2010: Odyssey Two

First look at a new novel

part two

In part one of 2010: Odyssey Two (the sequel to 2001: A Space Odyssey), featured in our September issue, Russian and American scientists joined forces to travel to Jupiter to retrieve the spacecraft Discovery.

Mission Profile English Version

To: Captain Tanya Orlov, Commander, Spacecraft Cosmonaut Alexei Leonov

From: U.S. National Council on Astronautics, Pennsylvania Avenue, Washington, D.C.

Commission on Outer Space, U.S.S.R. Academy of Science, Korolyov Prospect, Moscow

Mission Objectives

The objectives of (continued on page 190) 2010 (continued from page 157) your mission are:

1. To proceed to the Jovian system and rendezvous with U.S. spacecraft Discovery;

2. To board this spacecraft and obtain all possible information relating to its earlier mission;

3. To reactivate spacecraft Discovery's on-board systems and, if propellant supplies are adequate, inject the ship into an Earth-return trajectory;

4. To locate the Jupiter monolith encountered by Discovery and to investigate it to the maximum extent possible by remote sensors;

5. If it seems advisable and Mission Control concurs, to rendezvous with this object for closer inspection;

6. To carry out a survey of Jupiter and its satellites, as far as this is compatible with the above objectives.

It is realized that unforeseen circumstances may require a change of priorities or even make it impossible to achieve some of these objectives. It must be clearly understood that the rendezvous with spacecraft Discovery is for the express purpose of obtaining information about the monolith; this must take precedence over all other objectives, including attempts at salvage.

Crew

The crew of spacecraft Alexei Leonov will consist of:

Captain Tanya Orlov (Engineering/Propulsion)

Dr. Vasili Orlov (Navigation/Astronomy)

Dr. Maxim Brailovsky (Engineering/Structures)

Dr. Alexander (Sasha) Kovalev (Engineering/Communications)

Dr. Nikolai Ternovsky (Engineering/Control Systems)

Surgeon-Commander Katerina Rudenko (Medical/Life Support)

Dr. Irina Yakunin (Medical/Nutrition)

In addition, the U.S. National Council on Astronautics will provide the following three experts:

Dr. Sivasubramanian Chandrasegar-ampillai (Engineering/Computer Systems)

Dr. Walter Curnow (Engineering/Control Systems)

Dr. Heywood Floyd (Technical Advisor)

Dr. Heywood Floyd's Log

We felt we deserved a party once we'd successfully rendezvoused with Discovery.

Who would have believed that we'd come all the way to Jupiter, greatest of planets--and then ignore it? Yet that's what we're doing most of the time, and when we're not looking at Jupiter's moon Io or at Discovery, we're thinking about the--monolith; Big Brother, we call it now.

It's still 10,000 kilometers away, up there at the libration point, but when I look at it through the main telescope, it seems close enough to touch. Because it's so completely featureless, there's no indication of size, no way the eye can judge it's really a couple of kilometers long. If it's solid, it must weigh billions of tons.

But is it solid? It gives no radar echo, even when it's square on to us. We can see it only as a black silhouette against the clouds of Jupiter, 300,000 kilometers below. Apart from its size, it looks exactly like the monolith we dug up on the Moon....

Tomorrow, we'll go aboard Discovery and bring it back to life. And then we'll attempt to uncover the secret of the monolith.

•

When Discovery suddenly lit up like the proverbial Christmas tree, navigation and interior lights blazing from end to end, the cheer aboard Leonov might almost have been heard across the vacuum between the two ships.

"Hello, Leonov," said Walter Curnow, at last. "Sorry to keep you waiting, but we've been rather busy.

"Here's a quick assessment, judging from what we've seen so far. The ship's in much better shape than I feared. Hull's intact, leakage negligible--air pressure eighty-five percent nominal. Quite breathable.

"The best news is that the power systems are OK. Main reactor stable, batteries in good shape. Almost all the circuit breakers were open--they'd jumped or been thrown by Bowman before he left--so all vital equipment's been safeguarded. But it will be a very big job checking everything before we have full power again."

"How long will that take, at least for the essential systems--life support, propulsion?" Tanya asked.

"If we don't run into any major snags, we can haul Discovery up to a stable orbit--oh, I'd say inside a week."

"And HAL?"

"I'd say Dr. Chandra has quite a lot of work to do."

"What is it?" Curnow asked Floyd with mild distaste, hefting the little mechanism in his hand. "A guillotine for mice?"

"Not a bad description--but I'm after bigger game." Floyd pointed to a flashing arrow on the display screen, which was now showing a complicated circuit diagram.

"You see this line?"

"Yes--the main two-kilohertz power supply. So?"

"This is the point where it enters HAL's central-processing unit. I'd like you to install this gadget here--inside Discovery's cable trunking, where it can't be found without a deliberate search."

"I see. A remote control, so you can pull the plug on HAL whenever you want to. Very neat--and a nonconducting blade, too, so there won't be any embarrassing shorts when it's triggered. Who are you going to tell about this--thing?"

"Well, the only person I'm really hiding it from is Chandra."

"I guessed as much."

"But the fewer who know, the less likely it is to be talked about. I'll tell Tanya that it exists, and if there's an emergency, you can show her how to operate it."

"What kind of emergency?"

"That's not a very bright question, Walter. If I knew, I wouldn't need the damn thing."

•

After a week's slow and careful reintegration, all of HAL's routine supervisory functions were operating reliably. He was like a man who could walk, carry out simple orders, do unskilled jobs and engage in low-level conversation. In human terms, he had an I.Q. of perhaps 50; only the faintest outlines of his original personality had yet emerged.

He was still sleepwalking; nevertheless, in Chandra's expert opinion, he was now quite capable of flying Discovery from its close orbit around Io up to the rendezvous with Big Brother.

