"Pull me in," he said, as soon as the latches had clicked shut. "I call that a well-planned EVA. There's a whole kilogram of propellant left to take Nina out for the last time."
Normally, there was little drama about a burn in deep space; it was not like the fire and thunder - and always present risks - of a lift-off from a planetary surface. If something went wrong, and the motors failed to come up to full thrust - well, matters could usually be corrected by a slightly longer burn. Or one could wait until the appropriate point in orbit, and try again.
But this time, as the countdown proceeded toward zero, the tension aboard both ships was almost palpable. Everyone knew that it was the first real test of Hal's docility; only Floyd, Curnow, and the Orlovs realized that there was a back-up system. And even they were not absolutely sure that it would work.
"Good luck, Leonov," said Mission Control, timing the message to arrive five minutes before ignition. "Hope everything's running smoothly. And if it's not too much trouble, could you please get some close-ups of the equator, longitude 115, as you go around Jupiter. There's a curious dark spot there - presumably some kind of upwelling, perfectly round, almost a thousand kilometres across. Looks like the shadow of a satellite, but it can't be."
Tanya made a brief acknowledgement that managed to convey, in a remarkably few words, a profound lack of interest in the meteorology of Jupiter at that moment. Mission Control sometimes showed a perfect genius for tactlessness and poor timing.
"All systems functioning normally," said Hal. "Two minutes to ignition."
Strange, thought Floyd, how terminology often survives long after the technology that gave it birth. Only chemical rockets were capable of ignition; even if the hydrogen in a nuclear or plasma drive did come into contact with oxygen, it would be far too hot to burn. At such temperatures, all compounds were stripped back into their elements.
His mind wandered, seeking other examples. People - particularly older ones - still spoke of putting film into a camera, or gas into a car. Even the phrase 'cutting a tape' was still sometimes heard in recording studios - though that embraced two generations of obsolete technologies.
"One minute to ignition."
His mind flashed back to the here and now. This was the minute that counted; for almost a hundred years, on launch pads and in control centres, this was the longest sixty seconds that had ever existed. Countless times it had ended in disaster; but only the triumphs were remembered. Which will ours be?
The temptation to put his hand once more into the pocket that held the activator for the cut-out switch was almost irresistible, even though logic told him there was plenty of time for remedial action. If Hal failed to obey his programming, that would be a nuisance - not a disaster. The really critical time would be when they were rounding Jupiter.
"Six... five... four... three... two... one. IGNITION!"
At first, the thrust was barely perceptible; it took almost a minute to build up to the full tenth of a gee. Nevertheless, everyone started clapping immediately, until Tanya signalled for silence. There were many checks to be made; even if Hal was doing his best - as he certainly seemed to be - there was so much that could still go wrong.
Discovery's antenna mount - which was now taking most of the strain from Leonov's inertia - had never been intended for such mistreatment. The ship's chief designer, called out of retirement, had sworn that the safety margin was adequate. But he might be wrong, and materials had been known to become brittle after years in space.
And the tapes holding the two ships together might not have been located accurately; they might stretch or slip. Discovery might not be able to correct for the off-centre of mass, now that it was carrying a thousand tons piggyback. Floyd could imagine a dozen things that could go wrong; it was little consolation to remember that it was always the thirteenth that actually happened.
But the minutes dragged on uneventfully; the only proof that Discovery's engines were operating was the fractional, thrust-induced gravity and a very slight vibration transmitted through the walls of the ships. Io and Jupiter still hung where they had been for weeks, on opposite sides of the sky.
"Cut-off in ten seconds. Nine... eight... seven... six... five... four... three... two... NOW!"
"Thank you, Hal, On the button."
Now that was another phrase that was badly dated; for at least a generation, touch pads had almost entirely replaced buttons. But not for all applications; in critical cases, it was best to have a device that moved perceptibly with a nice, satisfying click.
"I confirm that," said Vasili. "No need for any corrections until mid-course."
"Say goodbye to glamorous, exotic Io - real estate agent's dream world," said Curnow. "We'll all be happy to miss you."
That sounds more like the old Walter, Floyd told himself. For the last few weeks, he had been oddly subdued, as if he had something on his mind. (But who did not?) He seemed to spend a good deal of his scanty free time in quiet discussions with Katerina: Floyd hoped that he had not developed some medical problem. They had been very lucky so far on that score; the last thing they needed at this stage was an emergency that required the Surgeon-Commander's expertise.
"You're being unkind, Walter," said Brailovsky. "I was beginning to like the place. It might be fun to go boating on those lava lakes."
"What about a volcano barbecue?"
"Or genuine molten sulphur baths?"
Everyone was lighthearted, even a little hysterical with relief. Though it was far too early to relax and the most critical phase of the escape manoeuvre still lay ahead, the first step had been safely taken on the long journey home. That was cause enough for a little modest rejoicing.
It did not last long, for Tanya quickly ordered all those not on essential duty to get some rest - if possible, some sleep - in preparation for the Jupiter swing-by only nine hours ahead. When those addressed were slow to move, Sasha cleared the decks by shouting, "You'll hang for this, you mutinous dogs!" Only two nights before, as a rare relaxation, they had all enjoyed the fourth version of Mutiny on the Bounty, generally agreed by movie historians to have the best Captain Bligh since the fabled Charles Laughton. There was some feeling on board that Tanya should not have seen it, lest it give her ideas.
