His companions thought this was hilarious, but he was lost in thought for a while, and didn't notice.

"Listen, Claire, do you think we could go out and have a look at one of the glaciers? Do some of the work on-site?"

Claire stopped giggling and nodded. "Sure. In fact that reminds me. We've got a permanent experimental station out at Arena Glacier, with a good lab. And we've been contacted by a biotech group from Armscor, one with a lot of clout with the Transitional Authority. They want to be taken out to see the station and the ice. I guess they're planning to build a similar station in Marineris. We can go out with that group and show them around, and do some fieldwork, and kill two birds with one stone."

Plans to make this trip actually made it from the Lowen into the lab, and then the front office. Approval came swiftly, as was usual in Biotique. So Sax worked hard for a couple of weeks, preparing for the fieldwork, and at the end of that intensive period he packed his bag, and one morning took the subway out to West Gate. There in the Swiss garage he spotted some people from the office, gathered with several strangers. Introductions were still being made. Sax approached, and Claire saw him and drew him into the crowd, looking excited. "Here, Stephen, I want to introduce you to our guest for the trip." A woman wearing some kind of prisming fabric turned around, and Claire said, "Stephen, I'd like you to meet Phyllis Boyle. Phyllis, this is Stephen Lindholm."

"How do you do?" Phyllis said, extending a hand.

Sax took her hand and shook. "I do fine," he said.

Vlad had nicked his vocal cords to give him a different vocal print if he was ever tested, but everyone in Gamete had agreed that he sounded just the same. And now Phyllis c.o.c.ked her head curiously at him, alerted by something. "I'm looking forward to the trip," he said, and glanced at Claire. "I hope I haven't held you up?"

"No no, we're still waiting for the drivers."

"Ah." Sax backed away. "Good to meet you," he said to Phyllis politely. She nodded, and with a final curious glance turned back to the people she had been talking to. Sax tried to concentrate on what Claire was saying about the drivers. Apparently driving a rover across open terrain was a specialized occupation now.

That was fairly cool, he thought. Of course coolness was a Sax trait. Probably he ought to have gushed all over her, said he knew her from the old vids and had admired her for years, etc. Although how someone could admire Phyllis he had no idea. Surely she had come out of the war fairly compromised; on the winning side, but the only one of the First Hundred to have chosen it. A quisling, did they call that? Something like that. Well, she hadn't been the only one of the First Hundred; Vasili had stayed in Burroughs throughout, and George and Edvard had been on Clarke with Phyllis when it detached from the cable and catapulted out of the plane of the ecliptic. A neat bit of work to survive that, actually. He wouldn't have thought it possible- but there she was, chattering with her host of admirers. Luckily he had heard of her survival a few years before; otherwise it would have been a shock to see her.

She still looked about sixty years old, although she had been born the same year as Sax, and so was now 115. Silver-haired, blue-eyed, her jewelry made of gold and bloodstone, her blouse made of a material that shone through all the colors of the spectrum- right now her back was a vibrant blue, but as she turned to glance over her shoulder at him it went emerald green. He pretended not to notice the look.

Then the drivers came, and they were into the rovers and off, and for a blessing Phyllis was in one of the other cars. The rovers were big hydrazine-powered things, and they followed a concrete road north, so that Sax could not see the necessity for specialist drivers, unless it was to handle the rovers' speed; they were rolling along at about a hundred and sixty kilometers an hour, and to Sax, who was used to rover speeds about a quarter that, it felt fast and smooth. The other pa.s.sengers complained at how b.u.mpy and slow the ride was- apparently express trains now floated over the pistes at about six hundred kilometers per hour.

The Arena Glacier was some eight hundred kilometers northwest of Burroughs, spilling from the highlands of Syrtis Major north onto Utopia Planitia. It ran in one of the Arena Fossae for a distance of some three hundred fifty kilometers. Claire and Berkina and the others in the car told Sax the glacier's history, and he did his best to indicate absorbed interest; indeed it was interesting, for they were aware that Nadia had rerouted the outbreak of the Arena aquifer. Some of the people who had been with Nadia when she did it had ended up in South Fossa after the war, and the story had been told there, and had spread into the public domain.

In fact these people seemed to think they knew a lot about Nadia. "She was against the war," Claire told him confidently, "and she did everything she could to stop it and then to repair the damage, even while it was happening. People who saw her on Elysium say she never slept at all, just took stimulants to keep going. They say she saved ten thousand lives in the week she was active around South Fossa."

