2010: Odyssey Two

Authur C. Clarke

Dedicated, with respectful admiration, to two great Russians, both depicted herein:

General Alexei Leonov - Cosmonaut, Hero of the Soviet Union, Artist

and

Academician Andrei Sakharov - Scientist, Nobel Laureate, Humanist.

Author’s Note

The novel 2001: A Space Odyssey was written during the years 1964-8 and was published in July 1968, shortly after release of the movie. As I have described in The Lost Worlds of 2001, both projects proceeded simultaneously, with feedback in each direction. Thus I often had the strange experience of revising the manuscript after viewing rushes based upon an earlier version of the story - a stimulating, but rather expensive, way of writing a novel.

As a result, there is a much closer parallel between book and movie than is usually the case, but there are also major differences. In the novel, the destination of the spaceship Discovery was Iapetus (or Japetus), most enigmatic of Saturn’s many moons. The Saturnian system was reached via Jupiter: Discovery made a close approach to the giant planet, using its enormous gravitational field to produce a “slingshot” effect and to accelerate it along the second lap of its journey. Exactly the same manoeuvre was used by the Voyager space probes in 1979, when they made the first detailed reconnaissance of the outer giants.

In the movie, however, Stanley Kubrick wisely avoided confusion by setting the third confrontation between Man and Monolith among the moons of Jupiter. Saturn was dropped from the script entirely, though Douglas Trumbull later used the expertise he had acquired to film the ringed planet in his own production, Silent Running.

No one could have imagined, back in the mid-sixties, that the exploration of the moons of Jupiter lay, not in the next century, but only fifteen years ahead. Nor had anyone dreamed of the wonders that would be found there - although we can be quite certain that the discoveries of the twin Voyagers will one day be surpassed by even more unexpected finds. When 2001 was written, Io, Europa, Ganymede, and Callisto were mere pinpoints of light in even the most powerful telescope; now they are worlds, each unique, and one of them - Io - is the most volcanically active body in the Solar System.

Yet, all things considered, both movie and book stand up quite well in the light of these discoveries, and it is fascinating to compare the Jupiter sequences in the film with the actual movies from the Voyager cameras. But clearly, anything written today has to incorporate the results of the 1979 explorations: the moons of Jupiter are no longer uncharted territory.

And there is another, more subtle, psychological factor to be taken into consideration. 2001 was written in an age that now lies beyond one of the Great Divides in human history; we are sundered from it forever by the moment when Neil Armstrong set foot upon the Moon. The date 20 July 1969 was still half a decade in the future when Stanley Kubrick and I started thinking about the “proverbial good science-fiction movie” (his phrase). Now history and fiction have become inextricably intertwined.

The Apollo astronauts had already seen the film when they left for the Moon. The crew of Apollo 8, who at Christmas 1968 became the first men ever to set eyes upon the Lunar Farside, told me that they had been tempted to radio back the discovery of a large black monolith: alas, discretion prevailed.

And there were, later, almost uncanny instances of nature imitating art. Strangest of all was the saga of Apollo 13 in 1970.

As a good opening, the Command Module, which houses the crew, had been christened Odyssey, Just before the explosion of the oxygen tank that caused the mission to be aborted, the crew had been playing Richard Strauss’s Zarathustra theme, now universally identified with the movie. Immediately after the loss of power, Jack Swigert radioed back to Mission Control: “Houston, we’ve had a problem.” The words that Hal used to astronaut Frank Poole on a similar occasion were: “Sorry to interrupt the festivities, but we have a problem.”

When the report of the Apollo 13 mission was later published, NASA Administrator Tom Paine sent me a copy, and noted under Swigert’s words: “Just as you always said it would be, Arthur.” I still get a very strange feeling when I contemplate this whole series of events - almost, indeed, as if I share a certain responsibility.

Another resonance is less serious, but equally striking. One of the most technically brilliant sequences in the movie was that in which Frank Poole was shown running round and round the circular trick of the giant centrifuge, held in place by the “artificial gravity” produced by its spin.

Almost a decade later, the crew of the superbly successful Skylab realized that its designers had provided them with a similar geometry; a ring of storage cabinets formed a smooth, circular hand around the space station’s interior. Skylab, however, was not spinning, but this did not.deter its ingenious occupants. They discovered that they could run around the track, just like mice in a squirrel cage, to produce a result visually indistinguishable from that shown in 2001. And they televised the whole exercise back to Earth (need I name the accompanying music?) with the comment:

“Stanley Kubrick should see this.” As in due course he did, because I sent him the telecine recording. (I never got it back; Stanley uses a tame Black Hole as a filing system.)