After a couple of restless hours in his cocoon, Floyd abandoned the quest for sleep and wandered up to the observation deck. Jupiter was much larger and slowly waning as the ships hurtled toward their closest approach over the nightside. A glorious, gibbous disk, it showed such an infinite wealth of detail - cloud belts, spots of every colour from dazzling white to brick red, dark upwellings from the unknown depths, the cyclonic oval of the Great Red Spot -that the eye could not possibly absorb it all. The round, dark shadow of one moon - probably Europa, Floyd guessed - was in transit. He was seeing this incredible sight for the last time; even though he had to be at maximum efficiency in six hours, it was a crime to waste precious moments in sleep.
Where was that spot that Mission Control had asked them to observe? It should have been coming into view, but Floyd was not sure if it would be visible to the naked eye. Vasili would be too busy to bother about it; perhaps he could help by doing a little amateur astronomy. There had, after all, been a brief time, only thirty years ago, when he had earned his living as a professional.
He activated the controls of the main fifty-centimetre telescope - fortunately, the field of view was not blocked by the adjacent bulk of Discovery - and scanned along the equator at medium power. And there it was, just coming over the edge of the disk.
By force of circumstance, Floyd was now one of the Solar System's ten greatest experts on Jupiter; the other nine were working or sleeping around him. He saw at once that there was something very odd about this spot; it was so black that it looked like a hole punched through the clouds. From his point of view it appeared to be a sharp-edged ellipse; Floyd guessed that from directly above, it would be a perfect circle.
He recorded a few images, then increased the power to maxim
um. Already Jupiter's rapid spin had brought the formation into clearer view; and the more he stared, the more puzzled Floyd became.
"Vasili," he called over the intercom, "if you can spare a minute - have a look at the fifty-centimetre monitor."
"What are you observing? Is it important? I'm checking the orbit."
"Take your time, of course. But I've found that spot Mission Control reported. It looks very peculiar."
"Hell! I'd forgotten all about it. We're a fine lot of observers if those guys back on Earth have to tell us where to look. Give me another five minutes - it won't run away."
True enough, thought Floyd; in fact it will get clearer. And there was no disgrace in missing something that terrestrial - or lunar - astronomers had observed. Jupiter was very big, they had been very busy, and the telescopes on the Moon and in Earth orbit were a hundred times more powerful than the instrument he was using now.
But it was getting more and more peculiar. For the first time, Floyd began to feel a distinct sense of unease. Until that moment, it had never occurred to him that the spot could be anything but a natural formation - some trick of Jupiter's incredibly complex meteorology. Now he began to wonder.
It was so black, like night itself. And so symmetrical; as it came into clearer view it was obviously a perfect circle. Yet it was not sharply defined; the edge had an odd fuzziness, as if it was a little out of focus.
Was it imagination, or had it grown, even while he was watching? He made a quick estimate, and decided that the thing was now two thousand kilometres across. It was only a little smaller than the still-visible shadow of Europa, but was so much darker that there was no risk of confusion.
"Let's have a look," said Vasili, in a rather condescending tone. "What do you think you've found? Oh..." His voice trailed away into silence.
This is it, thought Floyd, with a sudden icy conviction. Whatever it may be.
47
Final Flyby
Yet on further reflection, after the initial amazement had worn off, it was hard to see how a spreading black stain on the face of Jupiter could represent any kind of danger. It was extraordinary - inexplicable - but not as important as the critical events now only seven hours in the future. A successful burn at perijove was all that mattered; they would have plenty of time to study mysterious black spots on the way home.
And to sleep; Floyd had given up all attempts at that.
Though the feeling of danger - at least, of known danger - was much less than on their first approach to Jupiter, a mixture of excitement and apprehension kept him wide awake. The excitement was natural and understandable; the apprehension had more complex causes. Floyd made it a rule never to worry about events over which he could have absolutely no control; any external threat would reveal itself in due time and be dealt with then. But he could not help wondering if they had done everything possible to safeguard the ships.
Apart from onboard mechanical failures, there were two main sources of concern. Although the tapes that secured Leonov and Discovery together had shown no tendency to slip, their severest test was still to come. Almost equally critical would be the moment of separation when the smallest of the explosive charges once intended to jolt Big Brother would be used at uncomfortably close quarters. And, of course, there was Hal.
He had carried out the deorbiting manoeuvre with exquisite precision. He had run the simulations of the Jupiter flyby, right down to Discovery's last drop of fuel, without any comments or objections. And although Chandra, as agreed, had carefully explained what they were trying to do, did Hal really understand what was happening?
Floyd had one overriding concern, which in the preceding few days had become almost an obsession. He could picture everything going perfectly, the ships halfway through the final manoeuvre, the enormous disk of Jupiter filling the sky only a few hundred kilometres below them - and then Hal electronically clearing his throat and saying:
"Dr Chandra, do you mind if I ask you a question?" It did not happen exactly that way.