"What happened to her?" Sax asked.

"No one knows. She disappeared from South Fossa."

"She was headed for Low Point," Berkina said. "If she got there in time for that flood, she was probably killed."

"Ah." Sax nodded solemnly. "That was a bad time."

"Very bad," Claire said vehemently. "So destructive. It set the terraforming back decades, I'm sure."

"Although the aquifer outbreaks have been useful," Sax murmured.

"Yes, but those could have been done anyway, in a controlled manner."

"True." Sax shrugged and let the conversation go on without him. After the encounter with Phyllis it was a bit much to get into a discussion of '61.

He still couldn't quite believe she hadn't recognized him. The pa.s.senger compartment they were in had shiny magnesium panels over the windows, and there, among the faces of his new colleagues, was the little face of Stephen Lindholm. A bald old man with a slightly hooked nose, which made the eyes somewhat hawkish rather than just birdlike. Visible lips, strong jaw, a chin- no, it didn't look like him at all. No reason why she should have recognized him.

But looks weren't everything.

He tried not to think about that as they hummed north over the road. He concentrated on the view. The pa.s.senger compartment had a domed skylight, as well as windows on all four sides, so he could see a lot. They were driving up the slope of west Isidis, a section of the Great Escarpment that was like a great shaved berm. The jagged dark hills of Syrtis Major rose over the northwest horizon, sharp as the edge of a saw. The air was clearer than it had been in the old days, even though it was fifteen times thicker. But there was less dust in it, as snowstorms were knocking the fines down and then fixing them on the surface in a crust. Of course this crust was often broken by strong winds, and the trapped fines reintroduced to the air. But these breaks were localized, and the sky-cleaning storms were slowly getting the upper hand.

And so the sky was changing color. Overhead it was a rich violet, and above the western hills it was whitish, shading up into lavender, and some color between lavender and violet that Sax didn't have a name for. The eye could distinguish differences in light frequency of only a few wavelengths, so the few names for the colors between red and blue were totally inadequate to describe the phenomena. But whatever you called them, or didn't, they were sky colors very unlike the tans and pinks of the early years. Of course a dust storm would always temporarily return the sky to that primeval ochre tone; but when the atmosphere washed out, its color would be a function of its thickness and chemical composition. Curious as to what they could expect to see in the future, Sax took his lectern from his pocket to try some calculations.

He stared at the little box, suddenly realizing that it was Sax Russell's lectern- that if checked, it would give him away. It was like carrying around a genuine pa.s.sport.

He dismissed the thought, as there was nothing to be done about it now. He concentrated on the color of the sky. In clean air, sky color was caused by preferential light scattering in the air molecules themselves. Thus the thickness of the atmosphere was critical. Air pressure when they had arrived had been about 10 millibars, and now it averaged about 160. But since air pressure was created by the weight of the air, creating 160 millibars on Mars had taken about three times as much air over any given spot than would have created such a pressure on Earth. So the 160 millibars here ought to scatter light about as much as 480 millibars on Earth; meaning the sky overhead ought to have something like the dark blue color seen in photos taken in mountains about 4,000 meters high.

But the actual color filling the windows and skylight of their rover was much more reddish than that, and even on clear mornings after heavy storms, Sax had never seen it look anywhere near as blue as a Terran sky. He thought about it more. Another effect of Mars's light gravity was that the air column lofted taller than Earth's. It was possible that the smallest fines were effectively in suspension, and had been blown above the alt.i.tude of most clouds, where they escaped being scrubbed out by storms. He recalled that haze layers had been photographed that were as much as fifty kilometers high, well above the clouds. Another factor might be the composition of the atmosphere; carbon dioxide molecules were more efficient light scatterers than oxygen and nitrogen, and Mars, despite Sax's best efforts, still had much more CO2 in its atmosphere than Earth did. The effects of that difference would be calculable. He typed up the equation for Rayleigh's law of scattering, which states that the light energy scattered per unit volume of air is inversely proportional to the fourth power of the wavelength of the illuminating radiation. Then he scribbled away on his lectern screen, altering the variables, checking handbooks, or filling in quant.i.ties by memory, or guesswork.

He concluded that if the atmosphere was thickened to one bar, then the sky would probably turn milk white. He also confirmed that in theory the present-day Martian sky ought to be a lot bluer than it was, with its scattered blue light about sixteen times the intensity of the red. This suggested that fines very high in the atmosphere were probably reddening the sky. If that was the correct explanation, one could infer that the color and opacity of the Martian sky would for many years be subject to very wide variation, depending on weather and other influences on the cleanness of the air....