Yet another link between film and reality is the painting by Apollo-Soyuz Commander, Cosmonaut Alexei Leonov, “Near the Moon”. I first saw it in 1968, when 2001 was presented at the United Nations Conference on the Peaceful Uses of Outer Space. Immediately after the screening, Alexei pointed out to me that his concept (on page 32 of the Leonov-Sokolov book The Stars Are Awaiting Us, Moscow, 1967) shows exactly the same line-up as the movie’s opening: the Earth rising beyond the Moon, and the Sun rising beyond them both. His autographed sketch of the painting now hangs on my office wall; for further details see Chapter 12.

Perhaps this is the appropriate point to identify another and less well-known name appearing in these pages, that of Hsue-shen Tsien. In 1936, with the great Theodore von Karman and Frank J. Malina, Dr Tsien founded the Guggenheim Aeronautical Laboratory of the California Institute of Technology (GALCIT) - the direct ancestor of Pasadena’s famed Jet Propulsion Laboratory. He was also the first Goddard Professor at Caltech, and contributed greatly to American rocket research through the 1940s. Later, in one of the most disgraceful episodes of the McCarthy period, he was arrested on trumped-up security charges when he wished to return to his native country. For the last two decades, he has been one of the leaders of the Chinese rocket programme.

Finally, there is the strange case of the ‘Eye of Japetus’ - Chapter 35 of 2001. Here I describe astronaut Bowman’s discovery on the Saturnian moon of a curious feather ‘a brilliant white oval, about four hundred miles long and two hundred wide... perfectly symmetrical... and so sharp-edged that it almost looked... painted on the face of the little moon.’ As he came closer, Bowman convinced himself that ‘the bright ellipse set against the dark background of the satellite was a huge empty eye staring at him as he approached...’ Later, he noticed ‘the tiny black dot at the exact centre’, which turns out to be the Monolith (or one of its avatars).

Well, when Voyager 1 transmitted the first photographs of Iapetus, they did indeed disclose a large, clear-cut white oval with a tiny black dot at the centre. Carl Sagan promptly sent me a print from the Jet Propulsion Laboratory with the cryptic annotation “Thinking of you...” I do not know whether to be relieved or disappointed that Voyager 2 has left the matter still open.

Inevitably, therefore, the story you are about to read is something much more complex than a straightforward sequel to the earlier novel - or the movie. Where these differ, I have followed the screen version; however, I have been more concerned with making this book self-consistent, and as accurate as possible in the light of current knowledge.

Which, of course, will once more be out of date by 2001...

Arthur C. Clarke

COLOMBO, SRI LANKA

JANUARY 1982

I: LEONOV

1

Meeting at the Focus

Even in this metric age, it was still the thousand-foot telescope, not the three-hundred-metre one. The great saucer set among the mountains was already half full of shadow, as the tropical sun dropped swiftly to rest, but the triangular raft of the antenna complex suspended high above its centre still blazed with light. From the ground far below, it would have taken keen eyes to notice the two human figures in the aerial maze of girders, support cables, and wave-guides.

“The time has come,” said Dr Dimitri Moisevitch to his old friend Heywood Floyd, “to talk of many things. Of shoes and spaceships and sealing wax, but mostly of monoliths and malfunctioning computers.”

“So that’s why you got me away from the conference. Not that I really mind - I’ve heard Carl give that SETI speech so many times that I can recite it myself. And the view certainly is fantastic - you know, all the times I’ve been to Arecibo, I’ve never made it up here to the antenna feed.”

“Shame on you. I’ve been here three times. Imagine - we’re listening to the whole universe - but no one can overhear us. So let’s talk about your problem.”

“What problem?”

“To start with, why you had to resign as Chairman of the National Council on Astronautics.”

“I didn’t resign. The University of Hawaii pays a lot better.”

“Okay - you didn’t resign - you were one jump ahead of them. After all these years, Woody, you can’t fool me, and you should give up trying. If they offered the NCA back to you right now, would you hesitate?”

“All right, you old Cossak. What do you want to know?”

