The electronic psychoanalysis had proceeded at a speed totally beyond human comprehension as repair and diagnostic programs flashed through Hal's circuits at billions of bits a second, pinpointing possible malfunctions and correcting them. Though most of these programs had been tested in advance on Hal's twin, SAL 9000, the impossibility of a real-time dialogue between the two computers was a serious handicap. Sometimes hours were wasted when it proved necessary to check back with Earth at a critical point in the therapy.

For despite all Chandra's work, the computer's rehabilitation was still far from complete. Hal exhibited numerous idiosyncrasies and nervous tics, sometimes even ignoring spoken words – though he would always acknowledge keyboard inputs from anyone. In the reverse direction, his outputs were even more eccentric.

There were times when he would give verbal replies, but would not display them visually. At other times he would do both – but refused to print hard copy. He would give no excuses or explanations – not even the stubbornly impenetrable 'I prefer not to' of Melville's autistic scrivener, Bartelby.

However, he was not actively disobedient so much as reluctant, and only where certain tasks were concerned. It was always possible to win his cooperation eventually – 'to talk him out of his sulk', as Curnow put it neatly.

It was not surprising that Dr Chandra was beginning to show the strain. On one celebrated occasion when Max Brailovsky innocently revived an old canard, he almost lost his temper.

'Is it true, Dr Chandra, that you chose the name Hal to be one step ahead of IBM?'

'Utter nonsense! Half of us come from IBM and we've been trying to stamp out that story for years. I thought that by now every intelligent person knew that H-A-L is derived from Heuristic ALgorithmic.'

Afterward, Max swore that he could distinctly hear the capital letters.

In Floyd's private opinion, the odds were at least fifty to one against flying Discovery safely back to Earth. And then Chandra came to him with an extraordinary proposal.

'Dr Floyd, can I have a word with you?'

After all the weeks and shared experiences, Chandra was still as formal as ever – not only to Floyd, but to all the crew. He would not even address the ship's baby, Zenia, without the prefix 'ma'am'.

'Of course, Chandra. What is it?'

'I've virtually completed the programming for the six most probable variations on the Hohmann return orbit. Five have now been run on a simulation, without any problems.'

'Excellent. I'm sure that no one else on Earth – in the Solar System – could have done it.'

'Thank you. However, you know as well as I do that it's impossible to program for every eventuality. Hal may – will – function perfectly, and will be able to handle any reasonable emergency. But all sorts of trivial accidents – minor equipment failures that could be fixed with a screwdriver, broken wires, stuck switches – could leave him helpless and abort the whole mission.'

'You're absolutely right, of course, and it's been worrying me. But what can we do about it?'

'It's really quite simple. I'd like to stay with Discovery.'

Floyd's immediate reaction was that Chandra had gone crazy. On second thoughts, perhaps he was only half crazy. It might indeed make all the difference between success and failure to have a human being – that superb all-purpose trouble-shooting and repair device – aboard Discovery for the long voyage back to Earth. But the objections were completely overwhelming.

'It's an interesting idea,' Floyd answered with extreme caution, 'and I certainly appreciate your enthusiasm. But have you thought of all the problems?' That was a silly thing to say; Chandra would have all the answers already filed away for immediate retrieval.

'You'll be on your own for over three years! Suppose you had an accident or a medical emergency?'

'That's a risk I'm prepared to take.'

'And what about food, water? Leonov doesn't have enough to spare.'

'I've checked Discovery's recycling system; it can be made operational again without too much difficulty. Besides, we Indians can manage on very little.'

It was unusual for Chandra to refer to his origins, or indeed to make any personal statements; his 'true confession' was the only example Floyd could remember. But he did not doubt the claim; Curnow had once remarked that Dr Chandra had the sort of physique that could only be achieved by centuries of starvation. Although it sounded like one of the engineer's unkinder wisecracks, it had been made entirely without malice – indeed, with sympathy; though not, of course, in Chandra's hearing.

'Well, we still have several weeks to decide. I'll think it over and talk to Washington.'

'Thank you; do you mind if I start making the arrangements?'

'Er – not at all, as long as they don't interfere with the existing plans. Remember – Mission Control will have to make the final decision.'

And I know exactly what Mission Control will say. It was madness to expect a man to survive in space for three, years, alone.

But, of course, Chandra had always been alone.

36 – Fire in the Deep

Earth was already far behind, and the awesome wonders of the Jovian system were expanding swiftly before him, when he had his revelation.

How could he have been so blind – so stupid! It was as if he had been walking in his sleep; now he was starting to awaken.

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

There was no answer, yet he was certain that he had been heard. He sensed a... presence, even as a man can tell, though his eyes are tightly shut, that he is in a closed room and not some empty, open space. Around him there was the faint echo of a vast mentality, an implacable will.

He called again into the reverberant silence, and again there was no direct reply – only that sense of watchful companionship. Very well; he would find the answers for himself.

Some were obvious; whoever or whatever they were, they were interested in Mankind. They had tapped and stored his memories, for their own inscrutable purposes. And now they had done the same with his deepest emotions, sometimes with his cooperation, sometimes without.

He did not resent that; indeed, the very processing he had experienced made such childish reactions impossible. He was beyond love and hate and desire and fear – but he had not forgotten them, and could still understand how they ruled the world of which he had once been part. Was that the purpose of the exercise? If so, for what ultimate goal?

He had become a player in a game of gods, and must learn the rules as he went along.

The jagged rocks of the four tiny outer moons, Sinope, Pasiphae, Carme, and Ananke, flickered briefly across his field of consciousness; then came Elara, Lysithea, Himalia, and Leda at half their distance from Jupiter. He ignored them all; now the pock-marked face of Callisto lay ahead.

Once, twice, he orbited the battered globe, larger than Earth's own Moon, while senses of which he had been unaware probed its outer layers of ice and dust. His curiosity was quickly satisfied; the world was a frozen fossil, still bearing the marks of collisions that, aeons ago, must have come close to shattering it. One hemisphere was a giant bull's-eye, a series of concentric rings where solid rock had once flowed in kilometre-high ripples under some ancient hammer blow from space.

Seconds later, he was circling Ganymede. Now there was a far more complex and interesting world; though so near to Callisto, and almost the same size, it presented an utterly different appearance. There were, it was true, numerous craters – but most of them seemed to have been, quite literally, ploughed back into the ground. The most extraordinary feature of the Ganymedean landscape was the presence of meandering stripes, built up from scores of parallel furrows a few kilometres apart. This grooved terrain looked as if it had been produced by armies of intoxicated ploughmen, weaving back and forth across the face of the satellite.