And so he worked on, trying to incorporate into the calculation skylight radiance intensities, Chandrasekhar's radiative transfer equation, chromaticity scales, aerosol chemical compositions, Legendre polynomials to evaluate the angular scattering intensities, Riccati-Bessel functions to evaluate the scattering cross sections, and so on- occupying the better part of the drive to Arena Glacier, concentrating hard and steadfastly ignoring the world around him and the situation in which he now found himself.

Early that afternoon they came to a small town called Bradbury, which under its Nicosia-cla.s.s tent looked like something out of Illinois: treelined blacktop streets, screened-in porches fronting two-story brick houses with shingle roofs, a main street with shops and parking meters, a central park with a white gazebo under giant maples....

They headed west on a smaller road, across the top of Syrtis Major. The road was made of black sand that had been cleared of rocks and sprayed with a fixative. This whole region was very dark- Syrtis Major had been the first Martian surface feature spotted through Earth telescopes, by Christiaan Huygens on November 28, 1659, and it was this dark rock that had allowed him to see it. The ground was almost black, sometimes a kind of eggplant purple; the hills and grabens and escarpments that the road twisted through were black; the fretted mesas were black; the thulleya thulleya or little ribs were black, ridge after ridge after ridge of them; the giant ejecta erratics, on the other hand, were often rust-colored, reminding them forcibly of the color from which they had temporarily escaped. or little ribs were black, ridge after ridge after ridge of them; the giant ejecta erratics, on the other hand, were often rust-colored, reminding them forcibly of the color from which they had temporarily escaped.

Then they drove over a black bedrock rib and the glacier lay before them, crossing the world from left to right like a lightning bolt inlaid into the landscape. A bedrock rib on the far side of the glacier paralleled the one they were on, and the two ribs together looked like old lateral moraines, although really they were just parallel ridges that had channelized the outbreak flood.

The glacier was about two kilometers across. It appeared to be no more than five or six meters thick, but apparently it had run down a canyon, so there were hidden depths.

Parts of its surface were like ordinary regolith, just as rocky and dusty, with a kind of gravel surface that revealed no sign of the ice below. Other parts looked like chaotic terrain, except clearly made of ice, with knots of white seracs sticking up out of what looked like boulders. Some of the seracs were broken plates, bunched like the back of a stegosaurus, translucent yellow with the setting sun behind them.

All was motionless, to every horizon- not a movement to be seen anywhere. Of course not; Arena Glacier had been here for forty years. But Sax could not help remembering the last time he had seen such a sight, and he glanced involuntarily to the south, as if a new flood might burst out at any moment.

The Biotique station was located a few kilometers upstream, on the rim and ap.r.o.n of a small crater, so that it had an excellent view over the glacier. In the last part of sunset, as some of the regulars got the station activated, Sax went with Claire and the visitors from Armscor, including Phyllis, up to a big observation room on the top floor of the station, to look at the broken ma.s.s of ice in the waning moments of the day.

Even on a relatively clear afternoon like this one, the horizontal rays of the sun turned the air a burnished dark red, and the surface of the glacier sparked in a thousand places, the recently broken ice reflecting the light like mirrors. The majority of these scarlet gleams lay in a rough line between them and the sun, but there were a few elsewhere on the ice, where the reflecting surfaces stood at odd angles. Phyllis pointed out how much larger the sun looked, now that the soletta was in position. "Isn't it wonderful? You can almost see the mirrors, can't you?"

"It looks like blood."

"It looks positively Jura.s.sic Jura.s.sic."

To Sax it looked like a G-type star about one astronomical unit away. Of course this was significant, as they were 1.5 astronomical units away. As for the talk of rubies, or dinosaur's eyes...

The sun slipped over the horizon and all the points of red light disappeared at once. A great fan of crepuscular rays stretched across the sky, the pinkish beams cutting a dark purple sky. Phyllis exclaimed over the colors, which were indeed very clear and pure. She said, "I wonder what makes those magnificent rays," and automatically Sax opened his mouth to explain about the shadows of hills or clouds over the horizon, when it occurred to him that a a, it was a rhetorical question (perhaps), and b b, to give a technical answer would be a very Sax Russell thing to do. So he shut his mouth, and considered what Stephen Lindholm would say in such a situation. This kind of self-consciousness was new to him, and distinctly uncomfortable, but he was going to have to say things, at least some of the time, because long silences were also fairly Sax Russellish, and not at all like Lindholm as he had been playing him so far. So he tried his best.

"Just think how close those photons came to hitting Mars," he said, "and now they're going to run all the way across the universe instead."

People squinted at this odd observation. But it drew him into the group nonetheless, and so served its purpose.

After a while they went down to the dining room, to eat pasta and tomato sauce, and bread just out of the ovens. Sax stayed at the main table, and ate and talked as much as the rest, striving for the norm, doing his best to follow the elusive rules of conversation and of social discourse. These he had never understood well, and less so the more he thought about them. He knew that he had always been considered eccentric; he had heard the story of the hundred transgenic lab rats taking over his brain.- A strange moment, that, standing outside the lab door in the dark, hearing the tale being promulgated with much hilarity from one generation of postdocs to the next, experiencing the rare discomfort of seeing himself as if he were someone else, someone strikingly peculiar.

But Lindholm, now: he was a congenial fellow. He knew how to get along. Someone who could partake of a bottle of Utopian zinfandel, someone who could do his part to make a dinner party festive. Someone who understood intuitively the hidden algorithms of good fellowship, so that he would be able to operate the system without even thinking about it.

So Sax ran a forefinger up and down the bridge of his new nose, and drank the wine which did indeed suppress his parasympathetic nervous system to the point of making him less inhibited and more voluble, and he chattered away very successfully, he thought, although several times he was alarmed by the way he was drawn into conversation by Phyllis, sitting across the table from him- and by the way she looked at him- and by the way he looked back! There were protocols for this kind of thing too, but he had never understood them them in the slightest. Now he recalled the way Jessica had leaned on him at the Lowen, and drank another half gla.s.s and smiled, and nodded, thinking uneasily about s.e.xual attraction and its causes. in the slightest. Now he recalled the way Jessica had leaned on him at the Lowen, and drank another half gla.s.s and smiled, and nodded, thinking uneasily about s.e.xual attraction and its causes.

Someone asked Phyllis the inevitable question about the escape from Clarke, and as she launched into the tale she glanced frequently at Sax, seeming to a.s.sure him that she was telling the story princ.i.p.ally to him. He attended politely, resisting a certain tendency to go cross-eyed, which might indicate his dismay.

"There was no warning of any kind," Phyllis said to the questioner. "One minute we were orbiting Mars at the top of the elevator, just sick at what was happening down on the surface, and doing our best to figure out some way to stop the unrest, and then the next minute there was a jerk like an earthquake, and we were on our way out of the solar system." She smiled and paused for the laugh that followed, and Sax saw that she had told the story many times before in just this way.

"You must have been terrified!" someone said.

"Well," Phyllis said, "it's strange how in an emergency there isn't really time for any of that. As soon as we understood what had happened, we knew that every second we stayed on Clarke diminished our chances of surviving by hundreds of kilometers. So we convened in the command center and counted heads and talked it over and took stock of what we had available. It was hectic but not panicked, if you see what I mean. Anyway, there turned out to be about the usual number of Earth-to-Mars freighters in the hangars, and the AI calculations indicated we would need the thrust of almost all of them to get ourselves back down into the plane of the ecliptic in time to intersect the Jovian system. We were on our way out as well as up, and in the general direction of Jupiter, which was a blessing. Anyway, that was when it got crazy. We had to get all the freighters outside the hangars and flying beside Clarke, and then link them together and stock them with everything they could hold of Clarke's air and fuel and so on. And we were off in that jury-rigged lifeboat only thirty hours after launching, which now that I look back on it, is almost unbelievable. Those thirty hours..."

She shook her head, and Sax thought he saw a real memory suddenly invade her tale, shaking her slightly. Thirty hours was a remarkably fast evacuation, and no doubt the time had flashed by in a dreamlike rush of action, in a state of mind so different from ordinary time that it might pa.s.s for transcendence.

"After that it was just a matter of cramming into a couple of crew quarters- two hundred and eighty-six of us, there were- and going out on EVAs to cut away inessential parts of the freighters. And hoping there would be enough fuel to get us on course down to Jupiter. It was more than two months before we could be positive we would intercept the Jovian system, and ten weeks before we actually did. We used Jupiter itself as a gravity handle, and swung around toward Earth, which at that time was closer than Mars. And we swung so hard around Jupiter that we needed Earth's atmosphere and Luna's gravity to slow us down, because we were almost out of fuel at the very same time that we were the fastest humans in history, by a factor of two. Eighty thousand kilometers an hour, I think it was when we hit the stratosphere the first time. A useful speed, really, because we were running out of food and air. We got really hungry near the end. But we made it. And we saw Jupiter from about this close this close," holding thumb and forefinger apart a couple of centimeters.

People laughed, and the gleam of triumph in Phyllis's eye had nothing to do with Jupiter. But there was a tightening at the corner of her mouth; something at the end of her tale had darkened the triumph, somehow.

"And you were the leader, right?" someone asked.

Phyllis held up a hand, to say she could not deny it though she wanted to. "It was a cooperative effort," she said. "But sometimes someone has to decide when there's an impa.s.se, or simply a need for speed. And I had been head of Clarke before the catastrophe."

She flashed her big smile, confident that they had enjoyed the account. Sax smiled with the rest, and nodded when she looked his way. She was an attractive woman, but not, he thought, very bright. Or maybe it was just that he did not like her very much. For certainly she was very intelligent in some ways, a good biologist when she had done biology, and certain to score high on an IQ test. But there were different types of intelligence, and not all of them were subject to a.n.a.lytic testing. Sax had noticed this fact in his student years: that there were people who would score high on any intelligence test, and were very good at their work, but who at the same time could walk into a room of people and within an hour have many of the occupants of that room laughing at them, or even despising them. Which was not very smart. Indeed the most giddy of high school cheerleaders, say, managing to be friendly with everyone and therefore universally popular, seemed to Sax to be exercising an intelligence at least as powerful as any awkward brilliant mathematician's- the calculus of human interaction being so much more subtle and variable than any physics, somewhat like the emerging field of math called cascading recombinant chaos, only less simple. So that there were at least two kinds of intelligence, and probably many more: spatial, aesthetic, moral or ethical, interactional, a.n.a.lytic, synthetic, and so forth. And it was those people who were intelligent in a number of different ways who were truly exceptional, who stood out as something special.

Phyllis, however, basking in the attention of her listeners, most of them much younger than her and, at least on the surface, in awe of her historicity- Phyllis was not one of those polymaths. On the contrary, she seemed rather dim when it came to judging what people thought of her. Sax, who knew he shared the deficiency, watched her with the best Lindholm smile he could muster. But it seemed to him a fairly obviously vain performance on her part, even a bit arrogant. And arrogance was always stupid. Or else a mask for some kind of insecurity. Hard to guess what that insecurity might be, in such a successful and attractive person. And she certainly was attractive.

After supper they went back up to the observation room on the top floor, and there under a glittering bowl of stars the crowd from Biotique turned on some music. It was the kind called nuevo calypso, the current rage in Burroughs, and several members of the group brought out instruments and played along, while others moved to the middle of the room and began to dance. The music was paced at about a hundred beats a minute, Sax calculated, perfect physiological timing for stimulating the heart just a bit; the secret to most dance music, he supposed.

And then Phyllis was there by his side, grabbing for his hand and pulling him out among the dancers. Sax only just restrained himself from jerking his hand away from her, and he was sure that his response to her smiling invitation was sickly at best. He had never danced in his life; as far as he could recall. But that was Sax Russell's life. Surely Stephen Lindholm had danced a lot. So Sax began to hop gently up and down in time with the ba.s.s steel drum, wiggling his arms uncertainly at his sides, smiling at Phyllis in a desperate simulation of debonair pleasure.

Later that evening the younger Biotique crew were still dancing, and Sax took the elevator down to bring some tubs of ice milk back up from the kitchens. When he got back into the elevator Phyllis was already inside, coming back up from the dorm floor. "Here, let me help with those," she said, and took two of the four plastic bags hanging from his fingers. Then when she had them she leaned down (she was a few centimeters taller than him) and kissed him full on the mouth. He kissed back, but it was such a shock that he didn't really start to feel it until she pulled away; then the memory of her tongue between his lips was like another kiss. He tried to look less than befuddled, but by the way she laughed he knew he had failed. "I see you're not as much of a lady-killer as you look," she said, which given the situation only made him more alarmed. In point of fact, no one had ever done that to him before. He tried to rally, but the elevator slowed and the doors hissed open.

Through dessert and the rest of the party Phyllis did not approach him again. But when the timeslip began he went to the elevators to go back to his room, and as the doors began to close Phyllis slipped through them and in, and as soon as the elevator began to drop she was kissing him again. He put his arms around her and kissed back, trying to figure out what Lindholm would do in this situation, and if there was any way out of it that wouldn't lead to trouble. When the elevator slowed, Phyllis leaned back with a dreamy unfocused gaze and said, "Come walk me to my room." Reeling a bit, Sax held her upper arm like a bit of delicate lab equipment, and was led to her room, a tiny chamber like all the rest of the bedrooms. Standing in the doorway they kissed again, despite Sax's strong feeling that this was his last chance to escape, gracefully or not; but he was kissing her back pretty pa.s.sionately, he noticed, and when she pulled back to murmur, "You might as well come inside," he followed without protest; indeed his p.e.n.i.s was snagged halfway up in its blind grope toward the stars, all his chromosomes humming loudly, the silly fools, at this chance at immortality. It had been a long time since he had made love to anyone except Hiroko, and those encounters, though friendly and pleasant, were not pa.s.sionate, more an extension of their bathing; whereas Phyllis, fumbling at their clothes as they fell onto her bed kissing, was clearly excited, and this excitement was transferring to Sax by a kind of immediate conduction. His erection sprang free eagerly from his pants as Phyllis got the pants down his legs, as if in ill.u.s.tration of the selfish gene theory, and he could only laugh and tug at the long ventral zipper of her jumpsuit. Lindholm, free of any worries, would certainly be aroused by the encounter. That was clear. And so he had to be too. And besides, although he did not especially like Phyllis, he did know her; there was that old First Hundred bond, the memories of those years together in Underhill- there was something provocative in the notion of making love to a woman he had known so long. And every one else in the First Hundred had been polygamous, it seemed, everyone but Phyllis and him. So now they were making up for it. And she was very attractive. And it was something, actually, just to be wanted.

All these rationalizations were easy in the moment itself, and indeed forgotten entirely in the rush of s.e.xual sensation. But immediately upon completion of the act Sax began to worry again. Should he go back to his room, should he stay? Phyllis had fallen asleep with her hand on his flank, as if to a.s.sure herself that he would stay. In sleep everyone looked like a child. He surveyed the length of her body, shocked slightly once again by the various manifestations of s.e.xual dimorphism. Breathing so calmly. Just to be wanted... her fingers, still tensed across his ribs. And so he stayed; but he did not sleep much.

Sax threw himself into the work on the glacier and the surrounding terrain. Phyllis went out in the field sometimes, but she was always discreet in her behavior with him; Sax doubted if Claire (or Jessica!) or anyone else realized what had happened- or realized that every few days, it was happening again. This was another complication; how would Lindholm react to Phyllis's apparent desire for secrecy? But in the end it was not an issue. Lindholm was more or less forced, as a matter of chivalry or compliance or something like that, to act as Sax would have. And so they kept their affair to themselves, much as they would have in Underhill, or on the Ares, or in Antarctica. Old habits die hard.

And with the distraction of the glacier, it was easy enough to keep the affair secret. The ice and the ribbed land around it were fascinating environments, and there was a lot to study and try to understand out there.

The surface of the glacier proved to be extremely broken, as the literature had suggested- mixed with regolith during the flooding, and shot through with trapped carbonation bubbles. Rocks and boulders caught on the surface had melted the ice underneath them, and then it had refrozen around them, in a daily cycle that had left them all about two-thirds submerged. All the seracs, standing above the jumbled surface of the glacier like t.i.tanic dolmens, were on close inspection found to be deeply pitted. The ice was brittle because of the extreme cold, and slow to flow downhill because of the reduced gravity; nevertheless it was moving downstream, like a river in slow motion, and because its source was emptied, the whole ma.s.s would eventually end up on Vast.i.tas Borealis. And signs of this movement could be found in the newly broken ice seen every day- new creva.s.ses, fallen seracs, cracked bergs. These fresh surfaces were quickly covered by crystalline ice flowers, whose saltiness only added to the speed of crystallization.

Fascinated by this environment, Sax got in the habit of going out by himself every day at dawn, following flagged trails the station crew had set out. In the first hour of the day all the ice glowed in vibrant pink and rose tones, reflecting tints of the sky. As direct sunlight struck the glacier's smashed surfaces, steam would begin to rise out of the cracks and iced-over pools, and the ice flowers glittered like gaudy jewelry. On windless mornings a small inversion layer trapped the mist some twenty meters overhead, forming a thin orange cloud. Clearly the glacier's water was diffusing fairly quickly out into the world.

As he hiked through the frigid air he spotted many different species of snow algae and lichen. The glacier-facing slopes of the two lateral ridges were especially well populated, flecked by small patches of green, gold, olive, black, rust, and many other colors- perhaps thirty or forty all told. Sax strolled over these pseudo-moraines carefully, as unwilling to step on the plant life as he would be to step on any experiment in the lab. Although truthfully it looked as though most of the lichens would not notice. They were tough; bare rock and water were all they required, plus light- though not much of that appeared necessary- they grew under ice, inside ice, and even inside porous chunks of translucent rock. In something as hospitable as a crack in the moraine, they positively flourished. Every crack Sax looked in sported k.n.o.bs of Iceland lichen, yellow and bronze, which under the gla.s.s revealed tiny forking stalks, fringed by spines. On flat rocks he found the crustose lichens: b.u.t.ton lichen, stud lichen, shield lichen, candellaria candellaria, apple-green map lichen, and the red-orange jewel lichen that indicated a concentration of sodium nitrate in the regolith. Clumped under the ice flowers were growths of pale gray-green snow lichen, which under magnification proved to have stalks like the Iceland lichen, great ma.s.ses of them looking delicate as lace. Worm lichen was dark gray, and under magnification revealed weathered antlers that appeared extremely delicate. And yet if pieces broke off, the algal cells enclosed in their fungal threads would simply keep growing, and develop into more lichen, attaching wherever they came to rest. Reproduction by fragmentation; useful indeed in such an environment.

So the lichen were prospering, and along with the species that Sax could identify, with the help of photos on his wristpad's little display screen, were many more that seemed not to correspond to any listed species. He was curious enough about these nondescripts to pluck a few samples, to take back and show to Claire and Jessica.

But lichen was only the beginning. On Earth, regions of broken rock newly exposed by retreating ice, or by the growth of young mountains, were called boulder fields, or talus. On Mars the equivalent zone was the regolith- thus effectively the greater part of the surface of the planet. Talus world. On Earth these regions were first colonized by microbacteria and lichen, which, along with chemical weathering, began to break the rock down into a thin immature soil; slowly filling the cracks between rocks. In time there was enough organic material in this matrix to support other kinds of flora, and areas at this stage were called fellfields, fell fell being Gaelic for stone. It was an accurate name, for stone fields they were, the ground surface studded with rocks, the soil between and under them less than three centimeters thick, supporting a community of small ground-hugging plants. being Gaelic for stone. It was an accurate name, for stone fields they were, the ground surface studded with rocks, the soil between and under them less than three centimeters thick, supporting a community of small ground-hugging plants.

And now there were fellfields on Mars. Claire and Jessica suggested to Sax that he cross the glacier, and hike downstream along the lateral moraine, and so one morning (slipping away from Phyllis) he did so, and after half an hour's hiking, stopped on a knee-high boulder. Below him, sloping into the rocky trough next to the glacier, was a wet patch of flat ground, twinkling in the late-morning light. Clearly melt.w.a.ter ran over it most days- already in the utter stillness of the morning he could hear the drips of little streams under the glacier's edge, sounding like a choir of tiny wooden chimes. And on this miniature watershed, among the threads of running water, were spots of color, everywhere, leaping out at the eye- flowers. A patch of fellfield, then, with its characteristic millefleur millefleur effect, the gray waste peppered with dots of red, blue, yellow, pink, white.... effect, the gray waste peppered with dots of red, blue, yellow, pink, white....

The flowers were mounted on little mossy cushions or florettes, or tucked among hairy leaves. All the plants hugged the dark ground, which would be markedly warmer than the air above it; nothing but gra.s.s blades stuck higher than a few centimeters off the soil. He tiptoed carefully from rock to rock, unwilling to step on even a single plant. He knelt on the gravel to inspect some of the little growths, the magnifying lenses on his faceplate at their highest power. Glowing vividly in the morning light were the cla.s.sic fellfield organisms: moss campion, with its rings of tiny pink flowers on dark green pads; a phlox cushion; five-centimeter sprigs of bluegra.s.s, like gla.s.s in the light, using the phlox taproot to anchor its own delicate roots... there was a magenta alpine primrose, with its yellow eye and its deep green leaves, which formed narrow troughs to channel water down into the rosette. Many of the leaves of these plants were hairy. There was an intensely blue forget-me-not, the petals so suffused with warming anthocyanins that they were nearly purple- the color that the Martian sky would achieve at around 230 millibars, according to Sax's calculations on the drive to Arena. It was surprising there was no name for that color, it was so distinctive. Perhaps that was cyanic blue.

The morning pa.s.sed as he moved very slowly from plant to plant, using his wristpad's field guide to identify sandwort, buckwheat, p.u.s.s.ypaws, dwarf lupines, dwarf clovers, and his namesake, saxifrage. Rock breaker. He had never seen one in the wild before, and he spent a long time looking at the first one he found: arctic saxifrage, Saxifraga hirculus Saxifraga hirculus, tiny branches covered with long leaves, ending in small pale blue flowers.

As with the lichens, there were many plants that he couldn't identify; they exhibited features from different species, even genuses, or else they were completely nondescript, their features an odd melange of features from exotic biospheres, some looking like underwater growths, or new kinds of cacti. Engineered species, presumably, although it was surprising these weren't listed in the guide. Mutants, perhaps. Ah but there, where a wide crack had collected a deeper layer of humus and tiny rivulet, was a clump of kobresia. Kobresia and the other sedges grew where it was wet, and their extremely absorbent turf chemically altered the soil under it quite rapidly, performing important work in the slow transition from fellfield to alpine meadow. Now that he had spotted it he could see minuscule watercourses marked by their population of sedges, running down through the rocks. Kneeling on a thinsulate pad, Sax clicked off his magnifying gla.s.ses and looked around, and as low as he was, he could suddenly see a whole series of little fellfields, scattered on the slope of the moraine like patches of Persian carpet, shredded by the pa.s.sing ice.

Back at the station Sax spent a lot of time sequestered in the labs, looking at plant specimens through microscopes, running a variety of tests, and talking about the results to Berkina and Claire and Jessica.

"They're mostly polyploids?" Sax asked.

"Yes," Berkina said.

Polyploidy was fairly frequent at high alt.i.tudes on Earth, so it was not surprising. It was an odd phenomenon- a doubling or tripling or even quadrupling of the original chromosome number in a plant. Diploid plants, with ten chromosomes, would be succeeded by polyploids with twenty or thirty or even forty chromosomes. Hybridizers had used the phenomenon for years to develop fancy garden plants, because polyploids were usually larger- larger leaves, flowers, fruits, cell sizes- and they often had a wider range than their parents. That kind of adaptability made them better at occupying new areas, like the s.p.a.ces in and under a glacier. There were islands in the Terran Arctic where eighty percent of the plants were polyploid. Sax supposed that it was a strategy to avoid the destructive effects of excessive mutation rates, which would explain why it occurred in high-UV areas. Intense UV irradiation would break a number of genes, but if they were replicated in the other sets of chromosomes, then there was likely to be no genotypic damage, and no impediment to reproduction.

"We find that even when we haven't started with polyploids, which we usually do, they change within a few generations."

"Have you identified the triggering mechanism that causes it?"

"No."

Another mystery. Sax stared into the microscope, vexed by this rather astonishing gap in the bizarrely rent fabric of biological science. But there was nothing to be done about it; he had looked into the matter himself in his Echus Overlook labs in the 2050s, and it had appeared that polyploidy was indeed stimulated by more UV radiation than the organism was used to, but how cells read this difference, and then actually doubled or tripled or quadrupled their chromosome count...

"I must say, I'm surprised at how much everything is flourishing."

Claire smiled happily. "I was afraid that after Earth you might think this was pretty barren."

"Well, no." He cleared his throat. "I guess I expected nothing. Or just algae and lichen. But those fellfields seem to be thriving. I thought it would take longer."

"It would on Earth. But you have to remember, we're not just throwing seeds out there and waiting to see what happens. Every single species has been augmented to increase hardiness and speed of growth."

"And we've been reseeding every spring," Berkina said, "and fertilizing with nitrogen-fixing bacteria."

"I thought it was denitrifying bacteria that were all the rage."

"Those are distributed specifically in thick deposits of sodium nitrate, to transpire the nitrogen into the atmosphere. But where we're gardening we need more nitrogen in the soil, so we spread nitrogen-fixers."

"It still seems to be going very fast to me. And all of this must have happened before the soletta."

"The thing is," Jessica said from her desk across the room, "there isn't any compet.i.tion at this point. Conditions are harsh, but these are very hardy plants, and when we put them out there, there isn't any compet.i.tion to slow them down."