“First of all, there are lots of loose ends in the report you finally issued after so much prodding. We’ll overlook the ridiculous and frankly illegal secrecy with which your people dug up the Tycho monolith—”

“That wasn’t my idea.”

“Glad to hear it: I even believe you. And we appreciate the fact that you’re now letting everyone examine the thing - which of course is what you should have done in the first place. Not that it’s done much good…”

There was a gloomy silence while the two men contemplated the black enigma up there on the Moon, still contemptuously defying all the weapons that human ingenuity could bring to bear upon it. Then the Russian scientist continued.

“Anyway, whatever the Tycho monolith may be, there’s something more important out at Jupiter. That’s where it sent its signal, after all. And that’s where your people ran into trouble. Sorry about that, by the way - though Frank Poole was the only one I knew personally. Met him at the ‘98 IAF Congress - he seemed a good man.”

“Thank you; they were all good men. I wish we knew what happened to them.”

“Whatever it was, surely you’ll admit that it now concerns the whole human race - not merely the United States. You can no longer try to use your knowledge for purely national advantage.”

“Dimitri - you know perfectly well that your side would have done exactly the same thing. And you’d have helped.”

“You’re absolutely right. But that’s ancient history - like the just-departed administration of yours that was responsible for the whole mess. With a new President, perhaps wiser counsels will prevail.”

“Possibly. Do you have any suggestions, and are they official or just personal hopes?”

“Entirely unofficial at the moment. What the bloody politicians call exploratory talks. Which I shall flatly deny ever occurred.”

“Fair enough. Go on.”

“Okay - here’s the situation. You’re assembling Discovery 2 in parking orbit as quickly as you can, but you can’t hope to have it ready in less than three years, which means you’ll miss the next launch window.”

“I neither confirm nor deny. Remember I’m merely a humble university chancellor, the other side of the world from the Astronautics Council.”

“And your last trip to Washington was just a holiday to see old friends, I suppose. To continue: our own Alexei Leonov—

“I thought you were calling it Gherman Titov.”

“Wrong, Chancellor. The dear old CIA’s let you down again. Leonov it is, as of last January. And don’t let anyone know I told you it will reach Jupiter at least a year ahead of Discovery.”

“Don’t let anyone know I told you we were afraid of that. But do go on.”

“Because my bosses are just as stupid and shortsighted as yours, they want to go it alone. Which means that whatever went wrong with you may happen to us, and we’ll all be back to square one - or worse.”

“What do you think went wrong? We’re just as baffled as you are. And don’t tell me you haven’t got all of Dave Bowman’s transmissions.”

“Of course we have. Right up to that last ‘My God, it’s full of stars!’ “ We’ve even done a stress analysis on his voice patterns. We don’t think he was hallucinating; he was trying to describe what he actually saw.”

“And what do you make of his doppler shift?”

“Completely impossible, of course. When we lost his signal, he was receding at a tenth of the speed of light. And he’d reached that in less than two minutes. A quarter of a million gravities!”

“So he must have been killed instantly.”

“Don’t pretend to be naive, Woody. Your space-pod radios aren’t built to withstand even a hundredth of that acceleration. If they could survive, so could Bowman - at least, until we lost contact.”

“Just doing an independent check on your deductions. From there on, we’re as much in the dark as you are. If you are.”

“Merely playing with lots of crazy guesses I’d be ashamed to tell you. Yet none of them, I suspect, will be half as crazy as the truth.”

In small crimson explosions the navigation warning lights winked on all around them, and the three slim towers supporting the antenna complex began to blaze like beacons against the darkling sky. The last red sliver of the sun vanished below the surrounding hills; Heywood Floyd waited for the Green Flash, which he had never seen. Once again, he was disappointed.

“So, Dimitri,” he said, “let’s get to the point. Just what are you driving at?”

“There must be a vast amount of priceless information stored in Discovery’s data banks; presumably it’s still being gathered, even though the ship’s stopped transmitting. We’d like to have that.”

“Fair enough. But when you get out there, and Leonov makes a rendezvous, what’s to prevent you from boarding Discovery and copying everything you want?”

“I never thought I’d have to remind you that Discovery is United States territory, and an unauthorized entry would be piracy.”

“Except in the event of a life-or-death emergency, which wouldn’t be difficult to arrange. After all, it would be hard for us to check what your boys were up to, from a billion kilometres away.”

