11

How early had she known? From the moment she had named the star Nemesis? Had she felt what it was and what it meant, and had she named it appropriately without conscious thought?

When she had first spotted the star, it had been only the act of finding it that counted. There had been no room in her mind for anything but immortality. It was her own star, Insigna's Star. She had been tempted to call it that. How glorious that had sounded, even as she had reluctantly avoided it with a hollow internal grimace of mock modesty. How unbearable it would have been now if she had fallen into that trap.

After the discovery, there had come the shock of Pitt's demand for secrecy, and then the furious preparation for the Leaving. (Would that be what it would be called in the history books someday? The Leaving? Capitalized?)

Then, after the Leaving, there were two years in which the ship skipped steadily and barely into and out of hyperspace - and the endless calculations that were involved in that hyper-assistance, for which astronomical data was constantly required, with herself supervising the supply. The density and composition of interstellar matter alone-

At no time in those four years had she been able to think of Nemesis in detail; not once could she zero in on the obvious.

Was that possible? Or did she simply turn away from what she did not want to see? Had she deliberately sought refuge in all the secrecy and scurry and excitement that presented itself to her?

But there came a time when the last hyperspatial period was behind them; when, for a month, they would be decelerating through an initial hail of hydrogen atoms, which they struck with such speed that those atoms were converted into cosmic ray particles.

No ordinary space vehicle could have endured that, but Rotor had a thick layer of soil around it that had been thickened for the trip, and the particles were absorbed.

There would come a time, she had been assured by one of the hyperspatialists when one would enter and leave hyperspace at ordinary speeds. 'Given hyperspace in the first place,' he had said, 'no new conceptual breakthrough is required. It's just engineering.'

Maybe! The remaining hyperspatialists, however, considered the notion so much star exhaust.

Insigna hurried in to see Pitt when the appalling truth descended upon her. He had had little time for her in the last year, and she had understood. There was a certain tension that became more and more evident as the excitement of the trip wound down, as people realized that in a matter of months they would be in the neighborhood of another star. They would then have the constant problem of having to survive over a long period in the vicinity of a strange red dwarf star without any guarantee of reasonable planetary material to serve as a supply source, let alone a living place.

Janus Pitt no longer looked like a young man, although his hair was still dark, his face unlined. Only four years had passed since she had come to him with the news of Nemesis' existence. There was, however, a harried look in his eyes, a sense of having had his joy rubbed away and his cares left naked to the world.

He was Commissioner-elect now. Perhaps that might account for a great deal of what might be troubling him, but who could tell? Insigna had never known true power - or the responsibility that accompanied it - but something told her it might have the capacity for souring one who did.

Pitt smiled at her absently. They had been forced to be close when they had shared a secret that at first no-one - and then almost no-one - had shared with them. They could then talk unguardedly with each other, when they could not do so with anyone else. After the Leaving, however, when the secret was revealed, they had grown apart again.

'Janus,' she said, 'there is something eating away at me and I had to come to you with it. It's Nemesis.'

'Is there anything new? You can't say you've found out it isn't where you thought it was. It's right out there, less than sixteen billion kilometers away. We can see it.'

'Yes, I know. But when I first found it, at a distance of two-plus light-years, I took it for granted that it was a companion star, that Nemesis and the Sun were circling a common center of gravity. Something that close would almost have to be. It would be so dramatic.'

'All right. Why shouldn't things be dramatic now and then?'

'Because as close as it is, it is clearly too far away to be a companion star. The gravitational attraction between Nemesis and the Sun is terribly weak, so weak that the gravitational perturbations of nearby stars would make the orbit unstable.'

'But Nemesis is there.'

'Yes, and more or less between ourselves and Alpha Centauri.'

'What has Alpha Centauri got to do with it?'

'The fact is that Nemesis is not much farther from Alpha Centauri than it is from the Sun. It's just as likely to be a companion star of Alpha Centauri. Or, more likely, whichever system it belongs to, the presence of the other star is now disrupting it, or has already disrupted it.'

Pitt looked at Insigna thoughtfully and tapped his fingers lightly on the arm of his chair. 'How long does it take Nemesis to go around the Sun - assuming it's the Sun's companion?'

'I don't know. I'd have to work out its orbit. That's something I should have done before the Leaving, but there were so many other things occupying me then, and now, too - but that's no excuse.'

'Well, make a guess.'

Insigna said, 'If it's a circular orbit, it would take Nemesis just over fifty million years to make a circuit about the Sun, or, more properly, about the center of gravity of the system, with the Sun making a similar circuit. The line between the two, as they moved, would always pass through that center. On the other hand, if Nemesis is following a highly elliptical orbit and is now at its farthest - as it must be, for if it ventured farther still, it would certainly not be a companion star - then perhaps as little as twenty-five million years.'