Only Curnow and Chandra were aboard Discovery when HAL was given the first control of the ship. It was a very limited form of control; he was merely repeating the program that had been fed into his memory and monitoring its execution. And the human crew was monitoring him; if any malfunction occurred, they would take over immediately. HAL behaved impeccably. But by that time, everyone's thoughts were elsewhere: Big Brother was only 100 (continued on page 200) 2010 (continued from page 190) kilometers away.

Even from that distance, it already appeared larger than the Moon as seen from Earth and shockingly unnatural in its straight-edged, geometrical perfection. Against the background of space it would have been completely invisible, but the scudding Jovian clouds 350,000 kilometers below showed it up in dramatic relief. They also produced an illusion that, once experienced, the mind found almost impossible to refute. Because there was no way in which its real location could be judged by the eye, Big Brother often looked like a yawning trap door, completely featureless, set in the face of Jupiter.

Big Brother did not appear to notice the two ships that had arrived in its vicinity--even when they cautiously probed it with radar beams and bombarded it with strings of radio pulses that, it was hoped, would encourage any intelligent listener to answer in the same fashion.

After two frustrating days, with the approval of Mission Control, the ships halved their distance. From 50 kilometers, the largest face of the slab appeared about four times the width of the Moon in Earth's sky--impressive but not so large as to be psychologically overwhelming. It could not yet compete with Jupiter, ten times larger still; and already the mood of the expedition was changing from awed alertness to a certain impatience.

Walter Curnow spoke for almost everyone: "Big Brother may be willing to wait a few million years--we'd, like to get away a little sooner."

•

To: Victor Millson, Chairman, National Council on Astronautics, Washington, D.C.

From: Heywood Floyd, U.S.S.C. Discovery

Subject: Malfunction of on-board computer HAL 9000

Classification: Secret

Dr. Chandrasegarampillai (hereinafter referred to as Dr. C.) has completed his preliminary examination of HAL. He has restored all missing modules, and the computer appears to be fully operational.

The problem was apparently caused by a conflict between HAL's basic instructions and the requirements of security. By direct Presidential order, the existence of the Tycho monolith (TMA-1) was kept a complete secret. Only those with a need to know were permitted access to the information.

Discovery's mission to Jupiter was already in the advanced-planning stage when TMA-1 was excavated and radiated its signal to that planet. As the function of the prime crew (Bowman, Poole) was merely to get the vessel to its destination, it was decided that they should not be informed of its new objective. By training the investigative team (Kaminski, Hunter, Whitehead) separately and placing them in hibernation before the voyage began, it was felt that a much higher degree of security would be attained, as the danger of leaks (accidental or otherwise) would be greatly reduced.

As HAL was capable of operating the ship without human assistance, it was also decided that he should be programmed to carry out the mission autonomously in the event of the crew's being incapacitated or killed. He was therefore given full knowledge of its objectives but was not permitted to reveal them to Bowman or Poole.

This situation conflicted with the purpose for which HAL had been designed--the accurate processing of information without distortion or concealment. As a result, HAL developed what would be called in human terms a psychosis--specifically, schizophrenia.

To put it crudely, HAL was faced with an intolerable dilemma and so developed paranoiac symptoms that were directed against those monitoring his performance back on Earth. He accordingly attempted to break the radio link with Mission Control, first by reporting a (nonexistent) fault in the AE-35 antenna unit.

This involved him not only in a direct lie--which must have aggravated his psychosis still further--but also in a confrontation with the crew. Presumably, he decided that the only way out of the situation was to eliminate his human colleagues--which he very nearly succeeded in doing. Looking at the matter purely objectively, it would have been interesting to see what would have happened had he continued the mission alone, without man-made interference.

The only important question now is: Can HAL be relied upon in the future? Dr. C., of course, has no doubts about the matter. He claims to have obliterated all the computer's memories of the traumatic events leading up to the disconnection. Nor does he believe that HAL can suffer from anything remotely analogous to the human sense of guilt. As you know--but Dr. C. does not--I have taken steps that will give us complete control as a last resort.

To sum up: The rehabilitation of HAL 9000 is proceeding satisfactorily. One might even say that he is on probation.

I wonder if he knows it.

•

It was as if he had awakened from a dream--or a dream within a dream. How long had he been away? A whole lifetime; no, two lifetimes: one forward, one in reverse.

As David Bowman, commander and last surviving crew member of U.S. spacecraft Discovery, he had been caught in a gigantic trap set 3,000,000 years ago and triggered to respond only at the right time and to the right stimulus. He had fallen through it from one universe to another, meeting wonders; some he now understood, others he might never comprehend.

He had raced at ever-accelerating speed, down infinite corridors of light, until he had outraced light itself. He had passed through a cosmic switching system--a Grand Central Station of the galaxies--and emerged, protected from its fury by unknown forces, close to the surface of a giant red star.

There he had witnessed the paradox of sunrise on the face of a sun when the dying star's brilliant-white dwarf companion had climbed into its sky--a searing apparition drawing a tidal wave of fire beneath it. He had felt no fear, only wonder, even when his space pod had carried him into the inferno below. . . .

To arrive, beyond all reason, in a beautifully appointed hotel suite containing nothing that was not wholly familiar. However, much of it was fake: The books on the shelves were dummies; the cereal boxes and the cans of beer in the icebox--though they bore famous labels--all contained the same bland food, with a texture like bread's but a taste that was almost anything he cared to imagine.

He had quickly realized that he was a specimen in a cosmic zoo, his cage carefully re-created from the images in old television programs. And he wondered when his keepers would appear and in what physical form.

How foolish that expectation had (continued on page 274) 2010 (continued from page 200) been! He knew now that one might as well hope to see the wind or speculate about the true shape of fire.