“Thanks for the most interesting suggestion; I’ll pass it on. But even if we went aboard, it would take us weeks to learn all your systems, and read out all your memory banks. What I propose is cooperation. I’m convinced that’s the best idea - but we may both have a job selling it to our respective bosses.”

“You want one of our astronauts to fly with Leonov?”

“Yes - preferably an engineer who’s specialized in Discovery’s systems. Like the ones you’re training at Houston to bring the ship home.”

“How did you know that?”

“For heaven’s sake, Woody - it was on Aviation Week’s videotext at least a month ago.”

“I am out of touch; nobody tells me what’s been declassified.”

“All the more reason to spend time in Washington. Will you back me up?”

“Absolutely. I agree with you one hundred per cent. But—”

“But what?”

“We both have to deal with dinosaurs with brains in their tails. Some of mine will argue: Let the Russians risk their necks, hurrying out to Jupiter. We’ll be there anyway a couple of years later - and what’s the hurry?”

For a moment there was silence on the antenna raft, except for a faint creak from the immense supporting cables that held it suspended a hundred metres in the sky. Then Moisevitch continued, so quietly that Floyd had to strain to hear him: ‘Has anyone checked Discovery’s orbit lately?”

“I really don’t know - but I suppose so. Anyway, why bother? It’s a perfectly stable one.”

“Indeed. Let me tactlessly remind you of an embarrassing incident from the old NASA days. Your first space station - Skylab. It was supposed to stay up at least a decade, but you didn’t do your calculations right. The air drag in the ionosphere was badly underestimated, and it came down years ahead of schedule. I’m sure you remember that little cliffhanger, even though you were a boy at the time.”

“It was the year I graduated, and you know it. But Discovery doesn’t go anywhere near Jupiter. Even at perigee - er, perijove - it’s much too high to be affected by atmospheric drag.”

“I’ve already said enough to get me exiled to my dacha again - and you might not be allowed to visit me next time. So just ask your tracking people to do their job more carefully, will you? And remind them that Jupiter has the biggest magnetosphere in the Solar System.”

“I understand what you’re driving at - many thanks. Anything else before we go down? I’m starting to freeze.”

“Don’t worry, old friend. As soon as you let all this filter through to Washington - wait a week or so until I’m clear -things are going to get very, very hot.”

2

The House of the Dolphins

The dolphins swam into the dining room every evening, just before sunset. Only once since Floyd had occupied the Chancellor’s residence had they broken their routine. That was the day of the ‘05 tsunami, which, fortunately, had lost most of its power before it reached Hilo. The next time his friends failed to turn up on schedule, Floyd would throw the family into the car and head for high ground, in the general direction of Mauna Kea.

Charming though they were, he had to admit that their playfulness was sometimes a nuisance. The wealthy marine geologist who had designed the house had never minded getting wet because he usually wore bathing trunks - or less. But there had been one unforgettable occasion when the entire Board of Regents, in full evening attire, had been sipping cocktails around the pool while awaiting the arrival of a distinguished guest from the mainland. The dolphins had deduced, correctly, that they would get second billing. So the visitor was quite surprised to be greeted by a bedraggled committee in ill-fitting bathrobes - and the buffet had been very salty.

Floyd often wondered what Marion would have thought of his strange and beautiful home on the edge of the Pacific. She had never liked the sea, but the sea had won in the end. Though the image was slowly fading, he could still recall the flashing screen on which he had first read the words: DR FLOYD - URGENT AND PERSONAL. And then the scrolling lines of fluorescent print that had swiftly burned their message into his mind:

REGRET TO INFORM YOU LONDON-WASHINGTON FLIGHT 452 REPORTED DOWN OFF NEWFOUNDLAND. RESCUE CRAFT PROCEEDING TO LOCATION BUT FEAR NO SURVIVORS.

Apart from an accident of fate, he would have been on that flight. For a few days, he had almost regretted the European Space Administration business that had delayed him in Paris; that haggle over the Solaris payload had saved his life.

And now, he had a new job, a new home and a new wife. Fate had also played an ironic role here. The recriminations and inquiries over the Jupiter mission had destroyed his Washington career, but a man of his ability was never unemployed for long. The more leisurely tempo of university life had always appealed to him, and when combined with one of the world’s most beautiful locations it had proved irresistible. He had met the woman who was to be his second wife only a month after he had been appointed, while watching the fire fountains of Kilauea with a crowd of tourists.

