of crisis for Arachne Arachne and and Santa Maria Santa Maria-and, indeed, for all of them.

Merton swung the periscope until he found the two dark shadows drifting against the stars. They were very close together-perhaps less than three miles apart. They might, he decided, just be able to make it...

Dawn flashed like an explosion along the rim of Earth as the Sun rose out of the Pacific. The sail and shroud lines glowed a brief crimson, then gold, then blazed with the pure white light of day. The needles of the dynamometers began to lift from their zeroes-but only just. Diana Diana was still almost completely weightless, for with the sail pointing toward the Sun, her acceleration was now only a few millionths of a gravity. was still almost completely weightless, for with the sail pointing toward the Sun, her acceleration was now only a few millionths of a gravity.

But Arachne Arachne and and Santa Maria Santa Maria were crowding on all the sail that they could manage, in their desperate attempt to keep apart. Now, while there was less than two miles between them, their glittering plastic clouds were unfurling and expanding with agonizing slowness as they felt the first delicate push of the Sun's rays. Almost every TV screen on Earth would be mirroring this protracted drama; and even now, at this last minute, it was possible to tell what the outcome would be. were crowding on all the sail that they could manage, in their desperate attempt to keep apart. Now, while there was less than two miles between them, their glittering plastic clouds were unfurling and expanding with agonizing slowness as they felt the first delicate push of the Sun's rays. Almost every TV screen on Earth would be mirroring this protracted drama; and even now, at this last minute, it was possible to tell what the outcome would be.

The two skippers were stubborn men. Either could have cut his sail and fallen back to give the other a chance; but neither would do so. Too much prestige, too many millions, too many reputations were at stake. And so, silently and softly as snowflakes falling on a winter night, Arachne Arachne and and Santa Maria Santa Maria collided. collided.

The square kite crawled almost imperceptibly into the circular spider web. The long ribbons of the shroud lines twisted and tangled together with dreamlike slowness. Even aboard Diana Diana, Merton, busy with his own rigging, could scarcely tear his eyes away from this silent, long-drawn-out disaster.

For more than ten minutes the billowing, s.h.i.+ning clouds continued to merge into one inextricable ma.s.s. Then the crew capsules tore loose and went their separate ways, missing each other by hundreds of yards. With a flare of rockets, the safety launches hurried to pick them up.

That leaves five of us, thought Merton. He felt sorry for the skippers who had so thoroughly eliminated each other, only a few hours after the start of the race, but they were young men and would have another chance.

Within minutes, the five had dropped to four. From the beginning, Merton had had doubts about the slowly rotating Sunbeam; Sunbeam; now he saw them justified. now he saw them justified.

The Martian s.h.i.+p had failed to tack properly. Her spin had given her too much stability. Her great ring of a sail was turning to face the Sun, instead of being edge-on to it. She was being blown back along her course at almost her maximum acceleration.

That was about the most maddening thing that could happen to a skipper-even worse than a collision, for he could blame only himself. But no one would feel much sympathy for the frustrated colonials, as they dwindled slowly astern. They had made too many brash boasts before the race, and what had happened to them was poetic justice.

Yet it would not do to write off Sunbeam Sunbeam completely; with almost half a million miles still to go, she might yet pull ahead. Indeed, if there were a few more casualties, she might be the only one to complete the race. It had happened before. completely; with almost half a million miles still to go, she might yet pull ahead. Indeed, if there were a few more casualties, she might be the only one to complete the race. It had happened before.

The next twelve hours were uneventful, as the Earth waxed in the sky from new to full. There was little to do while the fleet drifted around the unpowered half of its...o...b..t, but Merton did not find the time hanging heavily on his hands. He caught a few hours of sleep, ate two meals, wrote his log, and became involved in several more radio interviews. Sometimes, though rarely, he talked to the other skippers, exchanging greetings and friendly taunts. But most of the time he was content to float in weightless relaxation, beyond all the cares of Earth, happier than he had been for many years. He was-as far as any man could be in s.p.a.ce-master of his own fate, sailing the s.h.i.+p upon which he had lavished so much skill, so much love, that it had become part of his very being.

The next casualty came when they were pa.s.sing the line between Earth and Sun, and were just beginning the powered half of the orbit. Aboard Diana Diana, Merton saw the great sail stiffen as it tilted to catch the rays that drove it. The acceleration began to climb up from the microgravities, though it would be hours yet before it would reach its maximum value.