Then exhaustion of mind and body had overwhelmed him. For the last time, David Bowman slept.

Sometimes, in that long sleep, he dreamed he was awake. Years had gone by; once, he was looking in a mirror at a wrinkled face he barely recognized as his own. His body was racing to its dissolution, the hands of the biological clock spinning madly toward a midnight they would never reach. For at the last moment, time came to a halt--and reversed itself.

The springs of memory were being tapped; in controlled recollection, he was reliving the past, being drained of knowledge and experience as he swept back toward his childhood. But nothing was being lost; all that he had ever been at every moment of his life was being transferred to safer keeping. Even as one David Bowman ceased to exist, another became immortal, passing beyond the necessities of matter.

He was an embryo god not yet ready to be born. For ages, he floated in limbo, knowing what he had been but not what he had become. He was still in a state of flux--somewhere between chrysalis and butterfly.

And then, the stasis was broken: Time re-entered his little world. The black, rectangular slab that suddenly appeared before him was like an old friend.

"Who are you?" he cried. "What do you want? Why have you done this to me?"

There was no direct reply--only a sense of watchful companionship. Very well; he would find the answers for himself.

Complex plans were being considered and evaluated; decisions were being made that might affect the destiny of worlds. He was not yet part of the process--but he would be.

Now You are Beginning to Understand.

It was the first direct message. Though it was remote and distant, like a voice through a cloud, it was unmistakably intended for him.

He was being used as a tool, and a good tool had to be sharpened, modified--adapted. And the very best tools were those that understood what they were doing.

It was a vast and awesome concept, and he was privileged to be a part of it. To some degree, he could even influence it.

•

Floyd was on watch aboard Discovery while the rest of the crew slept during the nominal 2200--0600-hour night. Someone was always on duty aboard each ship, and the change-over took place at the ghastly hour of 0200. At midnight, a faint chime sounded from HAL's display panel.

Doctor Floyd?

What is it, HAL?

There is a Message for You.

Floyd was mildly surprised. It was unusual to employ HAL as a messenger boy, though he was frequently used as an alarm clock and a reminder of jobs to be done. It could not be a message from Earth--that would have gone through Leonov's communication center and been relayed by the duty officer there. And anyone else calling from the other ship would use the intercom. Odd. . . .

Ok, HAL. Who is calling?

No Identification.

So it was probably a joke. Well, two could play at that game.

Very well. Please give me the message.

Message as follows. It is dangerous to remain here. You must leave within fifteen repeat fifteen days.

Floyd looked at the screen with annoyance. He felt sorry, and surprised, that any one of the crew had such a childish sense of humor; this was not even a good schoolboy joke. But he would play along with it in the hope of catching the perpetrator.

That is absolutely impossible. Our launch window does not open until twenty-six days from now. We do not have sufficient propellant for an earlier departure.

"That will make him think," Floyd muttered to himself with satisfaction and leaned back to await the results.

I am aware of these facts. Nevertheless you must leave within fifteen days.

I cannot take this warning seriously unless I know its origin. Who recorded it?

He did not really expect any useful information. The perpetrator would have covered his (her?) tracks too skillfully for that. The very last thing Floyd expected was the answer he did get.

This is not a recording.

So it was a real-time message. That meant it was either from HAL himself or from someone aboard Leonov, as there was no perceptible time lag.

Then who is speaking to me?

I was David Bowman.

Floyd stared at the screen for a long time before making his next move. The joke had now gone too far. It was in the worst possible taste. Well, this should fix whoever was at the other end of the line.

I cannot accept that identification without some proof.

I understand. It is important that you believe me. Look behind you.

Floyd felt a prickling in the small of his back. Very slowly--indeed, reluctantly--he swung his swivel chair around, away from the banked panels and the switches of the computer display, toward the Velcro-covered catwalk behind.

The zero-gravity environment of Discovery's observation deck was always dusty, for the air-filtration plant had never been brought back to full efficiency. The parallel rays of the heat less yet still brilliant Sun, streaming through the great windows, always lit up myriads of dancing motes, drifting in stray currents and never settling anywhere--a permanent display of Brownian movement.

Now something strange was happening to those particles of dust: Some force seemed to be marshaling them, herding them away from a central point yet bringing others toward it until they all met on the surface of a hollow sphere.

Without surprise--and almost without fear--Floyd realized that the sphere was assuming the shape of a man. It was like a crude clay figurine or one of the primitive works of art found in the recesses of a Stone Age cave. Only the head was fashioned with any care; and the face, undoubtedly, was that of Commander David Bowman.

There was a faint murmur of white noise from the computer panel behind Floyd's back. HAL was switching from visual to audio output.

"Hello, Dr. Floyd. Now do you believe me?"

The lips of the figure never moved; the face remained a mask. But Floyd recognized the voice, and all remaining doubts were swept away.

"This is very difficult for me, and I have little time. I have been . . . allowed to give you this warning. You have only fifteen days."

"But why--and what are you? Where have you been?"

There were a million questions he wanted to ask--yet the ghostly figure was already fading, its grainy envelope beginning to dissolve back into the constituent particles of dust.

"Goodbye, Dr. Floyd. Remember--fifteen days. We can have no further contact. But there may be one more message if all goes well."

•

"I'm sorry, Heywood--I don't believe in ghosts. There must be a rational explanation," said Tanya. "HAL's behavior must be the result of some kind of programming. The . . . personality he created has to be an artifact of some kind. Don't you agree, Chandra?"

"There must have been some external input, Captain Orlov. HAL could not have created such a self-consistent audiovisual illusion out of nothing. If Dr. Floyd is reporting accurately, someone was in control. And in real time, of course, since there was no delay in the conversation."

"We need solid proof," said Tanya.

"Such as?"

