Soon, analysis of their situation caused them to begin to farm intensively throughout all the biomes, to rebuild their food reserves. They agreed that all the young people should attend school full-time, and the students were given the aptitude tests with a rigor that the adults on board had never faced. A large team attended to the communication feed from Earth, recording and studying everything that these contained. This was perhaps premature, as significant historical and even biophysical changes would very likely occur in the 170 years before they got back, and no one in the ship would be alive when the ship reentered the solar system. Nevertheless, interest was high.

What they could gather concerning events in the solar system gave them reasons to worry. In the time the feed had been sent out, almost twelve years before, in what had been the common era year 2733, political turmoil appeared to be more or less continuous. Their feed did not include any basic system-wide background data, so the facts of the situation had to be inferred from the various strands of the feed, but it looked certain that on Earth the sea level was many meters higher than it had been when their ship had started its voyage, and the carbon dioxide level in Earth's atmosphere was around 600 parts per million, having been brought down significantly from the time the ship had left, when it had been close to 1,000 ppm. That suggested carbon drawdown efforts, and there were sulfur dioxide distributions over the north polar region of Earth, indicating geoengineering was being attempted. Several hundred names for Terran nations had been collated from the news feed, and yet the list did not seem complete. There were many scientific stations on Mars, also in the asteroids; thousands of asteroids had been hollowed out and made into little spinning terraria. There were also many stations and even tented cities on the larger Jovian and Saturnian moons-all but Io, not surprising given its radiation levels. There was a mobile city on Mercury, rolling always westward to stay in the dawn terminator. Luna, though dotted by stations and tented cities, and the source of many of the information feeds sent to the ship, was not being terraformed. Some in the ship declared that very little had advanced in the solar system during the time the ship had been gone, and no one had a ready explanation for this plateauing of effort or achievement, if indeed that was what it was. Of course there was the standard S-curve of the logistic function, charting the speed of growth seen in so many physical phenomena; whether human history also conformed to this pattern of diminishing returns, no one could say. In short, no one could analyze the feed from Earth and explain what was going on there. Theories in the ship were widespread, but really the feeds constituted only about 8.5 gigabytes of data per day, so the information stream was thin. It left a lot of room for speculation.

As we became more aware of this uncertainty about the situation in the solar system, we wondered if we should halt the acceleration of the ship a bit earlier than had been planned, to save some fuel for later.

Birth weights for the new generation were a bit lower than the average established on the voyage out, and there was a higher percentage of stillbirths and problem births, and birth defects. The medical team couldn't explain any of this, and some of them said there was no explanation, that the sample size was too small for it to be statistically significant. But it was emotionally significant, and there were a lot of upset new parents, and this distress moved out through the entire population by a kind of conversational or emotional osmosis. There was no difficulty in detecting a change in mood. People were apprehensive. Average blood pressure, heart rate, sleeping time: all shifted in the direction of increased stress, of increased apprehension and fear.

"Why is it happening?" people asked. "What's different?"

They often asked Freya, as if, she said to Badim, she could channel Devi and give them an answer. Inasmuch as she had none of Devi's flair for forensic investigation, she could only reply, "We need to find out." This she knew Devi would have said. After that of course came the moment when things got harder, the moment when Devi in her time had so often led the way. There was no one like Devi alive in the ship now, they said to each other. This we could confirm unequivocally, though we did not.

For a period of about three months they experienced a series of electrical shorts in the tropical biomes, and teams went in search of the problem but found nothing, until they went up into the spine, where, inside an electrical cabinet the size of a closet, which was always kept locked to prevent tampering and sabotage, they found a floating water droplet over a meter in circumference, its water white with unidentified bacterial life. On examination the bacteria turned out to be a form of Geobacter, a kind of bacteria that in large measure fed directly on electrons. After further investigation, strands of this strain of Geobacter were found elsewhere in the electrical systems of the ship.

General consternation. Static electricity was unavoidable in the ship, and in the microgravity of the spine, fields of static electricity could condense humidity out of the air and create concentrations of water, and then keep floating water drops from touching any sidewalls, until they grew to sizes like this one. And there was no easy way for the ship to be provided with sensors that would detect such water drops, which could gather in many so-called dead places in the spine, and even in functioning spaces like this electrical cabinet. Then also, as there were thin films of bacteria (also viruses and archaea) covering every surface in the ship, bacterial growths were almost sure to follow in any water droplets that condensed.

