“So do you want the treatment?” Ursula asked, her back to him, her voice casual.

“The treatment?”

“ It’s a kind of geronotological therapy. An experimental procedure. Somewhat like an inoculation, but with a DNA strengthener. Repairs broken strands, and restores cell division accuracy to a significant degree.”

John sighed. “And what does that mean?”

“Well, you know. Ordinary aging is mostly caused by cell division error. After a number of generations, ranging from hundreds to tens of thousands depending which kind of cells you’re talking about, errors in reproduction start to increase, and everything gets weaker. The immune system is one of the first to weaken, and then other tissues, and then finally something goes wrong, or the immune system gets overwhelmed by a disease, and that’s it.”

“And you’re saying you can stop these errors?”

“Slow them down, anyway, and fix the ones that are already broken. A mix, really. The division errors are caused by breaks in DNA strands, so we wanted to strengthen DNA strands. To do it we would read your genome, and then build an auto repair genomic library of small segments that will replaced the broken strands-”

“Auto repair?”

She sighed. “All Americans think that is funny. Anyhow we push this auto repair library into the cells, where they bind to the original DNA and help keep them from breaking.” She began to draw double and quadruple helixes as she talked, shifting inexorably into biotech jargon, until John could only catch the general drift of the argument, which apparently had its origins in the genome project and the field of genetic abnormality correction, with application methods taken from cancer therapy and GEM technique. Aspects of these and many other different technologies had been combined by the Acheron group, Ursula explained. And the result seemed to be that they could give him an infection of bits of his own genome, an infection which would invade every cell in his body except for parts of his teeth and skin and bones and hair; and afterwards he would have nearly flawless DNA strands, repaired and reinforced strands that would make subsequent cell division more accurate.

“How accurate?” he asked, trying to grasp what it all meant.

“Well, about like if you were ten years old.”

“You’re kidding.”

“No, no. We’ve all done it to ourselves, back around Ls ten of this year, and so far as we can tell, it’s working.”

“Does it last forever?”

“Nothing lasts forever, John.”

“How long then?”

“We don’t know. We ourselves are the experiment, we figure we’ll find out as we go along. It seems possible we might be able to do the therapy again when the rate of division error begins to increase again. If that is successful, it could mean you would last for quite a while.”

“Like how long?” he insisted.

“Well, we don’t know, do we. Longer than we live now, that’s pretty sure. Possibly a lot longer.”

John stared at her. She smiled at the expression on his face, and he could feel that his jaw was slack with amazement; no doubt he looked less than brilliant, but what did she expect? It was… it was…

He was following his thoughts with difficulty as they skittered around. “Who have you told about this?” he asked.

“Well, we have asked everyone in the first hundred, when they get a check-up with us. And everyone here at Acheron has tried it. And the thing is, we’ve only combined methods that everyone has, so it won’t be long before others try putting it all together too. So we’re writing it up for publication, but we’re going to send the articles first to be reviewed by the World Health Organization. Political fallout, you know.”

“Um,” John said, considering it. News of a longevity drug loose on Mars, back among the teeming billions… my Lord, he thought. “Is it expensive?”

“Not extremely. Reading your genome is the most expensive part, and it takes time. But it’s just a procedure, you know, it’s just computer time. It’s very possible you could inoculate everyone on Earth. But the population problem down there is already critical as it is. They’d have to institute some pretty intense population control, or else they’d go Malthusian really fast. We thought we’d better leave the decisions to the authorities down there.”

“But word is sure to get out.”

“Is that true? They might try to put a clamp on it. Maybe even a comprehensive clamp, I don’t know.”

“Wow. But you folks… you just went ahead and did it?”

“We did.” She shrugged. “So what do you say? Want to do it?”

“Let me think about it.”

He went for a walk on the crest of the fin, up and down the long greenhouse stuffed with bamboo and food crops. Walking west he had to shield his eyes from the glare of the afternoon sun, even through the filtered glass; walking back east, he could look out at the broken slopes of lava stretching up to Olympus Mons. It was hard to think. He was sixty-five years old; born in 1989, and what was it back on Earth now, 2048? M-11, eleven long hi-rad martian years. And he had spent thirty-five months in space, including three trips between Earth and Mars, which was still the record. He had taken on 195 rems in those trips alone, and he had low blood presssure and a bad HDL to LDL ratio, and his shoulders ached when he swam and he felt tired a lot. He was getting old. He didn’t have all that many years left, weird though it was to think of it; and he had a lot of faith in the Acheron group, who, now that he thought of it, were wandering around their aerie working and eating and playing soccer and swimming and so on with little smiles of absorbed concentration, with a kind of humming. Not like ten year-olds, certainly not; but with an aura of suffused, absorbed happiness. Of health, and more than health. He laughed out loud, and went back down into Acheron looking for Ursula. When she saw him she laughed too. “It’s not really that hard a choice, is it.”

“No.” He laughed with her: “I mean, what have I got to lose?”

So he agreed to it. They had his genome in their records, but it would take a few days to synthesize the collection of repair strands and clip them onto plasmids, and clone millions more. Ursula told him to come back in three days.

When he got back to the guest rooms Maya was already there, looking as shocked as he felt, wandering nervously from dresser to sink to window, touching things and looking around as if she had never seen such a room before. Vlad had told her about it after her physical, just as Ursula had with John. “Immortality plague!” she exclaimed, and laughed strangely. “Can you believe it?”

“Longevity plague,” he corrected her. “And no, I can’t. Not really.” He felt a little dizzy, and he could see she hadn’t heard him. Her agitation made him nervous. They heated soup, ate in a daze. Vald had told Maya to come to Acheron, and intimated what it was all about; that was why she had insisted that John accompany her to Acheron. When she told him that, he felt a shiver of fondness for her. Standing next to her washing the dishes, observing her hands shake as she spoke, he felt exceptionally close to her; it was as if they knew each other’s thoughts, as if, after all the years, in the face of this bizarre development, there were no need for words, only for each other’s presence. That night in the warm dark of their bed she whispered hoarsely, “We’d better do it twice tonight. While it’s still us.”

Three days later they both got the treatment. John lay back on a medical couch in a small room, and stared at an intravenous plug in the back of his hand. An IV feed shot, just like all those he’d had before. Except this time he could feel a strange heat rising up his arm, flushing his chest, pouring down his legs. Was it real? Was he imagining it? For a second he felt extremely odd all over, as if his ghost had walked through him. Then he was just very hot. “Should I be this hot?” he asked Ursula anxiously.