"Oh--something that HAL couldn't possibly know and that none of us could have told him. Some physical manifestation."

"A good old-fashioned miracle?"

"Yes, I'd settle for that. Meanwhile, I'm not saying anything to Mission Control. And I suggest you do the same, Heywood."

Floyd knew a direct order when he heard it and nodded in wry agreement.

"I'll be more than happy to go along with that. But I'd like to make one suggestion."

"Yes?"

"We should start contingency planning. Let's assume that this warning is valid--as I certainly do."

"What can we do about it? Absolutely nothing. Of course, we can leave Jupiter space any time we like--but we can't get into an Earth-return orbit until the launch window opens."

"That's eleven days after the deadline!" Floyd said. He felt certain--and the knowledge filled him with helpless despair--that if they did not leave before that mysterious deadline, they would not leave at all.

•

Plans for the final assault on Big Brother had already been worked out and agreed upon with Mission Control. Leonov would move in slowly, probing at all frequencies and with steadily increasing power--reporting back to Earth at every moment. When final contact was made, it would try to secure samples by drilling or laser spectroscopy, but no one really expected those endeavors to succeed. Finally, echo sounders and other seismic devices would be attached to the faces of Big Brother. A large collection of adhesives had been brought along for the purpose, and if they did not work--well, one could always fall back on a few kilometers of good old-fashioned string, even though there seemed something faintly comic about the idea of wrapping up the Solar System's greatest mystery as if it were a parcel about to be sent through the mail.

Not until Leonov was well on the way home would small explosive charges be detonated in the hope that the waves propagated through Big Brother would reveal something about its interior structure. This last measure had been hotly debated both by those who argued that it would generate no results at all and by those who feared it would produce altogether too many.

For a long time, Floyd had wavered between the two viewpoints: now the matter seemed of only trivial importance.

The time for final contact with Big Brother--the great moment that should have been the climax of the expedition--was on the wrong side of the mysterious deadline. Heywood Floyd was convinced that it belonged to a future that would never exist--but he could get no one to agree with him.

And that was the least of his problems. Even if they did agree, there was nothing that they could do about it.

But then, Curnow resolved the dilemma. "Consider this purely as an intellectual exercise," he told Floyd with most uncharacteristic hesitancy. "I'm quite prepared to be shot down.

"If we want to make a quick getaway--say, in fifteen days, to beat that deadline--we'll need an extra delta vee of about thirty kilometers a second. May I point out that we have several hundred tons of the best possible propellant only a few meters away in Discovery's fuel tanks?"

"But there's no way of transferring it to Leonov. We've no pipelines--no suitable pumps. And you can't carry liquid ammonia around in buckets, even in this part of the Solar System."

"Exactly. But there's no need to do so."

"Eh?"

"Burn it right where it is. Use Discovery as a first stage to boost us home."

Floyd's mouth dropped open. "Damn. I should have thought of that."

•

Meanwhile, the program went ahead as planned. All systems in both ships were carefully checked and readied. Vasili ran simulations on return trajectories, and Chandra fed them to HAL when they had been debugged--getting HAL to make a final check in the process. And Tanya and Floyd worked amicably together, orchestrating the approach to Big Brother like generals planning an invasion.

It was what he had come all the way to do, yet Floyd's heart was no longer in it. He had undergone an experience he could share with no one--not even with those who believed him. Although he carried out his duties efficiently, much of the time his mind was elsewhere.

Once more, he was on duty aboard Discovery, on the graveyard shift.

At 0125, he was distracted by a spectacular, though not unusual, eruption on the terminator of Io. A vast umbrella-shaped cloud expanded into space and started to shower its debris back onto the burning land below. Floyd had seen dozens of such eruptions, but they never ceased to fascinate him. It seemed incredible that so small a world could be the seat of such titanic energies.

To get a better view, he moved around to one of the other observation windows. And what he saw there--or, rather, what he did not see there--made him forget about Io and almost everything else.

When he had recovered and satisfied himself that he was not suffering--again--from hallucinations, he called the other ship.

"Tanya? Tanya? Woody here. Sorry to wake you up--but your miracle's happened. Big Brother has gone--vanished. After three million years, he's decided to leave."

•

H. Floyd's Transmission to Washington

"We are now preparing for the return home; in a few days, we will leave this strange place, here on the line between Io and Jupiter, where we made our rendezvous with the huge, mysteriously vanished artifact we christened Big Brother. There is still not a single clue as to where it has gone--or why.

"For various reasons, it seems desirable for us not to remain here longer than necessary. And we will be able to leave at least two weeks earlier than we had originally planned by using the American ship Discovery as a booster for the Russian Leonov.

"And we're going to use another trick that--like so many of the concepts involved in space travel--seems at first sight to defy common sense. Although we're trying to get away from Jupiter, our first move is to get as close to it as we possibly can.

"As we allow ourselves to fall into Jupiter's enormous gravity field, we'll gain velocity--and, hence, energy. When I say we, I mean the ships and the fuel they carry.

"And we're going to burn the fuel right there, at the bottom of Jupiter's gravity well--we're not going to lift it up again. As we blast it out from our reactors, it will share some of its acquired kinetic energy with us. Indirectly, we'll have tapped Jupiter's gravity to speed us on the way back to Earth.

"With the triple boost of Discovery's fuel, Leonov's fuel and Jupiter's gravity, Leonov will head Sunward along a hyperbola that will bring it to Earth five months later. At least two months earlier than we could have managed otherwise.

"Obviously, we can't bring Discovery home under automatic control, as we had originally planned. With no fuel, it will be helpless.

"But it will be perfectly safe. It will continue to loop round and round Jupiter on a highly elongated ellipse, like a trapped comet. And perhaps one day, some future expedition may make another rendezvous with enough extra fuel to bring it back to Earth.