It would never reach it for Gossamer Gossamer. The moment when power came on again was always critical, and she failed to survive it.

Blair's radio commentary, which Merton had left running at low volume, alerted him with the news: "h.e.l.lo, Gossamer Gossamer has the wriggles!" He hurried to the periscope, but at first could see nothing wrong with the great circular disc of has the wriggles!" He hurried to the periscope, but at first could see nothing wrong with the great circular disc of Gossamer Gossamer's sail. It was difficult to study it because it was almost edge-on to him and so appeared as a thin ellipse; but presently he saw that it was twisting back and forth in slow, irresistible oscillations. Unless the crew could damp out these waves, by properly timed but gentle tugs on the shroud lines, the sail would tear itself to pieces.

They did their best, and after twenty minutes it seemed that they had succeeded. Then, somewhere near the center of the sail, the plastic film began to rip. It was slowly driven outward by the radiation pressure, like smoke coiling upward from a fire. Within a quarter of an hour, nothing was left but the delicate tracery of the radial spars that had supported the great web. Once again there was a flare of rockets, as a launch moved in to retrieve the Gossamer Gossamer's capsule and her dejected crew.

"Getting rather lonely up here, isn't it?" said a conversational voice over the s.h.i.+p-to-s.h.i.+p radio.

"Not for you, Dimitri," retorted Merton. "You've still got company back there at the end of the field. I'm the one who's lonely, up here in front." It was not an idle boast; by this time Diana Diana was three hundred miles ahead of the next compet.i.tor, and her lead should increase still more rapidly in the hours to come. was three hundred miles ahead of the next compet.i.tor, and her lead should increase still more rapidly in the hours to come.

A board Lebedev Lebedev, Dimitri Markoff gave a good-natured chuckle. He did not sound, Merton thought, at all like a man who had resigned himself to defeat.

"Remember the legend of the tortoise and the hare," answered the Russian. "A lot can happen in the next quarter-million miles."

It happened much sooner than that, when they had completed their first orbit of Earth and were pa.s.sing the starting line again-though thousands of miles higher, thanks to the extra energy the Sun's rays had given them. Merton had taken careful sights on the other yachts, and had fed the figures into the computer. The answer it gave for Woomera Woomera was so absurd that he immediately did a recheck. was so absurd that he immediately did a recheck.

There was no doubt of it-the Australasians were catching up at a completely fantastic rate. No solar yacht could possibly have such an acceleration, unless...

A swift look through the periscope gave the answer. Woomera Woomera's rigging, pared back to the very minimum of ma.s.s, had given way. It was her sail alone, still maintaining its shape, that was racing up behind him like a handkerchief blown before the wind. Two hours later it fluttered past, less than twenty miles away; but long before that, the Australasians had joined the growing crowd aboard the Commodore's launch.

So now it was a straight fight between Diana Diana and and Lebedev Lebedev-for though the Martians had not given up, they were a thousand miles astern and no longer counted as a serious threat. For that matter, it was hard to see what Lebedev Lebedev could do to overtake could do to overtake Diana Diana's lead; but all the way around the second lap, through eclipse again and the long, slow drift against the Sun, Merton felt a growing unease.

He knew the Russian pilots and designers. They had been trying to win this race for twenty years-and, after all, it was only fair that they should, for had not Pyotr Nikolaevich Lebedev been the first man to detect the pressure of sunlight, back at the very beginning of the twentieth century? But they had never succeeded.

And they would never stop trying. Dimitri was up to something-and it would be spectacular.

Aboard the official launch, a thousand miles behind the racing yachts, Commodore van Stratten looked at the radiogram with angry dismay. It had traveled more than a hundred million miles, from the chain of solar observatories swinging high above the blazing surface of the Sun; and it brought the worst possible news.

The Commodore-his t.i.tle was purely honorary, of course; back on Earth he was Professor of Astrophysics at Harvard-had been half expecting it. Never before had the race been arranged so late in the season. There had been many delays; they had gambled-and now, it seemed, they might all lose.

Deep beneath the surface of the Sun, enormous forces were gathering. At any moment the energies of a million hydrogen bombs might burst forth in the awesome explosion known as a solar flare. Climbing at millions of miles an hour, an invisible fireball many times the size of Earth would leap from the Sun and head out across s.p.a.ce.