With Caroline he had found the contentment that is just as important as happiness, and longer lasting. She had been a good stepmother to Marion’s two daughters, and had given him Christopher. Despite the twenty-year age difference between them, she understood his moods and could wean him out of his occasional depressions. Thanks to her, he could now contemplate the memory of Marion without grief, though not without a wistful sadness that would remain with him for the rest of his life.

Caroline was throwing fish to the largest dolphin - the big male they called Scarback - when a gentle tickling on Floyd’s wrist announced an incoming call. He tapped the slim metal band to quench the silent alarm and forestall the audible one, then walked to the nearest of the comsets scattered around the room.

“Chancellor here. Who’s calling?”

“Heywood? This is Victor. How are you?”

In a fraction of a second, a whole kaleidoscope of emotions flashed through Floyd’s mind. First there was annoyance: his successor - and, he was sure, principal contriver of his downfall - had never once attempted to contact him since his departure from Washington. Then came curiosity: what did they have to talk about? Next was a stubborn determination to be as unhelpful as possible, then shame at his own childishness, and, finally, a surge of excitement. Victor Millson could be calling for only one reason.

In as neutral a voice as he could muster, Floyd answered:

“I can’t complain, Victor. What’s the problem?”

“Is this a secure circuit?”

“No, thank God. I don’t need them any more.”

“Um. Well, I’ll put it this way. You recall the last project you administered?”

“I’m not likely to forget, especially as the Subcommittee on Astronautics called me back to give more evidence only a month ago.”

“Of course, of course. I really must get around to reading your statement, when I have a moment. But I’ve been so busy with the follow-up, and that’s the problem.”

“I thought that everything was right on schedule.”

“It is - unfortunately. There’s nothing we can do to advance it; even the highest priority would make only a few weeks’ difference. And that means we’ll be too late.”

“I don’t understand,” said Floyd innocently. “Though we don’t want to waste time, of course, there’s no real deadline.”

“Now there is - and two of them.”

“You amaze me.”

If Victor noticed any irony, he ignored it. “Yes, there are two deadlines - one man-made, one not. It now turns out that we won’t be the first to get back to the - er, scene of the action. Our old rivals will beat us by at least a year.”

“Too bad.”

“That’s not the worst. Even if there were no competition, we’d be too late. There wouldn’t be anything there when we arrive.”

“That’s ridiculous. I’m sure I’d have heard if Congress had repealed the law of gravitation.”

“I’m serious. The situation isn’t stable - I can’t give details now. Will you be in for the rest of the evening?”

“Yes,” Floyd answered, realizing with some pleasure that it must now be well after midnight in Washington.

“Good. You’ll have a package delivered within the hour. Call me back as soon as you’ve had the time to study it.”

“Won’t it be rather late by then?”

“Yes, it will be. But we’ve wasted too much time already. I don’t want to lose any more.”

Millson was true to his word. Exactly an hour later a large sealed envelope was delivered by an Air Force colonel, no less, who sat patiently chatting with Caroline while Floyd read its contents. “I’m afraid I’ll have to take it away when you’ve finished,” the high-ranking messenger boy said apologetically.

“I’m glad to hear it,” Floyd answered, as he settled down in his favourite reading hammock.

There were two documents, the first very short. It was stamped TOP SECRET, though the TOP had been crossed out and the modification endorsed by three signatures, all completely illegible. Obviously an extract from some much longer report, it had been heavily censored and was full of blanks, which made it most annoying to read. Fortunately, its conclusions could be summed up in one sentence: The Russians would reach Discovery long before its rightful owners could do so. As Floyd already knew this, he turned quickly to the second document - though not before noticing with satisfaction that this time they’d managed to get the name right. As usual, Dimitri had been perfectly accurate. The next manned expedition to Jupiter would travel aboard spacecraft Cosmonaut Alexei Leonov.

The second document was much longer and was merely confidential; indeed, it was in the form of a draft letter to Science, awaiting final approval before publication. Its snappy title was ‘Space Vehicle Discovery: Anomalous Orbital Behavior’.