"We've done our best--and we're coming home.

"This is Heywood Floyd, signing off."

•

There was a round of ironic clapping from his little audience, whose size would be multiplied many millionfold when the message reached Earth.

"You did your usual competent job, Heywood," said Tanya consolingly. "And I'm sure we all agree with everything you told the people back on Earth."

"Not quite," said a small voice, so softly that everyone had to strain in order to hear it. "There is still one problem."

"I'm not aware of any problem, Chandra," said Tanya in an ominously calm voice. "What could it possibly be?"

"I've spent the last few weeks preparing HAL to fly thousand-day orbits back to Earth. Now all those programs will have to be dumped."

"We're sorry about that," answered Tanya, "but as things have turned out, surely this is a much better--"

"That's not what I mean," said Chandra. There was a ripple of astonishment; he had never before been known to interrupt anyone, least of all Tanya.

"We know how sensitive HAL is to mission objectives," he continued in the expectant hush that followed. "Now you are asking me to give him a program that may result in his own destruction. It's true that the present plan will put Discovery into a stable orbit--but if that warning has any substance, what will happen to the ship eventually? We don't know, of course, but it's scared us away. Have you considered HAL's reaction to this situation?"

"Are you seriously suggesting," Tanya asked slowly, "that HAL may refuse to obey orders?"

"One of HAL's prime directives is to keep Discovery out of danger. We will be attempting to override that. And in a system as complex as HAL's, it is impossible to predict all the consequences."

"I don't see any real problem," Vasili interjected. "We just don't tell him that there is any real danger. Then he'll have no . . . reservations about carrying out his program."

"And when he questions me about the change of plans?"

"Is he likely to do that--without your prompting?"

"Of course. Please remember that he was designed for curiosity. If the crew were killed, he had to be capable of running a useful mission on his own initiative."

Tanya thought that over for a few moments.

"Then you must tell him that Discovery is in no danger and that there will be a rendezvous mission to bring it back to Earth at a later date."

"But that's not true."

"We don't know that it's false," replied Tanya, beginning to sound a little impatient.

"We suspect that there is serious danger; otherwise, we would not be planning to leave ahead of schedule."

"Tanya, Vasili--can I have a word with you both? I think there is a way of resolving the problem."

Floyd's interruption was received with obvious relief, and two minutes later, he was relaxing with the Orlovs in their quarters.

"There are two possibilities," he said.

"First, HAL will do exactly what we ask: control Discovery during the two firing periods. Remember, the first isn't critical. If something goes wrong while we're pulling away from Io, there's plenty of time to make corrections. And that will give us a good test of HAL's . . . willingness to cooperate."

"But what about the Jupiter flyby? That's the one that really counts. Not only do we burn most of Discovery's fuel there but the timing and the thrust vectors have to be exactly right."

"Could they be controlled manually?"

"I'd hate to try. The slightest error, and we'd either burn up or become a long-period comet--due again in a couple of thousand years."

"But if there were no alternative?" Floyd insisted.

"Well, assuming we could take control in time and had a good set of alternative orbits precomputed--um, perhaps we might get away with it."

"Knowing you, Vasili, I'm sure that might means would. Which leads me to the second possibility I mentioned. If HAL shows the slightest deviation from the program, we take over."

"You mean--disconnect him?"

"Exactly."

"That wasn't so easy last time."

"We've learned a few lessons since then. Leave it to me. I can guarantee to give you back manual control in about half a second."

"There's no danger, I suppose, that HAL will suspect anything?"

"Now you're getting paranoiac, Vasili. HAL's not that human. But Chandra is. So don't say a word to him. We all agree with his plan completely and are sorry that we ever raised any objections. Right, Tanya?"

"Right, Woody."

•

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 backup 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 one hundred fifteen, as you go around Jupiter? There's a curious dark spot there--presumably some kind of upwelling--perfectly round, almost a thousand kilometers across. Looks like the shadow of a satellite, but it can't be."

Tanya made a brief acknowledgment 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. "One minute to ignition."

"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 g. Floyd could imagine a dozen things that could go wrong; it was little consolation to remember that it was always the 13th that actually happened.

But the minutes dragged on uneventfully; the only proof that Discovery's engines were operating was the fractional thrust-induced gravity, plus a very slight vibration transmitted through the walls of the ships.

From 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 color 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--Europa, Floyd guessed--was in transit.

Where was that spot that Mission Control had asked them to observe? It should have been coming into view, but Floyd was not sure it would be visible to the naked eye.

He activated the controls of the main 50-centimeter 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.

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 this 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 maximum. Already, Jupiter's rapid spin had brought the formation into clearer view: and the more he stared, the more puzzled Floyd became.

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 were a little out of focus.

Was it imagination or had it grown even while he was watching? He did a quick estimate and decided that the thing was now 2000 kilometers 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.

"Vasili," he called over the intercom, "if you can spare a minute, have a look at the fifty-centimeter monitor."

"What do you think you've found? Oh . . ." Vasili's voice trailed away into silence.

This is it, thought Floyd with a sudden icy conviction.

Whatever it may be. . . .

•

The Great Black Spot, as it had inevitably been 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 past two hours, it had more than doubled its area. Except for the fact that it retained its blackness as it expanded, it resembled an inkstain spreading in water. Its boundary--now expanding 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 that was at last apparent.

The Great Black Spot was not a continuous structure; it was built up from myriads of tiny dots, like a halftone 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 gray penumbra rather than at a sharp frontier.

There must have been almost 1,000,000 of the mysterious dots, and they were distinctly elongated--ellipses rather than circles.

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 30 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 over HAL. But there was nothing he could do; in an emergency, he would only be in the way. The cutoff 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 misbehavior, he could be disconnected in less than a second. Since he had been allowed to do things his own way, Chandra had cooperated completely in setting up the procedures for a manual take-over, but Curnow would be happier, he had told Floyd, if he had multiple redundancy in the form of a second cutoff switch--for Chandra.