'Last time, then, that Nemesis was in this position, more or less between Alpha Centauri and the Sun, Alpha Centauri must have been in a much different position than it is now. Twenty-five to fifty million years would move Alpha Centauri, wouldn't it? How much?'

'A good fraction of a light-year.'

'Would that mean that this is the first time Nemesis is being fought over by the two stars? Till now, would it have been circling peacefully?'

'Not a chance, Janus. Even if you count out Alpha Centauri, there are other stars. One star may have arrived now, but there had to be another star in interfering distance at some other part of its orbit in the past. The orbit just isn't stable.'

'What's it doing here in our neighborhood, then, if it isn't orbiting the Sun?'

'Exactly,' said Insigna.

'What do you mean, "exactly"?'

'If it were orbiting the Sun, it would be moving at a speed, relative to the Sun, of somewhere between eighty and one hundred meters a second, depending on Nemesis' mass. That's very slow motion for a star, so it would seem to stay in the same place for a long time. It would therefore remain behind the cloud for a long time, especially if the cloud is moving in the same direction relative to the Sun. With such a slow motion and its light dimmed, it's no wonder it's never been noticed till now. However-' She paused.

Pitt, who made no effort to seem devouringly interested, sighed and said, 'Well? Can you get to the point?'

'Well, if it's not in orbit about the Sun, then it is in independent motion and it should be moving relative to the Sun at a hundred kilometers a second or so, a thousand times as fast as if it were in orbit. It just happens to be in our neighborhood now, but it is moving on, will pass the Sun, and will never return. But, just the same, it stays behind the cloud, scarcely budging from its position.'

'Why should that be?'

'There's one way it can be moving at a good clip, and yet not seem to be moving from its position in the sky.'

'Don't tell me it's vibrating back and forth.'

Insigna's lip curled. 'Please don't try to make jokes, Janus. This isn't funny. Nemesis might be moving more or less straight toward the Sun. It wouldn't be shifting either to the right or left, so that it would not seem to be changing position, but it would be coming right toward us; that is, right toward the Solar System.'

Pitt stared at her in surprise. 'Is there evidence for that?'

'Not yet. There was no reason to take the spectrum of Nemesis when it was first spotted. It was only after I had noticed the parallax that a spectral analysis would have made sense, and then I never got around to it. If you remember, you put me at the head of the Far Probe project, and told me to direct everyone's attention away from Nemesis. I couldn't have arranged a close spectral analysis at that time, and since the Leaving - well, I haven't. But I will investigate the matter now, you can be sure.'

'Let me ask you a question. Wouldn't it produce the same effect of motionlessness, if Nemesis were moving directly away from the Sun? It's a fifty-fifty chance whether it's moving toward the Sun or away from it, isn't it?'

'Spectral analysis will tell us. A red shift of the spectral lines will mean there's a recession; a violet shift, an approach.'

'But it's too late now. If you take its spectrum, it will tell you it's approaching us, because we're approaching it.'

'Right now, I wouldn't take the spectrum of Nemesis. I'd take it of the Sun. If Nemesis is approaching the Sun, then the Sun will be approaching Nemesis, and we can allow for our own motion. Besides, we're slowing and, in a month or so, we will be moving so slowly that our motion won't be affecting the spectroscopic results appreciably.'

For the space of half a minute, Pitt seemed lost in thought, staring at his uncluttered desk, his hand slowly stroking the computer terminal. Then he said, without bothering to look up, 'No. These are observations that need not be made. I don't want you worrying yourself about it any more, Eugenia. It's a nonproblem, so just forget it.'

The wave of his hand made it clear that she was to leave.

12

Insigna's breath made a whistling sound as it was forced out of angrily tightened nostrils. She said in a low husky voice, 'How dare you, Janus? How dare you?'

'How dare I what?' Pitt frowned.

'How dare you order me out of here as though I were a computer-puncher? If I hadn't found Nemesis, we wouldn't be here. You wouldn't be Commissioner-elect. Nemesis is mine. I have a say in it.'

'Nemesis isn't yours. It's Rotor's. So please leave now and let me get on with the business of the day.'

'Janus,' she said, raising her voice. 'I tell you again that, in all likelihood, Nemesis is moving toward our Solar System.'