Then followed a dozen pages of mathematics and astronomical tables. Floyd skimmed through these, picking out the words from the music, and trying to detect any note of apology or even embarrassment. When he had finished, he was compelled to give a smile of wry admiration. No one could possibly guess that the tracking stations and ephemeris calculators had been caught by surprise, and that a frantic cover-up was in progress. Heads would doubtless roll, and he knew that Victor Millson would enjoy rolling them - if his was not one of the first to go. Though to do him justice, Victor had complained when Congress had cut funds for the tracking network. Maybe that would get him off the hook.

“Thank you, Colonel,” said Floyd when he had finished skimming the papers. “Quite like old times, having classified documents. That’s one thing I don’t miss.”

The colonel placed the envelope carefully back in his briefcase, and activated the locks.

“Dr Millson would like you to return his call as soon as possible.”

“I know. But I don’t have a secure circuit, I’ve some important visitors coming shortly, and I’m damned if I’m driving down to your office in Hilo just to say I’ve read two documents. Tell him that I’ve studied them carefully and await any further communication with interest.”

For a moment it looked as if the colonel was going to argue. Then he thought better of it, made a stiff farewell, and departed morosely into the night.

“Now, what was all that about?” asked Caroline. “We’re not expecting any visitors tonight, important or otherwise.”

“I hate being pushed around, particularly by Victor Millson.”

“Bet he calls you back as soon as the colonel reports.”

“Then we must switch off video and make some party noises. But to be perfectly truthful, at this stage I really don’t have anything to say.”

“About what, if I’m allowed to ask.”

“Sorry, dear. It seems that Discovery is playing tricks on us. We thought the ship was in a stable orbit, but it may be about to crash.”

“Into Jupiter?”

“Oh no - that’s quite impossible. Bowman left it parked at the inner Lagrange point, on the line between Jupiter and Io. It should have stayed there, more or less, though the perturbations of the outer moons would have made it wander back and forth.

“But what’s happening now is something very odd, and we don’t know the full explanation. Discovery’s drifting more and more rapidly toward Io - though sometimes it accelerates, and sometimes even moves backward. If it keeps this up, it will impact within two or three years.”

“I thought this couldn’t happen in astronomy. Isn’t celestial mechanics supposed to be an exact science? So we poor backward biologists were always being told.”

“It is an exact science, when everything is taken into account. But some very strange things go on around Io. Apart from its volcanoes, there are tremendous electrical discharges - and Jupiter’s magnetic field is spinning round every ten hours. So gravitation isn’t the only force acting on Discovery; we should have thought of this sooner - much sooner.”

“Well, it’s not your problem anymore. You should be thankful for that.”

“Your problem” - the very expression that Dimitri had used. And Dimitri - cunning old fox! - had known him much longer than Caroline.

It might not be his problem, but it was still his responsibility. Though many others had been involved, in the final analysis he had approved the plans for the Jupiter Mission, and supervised their execution.

Even at the time, he had had qualms; his views as a scientist had conflicted with his duties as a bureaucrat. He could have spoken out, and opposed the old administration’s shortsighted policies - though to what extent those had actually contributed to the disaster was still uncertain.

Perhaps it was best if he closed this chapter of his life, and focused all his thoughts and energies upon his new career. But in his heart he knew that was impossible; even if Dimitri had not revived old guilts, they would have surfaced of their own accord.

Four men had died, and one had disappeared, out there among the moons of Jupiter. There was blood on his hands, and he did not know how to wash them clean.

3

SAL 9000

Dr Sivasubramanian Chandrasegarampillai, Professor of Computer Science at the University of Illinois, Urbana, also had an abiding sense of guilt, but one very different from Heywood Floyd’s. Those of his students and colleagues who often wondered if the little scientist was quite human would not have been surprised to learn that he never thought of the dead astronauts. Dr Chandra grieved only for his lost child, HAL 9000.

Even after all these years, and his endless reviews of the data radioed back from Discovery, he was not sure what had gone wrong. He could only formulate theories; the facts he needed were frozen in Hal’s circuits, out there between Jupiter and Io.

The sequence of events had been clearly established, up to the moment of the tragedy; thereafter, Commander Bowman had filled in a few more details on the brief occasions when he had re-established contact. But knowing what happened did not explain why.

The first hint of trouble had been late in the mission, when Hal had reported the imminent failure of the unit that kept Discovery’s main antenna aligned to Earth. If the half-billion-kilometre-long radio beam wandered off target, the ship would be blind, deaf, and dumb.