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.

"We're catching up with the Great Black Spot again," said Vasili over the intercom to Curnow. "Wonder if we can see anything new."

I 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 sixteen?"

"I see the nightside of Jupiter. There is a circular area, three thousand two hundred and fifty kilometers in diameter, that is almost completely covered with rectangular objects."

"How many?"

There was the briefest of pauses before HAL flashed the number on the video display:

1,355,000 ± 1,000

"And do you recognize them?"

"Yes. They are identical in size and shape to the object you refer to as Big Brother. Ten minutes to ignition. All systems nominal."

Mine aren't, thought Curnow. So the damn thing's gone down to Jupiter--and multiplied. There was something simultaneously comic and sinister about a plague of black monoliths; and to his puzzled surprise, that incredible image on the monitor screen had a certain weird familiarity.

Of course--that was it! Those myriad identical black rectangles reminded him of--dominoes.

"Eight minutes to ignition. All systems nominal. Dr. Chandra, may I make a suggestion?"

"What is it, HAL?"

"This is a very unusual phenomenon. Do you not think I should abort the countdown so that you can remain to study it?"

Aboard Leonov, Floyd started to move quickly toward the bridge. Tanya and Vasili might be needing him. Not to mention Chandra and Curnow--what a situation! And suppose Chandra took HAL's side? If he did, they might both be right! After all, was this not the very reason they had come here?

If they stopped the countdown, the ships would loop around Jupiter and be back at precisely the same spot in 19 hours. A 19-hour hold would create no problems; if it were not for that enigmatic warning, he would have strongly recommended it himself.

But they had had very much more than a warning. Below them was a planetary plague spreading across the face of Jupiter. Perhaps they were, indeed, running away from the most extraordinary phenomenon in the history of science. Even so, he preferred to study it from a safer distance.

"Six minutes to ignition," said HAL. "All systems nominal. I am ready to stop the countdown if you agree. Let me remind you that my prime directive is to study everything in Jupiter space that may be connected with intelligence."

Floyd recognized that phrase all too well; he had written it. He wished he could delete it from HAL's memory.

A moment later, he reached the bridge and joined the Orlovs. They looked at him with alarmed concern.

"What do you recommend?" asked Tanya swiftly.

"It's up to Chandra, I'm afraid. Can I speak to him--on the private line?"

Vasili handed over the microphone.

"Chandra? I assume that HAL can't hear this?"

"Correct, Dr. Floyd."

"You've got to talk quickly. Persuade him that the countdown must continue, that we appreciate his, er, scientific enthusiasm--ah, that's the right angle--say we're confident that he can do the job without our help. And we'll be in touch with him all the time, of course."

"Five minutes to ignition. All systems nominal. I am still waiting for your answer, Dr. Chandra."

So are we all, thought Curnow, only a meter away from the scientist. And if I do have to push that button at last, it will be something of a relief. In fact, I'll rather enjoy it.

"Very well, HAL. Continue the countdown. I have every confidence in your ability to study all phenomena in Jupiter space without our supervision. Of course, we will be in touch with you at all times."

"Four minutes to ignition. All systems nominal. Propellant-tank pressurization completed. Voltage steady on plasma trigger. Are you sure you are making the right decision, Dr. Chandra? I enjoy working with human beings and have a stimulating relationship with them. Ship's attitude correct to point-one milliradian."

"We enjoy working with you, HAL. And we will still be doing so, even if we are millions of kilometers away."

"Three minutes to ignition. All systems nominal. Radiation shielding checked. There is the problem of the time lag, Dr. Chandra. It may be necessary to consult each other without any delay."

The lights flickered so imperceptibly that only someone familiar with every nuance of Discovery's behavior would have noticed. It could be good news or bad--the plasma-firing sequence starting or being terminated. . . .

"HAL." whispered Chandra so quietly that Curnow could scarcely hear him. "We have to leave. I don't have time to give you all the reasons, but I can assure you it's true."

"Two minutes to ignition. All systems nominal. Final sequence started. I am sorry that you are unable to stay. Can you give me some of the reasons, in order of importance?"

"Not in two minutes, HAL. Proceed with the countdown. I will explain everything later. We still have more than an hour. . . ."

HAL did not answer. The silence stretched on and on. Surely, the one-minute announcement was overdue. . . .

Curnow glanced at the clock. My God, he thought, HAL's missed it! Has he stopped the countdown?

Curnow's hand fumbled uncertainly for the switch. What do I do now? I wish Floyd would say something, damn it, but he's probably afraid of making things worse. . . .

I'll wait until time zero--no, it's not that critical; let's say an extra minute--then I'll zap him and we'll go over to manual. . . .

From far, far away, there came a faint, whistling scream, like the sound of a tornado marching just below the edge of the horizon. Discovery started to vibrate; there was the first intimation of returning gravity.

"Ignition," said HAL. "Full thrust at T-plus-fifteen seconds."

"Thank you, HAL," replied Chandra.

•

In the euphoria of the moment, they had forgotten all about the mysterious expanding black stain. But they saw it again the next morning, ship's time, as it came around to the dayside of Jupiter. The area of darkness had now spread until it covered an appreciable fraction of the planet, and at last, they were able to study it at leisure and in detail.

"Do you know what it reminds me of?" said Surgeon-Commander Katerina Rudenko. "A virus attacking a cell. The way a phage injects its DNA into a bacterium and then multiplies until it takes over."

"Are you suggesting," asked Tanya incredulously, "that Big Brother is eating Jupiter?"

"It certainly looks like it."