'And I tell you again that it is only a fifty-fifty chance that it is. And even if it were heading toward the Solar System - not our Solar System any longer, by the way, but their Solar System - don't tell me it's going to hit the Sun. I won't believe you if you do. In its whole nearly five-billion-year history, the Sun has never been struck by a star, or even come close. The odds against stellar collisions even in relatively crowded parts of the Galaxy are enormous. I may not be an astronomer, but I know that much.'

'Odds are just odds, Janus, not certainties. It's conceivable, however unlikely, that Nemesis and the Sun might collide, but I recognize that it's very unlikely they will. The trouble is that a close approach, even without collision, might be fatal to Earth.'

'How close is a close approach?'

'I don't know. It will take a great deal of computation.'

'All right, then. You suggest that we take the trouble to make the necessary observations and computations and, if we find out that the situation is indeed fraught with danger to the Solar System, then what? Do we warn the Solar System?'

'Well, yes. What choice would we have?'

'And how would we warn them? We have no means of hypercomrnunication and, even if we had, they have no system for receiving hypermessages. If we sent out a luminal message of some sort - light, micro-waves, modulated neutrinos - it would take over two years to reach Earth, assuming we have a beam powerful enough, or sufficiently coherent. And even then, how would we know if they had received it? If they had and bothered to answer, that answer would take another two years to return. And what will be the final result of the warning? We will have to tell them where Nemesis is and they will see that the information is coming from that direction. The whole point of our secrecy, the whole plan for establishing a homogeneous civilization around Nemesis, free of interference, would be lost.'

'Whatever the cost, Janus, how could you consider not warning them?'

'Where's your concern? Even if Nemesis is moving toward the Sun, how long would it take for it to reach the Solar System?'

'It could reach the neighborhood of the Sun in five thousand years.'

Pitt sat back in his chair and regarded Insigna with a kind of wry amusement. 'Five thousand years. Only five thousand years? Look, Eugenia, two hundred and fifty years ago, the first Earthman stood on the Moon. Two and a half centuries have passed and here we are at the nearest star. Where will we be in another two and a half centuries, at this rate? At any star we wish. And in five thousand years, fifty centuries, we will be all over the Galaxy, barring the presence of other intelligent forms of life. We will be reaching out to other galaxies. Within five thousand years, technology will have advanced to the point where, if the Solar System were really in trouble, all its Settlements and its entire planetary population could take off for deep space and other stars.'

Insigna shook her head. 'Don't think that technological advance means that you can empty the Solar System by a mere wave of the hand, Janus. To remove billions of people without chaos and without tremendous loss of life would require long preparation. If they are in mortal danger five thousand years from now, they must know now. It is not too soon to begin to plan.'

Pitt said, 'You have a good heart, Eugenia, so I'll offer a compromise. Suppose we take a hundred years in which to establish ourselves here, to multiply, to build a cluster of Settlements that will be strong enough and stable enough to be secure. Then we can investigate Nemesis' destination and - if necessary - warn the Solar System. They will still have nearly five thousand years in which to prepare. Surely a small delay of a century will not be fatal.'

Insigna sighed. 'Is that your vision of the future? Humanity squabbling endlessly over the stars? Each little group trying to establish itself as supreme over this star or that? Endless hatred, suspicion, and conflict, of the kind we had on Earth for thousands of years, expanded into the Galaxy for thousands more?'

'Eugenia, I have no vision. Humanity will do as it pleases. It will squabble as you say, or it will perhaps set up a Galactic Empire, or do something else. I can't dictate what humanity will do, and I don't intend to try to shape it. For myself, I have only this one Settlement to care for, and this one century in which to establish it at Nemesis. By then, you and I will be safely dead, and our successors will handle the problem of warning the Solar System - if that should be necessary. I'm trying to be reasonable, not emotional, Eugenia. You are a reasonable person, too. Think about it.'

Insigna did. She sat there, looking somberly at Pitt, while he waited with almost exaggerated patience.

Finally she said, 'Very well. I see your point. I will get on with analyzing Nemesis' motion relative to the Sun. Perhaps we can forget the whole thing.'

'No.' Pitt raised an admonishing finger. 'Remember what I said earlier. These observations will not be made. If it turns out that the Solar System is not in danger, we will have gained nothing. We will then merely do what I insist we do in any case - spend a century strengthening the civilization of Rotor. If, however, you find that there is danger, then your conscience will hurt and you will be consumed with apprehensions and fears and guilt. The news will somehow get out and it will weaken the resolve of Rotorians, many of whom may be as sentimental as you are. We would then lose a great deal. Do you understand me?'

She was silent, and he said, 'Good. I see you do.' Again, the wave of his hand made it clear that she was to leave.

This time she left, and Pitt, looking after her, thought: She is really becoming insupportable.