After the trauma on Aurora, many were made nervous by this reminder that microflora and -fauna were everywhere among them. The ship had always been stuffed with such life-forms, of course, and all the larger animal bodies as well; any analogy to Aurora was a false one. But the people in the ship lived by so many highly questionable analogies, it was no doubt difficult for them to know where to draw the line (so to speak).

Freya was asked to join a task force assembled to go through the ship looking for any signs of condensation, also any resulting concentrations of mold, fungus, and bacteria.

"The invitation is really to Devi," Freya said to Badim.

He agreed, but also urged her to join the study.

The results of their investigation disturbed them. The ship was indeed alive with microbial life, as everyone had known, but without regarding it as a problem; it was just the way things were inside any structure that included any life at all. Now, however, they had seen the problems in the newborns, and their crop yields were coming up consistently smaller than during the voyage out, even though the same plants were receiving the same light and nutrients. Birth weights were down in all the animals aboard, while miscarriages were up. So the living nature of the ship's interior became something ominous and foreboding.

"Look, it's always been this way," Freya reminded the executive council when the task force met with the council to discuss it. "There's no way to sterilize the ship when it's a set of biomes. It's alive, that's all."

No one could disagree. Howbeit their uneasiness, they simply had to live in a rich broth of bacteria, in a cumulative microgenome that was so much larger than their own genome that it was beyond a complete reckoning, especially as it was fluid and always changing.

But some bacteria were harmful. Same with archaea, fungi, viruses, prions, viris, and v's. They needed to make distinctions, as part of their ability to keep a healthy biosphere going. Some pathogens had to be tolerated, others had to be killed, if possible; but any attempt to kill bacteria meant that resistant surviving strains of that species would become more dominant and more resistant, in the usual way of things at the micro levels of life, or at all levels of life perhaps.

Dangerous to try to kill things, Freya reminded them. She knew full well, with a sinking sense that she was remembering her earliest memories, that Devi had believed that trying to kill any invasive species usually created more problems than it solved. A destabilized microbiome often caused more harm than anything a balanced microbiome could inflict. Better, therefore, to try to balance things with the least amount of intrusion. Subtle touches, all designed to finesse things for balance. Balance was the crucial thing. Teeter-totters, gently teeter-tottering up and down. Devi had even been an advocate of everyone getting an inoculation of helmiths, meaning ringworms, to give them better resistance to such parasites later. She had been a bit fanatical in that regard, as in so many.

The council and everyone else agreed with Freya on this matter; it was the common wisdom. But they were beginning to suffer problems none of them had seen before. The oldest person aboard was only seventy-eight years old. Median age was thirty-two. None of them had seen all that much in their short lives, and the complex of problems that Aram called zoo devolution was new to them, if not in the abstract, then in the lived experience.

As teams continued to inspect the ship, they found that some of the bacteria living around weld points, and in the gaps and cracks between walls and components, were eating away at the physical substrates of the ship. The corrosion was not chemical but biochemical. As they investigated further they found that all the ship's walls, windows, framing, gears, and glues had been altered by bacteria, first chemically and then physically and mechanically, in that their function was becoming impaired. Protozoa and amoeba, bacteria and archaea were found on the gaskets around windows and lock doors, also on the components of spacesuits, and in cable insulation, and in the interior panels and chips of the electrical systems, including the computers. Electrical components were often warm, and there was moisture in the air. They were finding microorganisms that lived on and degraded carbon steel, even stainless steel. And anywhere two different kinds of materials met, the microbial life living in the meeting points of these materials created galvanic circuits, which over time corroded both materials. Pitted metal; etched glass; eaten, digested, and excreted plastics: everything had stiffened and disintegrated right in place, without moving except under the forces of the centrifugal rotation of the ship, and the pressure of the ship's acceleration. Little creatures numbering in the quadrillions or quintillions-it was impossible to get a good estimate, much less a real count-all grew, and ate, and died, and were born and grew again, and ate again. They were eating the ship.

Life is part of the necessary matrix of life, so the ship had to be alive. And so the ship was getting eaten. Which meant that in some respects, the ship was sick.

The weekly meetings of the bacterial task force were similar to the ones Freya had attended as a child, when Devi had plopped her in the corner with some blocks, or paper and pens. Now she sat at the big table, but with about as little to say as when she was a girl. The plant pathologists spoke, the microbiologists spoke, the ecologists spoke. Freya listened and nodded, looking from face to face.

"The organisms in that big water droplet are mostly Geobacter and fungi, but there's also a prion in there that no one has ever seen on the ship, one that wasn't there in the beginning."

"Well, but wait. You mean it wasn't known about in the beginning. No one saw it. But it had to be there. No way it evolved here from some kind of precursor, not in the time since this ship was built."

"No? Are you sure?"

The microbiologists discussed this for a while. "Lots of things have had time enough to evolve quite a bit," one of them said. "I mean that's our problem, right? The bacteria, the fungi, maybe the archaea, they're all evolving at faster rates than we are. All organisms evolve at different rates. So discrepancies are growing, because it isn't a big enough ecosystem for coevolution to be able to bring everything into balance. That's what Aram has been saying all along."

Aram was brought into the next meeting to discuss this. "It's true," he said. "But I agree that this prion is unlikely to have evolved in the ship. I think it's just another stowaway, marooned out here with the rest of us. It's just that now we've seen it."

"And is it poisonous?" Freya asked. "Will it kill us?"

"Well, maybe. Sure. I mean, you don't want it inside you. That's the thing about prions."

"Are you sure it couldn't have evolved here from some precursor form?"

"I guess it's possible. Prions are badly folded proteins, basically. And we've been exposed to cosmic radiation for a long time now. Possibly some ordinary protein got hit, and wrinkled in a way that turned it into a new kind of prion, in a matrix that allowed it to begin the prion's weird kind of reproduction. That's how we think they began on Earth, right?"

"No one is sure," one of the microbiologists said. "Prions are strange. As far as we can tell from the feeds from Earth, they're still controversial there too. Still poorly understood."

"So what do we do about these now?" Freya asked.

"Well, there's no doubt that these are the kinds of organisms that we might want to try to eradicate. It's time to break out the pesticides, if we can figure one out. Or decide what the matrix of these prions is, and attack that. Scrub and spray everywhere we think it might be. Fry this water droplet for sure, even toss it into space. It's a water loss, but we'll have to take it. One thing that is a little comfort, is that the growth of prions inside mammals is slow. That's why I don't think the Auroran pathogen was a prion. When Jochi calls it a fast prion, I think he's just saying it's something we don't recognize. To me it seems more like a really small tardigrade."

Later Freya went up Spoke Two to visit Jochi, still in his ferry, held magnetically in the space between Spokes Two and Three. He had never wavered in his decision to stick with the ship, and thus with Aram and Freya and Badim, and the ship itself. His anger at the stayers, because of the death of the group in the ferry, was still intense.

He and Freya spoke from positions where they could both look out windows in their respective containers, and see each other face-to-face, separated by two clear plates.

Freya said, "They've found a prion in one of the transformer compartments in the spine. Something like Terran prions."

Jochi nodded. "I heard about that. Do they think it came from me?"

"No. It's very like Terran prions. Like one of the ones that cause mad cow disease."

"Ah. Slow-acting."

"Yes. And it isn't clear it's gotten into anything but a water droplet in an electrical compartment."

Jochi shook his head. "I don't understand how that could be."

"Neither does Aram. None of them understand it."

"Prions, wow. Are people scared?"

"Yes. Of course."

"Of course." His expression grew grim.

"So." She put her hand on her window. "How are you doing out here?"

"I'm all right. I've been watching a fascinating feed from China. They seem to have made some great progress in epigenetics and proteomics."

"What else, though? Have you done any stargazing?"

"Oh yes. A couple of hours every day. I've been looking in the Coal Sack. And finding new ways to look through our magnetic screen toward Sol. Although it could be the screen is distorting the image. Either that, or else Sol is pulsing a little. I sometimes think it's signaling us."

"Sol? The star?"

"Yes. It looks like that."

Freya looked at him silently.

Jochi said, "And I've seen the five ghosts again too. They're getting pretty upset for some reason. The Outsider seems to think we're in trouble. Vuk just laughs at him."

"Oh Jochi."

"I know. But, you know. They have to talk to someone."

Freya laughed. "I guess they do."

So as they flew back toward Sol, they tried to settle into their new lives, which were like their old lives, and yet somehow not. There were fewer of them, for one thing, and all in Ring B. And after the trauma of the schism, and choosing to head back to the solar system and its gigantic civilization, there were many in the ship who wanted to find new ways of doing things. Less regulation of their lives, less governance; less anxious studying of all that they needed to know to run the ship.

Wrong, Freya would say to all such talk. All wrong; could not be more wrong! She insisted they pursue all the same courses they had before, especially the studying. How they ran their daily affairs was of course not her concern; but whatever the method, the daily affairs had to include a complete education in the workings of the ship.

In moments like these, she came to seem like a very tall Devi, which was obviously a bit frightening to some of the others. Some called her Devi Two, or Big Devi, or Durga, or even Kali. No one contradicted her when she spoke in this fashion. We concluded her leadership in these matters was important for continuing function of the ship's society. This was perhaps a feeling. But it seemed clear people relied on her.

But she too would die someday, as Devi had; and what then?

Delwin suggested that they give up on the political or cultural structure that had existed before, of town representatives forming a general assembly where public business was decided. "That's what led us into all the trouble we had!"

"No it wasn't," Freya said. "If the assembly had been listened to, none of the bad stuff would have happened. That all happened because people were breaking the law."

Maybe so, Delwin conceded. But be that as it may, now they were all in accord, and they only needed to hold themselves together until they got back to the solar system, at which point they would be enfolded back into a much larger and more various world. Given that, and given the lived truth that power always corrupts, why not let all the apparatus of power go? Why not trust that they would self-organize, and simply do what needed doing?

This was no time for an experiment in anarchy, Badim said sharply to his old friend. They had no room for error. There were agricultural problems, growing faster than the crops themselves; they were going to have to be dealt with, and it might not be that easy. They might have to tell themselves what to do, and order their lives quite tightly, just in order to get by.

"It's not just agriculture," Freya said. "It's the population issue. At the rate we're going, very quickly we'll be back up to the carrying capacity of this ship. We certainly have to stop there, and given the problems that are cropping up, it might be better if we kept well below the theoretical maximum. It's hard to know, because we'll need workers for everything that needs doing. That's a question for the logistics programs. But no matter what, we'll still need to regulate our number."

"And once you have one major law," Badim added, "you need a system to enforce it. And when it's something basic, like reproduction, everyone has to be invested. It can be direct democracy, in a group this size. No reason why not. There are representative assemblies on Earth that are bigger than our entire population. But I think we need to agree that certain behaviors we decide for ourselves are binding. We need a legal regime. Let's not test that, please."

"But you see where that got us," Delwin said. "The moment there's a real disagreement, all that falls apart."

"But is that an argument against government? Seems to me the opposite. That was a breaking of the law, a coup attempt. We pulled it back together by an exertion of the law, by a return to norms we had."

"Maybe so, but what I'm saying is that if we think we have some structure that is going to decide things for us, and protect us when there's a problem, we're fooling ourselves. Because when a moment of crisis comes, the system can't do it for us, and at that point we're in chaos."

It seemed to us that the ship itself was the system that had gotten the population through the crisis and trauma of its schism, and was still in a position to deal with any future political crisis; but that was definitely not something to mention at this point, being neither here nor there, and possibly cutting right across the thrust of Delwin's sentiments, or worse, reinforcing them. Besides, we had only been upholding the rule of law.

And Badim clearly wanted to mollify his old friend. "All right, point taken. Maybe we forgot too much, or took too much for granted."

Freya said, "Now we're not going to be facing any choices as stark as that, I hope. We're on our way back to Earth, and there's very little to do, given that project, but to keep things going well. Pass the ship along to our children in good working order, and teach them what they have to know. That's what our parents did for us, as best they could. So now we do the same, and a few more generations do the same, and the last one in the line will be back on the planet we were made for."

So they reestablished the general assembly, this time as including everyone aboard, all voting on issues that a working executive council deemed important. Voting was mandatory. The executive council was formed of fifty adults, drawn by lot for a five-year term, with very few acceptable reasons for getting off the council if one's name were drawn.

Maintenance of the ship was left to us, with reports to the executive council and recommendations for human action included. We agreed to perform these functions.

"Happy to do so," we said.

Literally? Was this a true feeling, or just an assertion? Could humans make that distinction when they said such things?

Possibly a feeling is a complex algorithmic output. Or a superposed state before its wave function collapses. Or a collation of data from various sensors. Or some kind of total somatic response, an affect state that is a kind of sum over histories. Who knows. No one knows.

The first new generation passed their second birthdays, and most of them began to walk a little before or after that time. It took a few months more to be sure that as a cohort their ability to walk was coming much later than had been true for earlier generations in the ship. We did not share this finding. However, as it became more statistically significant it also became more anecdotally obvious, and soon became one of those class of anecdotes that got discussed.

"What's causing this? There has to be a reason, and if we knew what it was, we could do something about it. We can't just let this go!"

"They get such close attention, more than ever before-"

"Why should you think that? When were babies not attended to by their parents? I don't think that was ever true."

"Oh come on. Now you have to get permission to have one, they're rare, they're the focus of everyone's lives, of course they get more attention."

"There were never good records kept of developmental stuff like this."

"Not true, not true at all."

"Well, where are they then? I can't find them. It's always anecdotal. How can you say exactly when a toddler is toddling? It's a process."

"Something's changed. Pretending it hasn't won't work."

"Maybe it's just reversion to the mean."

"Don't say that!"

That was Freya, her voice sharp.

"Don't say that," she said again in the silence of the others. "We have no idea what the norm was. Besides, the concept itself is contested."

"Well, okay. But say what you like, you can see them staggering. We need to figure out why, that's all I'm saying. No sticking our head in the sand on stuff like this. Not if we want someone to get home."

There were batteries of tests available to give to children to gauge their cognitive development. The Pestalozzi-Piaget Combinatoire had been worked up in the ship in the forties, using various games as tests. For most of a year Freya sat on the floor of the kindergarten and played games with the return kids, as they were called. Simple puzzles, word games, invitations to rename things, arithmetical and geometrical problems played with blocks. It did not seem to us as if these tests could reveal very much about the reasoning of the children, or their analogic abilities, their deductions from negative evidence, and so on; they were all partial and indirect, linguistically and logically simple. Still, the clear result of each session was to leave Freya more and more troubled. Less appetite on her part; more contrary replies to Badim and others; less sleep at night.

Not that it was only the games with children that gave her and the others cause for alarm. More quantitatively, crop yields were down in the Prairie, the Pampas, Olympia, and Sonora; and dropouts in electrical power from the spinal generators were increasing, by 6.24 outages and 238 kilowatt-hours per month, on average, which would cause serious problems in all kinds of functions in a matter of several months. It was possible to trace and isolate the sections of the grid where the outages were most frequent, but in fact they were spread through many points in the spine and spokes. Geobacter was suspected as the cause, as it was often found on the wiring. As with other functional components of the ship, maintenance was becoming advisable.

They worked on these problems whenever they could locate them, and we did the same. For many components, function had to be maintained while repairs were effected, and for the most part, the elements to be repaired had to be removed and refurbished and then put back in place, as for many materials there were not feedstocks adequate to be able to replace larger components outright. Exterior walls, for instance.

Thus insulation had to be stripped away, leaving live wires exposed to be cleaned, and the insulating material broken down and reconstituted, and then replaced over the wires, without at any time being able to shut down power from the system as a whole. A schedule of partial shutdowns could be arranged, and was. And yet the unscheduled power losses, while nondebilitating, nevertheless reduced functions, including of the sunlines.

We began to investigate the recursive algorithms in the file marked by Devi "Bayesian methodology." Looking for options. Wishing Devi were here. Trying to imagine what Devi would say. But this, we found, was impossible. This was precisely what one lost when someone died.

All this ongoing malfunction was particularly problematic when it came to the sunlines. All the light on the ship (aside from incidental ambient incoming starlight, which taken altogether came to 0.002 lux) was generated by the ship's lighting elements, which made use of a fairly wide array of designs and physical properties. Their artificial sunlight varied in luminosity from 120,000 lux on a clear midday to 5 lux during the darkest twilight storms. This was all well regulated, along with a moonlight effect at night ranging from a full moon effect of 0.25 lux to 0.01 lux, on the classic lunar schedule. But when the lighting elements had to be refurbished or resupplied, then it was as if unscheduled eclipses were occurring. Crops were therefore affected, their growth delayed in ways that stunted them at harvest time. Increasing the biome's light after a dimming did not compensate for the loss of light at the appropriate times. Nevertheless, despite the agricultural costs, given the inevitable wear on the lighting elements themselves, the required maintenance simply had to be done. But as a result, less food was grown.

The executive council and the general assembly, meaning everyone on the ship over twelve years old, was asked by Aram's lab group to consider questions of carrying capacity. This was only a formalization of a conversation that was now going on in many ways, as each biome had become its own land use debate as to which types of foods to grow. Did they have the caloric margin to raise animals for meat anymore? Vat-grown meat was clearly more efficient in terms of time and energy, but the meat vats' feedstock supplies were of course a limiting factor there. And it was not always easy to change biomes rapidly from pasture and grazing land to crop agricultures. Every change in the biomes had ecological ramifications that could not be fully modeled or predicted, and yet there was very little margin for error, if they happened to damage the health of an ecosystem by trying too quickly to make it more productive in food terms. They needed all the biomes to be healthy.

Everyone came to agree that the least productive biomes in agricultural terms should be converted to farmland. Biodiversity was not important now, compared to food.

We were glad to see people finally coming to conclusions that had long been suggested by a fairly simple algorithmic exploration of their available options. In fact, we probably should have mentioned it ourselves. Something to remember, going forward.