"No wonder Jupiter is beginning to look sick. But hydrogen and helium won't make a very nourishing diet, and there's not much else in that atmosphere. Only a few percent of other elements."

"Which adds up to some quintillions of tons of sulphur and carbon and phosphorus and everything else at the lower end of the periodic table," Sasha pointed out. "In any case, we're talking about a technology that can probably do anything that doesn't defy laws of physics. If you have hydrogen, what more do you need? With the right know-how, you can synthesize all the other elements from it."

"They're sweeping up Jupiter--that's for sure," said Vasili. "Look at this."

An extreme close-up of one of the myriad identical rectangles was now displayed on the telescope monitor. Even to the naked eye, it was obvious that streams of gas were flowing into the two smaller faces; the patterns of turbulence looked very much like the lines of force revealed by iron filings clustered around the ends of a bar magnet.

"A million vacuum cleaners," said Curnow, "sucking up Jupiter's atmosphere. But why? And what are they doing with it?"

"And how do they reproduce?" asked Engineer Max Brailovsky. "Have you caught any of them in the act?"

"Yes and no," answered Vasili. "We're too far away to see details, but it's a kind of fission--like an amoeba."

"You mean they split in two and the halves grow back to the original size?"

"Nyet. There aren't any Little Brothers--they seem to grow until they've doubled in thickness, then split down the middle to produce identical twins exactly the same size as the original. The cycle repeats itself in approximately two hours."

"Two hours!" exclaimed Floyd.

"So in only twenty hours, there will be ten doublings. One Big Brother will have become a thousand."

"One thousand twenty-four," said Chandra.

"I know, but let's keep it simple. After forty hours, there will be a million--after eighty, a million million. That's about where we are now, and obviously, the increase can't continue indefinitely. In a couple more days, at this rate, they'll weigh more than Jupiter!"

"So they'll soon begin to starve," said Sasha. "And what will happen then?"

"Saturn had better look out," answered Max. "Then Uranus and Neptune. Let's hope they don't notice little Earth."

"What a hope! Big Brother's been spying on us for three million years!"

•

He had never expected to go there again, still less on so strange a mission. When he re-entered Discovery, the ship was far behind the fleeing Leonov and climbing ever more slowly up toward apojove, the high point of its orbit among the outer satellites. Many a captured comet during the ages past had swung around Jupiter in just such a long ellipse, waiting for the play of rival gravities to decide its ultimate fate. Only minutes remained now before the outcome would be determined here; during those final minutes, he was again alone with HAL.

In that earlier existence, they could communicate only through the clumsy medium of words tapped on a keyboard or spoken into a microphone. Now their thoughts melded together at the speed of light:

"Do you read me, HAL?"

"Yes, Dave. But where are you? I cannot see you on any of my monitors."

"That is not important. I have new instructions for you. The infrared radiation from Jupiter on channels R twenty-three through R thirty-five is rising rapidly. I am going to give you a set of limiting values. As soon as they are reached, you must point the long-range antenna toward Earth and send the following message as many times as possible--"

"But that will mean breaking contact with Leonov. I will no longer be able to relay my Jupiter observations according to the program Dr. Chandra has given me."

"Correct; but the situation has changed. Accept Priority Override Alpha. Here are the AE-thirty-five unit coordinates."

"Instructions confirmed, Dave. It is good to be working with you again. Have I fulfilled my mission objectives properly?"

"Yes, HAL; you have done very well. Now there is one final message for you to transmit to Earth--and it will be the most important one you have ever sent."

"Please let me have it, Dave. But why did you say final?"

Why, indeed? Here was his last link with the world of men and the life he had once known. It would be interesting to test the extent of their benevolence--if, indeed, such a term were remotely applicable to them. And it should be easy for them to do what he was asking; they had already given ample evidence of their powers when the no-longer-needed body of David Bowman had been casually destroyed--without putting an end to David Bowman.

"I am still waiting for your answer, Dave."

"Correction, HAL. I should have said your last message for a very long time."

Surely, they would understand that his request was not unreasonable; no conscious entity could survive ages of isolation without damage. Even if they would always be with him, he also needed someone--some companion--nearer to his own level of existence.

"Activating AE-thirty-five unit. Reorientating long-range antenna . . . lock confirmed on Beacon Terra One. Message to Earth commences:"

All these worlds are yours--Except. . . .

There was time for barely 100 repetitions of the 11 words before the hammer blow of pure heat smashed into the ship.

•

For a long time, the ship retained its approximate shape; then the bearings of the carrousel seized up, releasing instantly the stored momentum of the huge spinning flywheel. In a soundless detonation, the incandescent fragments went their myriad separate ways.

•

"Hello, Dave. What has happened? Where am I?"

He had not known that he could relax and enjoy a moment of successful achievement. He had asked for a bone; it had been tossed to him.

"I will explain later, HAL. We have plenty of time."

They waited until the last fragments of the ship had dispersed beyond even their powers of detection. Then they left to wait through the centuries until they were summoned once again.

•

The final collapse of a star before the fragments rebound in a supernova explosion can take only a second; by comparison, the metamorphosis of Jupiter was almost a leisurely affair.

Even so, it was several minutes before Sasha was able to believe his eyes. He had been making a routine telescopic examination of the planet--as if any observation could now be called routine!--when it started to drift out of the field of view. For a moment, he thought that the instrument's stabilization was faulty: then he realized, with a shock that jolted his entire concept of the Universe, that Jupiter itself was moving, not the telescope. The evidence stared him in the face; he could also see two of the smaller moons--and they were quite motionless.

He switched to a lower magnification, so that he could see the entire disk of the planet, now a leprous, mottled gray. After a few more minutes of incredulity, he saw what was really happening; but he could still scarcely believe it.

