Collected Stories Of Arthur C. Clarke (168 page)

‘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 space, 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 space 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
! 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 fuel!’

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.

There they were, looking like strange silver flowers planted in the dark fields of space. The nearest, South America’s
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
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
was a simple parachute, four miles in circumference. General Spacecraft’s
Arachne
, as its name suggested, looked like a spider web, and had been built on the same principles, by robot shuttles spiralling out from a central point. Eurospace Corporation’s
Gossamer
was an identical design, on a slightly smaller scale. And the Republic of Mars’s
Sunbeam
was a flat ring, with a half-mile-wide hole in the centre, 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 coloured light, dwindling away for hundreds of yards toward that gigantic sail. Each had its own electric windlass, not much bigger than a game fisherman’s reel. The little windlasses 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 shipshape, 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 passed into the shadow of Earth. Then, manoeuvrability 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 Slocum, in his tiny
Spray
. The American skipper had sailed
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.

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. Coloured spirals of light expanded beneath his closed eyelids, widening outward to infinity. Then nothing …

The brazen clamour of the alarm dragged him back from his dreamless sleep. He was instantly awake, his eyes scanning the instrument panel. Only two hours had passed – but above the accelerometer, a red light was flashing. Thrust was falling;
Diana
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
, as if a cloud had passed 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 space.

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

‘Manoeuvre 4a,’ he muttered to himself. ‘We’ll see who can play best at
that
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
was trying to arrange an artificial eclipse, specially for
Diana
’s benefit.

The manoeuvre 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
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
’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
’s shadow was sliding harmlessly away, its cone of darkness lost in the deeper night of space.

Long before the shadow had vanished, and the disc of the Sun had cleared again, he reversed the tilt and brought
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 space, it was already time to think about stopping it.

He reset the alarm, ready for the next natural or manmade emergency. Perhaps
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 space, 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 – SPACETASTIES – 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 space 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 programme 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.

‘Hello, 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
,’ Merton answered cautiously.

‘Tell me, Doctor, why did you decide to sail
Diana
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 mass. 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
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.’