Bowman himself had gone out to retrieve the suspect unit, but when it was tested it appeared, to everyone’s surprise, to be in perfectly good order. The automatic checking circuits could find nothing wrong with it. Nor could Hal’s twin, SAL 9000, back on Earth, when the information was transmitted to Urbana.

But Hal had insisted on the accuracy of his diagnosis, making pointed remarks about ‘human error’. He had suggested that the control unit be put back in the antenna until it finally failed, so that the fault could be precisely located. No one could think of any objection, for the unit could be replaced in minutes, even if it did break down.

Bowman and Poole, however, had not been happy; they both felt that something was wrong, though neither could pinpoint it. For months they had accepted Hal as the third member of their tiny world, and knew his every mood. Then the atmosphere aboard the ship had subtly altered; there was a sense of strain in the air.

Feeling rather like traitors - as a distraught Bowman had later reported to Mission Control - the human two-thirds of the crew had discussed what should be done if their colleague was indeed malfunctioning. In the worst possible case, Hal would have to be relieved of all his higher responsibilities. This would involve disconnection - the computer equivalent of death.

Despite their doubts, they had carried out the agreed programme. Poole had flown out of Discovery in one of the little space pods that served as transporters and mobile workshops during extravehicular activities. Since the somewhat tricky job of replacing the antenna unit could not be performed by the pod’s own manipulators, Poole had started to do it himself.

What happened then had been missed by the external cameras, which was a suspicious detail in itself. Bowman’s first warning of disaster was a cry from Poole - then, silence. A moment later he saw Poole, tumbling over and over, spinning away into space. His own pod had rammed him, and was itself blasting away out of control.

As Bowman admitted later, he had then made several serious mistakes - all but one excusable. In the hope of rescuing Poole, if he was still alive, Bowman launched himself in another space pod - leaving Hal in full control of the ship.

The EVA was in vain; Poole was dead when Bowman reached him. Numb with despair, he had carried the body back to the ship - only to be refused entry by Hal.

But Hal had underestimated human ingenuity and determination. Though he had left his suit helmet in the ship, and thus had to risk direct exposure to space, Bowman forced his way in by an emergency hatch not under computer control. Then he proceeded to lobotomize Hal, unplugging his brain modules one by one.

When he regained control of the ship, Bowman made an appalling discovery. During his absence, Hal had switched off the life-support systems of the three hibernating astronauts. Bowman was alone, as no man had ever been before in the whole of human history.

Others might have abandoned themselves in helpless despair, but now David Bowman proved that those who had selected him had indeed chosen well. He managed to keep Discovery operational, and even re-established intermittent contact with Mission Control, by orienting the whole ship so that the jammed antenna pointed toward Earth.

On its preordained trajectory, Discovery had finally arrived at Jupiter. There Bowman had encountered, orbiting among the moons of the giant planet, a black slab of exactly the same shape as the monolith excavated in the lunar crater Tycho - but hundreds of times larger. He had gone out in a space pod to investigate, and had disappeared leaving that final, baffling message: “My God, it’s full of stars!”

That mystery was for others to worry about; Dr Chandra’s overwhelming concern was with Hal. If there was one thing his unemotional mind hated, it was uncertainty. He would never be satisfied until he knew the cause of Hal’s behaviour. Even now, he refused to call it a malfunction; at most, it was an ‘anomaly’.

The tiny cubbyhole he used as his inner sanctum was equipped only with a swivel chair, a desk console, and a blackboard flanked by two photographs. Few members of the general public could have identified the portraits, but anyone permitted thus far would have recognized them instantly as John von Neumann and Alan Turing, the twin gods of the computing pantheon.

There were no books, and not even paper and pencil on the desk. All the volumes in all the libraries of the world were instantly available at the touch of Chandra’s fingers, and the visual display was his sketchbook and writing pad. Even the blackboard was used only for visitors; the last half - erased block diagram upon it bore a date already three weeks in the past.

Dr Chandra lit one of the venomous cheroots which he imported from Madras, and which were widely - and correctly - believed to be his only vice. The console was never switched off he checked that no messages were flashing importantly on the display, then spoke into the microphone.

“Good morning, Sal. So you’ve nothing new for me?”

“No, Dr Chandra. Have you anything for me?”