In the greenhouse farms, on the other hand, the soils used had been heavily amended by nutrients and fertilizers and inoculants of all kinds; the result was something like what these scientists were trying for, but the quantity of soil in greenhouses was minuscule compared to what they wanted to put out on the surface. Mass producing soil was their goal. But they had gotten into something deeper than they had expected, Nadia could tell; they had the vexed absorbed air of a dog gnawing on a bone too big for its mouth.

The biology, chemistry, biochemistry, and ecology involved in these problems were far beyond Nadia’s expertise, and there was nothing she could do to make suggestions there. In many cases she couldn’t even understand the processes involved. It was not construction, nor even an analog of construction.

But they did have to incorporate some construction into whatever production methods they tried, and there Nadia was at least able to understand the issues. She began to concentrate on that aspect of things, looking at the mechanical design of the pedons, and also the holding tanks for the living constituents of the soil. She also studied the molecular structure of the parent clays, to see if it suggested anything to her about working with them. Martian smectites were aluminosilicates, she found, meaning each unit of the clay had a sheet of aluminum octahedrals sandwiched between two sheets of silicon tetrahedrals; the different kinds of smectites had different’amounts of variation in this general pattern, and the more variation there was, the easier it was for water to seep into the interlayer surfaces. The most common smectite clay on Mars, montmorillonite, had a lot of variety, and so was very open to water, expanding when wet, and shrinking when dry to the point of cracking.

Nadia found this interesting. “Look,” she said to Arne, “what about a pedon filled with a matrix of feeder veins, which would introduce the biota all through the parent material.” Take a batch of parent material, she went on, and get it wet, then let it dry. Insert into the crack systems the feeder vein matrix. Then pour in whatever important bacteria and other constitutents they could grow. Then if the bacteria and other creatures could eat their way out of their feeder veins, digesting that material as they emerged, they would all suddenly be there together in the clay, interacting. That would be a tricky time, no doubt many trials would be necessary to calibrate the initial amounts of the various biota needed to avoid population booms and crashes — but if they could get them to settle into their usual communities, then they would suddenly have living soil. “There are feeder-vein systems like this used for certain quick-setting construction materials, and now I hear that doctors feed apatite paste into broken bones the same way. The feeder veins are made of protein gels appropriate to whatever substance they’re going to contain, molded into the appropriate tubular structures.”

A matrix for growth. Worth looking into, Arne said. Which made Nadia smile. She went around that afternoon feeling happy, and that evening when she joined Art she said, “Hey! I did some work today.”

“Well!” Art said. “Let’s go out and celebrate.”

Easy to do, in Bogdanov Vishniac. It was a Bogdanovist city, all right, as buoyant as Arkady himself. A party every night. They had often joined the evening promenade, and Nadia loved walking along the railing of the highest terrace, feeling that Arkady was somehow there, had somehow persisted. And never more so than on this night, celebrating a bit of work done. She held Art’s hand, looked down and across at the crowded lower terraces and their crops, orchards, pools, sports fields, lines of trees, arcuate plazas occupied by cafes, bars, dance pavilions — bands battling for sonic space, the crowds chugging around them, some dancing but many more simply making the night’s promenade, like Nadia herself. All this still under a tent, with tenting that they hoped to remove someday; meanwhile it was warm, and the young natives wore an outlandish array of pantaloons, headdresses, sashes, vests, necklaces, so that Nadia was reminded of the video footage of Nirgal and Maya’s reception in Trinidad. Was this coincidence, or was there some supraplanetary culture coming into being among the young? And if there was, did that mean that their Coyote, the Trinidadian, had invisibly conquered the two worlds? Or her Arkady, posthumously? Arkady and Coyote, culture kings. It made her grin to think of it, and she took sips of Art’s cup of scalding kavajava, the drink of choice in this cold town, and watched all the young people moving like angels, always dancing no matter what they did, flowing in graceful arcs from terrace to terrace. “What a great little town,” Art said.

Then they came upon an old photo of Arkady himself, framed and hung on a wall next to a door. Nadia stopped and clutched Art’s arm: “That’s him! That’s him to the life!”

The photo had caught him talking with someone, standing just inside a tent wall and gesturing, his hair and beard lofting away from his head and blending into a landscape exactly the color of his wild curls. A face coming out of a hillside, it seemed, blue eyes squinting in the glare of all that red glee. “I’ve never seen a photo that looked so much like him. If he saw a camera pointed at him he didn’t like it, and the picture came out wrong.”

She stared at the photo, feeling flushed, and strangely happy; such a lifelike encounter! Like running into someone again after years of not seeing them. “You’re like him, in some ways, I think. But more relaxed.”

“It looks like it would be hard to get much more relaxed than that,” Art said, peering closely at the photo.

Nadia smiled. “It was easy for him. He was always sure he was right.”

“None of the rest of us have that problem.”

She laughed. “You’re cheerful like he was.”

“And why not.”

They walked on. Nadia kept thinking of her old companion, seeing the photo in her mind’s eye. There was still so much she remembered. The feelings connected to the memories were fading, however, the pain blunted — the fixative leached out, all that flesh and trauma now only a pattern of a certain kind, like a fossil. And very unlike the present moment, which, looking around, feeling her hand in Art’s, was real, vivid, brief, perpetually changing — alive. Anything could happen, everything was felt. “Shall we go back to our room?”

The four travelers to Earth returned at last, coming down the cable to Sheffield. Nirgal and Maya and Michel went their ways, but Sax flew down and joined Nadia and Art in the south, a move which pleased Nadia no end. She had come to have the feeling that wherever Sax went was the heart of the action.

He looked just as he had before the trip to Earth, and was if anything even more silent and enigmatic. He wanted to see the labs, he said. They took him through them.

“Interesting, yes,” he said. Then after a while: “But I’m wondering what else we might do.”

“To terraform?” Art asked.

“Well…”

To please Ann, Nadia thought. That was what he meant. She gave him a hug, which surprised him, and she kept her hand on his bony shoulder as they talked. So good to have him there in the flesh! When had she gotten so fond of Sax Russell, when had she come to rely on him so much?

Art too had figured out what he meant. He said, “You’ve done quite a bit already, haven’t you? I mean, at this point you’ve dismantled all the metanats’ monster methods, right? The hydrogen bombs under the permafrost, the so-letta and aerial lens, the nitrogen shuttles from Titan — ”

“Those are still coming,” Sax said. “I don’t even know how we could stop them. Shoot them down I guess. But we can always use nitrogen. I’m not sure I’d be happy if they were stopped.”

“But Ann?” Nadia said. “What would Ann like?”