'And there's something else,' Max interjected with sudden excitement, 'I caught it on one of the daily newscasts – it was only a small item. An old girlfriend of Commander Bowman's claimed she'd had a message from him.'

'Yes – I saw the same report,' confirmed Sasha.

'And you never mentioned it?' Floyd asked incredulously. Both men looked slightly abashed.

'Well, it was treated as a joke,' said Max sheepishly. 'The woman's husband reported it. Then she denied it – I think.'

'The commentator said it was a publicity stunt – like the rash of UFO sightings around the same time. There were dozens in that first week; then they stopped reporting them.'

'Perhaps some of them were real. If it's not been wiped, could you dig that item out of ship's archives, or ask for a repeat from Mission Control?'

'A hundred tales won't convince me,' scoffed Tanya. 'What we need is solid proof.'

'Such as?'

'Oh – something that Hal couldn't possibly know, and that none of us could have told him. Some physical – er, manifes... 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 anytime we like – but we can't get into an Earth-return orbit until the launch window opens.'

'That's eleven days after the deadline!'

'Yes. I'd be happy to get away sooner; but we don't have the fuel for a higher-energy orbit...' Tanya's voice trailed away into uncharacteristic indecision. 'I was going to announce this later, but now that the subject has come up...'

There was a simultaneous intake of breath, and an instant hush from the audience.

'I'd like to delay our departure five days, to make our orbit closer to the ideal Hohmann one and give us a better fuel reserve.'

The announcement was not unexpected, but it was greeted with a chorus of groans.

'What will that do to our arrival time?' asked Katerina, in a slightly ominous tone of voice. The two formidable ladies regarded each other for a moment like well-matched adversaries, respectful of each other but neither willing to give ground.

'Ten days,' Tanya answered at last.

'Better late than never,' said Max cheerfully, trying to ease the tension, and not succeeding very well.

Floyd hardly noticed; he was lost in his own thoughts. The duration of the trip would make no difference to him and his two colleagues, in their dreamless sleep. But that was now completely unimportant.

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.

'... This is an incredible situation, Dimitri, and a very frightening one. You're the only person on Earth who knows about it – but very soon Tanya and I will have to have a showdown with Mission Control.

'Even some of your materialistic countrymen are prepared to accept – at least as a working hypothesis – that some entity has – well, invaded Hal. Sasha has dug up a good phrase: "The Ghost in the Machine".

'Theories abound; Vasili produces a new one every day. Most of them are variations on that old science-fiction cliché, the organized energy field. But what kind of energy? It can't be electrical, or our instruments would have detected it easily. The same thing applies to radiation – at least all the kinds we know. Vasili's getting really far-out, talking about standing waves of neutrinos and intersections with higher-dimensional space. Tanya says this is all mystical nonsense – a favourite phrase of hers – and they've come closer to a fight than we've ever seen them. We actually heard them shouting at each other last night. Not good for morale.

'I'm afraid we're all tense and overwrought. This warning, and the delayed departure date, has added to the sense of frustration caused by our total failure to get anywhere with Big Brother. It would have helped – maybe – if I could have communicated with the Bowman thing. I wonder where it's gone? Perhaps it simply wasn't interested in us after that one encounter. What it could have told us, if it wanted to! Hell and chyort vozmi! Damn – I'm talking Sasha's hated Russlish again. Let's change the subject.

'I can't thank you too much for everything you've done, and for reporting on the situation at home. I feel slightly better about it now – having something even bigger to worry about is perhaps the best cure for any insoluble problem.

'For the first time, I'm beginning to wonder if any of us will ever see Earth again.'

43 – Thought Experiment

When one spends months with a small, isolated group of people, one becomes very sensitive to the moods and emotional states of all its members. Floyd was now aware of a subtle change in attitude toward him; its most obvious manifestation was the reappearance of the greeting 'Dr Floyd', which he had not heard for so long that he was often slow to respond to it.

No one, he was sure, believed that he had really gone crazy; but the possibility was being considered. He did not resent that; indeed, he was grimly amused by it as he set about the task of proving his sanity.

He did have some slight supporting evidence from Earth. José Fernandez still maintained that his wife had reported an encounter with David Bowman, while she continued to deny it and refused to speak to any of the news media. It was hard to see why poor José should have invented such a peculiar story, especially as Betty seemed a very stubborn and quick-tempered lady. From his hospital bed, her husband declared that he still loved her and theirs was only a temporary disagreement.

Floyd hoped that Tanya's present coolness toward him was equally temporary. He was quite sure that she was as unhappy about it as he was, and he was certain that her attitude was not a matter of deliberate choice. Something had happened that simply would not fit into her pattern of beliefs, so she would try to avoid any reminders of it. Which meant having as little to do with Floyd as possible – a very unfortunate situation now that the most critical stage of the mission was fast approaching.

It had not been easy to explain the logic of Tanya's operational plan to the waiting billions back on Earth – especially to the impatient television networks, which had grown tired of showing the same never-changing views of Big Brother. 'You've gone all this way, at enormous cost, and you just sit and watch the thing! Why don't you do something?' To all these critics Tanya had given the same answer: 'I will – just as soon as the launch window opens, so that we can leave immediately if there's any adverse reaction.'

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 – constantly reporting back to Earth at every moment. When final contact was made, they would try to secure samples by drilling or laser spectroscopy; no one really expected these endeavours to succeed, as even after a decade of study TMA-1 resisted all attempts to analyse its material. The best efforts of human scientists in this direction seemed comparable to those of Stone Age men trying to break through the armour of a bank vault with flint axes.

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 kilometres 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.