'Despite that, we send our love, and so does Sebastian. Say hello to any Europans you meet. Judging by the reports from Galaxy, some of them would make very good partners for Ms Wilkinson.'

Dr Heywood Floyd preferred not to talk about the first mission to Jupiter, and the second to Lucifer ten years later. It was all so long ago – and there was nothing he had not said a hundred times to Congressional Committees, Space Council boards and media persons like Victor Willis.

Nevertheless, he had a duty to his fellow passengers which could not be avoided. As the only living man to have witnessed the birth of a new sun – and a new solar system – they expected him to have some special understanding of the worlds they were now so swiftly approaching. It was a naïve assumption; he could tell them far less about the Galilean satellites than the scientists and engineers who had been working there for more than a generation. When he was asked 'What's it really like on Europa?' (or Ganymede, or Io, or Callisto...) he was liable to refer the enquirer, rather brusquely, to the voluminous reports available in the ship's library.

Yet there was one area where his experience was unique. Half a century later, he sometimes wondered if it had really happened, or whether he had been asleep aboard Discovery when David Bowman had appeared to him. Almost easier to believe that a spaceship could be haunted...

But he could not have been dreaming, when the floating dust motes assembled themselves into that ghostly image of a man who should have been dead for a dozen years. Without the warning it had given him (how clearly he remembered that its lips were motionless, and the voice had come from the console speaker) Leonov and all aboard would have been vaporized in the detonation of Jupiter.

'Why did he do it?' Floyd asked during one of the after-dinner sessions. 'I've puzzled over that for fifty years. Whatever he became, after he went out in Discovery's space pod to investigate the monolith, he must still have had some links with the human race; he was not completely alien. We know that he returned to Earth – briefly – because of that orbiting bomb incident. And there's strong evidence that he visited both his mother and his old girlfriend; that's not the action of – of an entity that had discarded all emotions.'

'What do you suppose he is now?' asked Willis. 'For that matter – where is he?'

'Perhaps that last question has no meaning – even for human beings. Do you know where your consciousness resides?'

'I've no use for metaphysics. Somewhere in the general area of my brain, anyway.'

'When I was a young man,' sighed Mihailovich, who had a talent for deflating the most serious discussions, 'mine was about a metre lower down.'

'Let's assume he's on Europa; we know there's a monolith there, and Bowman was certainly associated with it in some way – see how he relayed that warning.'

'Do you think he also relayed the second one, telling us to stay away?'

'Which we are now going to ignore -'

' in a good cause -' Captain Smith, who was usually content to let the discussion go where it wished, made one of his rare interjections.

'Dr Floyd,' he said thoughtfully, 'you're in a unique position, and we should take advantage of it. Bowman went out of his way to help you once. If he's still around, he may be willing to do so again. I worry a good deal about that ATTEMPT NO LANDINGS HERE order. If he could assure us that it was – temporarily suspended, let's say – I'd be much happier.'

There were several 'hear, hear's around the table before Floyd answered.

'Yes, I've been thinking along the same lines. I've already told Galaxy to watch out for any – let's say manifestations – in case he tries to make contact.'

'Of course,' said Yva, 'he may be dead by now – if ghosts can die.'

Not even Mihailovich had a suitable comment to this, but Yva obviously sensed that no-one thought much of her contribution.

Undeterred, she tried again.

'Woody, dear,' she said. 'Why don't you simply give him a call on the radio? That's what it's for, isn't it?'

The idea had occurred to Floyd, but it had somehow seemed too naïve to take seriously.

'I will,' he said. 'I don't suppose it will do any harm.'

This time, Floyd was quite sure he was dreaming...

He had never been able to sleep well in zero gravity, and Universe was now coasting, unpowered, at maximum velocity. In two days it would start almost a week of steady deceleration, throwing away its enormous excess speed until it was able to rendezvous with Europa.

However many times he adjusted the restraining straps, they always seemed either too tight or too loose. He would have difficulty in breathing – or else he would find himself drifting out of his bunk.

Once he had awoken in mid-air, and had flailed away for several minutes until, exhausted, he had managed to 'swim' the few metres to the nearest wall. Not until then had he remembered that he should merely have waited; the room ventilating system would have soon pulled him to the exhaust grille without any exertion on his part. As a seasoned space-traveller, he knew this perfectly well; his only excuse was simple panic.

But tonight, he had managed to get everything right; probably when weight returned, he would have difficulty in readjusting to that. He had lain awake for only a few minutes, recapitulating the latest discussion at dinner, and had then fallen asleep.

In his dreams, he had continued the conversation around the table. There had been a few trifling changes, which he accepted without surprise. Willis, for example, had grown his beard back – though on only one side of his face. This, Floyd presumed, was in aid of some research project, though he found it difficult to imagine its purpose.

In any event, he had his own worries. He was defending himself against the criticisms of Space Administrator Millson, who had somewhat surprisingly joined their little group. Floyd wondered how he had come aboard Universe (could he possibly have stowed away?). The fact that Millson had been dead for at least forty years seemed much less important.

'Heywood,' his old enemy was saying, 'the White House is most upset.'

'I can't imagine why.'

'That radio message you've just sent to Europa. Did it have State Department clearance?'

'I didn't think it was necessary. I merely asked permission to land.'

'Ah – but that's it. Who did you ask? Do we recognize the government concerned? I'm afraid it's all very irregular...

Millson faded away, still tut-tutting. I'm very glad this is only a dream, thought Floyd. Now what?

Well, I might have expected it. Hello, old friend. You come in all sizes, don't you? Of course, even TMA 1 couldn't have squeezed into my cabin – and its Big Brother could easily have swallowed Universe in one gulp.

The black monolith was standing – or floating – only two metres from his bunk. With an uncomfortable shock of recognition, Floyd realized that it was not only the same shape, but also the same size, as an ordinary tombstone. Although the resemblance had often been pointed out to him, until now the incongruity of scale had lessened the psychological impact. Now, for the first time, he felt the likeness was disquieting – even sinister. I know this is only a dream – but at my age, I don't want any reminders...

Anyway – what are you doing here? Do you bring a message from Dave Bowman? Are you Dave Bowman?

Well, I didn't really expect an answer; you weren't very talkative in the past, were you? But things always happened when you were around. Back in Tycho, sixty years ago, you sent that signal to Jupiter, to tell your makers that we'd dug you up. And look what you did to Jupiter, when we got there a dozen years later!