The cloud of electrified gas would probably miss the Earth completely. But if it did not, it would arrive in just over a day. s.p.a.ces.h.i.+ps could protect themselves, with their s.h.i.+elding and their powerful magnetic screens; but the lightly built solar yachts, with their paper-thin walls, were defenseless against such a menace. The crews would have to be taken off, and the race abandoned.

John Merton knew nothing of this as he brought Diana Diana around the Earth for the second time. If all went well, this would be the last circuit, both for him and for the Russians. They had spiraled upward by thousands of miles, gaining energy from the Sun's rays. On this lap, they should escape from Earth completely, and head outward on the long run to the Moon. It was a straight race now; around the Earth for the second time. If all went well, this would be the last circuit, both for him and for the Russians. They had spiraled upward by thousands of miles, gaining energy from the Sun's rays. On this lap, they should escape from Earth completely, and head outward on the long run to the Moon. It was a straight race now; Sunbeam Sunbeam's crew had finally withdrawn exhausted, after battling valiantly with their spinning sail for more than a hundred thousand miles.

Merton did not feel tired; he had eaten and slept well, and Diana Diana was behaving herself admirably. The autopilot, tensioning the rigging like a busy little spider, kept the great sail trimmed to the Sun more accurately than any human skipper could have. Though by this time the two square miles of plastic sheet must have been riddled by hundreds of micrometeorites, the pinhead-sized punctures had produced no falling off of thrust. was behaving herself admirably. The autopilot, tensioning the rigging like a busy little spider, kept the great sail trimmed to the Sun more accurately than any human skipper could have. Though by this time the two square miles of plastic sheet must have been riddled by hundreds of micrometeorites, the pinhead-sized punctures had produced no falling off of thrust.

He had only two worries. The first was shroud line number eight, which could no longer be adjusted properly. Without any warning, the reel had jammed; even after all these years of astronautical engineering, bearings sometimes seized up in vacuum. He could neither lengthen nor shorten the line, and would have to navigate as best he could with the others. Luckily, the most difficult maneuvers were over; from now on, Diana Diana would have the Sun behind her as she sailed straight down the solar wind. And as the old-time sailors had often said, it was easy to handle a boat when the wind was blowing over your shoulder. would have the Sun behind her as she sailed straight down the solar wind. And as the old-time sailors had often said, it was easy to handle a boat when the wind was blowing over your shoulder.

His other worry was Lebedev Lebedev, still d.o.g.g.i.ng his heels three hundred miles astern. The Russian yacht had shown remarkable maneuverability, thanks to the four great panels that could be tilted around the central sail. Her flipovers as she rounded the Earth had been carried out with superb precision. But to gain maneuverability she must have sacrificed speed. You could not have it both ways; in the long, straight haul ahead, Merton should be able to hold his own. Yet he could not be certain of victory until, three or four days from now, Diana Diana went flas.h.i.+ng past the far side of the Moon. went flas.h.i.+ng past the far side of the Moon.

And then, in the fiftieth hour of the race, just after the end of the second orbit around Earth, Markoff sprang his little surprise.

"h.e.l.lo, John," he said casually over the s.h.i.+p-to-s.h.i.+p circuit. "I'd like you to watch this. It should be interesting."

Merton drew himself across to the periscope and turned up the magnification to the limit. There in the field of view, a most improbable sight against the background of the stars, was the glittering Maltese cross of Lebedev Lebedev, very small but very clear. As he watched, the four arms of the cross slowly detached themselves from the central square, and went drifting away, with all their spars and rigging, into s.p.a.ce.

Markoff had jettisoned all unnecessary ma.s.s, now that he was coming up to escape velocity and need no longer plod patiently around the Earth, gaining momentum on each circuit. From now on, Lebedev Lebedev would be almost unsteerable-but that did not matter; all the tricky navigation lay behind her. It was as if an old-time yachtsman had deliberately thrown away his rudder and heavy keel, knowing that the rest of the race would be straight downwind over a calm sea. would be almost unsteerable-but that did not matter; all the tricky navigation lay behind her. It was as if an old-time yachtsman had deliberately thrown away his rudder and heavy keel, knowing that the rest of the race would be straight downwind over a calm sea.

"Congratulations, Dimitri," Merton radioed. "It's a neat trick. But it's not good enough. You can't catch up with me now."