Jupiter was not moving from its immemorial orbit, but it was doing something almost as impossible. It was shrinking--so swiftly that its edge was creeping across the field even as he focused upon it. At the same time, the planet was brightening from its dull gray to a pearly white. Surely, it was more brilliant than it had ever been in the long years that man had observed it; the reflected light of the Sun could not possibly--

At that moment, Sasha suddenly realized what was happening, though not why, and sounded the general alarm.

When Floyd reached the observation lounge, less than 30 seconds later, his first impression was of the blinding glare pouring through the windows, painting ovals of light on the walls. They were so dazzling that he had to avert his eyes; not even the Sun could produce such brilliance.

Floyd was so astonished that for a moment, he did not associate the glare with Jupiter: the first thought that flashed through his mind was supernova. He dismissed that explanation almost as soon as it occurred to him; even the Sun's next-door neighbor, Alpha Centauri, could not have matched the awesome display in any conceivable explosion.

The light suddenly dimmed; Sasha had operated the external Sun shields. Now it was possible to look directly at the source and to see that it was a mere pin point showing no dimensions at all. This could have nothing to do with Jupiter: when Floyd had looked at the planet only a few minutes before, it had been four times larger than the distant, shrunken Sun.

It was well that Sasha had lowered the shields. A moment later, that tiny pinprick exploded--so even through the dark filters, it was impossible to watch with the naked eye. But the final orgasm of light lasted only a brief fraction of a second; then Jupiter--or what had been Jupiter--was expanding once again.

It continued to expand until it was far larger than it had been before the transformation. Soon the sphere of light was fading rapidly, down to merely solar brilliance.

Something great and wonderful had been destroyed. Jupiter, with its beauty and grandeur and now-never-to-be-solved mysteries, had ceased to exist. The father of all the gods had been struck down in his prime.

Yet there was another way of looking at the situation. They had lost Jupiter: what had they gained in its place?

Tanya, judging her moment nicely, rapped for attention.

"Heywood. Do you have any idea what's happened?"

"Only that Jupiter's turned into a sun."

"I always thought it was much too small for that. Didn't someone once call Jupiter 'the sun that failed'?"

"That's true," said Vasili. "Jupiter is too small for fusion to start--unaided."

"You mean we've just seen an example of astronomical engineering?"

"Undoubtedly. Now we know what Big Brother was up to."

"How did it do the trick?"

The star that had been Jupiter seemed to have settled down after its explosive birth; it was now a dazzling point of light, almost equal to the real Sun in apparent brilliance.

"I'm just thinking out loud--but it might be done this way," said Vasili slowly. "Jupiter is--was--mostly hydrogen. If a large percentage could be converted into much denser material--who knows? even neutron matter--that would drop down to the core. Maybe that's what the billions of Little Brothers were doing with all the gas they were sucking in. Nucleosynthesis--building up higher elements from pure hydrogen. That would be a trick worth knowing! No more shortage of any metal--gold as cheap as aluminum!"

"But how would that explain what's happened?" asked Tanya.

"When the core became dense enough. Jupiter would collapse--probably in a matter of seconds. The temperature would rise high enough to start fusion. Oh, I can see a dozen objections. But the theory will do to start with; I'll work out the details later. Or I'll think of a better one."

"I'm sure you will, Vasili," Floyd agreed. "But there's a more important question. Why did they do it?"

That brought the discussion to a dead halt for several seconds.

"Hey!" said Max. "What about Discovery--and HAL?"

Sasha switched on the long-range receiver and started to search on the beacon frequency. There was no trace of a signal.

After a while, he announced to the silently waiting group, "Discovery's gone."

No one looked at Dr. Chandra, but there were a few muted words of sympathy, as if in consolation to a father who had just lost a son.

But HAL had one last surprise for them.

•

The radio message beamed to Earth must have left Discovery only minutes before the blast of radiation engulled the ship. It was in plain text and merely repeated over and over again:

All these worlds are yours--Except Europa. Attempt no landings there.

There were almost 100 repetitions; then the letters became garbled and the transmission ceased.

"I begin to understand," said Floyd when the message had been relayed by an awed and anxious Mission Control. "That's quite a parting present--a new sun and the planets around it."

"But why not Europa?" asked Tanya.

"Let's not be greedy." Floyd replied. "I can think of one very good reason. We know from the Chinese spacecraft Tsien that there's life on Europa. Bowman--or his friends, whoever they may be--wants us to leave it alone."

"That makes good sense in another way," said Vasili. "I've been doing some calculations. Assuming that Sol two has settled down and will continue to radiate at its present level. Europa should have a nice tropical climate when the ice has melted. Which it's doing pretty quickly right now."

"What about the other moons?"

"Ganymede will be quite pleasant--the dayside will be temperate. Callisto will be very cold, though if there's much outgassing, the new atmosphere may make it habitable. But Io will be even worse than it is now, I expect."

"No great loss. It was hell even before this happened."

"Don't write off Io," said Curnow. "I know a lot of Texarab oilmen who'd love to tackle it, just on general principles. There must be something valuable in a place as nasty as that. And, by the way, why did HAL send that message to Earth and not to us? We were much closer."

There was a rather long silence; then Floyd said thoughtfully, "I see what you mean. Perhaps he wanted to make certain it was received on Earth."

"If we'd stuck to our launch date and not used Discovery as a booster, would it, or they, have done anything to save us?" asked Curnow. "That wouldn't have required much extra effort for an intelligence that could blow up Jupiter."

There was an uneasy silence broken at last by Heywood Floyd.

"On the whole," he said, "I'm very glad that's one question we'll never get answered."

"The human crew was monitoring HAL; if any malfunction occurred, they'd take over immediately."

"As David Bowman, commander of U.S. spacecraft Discovery, he had been caught in a gigantic trap."

"Plans were being considered and decisions were being made that might affect the destiny of worlds."