The Great Black Spot, as it had been inevitably christened, was now being carried out of sight by Jupiter's swift rotation. In a few hours the still-accelerating ships would catch up with it over the nightside of the planet, but this was the last chance for a close daylight observation.
It was still growing at an extraordinary speed; in the last two hours, it had more than doubled its area. Except for the fact that it retained its blackness as it expanded, it resembled an ink-stain spreading in water. Its boundary - now moving at near-sonic speed in the Jovian atmosphere - still looked curiously fuzzy and out of focus; at the very highest power of the ship's telescope, the reason for this was at last apparent.
Unlike the Great Red Spot, the Great Black Spot was not a continuous structure; it was built up from myriads of tiny dots, like a half-tone print viewed through a magnifying glass. Over most of its area, the dots were so closely spaced that they were almost touching, but at the rim they became more and more widely spaced, so that the Spot ended in a grey penumbra rather than at a sharp frontier.
There must have been almost a million of the mysterious dots, and they were distinctly elongated - ellipses rather than circles. Katerina, the least imaginative person aboard, surprised everybody by saying that it looked as if someone had taken a sackful of rice, dyed it black, and poured it on the face of Jupiter.
And now the Sun was dropping down behind the huge, swiftly narrowing arch of the dayside, as for the second time Leonov raced into the Jovian night for an appointment with destiny. In less than thirty minutes the final burn would commence, and things would start to happen very quickly indeed.
Floyd wondered if he should have joined Chandra and Curnow, standing watch on Discovery. But there was nothing he could do; in an emergency, he would only be in the way. The cut-off switch was in Curnow's pocket, and Floyd knew that the younger man's reactions were a good deal swifter than his own. If Hal showed the slightest sign of misbehaviour, he could be disconnected in less than a second, but Floyd felt certain that such extreme measures would not be necessary. Since he had been allowed to do things his own way, Chandra had cooperated completely in setting up the procedures for a manual takeover, should that unfortunate necessity arise. Floyd was confident that he could be trusted to carry out his duty - however much he might regret the need.
Curnow was not quite so sure. He would be happier, he had told Floyd, if he had multiple redundancy in the form of a second cut-off switch - for Chandra. Meanwhile there was nothing that anyone could do but wait and watch the approaching cloudscape of the nightside, dimly visible by the reflected light of passing satellites, the glow of photo-chemical reactions, and frequent titanic lightning flashes from thunderstorms larger than Earth.
The sun winked out behind them, eclipsed in seconds by the immense globe they were so swiftly approaching. When they saw it again, they should be on their way home.
"Twenty minutes to ignition. All systems nominal."
"Thank you, Hal."
I wonder if Chandra was being quite truthful, thought Curnow, when he said that Hal would be confused if anyone else spoke to him. I've talked to him often enough, when nobody was around, and he always understood me perfectly. Still, there's not much time left for friendly conversation now, though it would help to reduce the strain.
What's Hal really thinking - if he thinks - about the mission? All his life, Curnow had shied away from abstract, philosophical questions: I'm a nuts-and-bolts man, he had often claimed, though there were not too many of either in a spaceship. Once, he would have laughed at the idea, but now he began to wonder: Did Hal sense that he would soon be abandoned, and if so, would he resent it? Curnow almost reached for the cut-off switch in his pocket, but checked himself. He had already done this so often that Chandra might be getting suspicious.
For the hundredth time, he rehearsed the sequence of events that were due to take place during the next hour. The moment that Discovery's fuel was exhausted, they would close down all but
essential systems, and dash back to Leonov through the connecting tube. That would be decoupled, the explosive charges would be fired, the ships would drift apart - and Leonov's own engines would start to fire. The separation should take place, if everything went according to plan, just when they were making their closest approach to Jupiter; that would take maximum advantage of the planet's gravitational largesse.
"Fifteen minutes to ignition. All systems nominal."
"Thank you, Hal."
"By the way," said Vasili, from the other ship, "we're catching up with the Great Black Spot again. Wonder if we can see anything new."
I rather hope not, thought Curnow; we've got quite enough on our hands at the moment. Nevertheless, he gave a quick glance at the image Vasili was transmitting on the telescope monitor.
At first he could see nothing except the faintly glimmering nightside of the planet; then he saw, on the horizon, a foreshortened circle of deeper darkness. They were rushing toward it with incredible speed.
Vasili increased the light amplification, and the entire image brightened magically. At last, the Great Black Spot resolved itself into its myriad identical elements.
My God, thought Curnow, I just don't believe it!
He heard exclamations of surprise from Leonov: all the others had shared in the same revelation at the same moment.
"Dr Chandra," said Hal, "I detect strong vocal stress patterns. Is there a problem?"
"No, Hal," Chandra answered quickly. 'The mission is proceeding normally. We've just had rather a surprise - that's all. What do you make of the image on monitor circuit 16?"
"I see the nightside of Jupiter. There is a circular area, 3,250 kilometres in diameter, which is almost compietely covered with rectangular objects."
"How many?"
There was the briefest of pauses, before Hal flashed the number on the video display: