Sax stared down at his plate and ate in silence, thinking hard about all these factors. The morning’s discussions had given him cause to wonder whether he had made the right decisions back in 2042-whether the volatile inventory could justify his attempt to go straight for a human-viable surface in a single stage. Not that there was much that could be done about it now. And all things considered, he still thought they were the right decisions; shikata ga nai, really, if they wanted to walk freely on the surface of Mars in their own lifetimes. Even if their lifetimes were going to be considerably extended.

But there were people who seemed more concerned with high temperatures than breathability. Apparently they were confident that they could balloon the CO₂ level, heat things tremendously, and then reduce the CO₂ without problems. Sax was dubious about that; any two-phase operation was going to be messy, so messy that Sax couldn’t help wondering if they would get stuck with the 20,000-year time scales predicted in the earliest two-phase models.

It made him blink to think of it. He couldn’t see the need. Were people really willing to risk such a long-term problem? Could they be so impressed by the new gigantic technologies that were becoming available that they believed anything was possible?

“How was the pastrami?” Berkina asked.

“The what?”

“The pastrami. That’s the kind of sandwich you just ate, Stephen.”

“Oh! Fine, fine. It must have been fine.”

The afternoon’s sessions were mostly devoted to problems caused by the successes of the global warming campaign. As surface temperatures rose, and the underground biota began to penetrate deeper into the regolith, the permafrost down there was melting, just as hoped. But this was proving disastrous in certain permafrost-rich regions. One of these, unfortunately, was Isidis Planitia itself. A well-attended talk by an areologist from a Praxis lab in Burroughs described the situation; Isidis was one of the big old impact basins, about the size of Argyre, with its northern side completely erased, and its southern rim now part of the Great Escarpment. Underground ice had been creeping off the Escarpment and pooling in the basin for billions of years. Now the ice near the surface was melting, and in the winters freezing again. This thaw-freeze cycle was causing frost heaving on an unprecedented scale; it was pretty near the usual two-magnitude enlargement compared to similar phenomena on Earth, and karsts and pingos a hundred times the size of their Terran analogues were big holes, and big mounds. All over Isidis these giant new holes and hummocks were blistering the landscape, and after her talk and a sequence of mind-boggling slides, the areologist led a large group of interested scientists to the south end of Burroughs, past Moeris Lacus Mesa to the tent wall, where the neighborhood looked like it had been devastated by earthquake, the ground having heaved up to reveal a rising mass of ice like a bald round hill.

“This is a fine specimen of a pingo,” the areologist said with a proprietary air. “The ice masses are relatively pure compared to the permafrost matrix, and they act in the matrix the same way rocks do-when the permafrost refreezes at night or in winter, it expands, and anything hard stuck in this expansion gets pushed upward toward the surface. There’s a lot of pingos in Terran tundra, but none as big as this one.” She led the group up the shattered concrete of what had been a flat street, and they stared out from an earthen crater rim, onto a mound of dirty white ice. “We’ve lanced it like a boil, and are melting it and piping it into the canals.”

“Out in the country one of these coming up would be like an oasis,” Sax remarked to Jessica. “It would melt in the summer, and hydrate the ground around it. We ought to develop a community of seeds and spores and rhizomes that we could scatter on any sites like this out in the country.”

“True,” Jessica said. “Although, to be realistic, the permafrost country is mostly going to end up under the Vastitas sea anyway.”

“Hmm.”

The truth was Sax had temporarily forgotten the drilling and mining in Vastitas. When they had returned to the conference center, he deliberately looked for a talk describing an aspect of that work. There was one at four: “Recent Advances in North Polar Lens Permafrost Pumping Procedures.”

He watched the speaker’s video show impassively. The lens of ice that extended underground from the northern polar cap was like the submerged part of an iceberg, containing some ten times as much water as the visible cap. The Vastitas permafrost contained even more. But getting that water to the surface … like the retrieval of nitrogen from Titan’s atmosphere, it was a project so massive that Sax had never even considered it in the early years; it simply hadn’t been possible then. All these big projects-the so-letta, the nitrogen from Titan, the northern ocean drilling, the frequent arrival of ice asteroids-were on a scale that Sax found he was having trouble adjusting to. They were thinking big these days, the transnational. Certainly the new abilities in design and in materials science, and the emergence of fully self-replicating factories, were what made the projects technically feasible; but the initial financial investments were still huge.

As for the technical capabilities involved, he found himself adjusting to the idea of them fairly rapidly. It was an extension of what they had done in the old days: solve some initial problems in materials, design, and homeostatic control, and one’s powers grew very considerable indeed. One might say that their reach no longer exceeded their grasp. Which, given the directions their reach sometimes took, was a frightening thought.

In any case, some fifty drilling platforms were now located in the northern Sixties, boring wells and inserting permafrost melting devices at their bottoms that ranged from heated collection galleries to nuclear explosives. The new meltwater was then being pumped up and distributed over the dunes of Vastitas Borealis, where it froze again. Eventually this ice sheet would melt, partly under its own weight, and they would have an ocean in the shape of a ring around the northern Sixties and Seventies, no doubt a very good thermal sink, as all oceans were, although while it remained an ice sea the increase in albedo would probably make it a net heat loss to the global system. Yet another example of their operations cutting against each other. As was the location of Burroughs itself, relative to this new sea; the city was well below the sea level most often mentioned, the datum itself. People talked of a dike, or a smaller sea, but no one knew for sure. It was all very interesting.

So Sax attended the conference every day, all day, living in the hushed rooms and halls of the conference center, chatting with colleagues, and the authors of posters, and his neighbors in audiences. More than once he had to pretend not to know old associates, and it made him nervous enough that he avoided them when he could. But people did not seem to feel that he reminded them of someone they knew, and for the most part he was able to concentrate on the science. He did that with gusto. People gave talks, asked questions, debated details of fact, discussed implications, all under the uniform fluorescent glow of the conference rooms, in the low hum of ventilators and video machines-as if they were in a world outside of time and space, in the imaginary space of pure science, surely one of the greatest achievements of the human spirit-a kind of Utopian community, cozy and bright and protected. For Sax, a scientific conference was Utopia.

The sessions at this conference, however, had a new tone, a kind of nervous edge that Sax had never witnessed before, and did not like. The questions after the presentations were more aggressive, the answers more quickly defensive. The pure play of scientific discourse which he so enjoyed (and which admittedly was never quite pure) was now more and more diluted by sheer argument, by obvious power struggles, motivated by something more than the usual egotism. It wasn’t like Simmon’s unconscionable lift from Borazjani, and Borazjani’s exquisite riposte; it was more a matter of direct assault. As at the end of a presentation on deep moholes and the possibility of reaching the mantle, when a short bald Terran stood and said, “I don’t think the basic model of the lithosphere here is valid,” and then walked out of the room.